Article

The Position and Number of Screws Influence Screw Perforation of the Humeral Head in Modern Locking Plates: A Cadaver Study

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Abstract

: Screw perforation of the humeral head in locking plate osteosynthesis occurs in up to 30% of cases. The current study compared different fixation possibilities (eg, number and position of screws) to reduce screw perforation in the humeral head. : A humeral head fracture with a missing medial support was created in 30 fresh-frozen cadavers and fixed with a polyaxial locking plate (NCB PH; Zimmer, Warsaw, IN). The constructs were loaded with increasing force and the number of cycles until screw perforation was recorded. Four different fixation methods were tested: group 1 five screws with fixed angle, group 2 five screws in polyaxial position according to bone strength, group 3 three screws, and group 4 five screws with 1 as an inferomedial support screw. : More screws in the humeral head significantly increased the number of cycles before screw perforation. An inferomedial support screw further increased the number of cycles. Polyaxial screw placement compared with fixed-angle placement had no effect on the screw perforation phenomenon. : We recommend to position an inferomedial support screw, and at least 5 screws in the head fragment, when using a locking plate in proximal humerus fractures with disrupted medial hinge.

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... [9,10] Screws that support the calcar region increase the stability on the plate. [11] Erhardt et al. [12] recommended that a minimum of 5 screws including an inferomedial support screw in the head fragment should be used for the fixation of PHFs with a disrupted medial hinge. Besides, the number of screws fixed to the humeral head has been shown to affect the fixation stability in the literature. ...
... Besides, the number of screws fixed to the humeral head has been shown to affect the fixation stability in the literature. [12] According to this recommendation, the patients in the current study divided into two groups and the cut-off rate were used as 60% for plate-screw density (PSD). PHLAP has 9 screw holes and due to applied screws, we divided patients into two groups. ...
... Because of the small sample group, we think that it is not meaningful. Erhardt et al. [12] emphasized that the number of screws applied to the humeral head in PHFs is im-Bayrak et al. Does PSD affect the functional outcomes in the treatment of PHFs? portant in screw cut out and that a minimum of five screws should be applied in stable osteosynthesis. ...
Article
Background: The aim of the study is to evaluate the relationship between plate-screw density (PSD), functional results, and complication rates in the treatment of proximal humerus fractures (PHFs) with proximal humerus locking anatomical plate (PHLAP). Methods: Consecutive 43 patients (22 females and 21 males) who underwent PHLAP for the treatment of PHF between 2010 and 2016 were evaluated. AO classifications were used for the classification of fractures. Based on the biomechanical stability the-ory of Erhardt et al., the patients were divided into two groups as <60% and >60% according to the number of screws fixed to the humeral head for the determination of PSD. The patients were divided into two groups as PSD <60% (n=21) and PSD>60% (n=22) according to the number of screws fixed to the humeral head for the determination of PSD. Functional results were evaluated using the Constant-Murley shoulder score (CMS). Radiological evaluation was performed with collodiaphyseal angle (CDA), varus-valgus angulation, avascular necrosis (AVN), and arthrosis. The groups were compared in terms of demographic characteristics, functional results, radiological scores, and complications. Results: The mean age was 54.47±17.43 years and the mean follow-up time was 19.51±5.27 months. Although the CMS scores of patients with a PSD of over 60% were higher than those below 60%, the CMS score did not differ statistically. In groups, the mean CDA of the operated shoulder was significantly lower than that of the non-injured side (p=0.002). Eight patients had varus angulation, whereas two patients had humerus head AVN. No significant relationship was observed between PDS and functional scores, radiolog-ical results, and complications. Conclusion: Functional results of PSD >60% are higher than PSD <60% group but there is no statistical difference between groups according to functional, radiological results, and complications.
... calcar reduction, using inferomedial or calcar screws, avoidance of varus reduction, fixing the shaft in a medialized and impacted position with respect to the humeral head, and ensuring sufficient fixation in the head itself. 1,2,4,7,8,12,14,[18][19][20][21][27][28][29] The aim of this study was to radiographically evaluate factors that either enhance or reduce fracture site stability after locking plate fixation for proximal humerus fractures. Secondarily, we compared reoperation rates between those with loss of reduction and those who maintained reduction postoperatively. ...
... Surgical data were extracted from the Discharge Abstract Database (DAD) that contains all hospital admission and discharge data including diagnostic and procedural codes; this database allowed us to capture any reoperations that occurred within the province and not just at the site of the index surgery. Diagnostic codes (1-25) of S422* (Fracture of upper end of humerus) and Procedure Codes (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) of 1TK74LA* (Fixation humerus, open approach) or 1TA74LA* (Fixation shoulder joint, open approach) were used to identify eligible patients between 2010 and 2016 in the initial cohort; a minimum of 12 months since surgery was required to be included in the analysis. Subsequent reoperations within 1 year of the discharge date on the initial cohort used Procedure Codes (1-20) of 1TK* or 1TA* and defined the reoperation cohort. ...
... The goal of any surgical intervention must be to minimize complications, which in part can be achieved with a stable construct that withstands the physiologic loads applied during fracture healing. Although several studies have reported the importance of biomechanical parameters in achieving stable fixation of proximal humerus fractures, 1,2,4,7,8,12,14,[18][19][20][21][27][28][29] clinical studies confirming these principles are lacking. In a large population-based cohort using administrative health data of patients receiving surgical fixation of proximal humeral fractures using locking plates, we found that clinical results support the available biomechanical evidence. ...
Article
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Background Loss of reduction (LoR) can occur after locking plate fixation of proximal humerus fractures(PHF). This study determined biomechanical features of fracture fixation associated with preventing LoR postoperatively. One-year re-operation rates were also compared between those with/without LoR. Methods Population-based administrative data for 359 adults treated using a locking plate for PHF between 2010 and 2016 were examined. Two trained assessors reviewed standardized shoulder radiographs. LoR (Yes/No) was defined as any fracture displacement >0.5cm, and/or >10° change in neck-shaft angle(NSA) alignment relative to intraoperative imaging. Multiple logistic regression assessed how the following affected maintaining reduction: 1) Sex, 2) Age, 3) Neer classification, 4) shaft impaction(SI), 5) shaft medialization(SM), 6) Calcar reduction(CR), 7) NSA alignment and 8) screw use. Results LoR was seen in 79(22%) patients. LoR was significantly associated with increasing age(OR=1.06/year, p<0.001), fracture severity(4-part versus 2-part fracture; OR=4.63; p=0.001), and varus NSA alignment([<125° versus ≥145°; OR=5.6, p=0.02]; [<125° versus 125-145°; OR=2.2, p=0.02]). Patients achieving simultaneous SI, SM, and CR were significantly less likely(OR=0.009, p<0.001) to lose reduction, after controlling for age, fracture severity and NSA alignment. If only SI was achieved, patients were still significantly less likely to lose reduction relative to achieving none of these mechanical features(OR=0.17, p=0.006). Reoperations were higher when LoR occurred (n=26/77[33.4%]) compared to no LoR(n=20/276[7.2%])(p<0.001). Conclusions SI was strongly associated with preventing LoR in patients treated using a locking plate for PHF. SI with concurrent SM, CR and a neutral or valgus NSA had the lowest rates of LoR. LoR was associated with higher rates of reoperation.
... The test setup was based on previously published work testing screw perforation. 33,34 Each specimen was mounted on an XY table, alleviating shear forces during loading, with the PHILOS plate inclined at 20°to the machine base. An artificial glenoid, made from plastic and coated with a copper lining was used to load the humeral head. ...
... [38][39][40] To the best of our knowledge, there is no previous work investigating the effect of screw length on the perforation risk in PHF. Katthagen et al. 34 and Erhardt et al. 33 tested for screw perforation by loading the humeral head. The primary focus of their study was not the same as in our investigation, so that they did not report on differences in TJD and the effect they have on perforation characteristics. ...
... Loading only the humeral head is a limitation to the study as there are currently no available in vivo studies, describing screw perforating from such a perspective, but only from in vitro testing. 33,34 On the basis of in vivo loading data, 50 biomechanical testing setups that load from 25°lateral angulation have been developed, inducing primary varus bending. 30,[51][52][53][54] However, the related failure mode was screw cut-out type failure rather than screw perforation. ...
Article
Secondary perforation of screws into the joint surface is a commonly reported mechanical fixation failure mode in locked plating of proximal humerus fractures (PHF). This study investigated the influence that screws tip to joint distance (TJD) has on the biomechanical risk of secondary screw perforation and stability of PHF. Ten pairs of cadaveric proximal humeri with a wide range of bone mineral density were used. Each specimen was osteotomized and instrumented with the PHILOS plate, simulating a highly unstable 3‐part fracture. Bones were randomised into a long screw group (LSG) with 4mm TJD, or a short screw group (SSG) with 8mm TJD. A custom biomechanical setup was used to test the samples to failure cyclically with a constant valley load and an increasing ramp. The number of cycles to the initial screw loosening event was significantly higher for the LSG (mean±SD: 17532±6458) compared to the SSG (11102±5440) (p<0.01). The mode of failure during testing was lateral‐inferior displacement combined with varus collapse, with calcar screws perforating first. The number of cycles to failure event for LSG (27849±5648) was not significantly different compared to SSG (28782±7307) (p=0.50). Screws which purchase closer to the joint had better initial stability and resistance against loosening. Placing longer screws, within limits dictated by the surgical guide, is expected to decrease the risk of secondary perforation failures in unstable PHF. These findings require clinical corroboration. This article is protected by copyright. All rights reserved.
... Erhardt et al. loaded the humeral head while the humeral shaft was set at 30° flexion and 30° abduction to simulate the physiological load vector of a shoulder with an intact rotator cuff during 30°-90° abduction [38]. This load vector is perpendicular to the glenoid plane and generates a glenohumeral contact force of 240 N at 30° of abduction and increases up to 582 N at 90° abduction, as defined by Konrad et al. [80]. ...
... This has been named the second generation locking technology as it allows the screw direction to be adjusted before locking, as opposed to the conventional locking systems where screw angles are predefined and therefore, monoaxial. One plate employing this strategy is the Non-Contact Bridging plate (NCB, Zimmer, Warsaw, IN, USA) biomechanical performance of which has been tested in three studies [28,38,57]. Zettl et al. [28] demonstrated statistically similar performance between the NCB plate and PHILOS plate under axial compression despite using fewer and thicker screws for NCB plate. ...
... Zettl et al. [28] demonstrated statistically similar performance between the NCB plate and PHILOS plate under axial compression despite using fewer and thicker screws for NCB plate. However, Erhardt et al. [38] revealed that during simulated 30° flexion and 30° abduction, insertion of polyaxial screws instead of monoaxial ones had no significant effect on the perforation of screws. Jabran et al. ...
Article
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Background: Proximal humerus fractures are the third most common in the human body but their management remains controversial. Open reduction and internal fixation with plates is one of the leading modes of operative treatment for these fractures. The development of technologies and techniques for these plates, during the recent decades, promise a bright future for their clinical use. A comprehensive review of in vitro biomechanical studies is needed for the comparison of plates' mechanical performance and the testing methodologies. This will not only guide clinicians with plate selection but also with the design of future in vitro biomechanical studies. This review was aimed to systematically categorise and review the in vitro biomechanical studies of these plates based on their protocols and discuss their results. The technologies and techniques investigated in these studies were categorised and compared to reach a census where possible. Methods and results: Web of Science and Scopus database search yielded 62 studies. Out of these, 51 performed axial loading, torsion, bending and/or combined bending and axial loading while 11 simulated complex glenohumeral movements by using tendons. Loading conditions and set-up, failure criteria and performance parameters, as well as results for each study, were reviewed. Only two studies tested four-part fracture model while the rest investigated two- and three-part fractures. In ten studies, synthetic humeri were tested instead of cadaveric ones. In addition to load-displacement data, three-dimensional motion analysis systems, digital image correlation and acoustic emission testing have been used for measurement. Conclusions: Overall, PHILOS was the most tested plate and locking plates demonstrated better mechanical performance than non-locking ones. Conflicting results have been published for their comparison with non-locking blade plates and polyaxial locking screws. Augmentation with cement [calcium phosphate or poly(methyl methacrylate)] or allografts (fibular and femoral head) was found to improve bone-plate constructs' mechanical performance. Controversy still lies over the use of rigid and semi-rigid implants and the insertion of inferomedial screws for calcar region support. This review will guide the design of in vitro and in silico biomechanical tests and also supplement the study of clinical literature.
... Lastly, the medial column lacks effective support [12][13][14]. For these reasons, some surgeons reported that shortening the length of the screws could reduce the risk of screw perforation, but this can increase the risk of implant failure [15][16][17][18]. The risk of varus collapse can be decreased by maximizing screw length and implanting the inferomedial support screws [12,13], which, paradoxically, may increase the incidence of screw perforation [12]. ...
... If the inferomedial screw No. 8 or No. 9 is inserted into the head segment that was part of the head above the anatomic neck plane (Figure 4), the screw can provide effective support to the medial column [12,13,15,22]; therefore, it was regarded as the effective screw. According to the number of effective inferomedial screws, patients were divided into an unimplanted group (group 0) and an implanted group (group 1 and group 2). ...
... In a clinical study, Gardner et al. [12] showed that the inferomedial screws were most important in maintaining fracture reduction and could improve the stability of fixation, especially for patients with a disrupted medial hinge. Concurrently, the stability of fixation with the implantation of the inferomedial screws can also reduce screw perforation [15]. Therefore, measures in obtaining the stability of fixation should focus on increasing the number and depth of the inferomedial screws [13]. ...
Article
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Background Screw perforation and varus collapse are common complications of treatment with a PHILOS (proximal humerus internal locking system) plate for proximal humerus fractures, which are associated with improper screw length selection and lack of medial column support. The purposes of this study were: (1) to measure the proper length of periarticular screws of the PHILOS plate in the humeral head, and (2) to determine what factors influence the screw length and implantation of the inferomedial support screw. Material/Methods Computed tomography (CT) images of the normal proximal humerus in 134 cases were retrospectively reviewed. The length of periarticular screws was measured using three-dimensional (3D) techniques. Intraobserver and interobserver reliability of measurement were evaluated using intraclass correlation coefficients (ICCs). Sex and body height influences on screw length and implantation of the inferomedial screw were analyzed. Results All measurements had excellent agreement (ICC>0.75). The screw length and implantation rate of the inferomedial screw were greater in males than in females. Positive correlations were observed between body height and screw length and implantation of the inferomedial screw (all P<0.001). Conclusions The screws were longer and the implantation rate was higher for inferomedial screws in males than in females, and were positively correlated with body height. Our data can be used as a reference for surgeons to reduce the number of times screws are changed intraoperatively and to reduce operation duration and minimize use of intraoperative fluoroscopy for proximal humerus fractures treated with the PHILOS plate.
... In addition to medial calcar support, the plate design can be optimized by using diverging screws to increase the volume of the humeral head occupied by peripheral screws, which is considered another important factor for evaluating the biomechanical strength of plate fixation [11]. Moreover, a cadaver study reported that more screws in the humeral head significantly increased the number of cycles before screw perforation [32]. As such, we believe that inserting more and longer screws into the humeral head may improve fixation stability and reduce screw perforation. ...
... As such, we believe that inserting more and longer screws into the humeral head may improve fixation stability and reduce screw perforation. Some surgeons modify their surgical techniques to minimize the risk of screw penetration by placing the screws 10 to 15 mm away from the articular surface [33]; however, the inserted screws may also be away from the subchondral bone, reducing the number of screws that should be used and possibly increasing the risk of loss of reduction [32]. Instead of using calcar screws, other surgeons have also modified their techniques by performing minimally invasive surgery through two incisions. ...
Article
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Background Studies have reported mixed results on the importance of medial calcar support for the treatment of proximal humeral fractures. The purpose of this study was to compare radiographic and functional outcomes of patients who had displaced proximal humeral fractures with varying levels of medial support. Methods We performed a retrospective comparative cohort study. The study was conducted at a Level III trauma center in Taiwan. Seventy patients with proximal humeral fractures were collected retrospectively from 2015 to 2019. Only patients with two-, three-, or four-part types (Neer type I, II, or III) of displaced proximal humeral fractures were included in this study. However, patients with head-split fracture patterns, shoulder dislocation, prior shoulder trauma, and poor fracture reduction present in postoperative films were excluded. We assessed the radiographic outcomes, including the reduction score and amount of impaction in the humeral head. The functional outcome was evaluated based on the Constant score. Results Patients were grouped into the intact medial calcar group and the medial calcar deficiency group. In a subgroup analysis, the group with intact medial support had a significantly lower amount of impaction and a higher Constant score compared with the medial calcar deficiency group. Additionally, the groups with intact medial support had a nonsignificant difference in the Constant score between the affected side and the contralateral side. Conclusion The amount of impaction and the reduction score in the humeral head at the 12-month radiographic follow-up were significantly higher in the group with medial support deficiency. However, the reduction score after surgery exhibited no difference. This implies that the inherent nature of medial comminution of proximal humeral fracture may lead to inferior radiographic outcomes.
... Second, long calcar screws that are positioned as close as possible to the joint provide further primary stability compared to short calcar screws. Previous studies have focused on the position of the calcar screws and showed that missing the calcar region results in significant reductions in axial stiffness [3,5,[11][12][13][14][15]. The current findings add to the narrative that medial column support is deciding to provide primary stability of locked plate fixation in proximal humeral fractures. ...
... 23,7 µm/m; max. 247,5 µm/m; SD 80,13) at 50 N, 298,17 µm/m (min. 60,2 µm/m; max. ...
Article
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Background Complex proximal humeral fracture ranks among the most common fracture types, especially in elderly patients. In locked plate fixation of proximal humerus fractures, the calcar is deciding for screws providing further medial column support. To date, the biomechanical effect of the length of these calcar screws is not well known. The purpose of this study was to analyze the effect of long calcar screws on fresh frozen prefractured cadaveric specimens. Methods In the present biomechanical study, 8 pairs of cadaveric proximal humeri were fractured identically using a custom-made fracture simulator. ORIF was performed using a locking plate (PHILOS; Fa. Synthes). The specimens were tested in a biomechanical setup under increased axial load without any calcar screws installed, with short calcar screws and long calcar screws installed. Strain gages (4-wire-120 Ohm, Fa. Vishay) mounted on the locking plate were used to evaluate the fixation strain and to give an estimate for primary stability.. Results The measured strain of the locking plate without calcar screws (804,64 µm/m) at maximum load (200 N) was significantly higher than with short (619,07 µm/m; p = 0.02) or long calcar screws (527,31 µm/m; p = 0.007). Additionally, strain with short calcar screws was noticeably higher in comparison to long calcar screws (619,07 µm/m vs. 527,31 µm/m; p = 0.03). Conclusion Use of calcar screws improves the stability of realistically impacted 3-part varus humeral fractures. Long calcar screws that are positioned as close as possible to the joint provide further primary stability compared to short calcar screws. Level of evidence Basic science study.
... There was a scarcity of previously reported data that focus on the essential number of proximal screws necessary for a stable fixation of a proximal humerus fracture. 31,32 Maddah et al. conducted a retrospective investigation on the correlation between screw position and complications observed in 367 patients who underwent proximal humeral fracture fixation with a locking plate. 31 Serial radiographic observations showed that the loss of fixation was observed in 15.8% (58 of 367) of the patients, and among those, cutting out of screws was found in 6.8%. ...
... Nevertheless, a cadaveric biomechanical study recommended that at least 5 screws should be inserted in the proximal holes of a proximal humerus locking plate with a disrupted medial hinge. 32 This means that inconsistency regarding the number of screws used in the proximal part of the plate exists. 34 The most likely reason for such inconsistency is the variability of the study designs regarding the fixation device and variability of the human bone used. ...
Article
Full-text available
Purpose This biomechanical study investigates the optimal number of proximal screws for stable fixation of a 2-part proximal humerus fracture model with a locking plate. Methods Twenty-four proximal humerus fracture models were included in the study. An unstable 2-part fracture was created and fixed by a locking plate. Cyclic loading and load-to-failure tests were used for the following 4 groups based on the number of screws used: 4-screw, 6-screw, 7-screw, and 9-screw groups. Interfragmentary gaps were measured following cyclic loading and compared. Consequently, the load to failure, maximum displacement, stiffness, and mode of failure at failure point were compared. Results The interfragmentary gaps for the 4-screw, 6-screw, 7-screw, and 9-screw groups were significantly reduced by 0.24 ± 0.09 mm, 0.08 ± 0.06 mm, 0.05 ± 0.01 mm, and 0.03 ± 0.01 mm following 1000 cyclic loading, respectively. The loads to failure were significantly different between the groups with the 7-screw group showing the highest load to failure. The stiffness of the 7-screw group was superior compared with the 6-screw, 9-screw, and 4-screw groups. The maximum displacement before failure showed a significant difference between the comparative groups with the 4-screw group having the lowest value. The 7-screw group had the least structural failure rate (33.3%). Conclusion At least 7 screws would be optimal for proximal fragment fixation of proximal humerus fractures with medial comminution to minimize secondary varus collapse or fixation failure. Level of Evidence Basic science study.
... The importance of the medial supporting screw has been emphasized, especially in the case of severe medial comminution and osteoporosis [1,3,6,10]. Many studies have found that the use of medial supporting screws can help prevent varus collapse or reduction loss [5,12,17,24]. In contrast to these studies, as the surgery using minimally invasive plate osteosynthesis technique has reported good surgical outcomes, questions arise about the need for the application of calcar screws, essentially [14]. ...
... Twenty-four complete humerus composite bone models (LD 5030 Humerus; Synbone, Malans, Switzerland) were used. [5,16]. About a 1 cm gap was created at the proximal humerus surgical neck area to produce a proximal humerus two-part fracture with comminution ( Fig. 1) [13,18]. ...
Article
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Introduction The purpose of this study was to evaluate the effect of a medial support screw through a proximal humerus fracture. For this purpose, we verified whether the biomechanics are different according to the position of the screw while using the same number of screws. In addition, we tried to verify whether the insertion of additional inferomedial screws would make a difference in stability. Materials and methods Twenty-four proximal humerus bones were included in the study. A two-part fracture was created and fixed using a locking plate. Cyclic loading and load-to-failure test were applied to three groups: group A (proximal 6 screws + calcar screws), group B (proximal 6 screws), and group C (proximal 4 screws + calcar screws). Interfragmentary gaps were measured following cyclic loading and compared. The failure was defined when the bone breakage or medial gap closing was observed during ultimate failure load applied. The load-to-failure, maximum displacement, stiffness, and yield load were recorded and compared. Results The interfragmentary gap was differently reduced by 0.29 ± 0.14 mm, 0.73 ± 0.25 mm, and 0.53 ± 0.09 mm following 1000 cyclic loading for groups A, B, and C, respectively. The load-to-failure was 945.22 ± 101.02 N, 941.40 ± 148.90 N, and 940.58 ± 91.78 N in groups A, B, and C, respectively. The stiffness of group A (214.76 ± 34.0 N/mm) was superior when compared to that of group C (171.12 ± 23.0 N/mm; p = 0.025). The maximum displacement prior to failure, yield load, showed no significant difference between comparative groups. Conclusion Our study did not show any additional biomechanical effects with the use of inferomedial supporting screws in non-osteoporotic proximal humerus fracture, besides making the fracture-plate construct stiff. The role of the inferomedial supporting screw was also unclear. However, the groups that used increased screw fixation and inferomedial screw insertion seemed to be more resistant to cyclic loading.
... 2,9 However, screw cutout has been identified as a frequent postoperative complication, occurring at a rate ranging from 5.4% to 23% as reported in the literature. 3,14,18,19,[23][24][25] Several authors have attempted to identify factors that may lead to a higher rate of complications following locked-plate fixation including the AO type C fracture pattern, 7 compromised vascularity of the humeral head fragment, 7 insufficient medial support and comminution, 10,13,21 initial coronal displacement in varus, 7,10 osteoporosis, 10,13 and older age. 2 Multiple surgical improvements have also been suggested to decrease complications, including using more screws in the humeral head, 5 ensuring mechanical support of the inferomedial proximal humerus, 5,6,21 augmenting the fracture site with calcium phosphate cement, 4 and using a supplemental endosteal fibular strut. 8,16,17 Although there are not specific indications for when to obtain a computed tomography (CT) scan for proximal humeral fractures, they are frequently obtained as they can provide additional information about the nature of a fracture that cannot be obtained from plain films. ...
... 2,9 However, screw cutout has been identified as a frequent postoperative complication, occurring at a rate ranging from 5.4% to 23% as reported in the literature. 3,14,18,19,[23][24][25] Several authors have attempted to identify factors that may lead to a higher rate of complications following locked-plate fixation including the AO type C fracture pattern, 7 compromised vascularity of the humeral head fragment, 7 insufficient medial support and comminution, 10,13,21 initial coronal displacement in varus, 7,10 osteoporosis, 10,13 and older age. 2 Multiple surgical improvements have also been suggested to decrease complications, including using more screws in the humeral head, 5 ensuring mechanical support of the inferomedial proximal humerus, 5,6,21 augmenting the fracture site with calcium phosphate cement, 4 and using a supplemental endosteal fibular strut. 8,16,17 Although there are not specific indications for when to obtain a computed tomography (CT) scan for proximal humeral fractures, they are frequently obtained as they can provide additional information about the nature of a fracture that cannot be obtained from plain films. ...
Article
Hypothesis and/or Background Preoperative Computerized Tomography (CT) scan can be used to measure thickness of the center of the humeral head in order to identify patients at a higher risk of screw cutout after open reduction internal fixation (ORIF). Methods A retrospective review was performed at an academic medical center of all patients who were 18 years or older who had sustained a proximal humerus fracture between 1/1/05 and 12/31/14 that was treated with ORIF and who had a preoperative shoulder CT. Ninety-four patients were included. Charts were reviewed for demographics and radiographs were reviewed for screw cutout. A standardized method was devised to measure the center of the humeral head thickness. Results Seventeen patients developed screw cutout (17.7%). The mean humeral head thickness was significantly smaller on the axial (18mm vs 21mm; p=0.0031), coronal (18mm vs 21mm; p=0.0084) and sagittal sections (18mm vs 21mm; p=0.0033) in the patients who experienced screw cutout. When the smallest of the three measurements for each patient was analyzed, the risk of cutout was markedly greater when the humeral head thickness was less than 20mm (25% vs 6%). Additionally, when the humeral head thickness was greater than 25mm the risk of cutout was reduced to zero. Low-energy injury was associated with a lower risk of cutout, while age, sex and fracture classification were not independent predictors of cutout on multivariate logistic regression. Conclusions In patients with proximal humerus fractures where a preoperative CT scan is available, calculating the thickness of the center of the humeral head may provide valuable information to both the surgeon and the patient in preoperative planning and counselling. A smaller thickness of the center of the humeral head on preoperative CT is predictive of screw cutout following locked plating of proximal humerus fractures. A measurement of 25mm in any one plane is highly protective against cutout, however extreme caution and consideration of supplemental fixation methods should be taken when the measurements in all planes are less than 15mm. This information may be helpful in counseling patients regarding the possibility of postoperative screw cutout.
... In these patients, the aim is to achieve maximal shoulder function, according to the current literature. 3,4,13,14,19,20,25,31,42,43,45,51 The second part of the algorithm considers elderly patients, usually older than 65 years (Fig. 2). 51 In the first step, their activity level and general health status are assessed. ...
... Primary arthroplasty pathways (nos. 11,13,14,15) were used correctly in 70% (7/10) with preferred RTSA treatment as the main reason for deviation (Table I). ...
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Background: On the basis of patients' demands, bone quality, and fracture type, we developed an evidence-based treatment algorithm for proximal humerus fractures (PHF)that includes all treatment modalities from open reduction and internal fixation, hemiprosthesis, to reverse total shoulder arthroplasty. This study was done to assess its feasibility and early clinical outcome. Materials and methods: Patients with isolated PHF in 2014 and 2015 were included in this prospective study. The quality of life (EQ-5D)and the level of autonomy before injury were recorded. The fractures were classified and local bone quality was measured. When possible, patients were treated according to the algorithm. Radiographic and clinical follow-up—Constant score, subjective shoulder value, and EQ-5D—took place after 3 months and 1 year. The rate of unplanned surgery was analyzed. Results: A total of 192 patients (mean age 66 years; 58 male, 134 female)were included. Of these, 160 (83%)were treated according to the algorithm. In total, 132 patients were treated conservatively, 36 with open reduction and internal fixation and 24 with reverse total shoulder arthroplasty or hemiarthroplasty. Generally, the mean EQ-5D before trauma and 1 year after treatment was equal to 0.88 to 0.9 points. After 1 year, the overall mean relative Constant score was 95% and mean subjective shoulder value 84%. Unplanned surgery was necessary in 21 patients. Conclusion: This comprehensive algorithm is designed as a noncompulsory treatment guideline for PHF, which prioritize the patient's demands and biology. The high adherence proves that it is a helpful tool for decision making. Furthermore, this algorithm leads to very satisfying overall results with low complication and revision rates.
... We believe that this decision is based on many factors including the screw's location, orientation and geometry. There is very little information in the literature on the optimal number of screws for a given fracture, with two studies recommending the insertion of at least five screws in the humeral head including at least one inferomedial screw [22,23]. ...
... Medial support in plates, both in form of screws and blade, targets the inferomedial region. Importance of these screws for minimising humeral head collapse in varus bending is well known, but less so on that of the blade [22,35,36]. In a similar fashion to PHILOS plate's zone 1 screws, the importance of the blade for varus stability in the Fx plate was manifested when it was removed, causing a 26% drop in varus mean stiffness, more than any of the other three directions. ...
Article
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Background: Treatment of proximal humerus fractures with locking plates is associated with complications. We aimed to compare the biomechanical effects of removing screws and blade of a fixed angle locking plate and hybrid blade plate, on a two-part fracture model. Methods: Forty-five synthetic humeri were divided into nine groups where four were implanted with a hybrid blade plate and the remaining with locking plate, to treat a two-part surgical neck fracture. Plates' head screws and blades were divided into zones based on their distance from fracture site. Two groups acted as a control for each plate and the remaining seven had either a vacant zone or blade swapped with screws. For elastic cantilever bending, humeral head was fixed and the shaft was displaced 5 mm in extension, flexion, valgus and varus direction. Specimens were further loaded in varus direction to investigate their plastic behaviour. Results: In both plates, removal of inferomedial screws or blade led to a significantly larger drop in varus construct stiffness than other zones. In blade plate, insertion of screws in place of blade significantly increased the mean extension, flexion valgus and varus bending stiffness (24.458%/16.623%/19.493%/14.137%). In locking plate, removal of screw zones proximal to the inferomedial screws reduced extension and flexion bending stiffness by 26-33%. Conclusions: Although medial support improved varus stability, two inferomedial screws were more effective than blade. Proximal screws are important for extension and flexion. Mechanical consequences of screw removal should be considered when deciding the number and choice of screws and blade in clinic.
... One biomechanical study recommended at least 5 humeral head screws including at least one in the inferomedial calcar region to prevent screw perforation. 41 Fixation in the central and inferior humeral head has been shown to be superior in one biomechanical model. 42 Following placement of all screws, we routinely use live fluoroscopy to assess for screw penetration while rotation the humeral head ( Figure 4). ...
... This is especially important in cases with osteoporotic bone. 41,43,44 loss of medial calcar support has careful attention should be paid to avoid stripping the medial hinge blood supply. Utilization of the Kapandji technique to mobilize medial fragments with a narrow periosteal elevator through the fracture is recommended in place of formal medial dissection. ...
Article
Full-text available
Surgeons continue to debate the role of surgery in the treatment of acute proximal humerus fractures. Recently, reports have shown a trend towards increased utilization of operative fixation. Surgical options include: All suture fixation, closed reduction and percutaneous pinning, open reduction internal fixation with locked proximal humerus plates, proximal humerus nailing, Bilboquet implants, and arthroplasty. No single form of treatment has been shown to be superior to another. In some patients, there remains debate if surgical options are superior to non-operative management alone. The purpose of this article is to review the natural history of non-operative treatment of proximal humerus fractures, describe the most common surgical treatments, and discuss the sequelae of fractures treated nonoperatively.
... The bone-implant-interface was fixed in casting resin so that prior plate cracking did not affect the screws stability within the plate. Similar to an already published setup, a transparent PMMA cylinder with a circular cavity fitting the articular surface was mounted under the dynamic plate, which eliminated shear forces ( Fig. 4C) 23 . Load was applied with constant displacement of 0.05mm/s pressing the humeral head articular fragment against the screw tips. ...
... Still, none of the tests showed any significant difference between the groups. Generally 23 . Within our comparable test setup for investigation of screw perforation, the humeral heads joint surface was continuously pressed against the underlying screws tips. ...
Article
Introduction: The main purpose was to compare the biomechanical properties of a carbon-fibre reinforced polyetheretherketone (CF-PEEK) composite locking plate with pre-existing data of a titanium-alloy plate when used for fixation of an unstable 2-part fracture of the surgical neck of the humerus. The secondary purpose was to compare the mechanical behaviour of locking bolts and conventional locking cancellous screws. Methods: 7 pairs of fresh frozen human humeri were allocated to two equal groups. All specimens were fixed with the CF-PEEK plate. Cancellous screws (PEEK/screw) were compared to locking bolts (PEEK/bolt) for humeral head fixation. Stiffness, fracture gap deflection and ultimate load as well as load before screw perforation of the articular surface were assessed. Results were compared between groups and with pre-existing biomechanical data of a titanium-alloy plate. Results: The CF-PEEK plate featured significantly lower stiffness compared to the titanium-alloy plate (P<0.001). In ultimate load testing, 6 out of 14 CF-PEEK plates failed due to irreversible deformation and cracking. No significant difference was observed between results of groups PEEK/screw and PEEK/bolt (P>0.05). Discussion: The CF-PEEK plate has more elastic properties and significantly increases movement at the fracture site of an unstable proximal humeral fracture model compared to the commonly used titanium-alloy plate. The screw design however does neither affect the constructs primary mechanical behaviour in the constellation tested nor the load before screw perforation.
... In a biomechanical study by Erhardt et al. a screw placed obliquely in the inferomedial region of the humeral head significantly increased the number of cycles before loss of fixation occurs and usage of more screws additionally enhanced the fixations strength. 16 However, to the authors' knowledge, despite biomechnical studies, no clinical study could verify these findings in a larger cohort of patients. Hence, aim of the study was to evaluate the relationship between loss of fixation following locked plating of proximal humeral fractures and the number and position of screws purchasing the humeral head. ...
... 22,23 Also, Erhardt et al. could show in a biomechanical study that the construct's strength benefits from an inferomedial supporting screw in terms of load to failure. 16 Although, placement of inferomedial screws may be beneficial in biomechanical studies, in this clinical study of 367 patients this effect could not be verified. However, Gardner et al. demonstrated in a radiographic study of 35 patients that placing a superiorly directed oblique locked screw in the inferomedial region of the proximal fragment, may achieve more stable medial column support and allow for better maintenance of reduction. ...
Article
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The aim of the study was to examine the correlation between the chosen position of screws and the complications observed in patients who underwent locked plating of proximal humeral fractures. We evaluated radiographs of 367 patients treated by locked-plating for proximal humeral fractures. Radiographs were taken at one day, 6 weeks, 3 months and 6 months after surgery, and were analyzed for secondary fracture displacement, loss of fixation, cutting out of screws and necrosis of the humeral head. Secondary loss of fixation occurred in 58 cases (15.8%) and among those cutting out of screws was observed in 25 cases (6.8%). In cases of secondary loss of fixation a mean of 6.7 screws were used to fix the fracture (vs 6.6, P=0.425). There was neither significant correlation between position of screws and the occurrence of postoperative loss of fixation in Spearman correlation nor relationship from backward logistic regression analysis. Loss of fixation following locked plating of proximal humeral fractures does not relate to the number of screws and their positions in the humeral head. In consequence, anatomic fracture reduction and restoration of the humeral head-shaft angle are still important factors and should not be disregarded.
... Towards subject-specificity, some plates utilize variable-angle locking designs, but even for these, the screw orientations providing optimal fixation stability remain unknown. Several studies have investigated the biomechanical behavior of locking plates with polyaxial screw holes, allowing a screw angulation range of 30-40° (Erhardt et al., 2009;Ruchholtz et al., 2011;Voigt et al., 2011;Zettl et al., 2011;Erhardt et al., 2012). However, the orientation of the screws within the humeral head were chosen by the surgeon during instrumentation based on intuition and thus the highest stability was potentially not achieved. ...
Article
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Joint-preserving surgical treatment of complex unstable proximal humerus fractures remains challenging, with high failure rates even following state-of-the-art locked plating. Enhancement of implants could help improve outcomes. By overcoming limitations of conventional biomechanical testing, finite element (FE) analysis enables design optimization but requires stringent validation. This study aimed to computationally enhance the design of an existing locking plate to provide superior fixation stability and evaluate the benefit experimentally in a matched-pair fashion. Further aims were the evaluation of instrumentation accuracy and its potential influence on the specimen-specific predictive ability of FE. Screw trajectories of an existing commercial plate were adjusted to reduce the predicted cyclic cut-out failure risk and define the enhanced (EH) implant design based on results of a previous parametric FE study using 19 left proximal humerus models (Set A). Superiority of EH versus the original (OG) design was tested using nine pairs of human proximal humeri (N = 18, Set B). Specimen-specific CT-based virtual preoperative planning defined osteotomies replicating a complex 3-part fracture and fixation with a locking plate using six screws. Bone specimens were prepared, osteotomized and instrumented according to the preoperative plan via a standardized procedure utilizing 3D-printed guides. Cut-out failure of OG and EH implant designs was compared in paired groups with both FE analysis and cyclic biomechanical testing. The computationally enhanced implant configuration achieved significantly more cycles to cut-out failure compared to the standard OG design (p < 0.01), confirming the significantly lower peri-implant bone strain predicted by FE for the EH versus OG groups (p < 0.001). The magnitude of instrumentation inaccuracies was small but had a significant effect on the predicted failure risk (p < 0.01). The sample-specific FE predictions strongly correlated with the experimental results (R2 = 0.70) when incorporating instrumentation inaccuracies. These findings demonstrate the power and validity of FE simulations in improving implant designs towards superior fixation stability of proximal humerus fractures. Computational optimization could be performed involving further implant features and help decrease failure rates. The results underline the importance of accurate surgical execution of implant fixations and the need for high consistency in validation studies.
... Non-locking plates constructs in 20° of abduction have been proven greater stiffness than locking plate (28,29). In order to assess the result of Polyaxial and monoaxial locking screws, Philos and NCB plates were compared in three studies (30)(31)(32): it has been proven that Philos plate needed more numerous, but thinner screws to report similar NCB plate performances under axial compression (28). At the same time, the use of monoaxial screws could cause a significant number of complications, due to the perforation of screws through the humeral head (28). ...
Article
Full-text available
Background and aim: Proximal humeral fracture is one of the most common osteoporotic fractures in elderly people. The proper treatment choice is controversial. Open reduction and internal fixation (ORIF) with plate and screws is currently the most common treatment for the majority of displaced proximal humeral fractures. The aim of this systematic review is to investigate the surgical treatment outcomes of PHFs, focusing on main used devices and surgical approaches. Methods: From the earliest record up to 21 July 2020, two independent authors conducted a systematic review of two medical electronic database (PubMed and Science Direct). To achieve the maximum sensitivity of the search strategy, the following terms were combined: "(proximal NOT shaft NOT distal) AND humeral AND fracture AND (plate OR locking plate OR osteosynthesis NOT nail NOT arthroplasty)" as either key words or MeSH terms. The risk of bias of the included studies was assessed, agreeing to the Cochrane Handbook guidelines. Results: Thirty-four articles were initially noticed after the term string research in the two electronic databases. Finally, after full-text reading and analyzing the reference list, 8 studies were selected. The mean age recorded was 69.5 years (Range 67-72). All the studies included two-, three-, four-fragments fracture. Seven studies investigated PHILOS (Synthes, Bettlach, Switzerland) implants results, while one investigated CFR-PEEK plate (PEEK Power Humeral Fracture Plate; Arthrex, Naples, Florida, USA) outcomes or other plates. Deltopectoral and Transdeltoid approaches were the more common used. Conclusions: Both deltopectoral and transdeltoid approaches are valid approach in plating after proximal humerus fractures, for these reasons, the surgeon experience is crucial in the choice. The more valid implant is still unclear. The develop of prospective randomized comparative studies is strongly encourages.
... Non-locking plates constructs in 20° of abduction have been proven greater stiffness than locking plate [28,29]. In order to assess the result of Polyaxial and monoaxial locking screws, Philos and NCB plates were compared in three studies [30][31][32]: it has been proven that Philos plate needed more numerous, but thinner screws to report similar NCB plate performances under axial compression [28]. At the same time, the use of monoaxial screws could cause a signi cant number of complications, due to the perforation of screws through the humeral head [28]. ...
Preprint
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Background: Proximal humeral fracture is one of the most common osteoporotic fractures in elderly people. The proper treatment choice is controversial. Open reduction and internal fixation (ORIF) with plate and screws is currently the most common treatment for the majority of displaced proximal humeral fractures. The aim of this systematic review is to investigate the surgical treatment outcomes of PHFs, focusing on main used devices and surgical approaches. Methods: From the earliest record up to 21 July 2020, two independent authors conducted a systematic review of two medical electronic database (PubMed and Science Direct). To achieve the maximum sensitivity of the search strategy, the following terms were combined: “(proximal NOT shaft NOT distal) AND humeral AND fracture AND (plate OR locking plate OR osteosynthesis NOT nail NOT arthroplasty)” as either key words or MeSH terms. The risk of bias of the included studies was assessed, agreeing to the Cochrane Handbook guidelines. Results: Thirty-four articles were initially noticed after the term string research in the two electronic databases. Finally, after full-text reading and analyzing the reference list, 8 studies were selected. The mean age recorded was 69.5 years (Range 67-72). All the studies included two-, three-, four-fragments fracture. Seven studies investigated PHILOS (Synthes, Bettlach, Switzerland) implants results, while one investigated CFR-PEEK plate (PEEK Power Humeral Fracture Plate; Arthrex, Naples, Florida, USA) outcomes or other plates. Deltopectoral and Transdeltoid approaches were the more common used. Conclusions: Both deltopectoral and transdeltoid approaches are valid approach in plating after proximal humerus fractures, for these reasons, the surgeon experience is crucial in the choice. The more valid implant is still unclear. The develop of prospective randomized comparative studies is strongly encourages.
... Moreover, biomechanical testing was related to a highly unstable fracture with inadequate anatomical reduction and absent medial support -two factors being shown to increase the secondary screw perforation risk in several studies (Gardner et al., 2007;Konigshausen et al., 2012;McMillan and Johnstone, 2018;Schnetzke et al., 2016). The current fracture model, adopted from previous studies, resembled a precarious situation with no medial and lateral interfragmentary support to the humeral head due to comminuted calcar region and GT fragment (Erhardt et al., 2012;Katthagen et al., 2016). Therefore, the construct stability depended entirely on the bone-screw interfaces in the humeral head. ...
Article
Locked plating of proximal humerus fractures (PHF) is associated with high failure rates (15-37%). Secondary screw perforation is a prominent mode of failure for PHF and typically requires reoperation. The anatomical fracture reduction is an essential factor to prevent fixation failure. However, recent studies indicate that the risk of secondary screw perforation may increase if the articular surface is perforated during predrilling of the screw boreholes (overdrilling). This study aimed to determine whether overdrilling increases the risk of secondary screw perforation in unstable PHF. Nine pairs of human cadaveric proximal humeri were osteotomized to simulate a malreduced and highly unstable 3-part fracture (AO/OTA 11 B1.1), followed by their assignment to two study groups for overdrilling or accurate predrilling in paired design, and fixation with a locking plate. Overdrilling was defined by drilling the calcar screw’s boreholes through the articular surface. All humeri were cyclically loaded to screw perforation failure. Number of cycles to initial screw loosening and final perforation failure were analysed. The accurately predrilled group revealed a significantly higher number of cycles to both initial screw loosening (p<0.01) and final screw perforation failure (p=0.02), compared to the overdrilled one. This is the first study reporting that drilling to the correct depth significantly increases endurance until screw perforation failure during cyclic loading after locked plating in a highly unstable PHF model. Prevention of overdrilling the boreholes could help reduce failure rates of locked plating. Future work should investigate the prevalence and consequences of overdrilling in clinics.
... This system is associated with intra-operative risks, chiefly cartilage damage while drilling or inserting the screws (incidence: 12-25% (Charalambous_et_al., 2007;Olerud_et_al., 2011)). This risk is higher in osteoporotic patients: due to the lack of bone in the center of the humeral head, the screws must be long enough to reach the subchondral bone, increasing the risk of cartilage perforation or prominence over the cartilage layer (Erhardt_et_al., 2012). Furthermore, four-parts fractures require a large number of screws to stabilize each fragment, multiplying the risks (Charalambous_et_al., 2007;Varga_et_al., 2018). ...
Article
Full-text available
Multi-fragment fractures are still a challenge: current clinical practice relies on plates and screws. Treatment of fractures of the proximal humerus has the intra-operative risk of articular damage when inserting multiple screws. Distal-varus collapse of the head is a frequent complication in osteoporotic patients. The aim of this biomechanical study was to investigate if an Innovative-cement-technique (the screws are replaced by injection of cement) provides the same or better stability of the reconstructed head compared to the Standard-technique (locking screws). A four-fragment fracture was simulated in twelve pairs of humeri, with removal of part of the cancellous bone to simulate osteoporotic "eggshell" defect. One humerus of each pair was repaired either with a Standard-technique (locking plate, 2 cortical and 6 locking screws), or with the Innovative-cement-technique (injection of a partially-resorbable reinforced bone substitute consisting of PMMA additivated with 26% beta-TCP). Cement injection was performed both in the lab and under fluoroscopic monitoring. The reconstructed specimens were tested to failure with a cyclic force of increasing amplitude. The Innovative-cement-technique withstood a force 3.57 times larger than the contralateral Standard reconstructions before failure started. The maximum force before final collapse for the Innovative-cement-technique was 3.56 times larger than the contralateral Standard-technique. These differences were statistically significant. The Innovative-cement-technique, based on the reinforced bone substitute, demonstrated better biomechanical properties compared to the Standard-technique. These findings, along with the advantage of avoiding the possible complications associated with the locking screws, may help safer and more effective treatment in case of osteoporotic multi-fragment humeral fractures.
... Much research has been conducted to choose the optimal size of the plate and number of screws. More screws, at least 5, in the proximal fragment and the placement of an inferior medial support screw increase stability [39]. Another option to enhance stability is cement augmentation of the screws [40]. ...
Article
Full-text available
PurposeThe section for the skeletal trauma and sport’s injuries of the European Society for Trauma and Emergency Surgery (ESTES) appointed a task force group to reach a consensus among European countries on proximal humeral fractures.Material/Methods The task force group organized several consensus meetings until a paper with final recommendations was confirmed during the ESTES Executive Board meeting in Berlin on 25 October 2018.Conclusion The Recommendations compare conservative and four possible operative treatment options (ORIF, nailing, hemi- and total reverse arthroplasty) and enable the smallest common denominator for the surgical treatment among ESTES members.
... Even though PPHP has a posterior sweep feature, due to the different screw angles, some PHILOS screws (IDs 4 and 6) purchase more posteriorly compared to PPHP screws (Fig. 1). Third, the importance of the calcar screws in stabilizing the medial aspect of the proximal humerus has been shown in several biomechanical (Erhardt et al., 2012;Ponce et al., 2013;Rothstock et al., 2012) and clinical (Burke et al., 2014;Gardner et al., 2007;Osterhoff et al., 2011;Zhang et al., 2011) studies. PHILOS features two horizontal calcar screws helping to prevent varus collapse of the head fragment. ...
Article
Background Management of proximal humerus fractures is challenging, especially in elderly. Locking plating is a common surgical treatment option. The Proximal Humerus Internal Locking System (plate-A) has shown to lower complication rates compared to conventional plates, but is associated with impingement risk, which could be avoided using Peri-articular Proximal Humerus Plate (plate-B). Nevertheless, biomechanical performance and optimal screw configuration of plate-B is unknown. The aim of this study was to evaluate different screw configurations of plate-B and compare with plate-A using finite element analyses. Methods Twenty-six proximal humerus models were osteotomised to create unstable three-part fractures, fixed with either of the two plates, and tested under three anatomical loading conditions using a previous established and validated finite element simulation framework. Various clinically relevant screw configurations were investigated for both plates and compared based on the predicted peri-implant bone strain, being a validated surrogate of cyclic cut-out failure. Findings Besides increasing the number of screws, the placement of the posterior screws in combination with the calcar screw in the plate-B significantly decreased the predicted failure risk. Generally, plate-A had a lower predicted failure risk than plate-B. Interpretation The posterior and calcar screws may be prioritized in plate-B. Compared to plate-A, the more distal positioning, less purchase in the posterior aspect and a smaller screw spread due to not fitting of the most distal calcar screw in most investigated subjects led to a significantly higher predicted failure risk for most plate-B configurations. The findings of the simulations study require clinical corroboration.
... according to the classification system of Arbeitsgemeinschaft für Osteosynthesefragen/Orthopedic Trauma Association (AO/OTA) with an osteotomy gap separating the greater tubercle from the humeral head fragment and a wedge osteotomy at the surgical neck simulating medial comminution (Fig. 1). The fragments were fixed using a short PHILOS plate positioned as per the surgical guide and fixed with a frequently used screw configuration including six proximal locking screws (Rows A, B, and E) and three distal locking screws ( Fig. 1) based on previous studies [30,31]. The length of each proximal screw was adjusted automatically to match the prescribed tip-to-joint distance of 6 mm and rounded to the closest commercially available screw length. ...
Article
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Background The implant-related failure risks of proximal humerus plates remain high, and therefore, improved solutions are needed. Systematic and efficient computational analyses can assist design optimization of implant systems and may help reduce complication rates. Methods A previously developed validated computer simulation framework was used to optimize the screw orientations of a standard locking plate. Twenty low-density proximal humerus models with simulated unstable -part fractures were fixed using the PHILOS plate (DePuy Synthes) with six proximal screws. In a parametric analysis, the screw orientations were varied by relocating their tips within the humeral head and optimized based on two different metrics. In a first approach, average bone mineral density (BMD) around the screw tips was maximized. In a second approach, the average bone strain around the screw tips was evaluated using finite element (FE) analyses in three physiological loading situations and minimized to maximize the predicted fixation stability. Results Optimization based on BMD did not deliver any improvement. The final FE-based optimized configuration involved the adjustment of each screw and exhibited significantly smaller peri-implant bone strain (−18.49% ± 9.56%, p < 0.001) than the standard plate. Moreover, the optimized configuration provided a proportionally larger benefit for those digital subjects that had a higher predicted failure risk with the PHILOS plate. Conclusion Our findings suggest that the design of the investigated proximal humerus plate could be improved by changing the screw orientations. This study demonstrates the potential of FE analyses for implant optimization. However, the results do not allow direct translation into a novel plate design, mainly owing to the use of a restricted set of bone samples, a single simplified fracture model, and lack of direct biomechanical confirmation of the computational findings. The translational potential of this article A cohort-specific optimized proximal humerus locking plate design was evaluated using a previously validated computer simulation framework. This study showed that screw angle optimization solely based on BMD is not sufficient and that incorporating the mechanical aspects is required. This approach could be used in the future to inform about the best screw trajectories for variable-angle locking plates or to develop novel implants for improved treatment of proximal humerus fractures. It is therefore expected to help reduce the complication rates of the implant-based treatment of these challenging injuries.
... Initial enthusiasm for locked plating arose in part from the predilection for osteoporotic bone in patients with proximal humerus fractures and from favorable biomechanical performance compared with conventional plating. 1 However, satisfactory patient outcomes after internal fixation of proximal humerus fractures are contingent on minimizing complications. 2 Surgical factors critical for maintenance of reduction include anatomic reduction of the medial calcar, correction of varus deformity, impaction of the lateral proximal fragment in the distal segment, and placement of an inferomedial calcar screw. 3,4 Multiple studies have demonstrated complication rates between 28% and 49%, 2,5-7 with reoperation rates of 14%-24%. 2,5,6,8 Overall, the complication rate remains high in spite of such advances in reduction techniques, approaches, and fixation strategies. ...
Article
Objectives: To determine reoperation rates following treatment of a proximal humerus fracture with Cage fixation. Design: Retrospective case series SETTING:: Eleven U.S. hospitals PATIENTS:: Fifty- two patients undergoing surgical treatment of proximal humerus fractures INTERVENTION:: Open reduction and internal fixation of a proximal humerus fracture with a proximal humerus Cage MAIN OUTCOME MEASUREMENTS:: Re-operation rate at one year RESULTS:: At a minimum follow-up of one year, reoperations occurred in 4/52 patients (7.7%). Avascular necrosis (2/41) occurred in 4.9% of patients. Conclusion: Standard locked plating remains an imperfect solution for proximal humerus fractures. Proximal humerus Cage fixation had low rates of revision surgery at one year. Proximal humerus Cage fixation may offer reduced rates of complication and reoperation when compared to conventional locked plating for the management of proximal humerus fractures. Level of evidence: IV-Therapeutic.
... On the other hand, the S3 plate only allows insertion of up to six screws where only one is inferomedial. This is more in line with the recommendations of Erhardt et al. 32 and Cohen et al. 33 that five humeral head screws should be inserted including at least one inferomedial screw. This, in addition to its smaller contact area with the humeral head, made the S3 plate much more compact than the PHILOS and Fx plates. ...
Article
Full-text available
Stabilisation of proximal humerus fractures remains a surgical challenge. Spatial subchondral support (S3) plate promises to overcome common complications associated with conventional proximal humerus plates. This study compared the biomechanical performance of S3 plate with a fixed-angle hybrid blade (Equinoxe Fx) plate and a conventional fixed-angle locking plate (PHILOS). The effects of removal of different S3 plate screws on the humeral stability were also investigated. A total of 20 synthetic left humeri were osteotomised transversely at the surgical neck to simulate a two-part fracture and were each treated with an S3 plate. Head screws were divided into three zones based on their distance from the fracture site. Specimens were divided into four equal groups where one group acted as a control with all screws and three groups had one of the screw zones missing. With humeral head fixed, humeral shaft was first displaced 5 mm in extension, flexion, valgus and varus direction (elastic testing) and then until 30 mm varus displacement (plastic testing). Load–displacement data were recorded to determine construct stiffness in elastic tests and assess specimens’ varus stability under plastic testing. Removal of the screw nearest to the fracture site led to a 20.71% drop in mean elastic varus bending stiffness. Removal of the two inferomedial screw above it resulted in a larger drop. The proximal screw pair had the largest contribution to extension and flexion bending stiffness. Varus stiffness of S3 plate constructs was higher than PHILOS and Fx plate constructs. Stability of humeri treated with S3 plate depends on screws’ number, orientation and location. Varus stiffness of S3 plate construct (10.54 N/mm) was higher than that of PHILOS (6.61 N/mm) and Fx (7.59 N/mm) plate constructs. We attribute this to S3 plates’ thicker cross section, the 135° inclination of its screws with respect to the humeral shaft and the availability of pegs for subchondral support.
... However, the changed power dissipation appears to shift in favor of the torsion, which at least prevents the screws from cutting through the head, similar to the medial support screws. Here, again, at least the rate of screw perforations was reduced in the two-part model [31]. Although we have to reject our hypothesis of a decrease in implant failure being associated with the use of hybrid double-plate osteosynthesis rather than with the use of calcar screws for the treatment of a two-part fracture of the proximal humerus, the failure events might differ in other cases, implicating an altered load distribution. ...
Article
Full-text available
Background Treating proximal humerus fractures can be challenging because of large metaphyseal defects that conceal anatomical landmarks. In such cases, medial cortical support with, for example, calcar screws, is mandatory. Nevertheless, varus dislocations and implant failures in patients with impaired bone quality persist. Thus, the need for effective treatment of these patients exists. Hybrid double plate osteosynthesis was introduced as an alternative, yielding similar results as calcar screws. However, a biomechanical comparison of the stability of these two techniques is pending. Methods Cadaveric humeral specimens were treated with plate osteosynthesis and calcar screws (group 1, n = 9) or hybrid double plate osteosynthesis (group 2, n = 9) using a proximal humerus fracture model with a two-part fracture. Displacement, stiffness, failure mode, and ultimate load were examined biomechanically in a cyclic compressive-loading scenario. Results Although the hybrid double plate osteosynthesis (group 2) tended to confer higher stiffnesses than the medial support screws at higher cycles (group 1), this trend was below the level of significance. The displacement revealed non-significantly lower values for group 1 as compared with group 2 for cycles 50 and 2000, but at 5000 cycles, group 2 offered non-significantly lower displacement values than group 1. The ultimate load tended to be non-significantly higher in the hybrid double plate osteosynthesis group (group 2: 1342±369 N, group 1: 855±408 N). Both groups yielded similar failure rates, with the majority of failures in group 2 being gap closures (n = 8), whereas those in group 1 being plate dislocations (n = 4). Conclusions The use of an additive plate osteosynthesis in the region of the bicipital groove may be a potential alternative to the previously-established method of using calcar screws. The biomechanical data obtained in this study suggests that hybrid double plate osteosynthesis is as rigid and robust as calcar screws.
... A calcar screw reduces the risk of a varus collapse with subsequent screw perforation by counteracting the varus deforming forces acting on the humeral head. This results in a significantly higher reposition stability after 6 and 12 months [39,40] and increases the failure load [49]. ...
Article
Full-text available
Despite numerous available treatment strategies, the management of complex proximal humeral fractures remains demanding. Impaired bone quality and considerable comorbidities pose special challenges in the growing aging population. Complications after operative treatment are frequent, in particular loss of reduction with varus malalignment and subsequent screw cutout. Locking plate fixation has become a standard in stabilizing these fractures, but surgical revision rates of up to 25% stagnate at high levels. Therefore, it seems of utmost importance to select the right treatment for the right patient. This article provides an overview of available classification systems, indications for operative treatment, important pathoanatomic principles, and latest surgical strategies in locking plate fixation. The importance of correct reduction of the medial cortices, the use of calcar screws, augmentation with bone cement, double-plate fixation, and auxiliary intramedullary bone graft stabilization are discussed in detail.
... The average number of screws we put in humeral head was 5.8 (5-9), including two calcar screws, however, this did not affect the secondary screw penetration rate. Erhardt et al. [19] advised putting five or more screws (especially including calcar screws) in the humeral head, which can reduce the risk of secondary screw penetration, so our study may have hidden the correlation between screws less than 5 and more than 5 in humeral head. ...
Article
Full-text available
Objectives In this study, we investigated the correlation between fracture classification and secondary screw penetration. Methods We retrospectively identified 189 patients with displaced proximal humeral fractures treated by ORIF at our hospital between June 2006 and June 2013. All fractures were classified radiographically before surgery and follow-up for least 2 years after surgery was recommended. At each follow-up, radiographs were taken in three orthogonal views to evaluate secondary screw penetration. Results The study population consisted of 189 patients. Of these, 70 were male and 119 female, with a mean age of 59.1 years; the mean follow-up time was 28.5 months. Secondary screw penetration occurred in 26 patients. The risk of developing secondary screw penetration was 11.3-fold higher in four-part fractures than two-part fractures (P < 0.05), 8.6-fold higher for type C fractures than type A fractures (P < 0.05) and 11.0-fold higher for medial hinge disruption group than intact medial hinge group fractures (P < 0.05). However there was no difference between three-part fractures and two-part fractures (P = 0.374), and between type B and type A fractures (P = 0.195). Age, gender, time to surgery and the number of screw in humeral head had no influence on the secondary screw penetration rate (P > 0.05). Conclusions Patients with four-part fractures, type C fractures and medial hinges disruption are vulnerable to secondary screw penetration. This allows additional precautions to be instituted and measures to be taken as needed.
... Whereas most implant designs have at least eight options for screw placement, a screw configuration with five screws has been chosen for the present study. This is in accordance with Erhardt et al. [33] who suggested that at least five screws in the humeral head fragment are necessary for the stabilization of proximal humeral fractures. The screw configuration that was used was defined by the angle stable locking plate and the necessary targeting device. ...
Article
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Background The purpose of this study was to investigate the accuracy of perforation detection with multiplanar reconstructions using a mobile 3D image intensifier. Methods In 12 paired human humeri, K-wires perforating the subchondral bone and placed just below the cartilage level were directed toward five specific regions in the humeral head. Image acquisition was initiated by a fluoroscopy scan. Within a range of 90°, 45° external rotation (ER) and 45° internal rotation (IR). The number and percentage of detected perforating screws were grouped and analyzed. Furthermore, the fluoroscopic images were converted into multiplanar CT-like reconstructions. Each K-wire perforation was characterized as “detected” or “not detected”. ResultsIn the series of fluoroscopy images in the standard neutral position at 30° internal rotation, and 30° external rotation, the perforations of all K-wires (n = 56) were detected. Twenty-nine (51.8%) of them were detected in one AP view, 22 (39.3%) in two AP views, and five (8.9%) in three AP views. All K-wire perforations (100%, n = 56) were detected in multiplanar reconstructions. Conclusion In order to reveal all of the intraoperative and postoperative screw perforations in a “five screw configuration”, conventional AP images should be established in both the neutral positions (0°), at 30° internal rotation and 30° external rotation. Alternatively, the intraoperative 3D scan with multiplanar reconstructions enables a 100% rate of detection of the screw perforations.
... The repair wires of the tendons were passed through holes in the plate. After the fracture had been reduced and the plate had been adequately positioned, definitive fixation was performed, with locking screws inserted proximally (minimum of five) 16 and cortical or locking screws distally (minimum of three). Following this, knots were made in the cuff repair threads. ...
Article
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Objective: To evaluate functional outcomes, radiographic findings and complications of proximal humeral fractures treated with locking plates and to determine prognostic factors for successful clinical outcomes. Methods: Forty patients undergoing internal fixation of fractures of the proximal humerus with the Philos(r) plate were included in the study. The surgeries were performed between 2004 and 2011 and the patients underwent radiographic and clinical evaluation, by Constant -Murley and Dash score. Outcomes were analyzed by use of multivariate regression with several different variables. Results: Patients were on average of 61.8 ± 16.28 years, and most were female (70%). The Constant -Murley score was 72.03 ± 14.01 and Dash score was 24.96 ± 19.99. The postoperative radiographs showed a head-shaft angle of 135.43º± 11.82. Regression analysis showed that the patient's age and the Hertel classification influenced the Constant -Murley scale (p = 0.0049 and 0.012, respectively). Other prognostic criteria such as Neer and AO classification, head-shaft angle, the presence of metaphyseal comminution and extension of the humeral metaphyseal fragment showed no effect on prognosis. Complications occurred in four patients (10%). Conclusion: The fixation with the Philos(r) plate provided good clinical and radiographic results in fractures of the proximal humerus, with a low complication rate. Patient's age and Hertel classification were defined as prognostic factors that led to worse functional outcomes.
... Os fios de reparo dos tendões eram passados em orifícios na placa. Com a fratura reduzida e a placa adequadamente posicionada, procedia-se à fixaç ão definitiva, com os parafusos bloqueados proximalmente (mínimo de cinco) 16 e parafusos corticais ou bloqueados distalmente (mínimo de três). Em seguida, eram dados os nós nos fios de reparo do manguito. ...
Article
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Objetivo: Avaliar os resultados clínicos e radiográficos e as complicaç ões das fraturas do terç o proximal do úmero tratadas com a placa Philos ® e correlacionar esses resultados com critérios prognósticos. Métodos: Foram estudados 40 pacientes submetidos a osteossíntese de fraturas do terç o pro-ximal do úmero com a placa Philos ® . As cirurgias foram feitas entre 2004 e 2011 e os pacientes foram submetidos a avaliaç ão funcional (escalas de Constant-Murley e Dash [Disability of Arm-Shoulder-Hand]) e radiográfica. Os resultados funcionais foram correlacionados com variáveis clínicas e radiográficas por meio de regressão múltipla. Resultados: Os pacientes apresentavam em média 61,8 ± 16,28 anos e a maioria era do sexo feminino (70%). Observamos pontuaç ão de 72,03 ± 14,01 pela escala de Constant-Murley e 24,96 ± 19,99 pela de Dash. A radiografia pós-operatória evidenciou um ângulo cabeça-diáfise de 135,43 • ± 11,82. A análise por regressão demonstrou que a idade do paciente e a classificaç ão de Hertel exercem influência direta na escala de Constant-Murley (p = 0,0049 e 0,012, respectivamente). Outros critérios prognósticos, como a classificação de Neer e AO, o ângulo cabeç a-diáfise, a presenç a de cominuiç ão metafisária e a extensão do fragmento metafisário não demonstraram influência no prognóstico em nossa amostra. Complicaç ões ocorreram em quatro pacientes (10%). Conclusão: A osteossíntese com a placa Philos ® proporcionou, em nossa amostra, bons resul-tados clínicos e radiográficos, com baixo índice de complicaç ões. A idade do paciente e a classificaç ão de Hertel foram demonstradas como fatores preditores do resultado funcional. © 2013 Sociedade Brasileira de Ortopedia e Traumatologia. Publicado por Elsevier Editora Ltda. Todos os direitos reservados.
Chapter
Proximal humerus fractures are common injuries. In displaced three- and four-part fractures, osteoporotic bone, varus deformity, or calcar comminution, surgical fixation can provide stability, improve pain, and restore function. A customized fibular allograft is a modern adjunct to a laterally based locking plate, which has yielded promising results with low failure rates, and functions to restore the critical inferomedial calcar. Here we describe the indications, preoperative evaluation, surgical technique, and pearls and pitfalls for endosteal fibular allograft reconstruction in proximal humerus fractures.
Article
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Objective: To review the research progress on intra-articular screw penetration in proximal humeral fracture treated with locking plate. Methods: The domestic and foreign literature about the proximal humeral fracture treated with locking plate was extensively reviewed. The incidence of screw penetration and risk factors were summarized from both primary and secondary screw penetrations, and the reasons of the intra-articular screw penetration and the technical solutions to avoid the penetration were analyzed. Results: The incidence of intra-articular screw penetration is about 11%-30%, which includes primary and secondary screw penetrations. The primary screw penetration is related to improper operation, inaccurate measurement, and "Steinmetz solid" effect, which results in inadequate fluoroscopy and blind zone. The secondary screw penetration is related to the loss of reduction and varus, collapse, and necrosis of the humeral head. The risk factors for intra-articular screw penetration include the bone mass density, the fracture type, the quality of fracture reduction, the applied location, number, and length of the plate and screws, and whether medial column buttress is restored. Improved fracture reduction, understanding the geometric distribution of screws, good intraoperative fluoroscopy, and reconstruction of medial column buttress stability are the key points for success. Conclusion: The risk of the intra-articular screw penetration in the proximal humeral fractures treated with locking plates is still high. Follow-up studies need to further clarify the cause and mechanism of screw penetration, and the risk factors that lead to screw penetration, in order to effectively prevent the occurrence of this complication.
Article
Surgical treatment of proximal humerus fractures remains challenging, with a reported failure rate ranging from 15% to 35%. The dominant failure mode is secondary, i.e. post-operative screw perforation through the glenohumeral joint. A better understanding and the ability to predict this complication could lead to improved fracture fixation and decreased failure rate. The aims of this study were (1) to develop an experimental model for single screw perforation in the human humeral head and (2) to evaluate the ability of densitometric measures and micro finite element (microFE) analyses to predict the experimental failure event. Screw perforation was investigated experimentally in twenty cuboidal specimens cut from four pairs of fresh-frozen human cadaveric proximal humeral heads. A centrally inserted 3.5 mm screw was pushed quasi-statically at a constant displacement rate until perforation of the articular cartilage in each specimen. Force and displacement were recorded and evaluated at both initial screw loosening and perforation events. Bone volume was calculated around and in front of the screw and tip-to-joint distance was measured on the combined pre- and post-instrumentation micro computed tomography (microCT) scans. Implicit linear and explicit non-linear microFE models were created based on the microCT scans. The strength of these densitometric, geometrical and microFE methods to predict the experimental results was evaluated via correlation analysis. The bone volume measures were optimized in a parametric analysis to maximize correlation coefficients. The strongest and quantitatively correct predictions of perforation force (R² = 0.93) and displacement (R² = 0.77) were achieved using the explicit, non-linear microFE models. Linear microFE simulations provided the strongest predictions of loosening force (R² = 0.90). Correlation strengths reached by optimized bone volume measures for predicting experimental force and by tip-to-joint distance for predicting displacement were only slightly inferior compared to the results of microFE models. The strong correlations achieved with densitometric and geometric measures indicate that monotonic perforation of single screws through the articular surface of the humeral head can be well predicted with these easily accessible measures. However, non-linear microFE models delivered even stronger correlations and quantitatively correct predictions of perforation force and displacement. This indicates that if computational resources are available, non-linear simulations may have a high potential to investigate more complex fixations and loading scenarios.
Article
Background: This study aimed to explore the effects of medial support screws (MSS) on the locking proximal humeral plate in elderly patients who suffered from proximal humeral fractures. Methods: From December 2016 to December 2018, eighty-five elderly patients who suffered from proximal humeral fracture and received standard plate or locking plate with or without MSS were selected. The patients were allocated into 3 groups: Standard plate group (n=23), Locking plate without MSS group (n=34) and Locking plate with MSS group (n=28). Clinical data from all these 3 groups were collected and analyzed. Results: These eighty-five elder patients (ranging 60-78 years) accomplished a follow-up with an average of 16.3 months. The outcome data showed that significant difference was found on the Constant score, humeral internal rotation angle and humeral height ratio (all the P<0.05) among 3 groups, and a highest Constant score and a lowest humeral internal rotation angle and humeral height ratio loss was revealed in Locking platelet with MSS group. Furthermore, the lowest incidence of post-operation complication events (7.1%, P=0.051) and an evident reduction of secondary surgery incidence (P=0.021) was also presented in Locking plate with MSS among these 3 groups. Conclusions: The medial support screws in the locking proximal humeral plate in treating proximal humeral fractures could reduce humerus restoration loss and humeral internal rotation angle.
Article
The most common operative treatment of proximal humerus fractures is internal fixation with fixed-angle locking plates. Although this surgical technique has been refined, a significant failure rate remains. This study aimed to determine whether the number of locking screws in the humeral head affects the biomechanical strength and stability of the construct in bone from elderly individuals. Ten pairs of embalmed cadaveric humeri were osteotomized in a gap model and fixed with periarticular locking plates placed in the standard position. Five or 7 proximal locking screws were inserted. Mechanical testing was performed, and cyclic displacements and maximum force to failure were recorded. No significant difference was found between 5 and 7 locking screws in mean cyclic displacement on the medial (1.09 mm vs 1.12 mm, P=.834) or posterior (0.45 mm vs 0.42 mm, P=.791) sides of the fracture model. On testing to failure, 7 and 5 screws showed similar stiffness (336 N/mm vs 292 N/mm, P=.176), force at ultimate load (745 N vs 662 N, P=.309), and displacement at ultimate load (5.90 mm vs 4.36 mm, P=.080). All samples failed at diaphyseal fixation, and no screw cutout or varus collapse was observed. Results from this study suggest that there is no significant difference between 5 and 7 metaphyseal locking screws for stiffness of fixation of proximal humeral fractures in elderly patients. With the inherent possibility of screw penetration of the humeral head, fewer screws may lead to fewer complications. [Orthopedics. 201x; xx(x):xx-xx.].
Article
The surgical treatment of proximal humerus fractures remains controversial primarily due to the high complication rate associated with the available fixation methods. In an attempt to reduce the incidence of serious complications and subsequent poor clinical outcomes, proximal humerus locking plates have become popular but even these implants cannot overcome the risk of complications, especially those associated with loss of fracture reduction and screw cut-out/migration through the humeral head. In an attempt to address these issues, we have reviewed the literature, investigating the most likely causes for these predominantly mechanical complications and propose technical solutions.
Article
Background: The present study aimed to determine anatomic references for the placement of five proximal humerus locking plates. Methods: Five proximal humerus locking-plate systems were placed on six human shoulder cadavers. Plates were positioned by fluoroscopic confirmation so that the inferior oblique screw was within 5 mm of the inferomedial cortex. Plate position was measured using the superior border of the pectoralis major tendon (PMT) to the bottom of the first slotted or nonlocking hole and top of the plate to the top of the greater tuberosity. The distance from the PMT insertion to the top of the humeral head was measured as a control. Results: There was consistency within each plating system for both the distance from the PMT insertion to the first hole and the top of the plate to the greater tuberosity: Synthes first-generation [mean (SD) 13.7 mm (3.1 mm); 10 mm (1.3) mm], Synthes second-generation [28.2 mm (2.2 mm); 18.5 mm (2.7 mm)], Biomet OptiLock® [25.5 mm (2.7 mm); 18.7 mm (2 mm)], Stryker AxSOS® [5 mm (2.8 mm); 12.3 mm (3.3 mm)] and Acumed Polarus® [9.5 mm (1.8 mm); 14.8 mm (1.6 mm)]. Conclusions: The present study provides measurements that improve the accuracy of plate positioning for five plating systems.
Article
Proximal humerus fractures are commonly treated with open reduction and internal fixation with periarticular locking plates. This study compared the geometry of proximal humerus locking plate's screw distribution, amount of bone-screw interface, and the volume the screws occupy within the humeral head as well as how leaving the screws short of the articular surface affects these measures. Locking plates from seven manufacturers were applied to foam humerus models. The entry and exit hole of each screw trajectory was digitized using a 3D-motion tracking system. A trajectory for each screw was modeled as well as the volume enclosed by the screw trajectories. The following outcome metrics were calculated: the bone-screw interface, the volume enclosed by the screws, and the effect of leaving the screws short of the articular surface. Biomet had the most bone-screw interface (7259mm) while Zimmer had the least (3982mm). The original Synthes plate had the largest screw volume, occupying 31.5% of the humeral head, while Smith+Nephew and Zimmer had the lowest volumes, occupying 21.2% and 12.6%, respectively. Leaving the screws 15mm short of the articular surface resulted in the most reduction in volume for the Depuy plate (50%) and the least reduction for the new version of the Synthes plate (29%). Many different manufactured periarticular locking plates exist to stabilize a proximal humeral fracture. Clinicians need to be familiar with the different plate configurations, screw lengths and trajectories which affect potential biomechanical performance and which can optimize fracture site maintenance.
Article
The objective of this study was to evaluate the biomechanical effect of an additional unlocked calcar screw compared to a standard setting with three proximal humeral head screws alone for fixation of an unstable 2-part fracture of the surgical neck. The additional calcar screw improves stiffness and failure load. Fourteen fresh frozen humeri were randomized into two equal sized groups. An unstable 2-part fracture of the surgical neck was simulated and all specimens were fixed with the MultiLoc(®)-nail. Group I represented a basic screw setup, with three locked head screws and two unlocked shaft screws. Group II was identical with a supplemental unlocked calcar screw (CS). Stiffness tests were performed in torsional loading, as well as in axial and in 20° abduction/20° adduction modes. Subsequently cyclic loading and load-to-failure tests were performed. Resulting stiffness, displacement under cyclic load and ultimate load were compared between groups using the t-test for independent variables (α=0.05). No significant differences were observed between the groups in any of the biomechanical parameters. Backing out of the CS was observed in three cases. The use of an additional unlocked calcar screw does not provide mechanical benefit in locked nailing of an unstable 2-part fracture of the surgical neck. Level III. Experimental biomechanical study with human specimen. Copyright © 2015 Elsevier Masson SAS. All rights reserved.
Thesis
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Fractures of the proximal humerus are one of the most debated topics in current traumatology . There is general consensus of the conservative treatment in undisplaced fractures. In the cases multifragmentary and complex fracture view of therapy is fragmented. Clinical use of angle-stable implants, especially locking plates , improved the possibilities for fracture fixation in the proximal fragment. However still persist problems with the vitality head during invasive approach. On the ground of preserve soft tissue many authors still prefer minimally invasive fixation techniques. Minimally invasive Plate osteosynthesis ( MIPO ) is often neglected because of the risk of injury to the axillary nerve and the inability to achieve adequate quality of reduction durring limited access . The aim of our study is evaluate the risk of injury to the axillary nerve and develop a technique to eliminate its iatrogenic damage . In the clinical part of our project is to evaluate the functional results with regard to the quality of the achieved reduction. Functional results are compared with the literature , patients operated on in our department with classical deltoideopectoral approach and the group of patients operated on in our department during the duration of the grant IGA MZ CR No. 7761.
Article
Introduction: In recent years, new angle-stable plate implants with polyaxial screw direction were developed with the aim of an improved treatment of displaced 3- and 4-part fractures of the proximal humerus. There are only a few studies available about polyaxial implants in the treatment of 3- and 4-part proximal humerus fractures. Therefore, the aim of this study was to evaluate clinical results and complications of open reduction and internal fixation of displaced 3- and 4-part fractures using a polyaxial plate. Patients and Methods: Within 51 months, 105 patients with a displaced 3- or 4-part fracture of the proximal humerus were treated with a polyaxial locking plate. The complications were evaluated and the Constant & Murley score was assessed and correlated with patient satisfaction ("very satisfied" to "not satisfied"). Additionally, the results were compared with those of monoaxial plates from the literature. Furthermore, the operative experience of the surgeons at the time of surgery was correlated with the objective results of the patients. Results: 65 patients (average age: 71.3 ± 11.4 years; average follow-up: 19,6 ± 9,8 month [10-44 month]) with a displaced 3- or 4-part fracture were re-examined retrospectively (female: n = 54; male: n = 11). Overall, there were 27 3-part fractures and 38 4-part fractures. The Constant and Murley Score was on average 62.1 ± 16.5 points and the complication rate was 26 %. The most frequent complication was screw perforation through the humeral head. Patient satisfaction with clinical outcome was high within the whole study group. 40 % of the patients were "very satisfied" with their shoulder function, 29 % were "satisfied" ("fair": 12 %, "not satisfied": 19 %). Additionally, the operative experience of the surgeons influenced the final clinical result. Conclusion: In comparison to the literature we could not delineate better clinical outcomes or lower complication rates with polyaxial implants compared to monoaxial plates in 3- and 4-part fractures. Nevertheless, the majority of patients were satisfied with the clinical result in the context of age-related shoulder function. In addition, a close correlation could be detected between the degree of satisfaction and the objectively measured shoulder function. A high level of operative experience is required to avoid typical complications and to achieve a good clinical result. Georg Thieme Verlag KG Stuttgart · New York.
Article
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The purpose of this cadaveric study was to evaluate the conformity of the anatomically preshaped proximal humerus internal locking plate system (PHILOS) to the humeri of the Korean and anatomical features of nine locking screws for the proximal humerus.
Article
Background The objective of this study was to investigate the biomechanical effects of medial fracture gap augmentation in locked plating of an unstable 2-part proximal humeral fracture with calcar screws and insertion of a corticocancellous bone block. Furthermore the mechanical behavior of dynamic locking screws in the non-parallel arrangement of a proximal humeral plate was of interest. Methods Thirty-two fresh frozen humeri were randomized in four equal groups. An unstable 2-part fracture was fixed by locked plating in all specimens. The basic screw setup was supplemented by additional calcar screws in one group. Humeral head screws were replaced by dynamic locking screws in a second group. The third group featured an additional corticocancellous femoral head allograft. Assessment of stiffness was followed by cyclic loading and load to failure tests. Resulting stiffness, fracture gap deflection and ultimate load were compared utilizing Bonferroni corrected t-test for independent samples. Findings The mechanical effect of additional calcar screws was non-significant as compared to the basic screw configuration whereas bone block insertion significantly increased construct stiffness and failure load. The use of dynamic locking screws did not significantly reduce construct stiffness when compared to conventional locking screws. Interpretation Additional calcar screws alone did not improve the initial biomechanical properties of an unstable 2-part proximal humeral fracture model. However bone block augmentation appeared to be a reliable alternative of additional bony support by raising stiffness and failure load. Dynamic locking screws did not show their expected dynamic component when used in a non-parallel arrangement.
Article
The treatment of complex proximal humeral fractures remains challenging, especially in patients with osteoporosis. Locking plate fixation has become a standard in stabilizing these fractures; however, complication rates are still high. In particular, loss of reduction with varus misalignment and subsequent cut-out of the proximal screws is frequent. Recently the restoration of medial support has been named as the primary aim of operative treatment. This article describes an alternative technique using intramedullary augmentation on the basis of a case report and explains the concept of medial support in locking plate fixation of proximal humeral fractures. Options, findings and recommendations of different procedures are presented in this respect. The importance of correct reduction of the medial cortices, the use of calcar screws, the double-plate fixation method as well as the presented technique of intramedullary augmentation are discussed.
Article
The treatment of proximal humerus fractures continues to evolve. While the many of these injuries can be managed nonoperatively, a certain percentage require operative treatment. Open reduction internal fixation can offer excellent outcomes when performed in the appropriate patient and utilizing proper techniques. This article reviews the most up-to-date literature regarding all phases of proximal humerus fracture osteosynthesis, including diagnosis, imaging, anatomic considerations, surgical indications, fixation, and surgical outcomes.
Article
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We reviewed all 717 manuscripts published in the 1997 issues of the British and American volumes of the Journal of Bone and Joint Surgery and in Clinical Orthopaedics and Related Research, from which 33 randomised, controlled trials were identified. The results and sample sizes were used to calculate the statistical power of the study to distinguish small (0.2 of standard deviation), medium (0.5 of standard deviation), and large (0.8 of standard deviation) effect sizes. Of the 33 manuscripts analysed, only three studies (9%) described calculations of sample size. To perform post-hoc power assessments and estimations of deficiencies of sample size, the standard effect sizes of Cohen (small, medium and large) were calculated. Of the 25 studies which reported negative results, none had adequate power (β < 0.2) to detect a small effect size and 12 (48%) lacked the power necessary to detect a large effect size. Of the 25 studies which did not have an adequate size of sample to detect small differences, the average used was only 10% of the required number Our findings suggest that randomised, controlled trials in clinical orthopaedic research utilise sample sizes which are too small to ensure statistical significance for what may be clinically important results.
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G*Power is a free power analysis program for a variety of statistical tests. We present extensions and improvements of the version introduced by Faul, Erdfelder, Lang, and Buchner (2007) in the domain of correlation and regression analyses. In the new version, we have added procedures to analyze the power of tests based on (1) single-sample tetrachoric correlations, (2) comparisons of dependent correlations, (3) bivariate linear regression, (4) multiple linear regression based on the random predictor model, (5) logistic regression, and (6) Poisson regression. We describe these new features and provide a brief introduction to their scope and handling.
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The medial periosteal hinge plays a key role in fractures of the head of the humerus, offering mechanical support during and after reduction and maintaining perfusion of the head by the vessels in the posteromedial periosteum. We have investigated the biomechanical properties of the medial periosteum in fractures of the proximal humerus using a standard model in 20 fresh-frozen cadaver specimens comparable in age, gender and bone mineral density. After creating the fracture, we displaced the humeral head medial or lateral to the shaft with controlled force until complete disruption of the posteromedial periosteum was recorded. As the quality of periosteum might be affected by age and bone quality, the results were correlated with the age and the local bone mineral density of the specimens measured with quantitative CT. Periosteal rupture started at a mean displacement of 2.96 mm (sd 2.92) with a mean load of 100.9 N (sd 47.1). The mean maximum load of 111.4 N (sd 42.5) was reached at a mean displacement of 4.9 mm (sd 4.2). The periosteum was completely ruptured at a mean displacement of 34.4 mm (sd 11.1). There was no significant difference in the mean distance to complete rupture for medial (mean 35.8 mm (sd 13.8)) or lateral (mean 33.0 mm (sd 8.2)) displacement (p = 0.589). The mean bone mineral density was 0.111 g/cm ³ (sd 0.035). A statistically significant but low correlation between bone mineral density and the maximum load uptake (r = 0.475, p = 0.034) was observed. This study showed that the posteromedial hinge is a mechanical structure capable of providing support for percutaneous reduction and stabilisation of a fracture by ligamentotaxis. Periosteal rupture started at a mean of about 3 mm and was completed by a mean displacement of just under 35 mm. The microvascular situation of the rupturing periosteum cannot be investigated with the current model.
Article
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We report early results using a second generation locking plate, non-contact bridging plate (NCB PH((R)), Zimmer Inc. Warsaw, IN, USA), for the treatment of proximal humeral fractures. The NCB PH combines conventional plating technique with polyaxial screw placement and angular stability. Prospective case series. A single level-1 trauma center. A total of 50 patients with proximal humeral fractures were treated from May 2004 to December 2005. Surgery was performed in open technique in all cases. Implant-related complications, clinical parameters (duration of surgery, range of motion, Constant-Murley Score, subjective patient satisfaction, complications) and radiographic evaluation [union, implant loosening, implant-related complications and avascular necrosis (AVN) of the humeral head] at 6, 12 and 24 weeks. All fractures available to follow-up (48 of 50) went to union within the follow-up period of 6 months. One patient was lost to follow-up, one patient died of a cause unrelated to the trauma, four patients developed AVN with cutout, one patient had implant loosening, three patients experienced cutout and one patient had an axillary nerve lesion (onset unknown). The average age- and gender-related Constant Score (n = 35) was 76. The NCB PH combines conventional plating technique with polyaxial screw placement and angular stability. Although the complication rate was 19%, with a reoperation rate of 12%, the early results show that the NCB PH is a safe implant for the treatment of proximal humeral fractures.
Article
Full-text available
We reviewed all 717 manuscripts published in the 1997 issues of the British and American volumes of the Journal of Bone and Joint Surgery and in Clinical Orthopaedics and Related Research, from which 33 randomised, controlled trials were identified. The results and sample sizes were used to calculate the statistical power of the study to distinguish small (0.2 of standard deviation), medium (0.5 of standard deviation), and large (0.8 of standard deviation) effect sizes. Of the 33 manuscripts analysed, only three studies (9%) described calculations of sample size. To perform post-hoc power assessments and estimations of deficiencies of sample size, the standard effect sizes of Cohen (small, medium and large) were calculated. Of the 25 studies which reported negative results, none had adequate power (beta < 0.2) to detect a small effect size and 12 (48%) lacked the power necessary to detect a large effect size. Of the 25 studies which did not have an adequate size of sample to detect small differences, the average used was only 10% of the required number Our findings suggest that randomised, controlled trials in clinical orthopaedic research utilise sample sizes which are too small to ensure statistical significance for what may be clinically important results.
Article
Background: Successful internal fixation of fractures of the surgical neck of the humerus can be difficult to achieve because of osteopenia of the proximal aspect of the humerus. The purpose of this study was to compare the biomechanical stability of a proximal humeral intramedullary nail and a locking plate for the treatment of a comminuted two-part fracture of the surgical neck in a human cadaver model. Methods: Twenty-four cadaveric humeri were instrumented with use of either a titanium proximal humeral nail (PHN) or a 3.5-mm locking compression plate for the proximal part of the humerus (LCP-PH). The specimens were matched by bone mineral density and were separated into four experimental groups with six humeri in each: PHN bending, LCP-PH bending, PHN torsion, or LCP-PH torsion. Comminuted fractures of the surgical neck were simulated by excising a 10-mm wedge of bone. Bending specimens were cyclically loaded from 0 to 7.5 Nm of varus bending moment at the fracture site. Torsion specimens were cyclically loaded to ±2 Nm of axial torque. The mean and maximum displacement in bending, mean and maximum angular rotation in torsion, and stiffness of the bone-implant constructs were compared. Results: In bending, the LCP-PH group demonstrated significantly less mean displacement of the distal fragment than did the PHN group over 5000 cycles (p = 0.002). In torsion, the LCP-PH group demonstrated significantly less mean angular rotation than did the PHN group over 5000 cycles (p = 0.04). A significant number of specimens in the PHN group failed prior to reaching 5000 cycles (p = 0.04). The LCP-PH implant created a significantly stiffer bone-implant construct than did the PHN implant (p = 0.007). Conclusions: The LCP proximal humeral plate demonstrated superior biomechanical characteristics compared with the proximal humeral nail when tested cyclically in both cantilevered varus bending and torsion. The rate of early failure of the proximal humeral nail could reflect the high moment transmitted to the locking proximal screw-bone interface in this implant. Clinical Relevance: The high failure rate in torsion of the proximal humeral nail-bone construct is concerning, and, with relatively osteoporotic bone and early motion, the results could be poor.
Article
Background Proximal fracture of the humeral head is the third most frequent fracture in humans. Most (70%) of those affected are over 60 years old. It is hoped that advanced locking medullary screws or plates will reduce the risk of secondary dislocation of screws or fracture segments when the bone of the humeral head is osteoporotic. Methods From January 2002 to August 2005, 225 displaced humeral head fractures in 223 patients aged on average 66±15 years were treated with a new locking proximal humeral plate. Results In 176 patients in whom follow-up was possible, the average Constant Score after 9 months was 70±19 points (raw data), or 81±22% in the normalized score. No significant difference was detected between the younger group up to 65 years of age (73% points) and those over 65 years of age (80% points). Axial deviations by more than 30° were noted in 11 (5%), and of 159 displaced tubercles, malreduction by more than 5 mm was noted in 14 (9%). Two infections and two haematomas had to be treated so far. Primary screw perforations were seen in 24 (11%) cases as well as further implant dislocations in 3 (1,7%). Plate dislocations out of the shaft existed in 4 (2,4%) and 14 collapses of the humeral head with secondary screw perforations were recorded. All other complications arose out of technical faults, such as 24 screw perforations (11%) into the glenohumeral joint and 3 (1.7%) cases of secondary implant dislocation from the humeral head and 5 (3%) from the shaft, and 14 (8%) sinterings with glenohumeral screw perforation. So far, in addition to 1 case of pseudarthrosis with a broken plate, 5 (3%) cases of total and 9 (5%) of partial avascular humeral head necrosis have been observed. Conclusion The new implant provides superior stability in the fixation of humeral head fragments and has proved its worth in everyday clinical practice when additional indirect fixation of the tubercle is needed, as it frequently is in elderly patients.
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G*Power (Erdfelder, Faul, & Buchner, 1996) was designed as a general stand-alone power analysis program for statistical tests commonly used in social and behavioral research. G*Power 3 is a major extension of, and improvement over, the previous versions. It runs on widely used computer platforms (i.e., Windows XP, Windows Vista, and Mac OS X 10.4) and covers many different statistical tests of the t, F, and chi2 test families. In addition, it includes power analyses for z tests and some exact tests. G*Power 3 provides improved effect size calculators and graphic options, supports both distribution-based and design-based input modes, and offers all types of power analyses in which users might be interested. Like its predecessors, G*Power 3 is free.
Article
Monoaxial and polyaxial screw insertion are used in angular stable plating of displaced proximal humeral fractures. Aim of the study was to compare both fixation techniques by radiographic evaluation. Prospective randomized treatment with monoaxial or polyaxial screw insertion in angular stable anatomic preshaped plates of displaced proximal humeral fractures. Analysis of standardized true anterior-posterior (true a.p.) and outlet-view radiographs at 1 day, 6 weeks, 3 months, and 6 months after surgery by two radiologists with respect to radiographic evidence of secondary varus displacement, cut out of screws, osteonecrosis, and hardware failure. Secondary varus displacement was defined as a varus decrease of the humeral head-shaft angle of > 10 degree in true a.p. radiographs. Sixty-six consecutive patients (48 women, [72.7%]; 18 men, [27.3%]; mean age 67.7 years [95% CI, 63.9-71.6]) with displaced proximal humeral fractures were evaluated in this study. Nineteen patients (29%) showed secondary varus displacement of > 10-degree angle. In 6 cases (9%), intra-articular cut out of screws was found. Furthermore, 1 case (2%) of nonunion was observed. No relationship between monoaxial and polyaxial screw insertion was found regarding occurrence of secondary varus displacement (monoaxial, 11/polyaxial, 8; p = 0.91) or screw cut out (monoaxial, 4/polyaxial, 2; p = 0.64). Prevalence of secondary varus displacement and hardware cut out was related to patients age (p = 0.02) and fracture pattern, according to Neer- and AO/OTA-classification (p < 0.001). The average immediate postoperative head-shaft angle was 135.2 degrees (CI, 132.3-138.1) in the group without radiographic complication, compared with 126.7-degree angle (CI, 123.6-129.7) among those with secondary varus displacement of > 10-degree angle and screw cut out (p < 0.001). Furthermore, in cases of an immediate postoperative head-shaft angle of < 130 degrees, there was a 48% incidence of secondary varus dislocation (n = 13) versus 15% in cases with a head-shaft angle > 130 degrees (n = 6, p = 0.004). Monoaxial and polyaxial screw insertion allow for mechanical stabilization in angular stable plating of unstable proximal humerus fractures. Radiographic evidence of secondary varus displacement of > 10-degree angle and screw cut out was seen similarly often in both fixation techniques. To avoid secondary varus displacement and screw cut out, restoration of a humeral head-shaft angle of > 130 degrees seems to be important in monoaxial and polyaxial fixation of proximal humeral fractures.
Article
Comminuted proximal humerus fracture fixation is controversial. Locked plate complications have been addressed by anatomic reduction or medial cortical support. The relative mechanical contributions of varus malalignment and lack of medial cortical support are presently assessed. Forty synthetic humeri divided into three subgroups were osteotomized and fixed at 0 degrees, 10 degrees, and 20 degrees of varus malreduction with a locking proximal humerus plate (AxSOS, Global model; Stryker, Mahwah, NJ) to simulate mechanical medial support with cortical contact retained. Axial, torsional, and shear stiffness were measured. Half of the specimens in each of the three subgroups underwent a second osteotomy to create a segmental defect simulating loss of medial support with cortex removed. Axial, torsional, and shear stiffness tests were repeated, followed by shear load to failure in 20 degrees of abduction. For isolated malreduction with cortical contact, the construct at 0 degrees showed statistically equivalent or higher axial, torsional, and shear stiffness than other subgroups examined. Subsequent removal of cortical support in half the specimens showed a drastic effect on axial, torsional, and shear stiffness at all varus angulations. Constructs with cortical contact at 0 degrees and 10 degrees yielded mean shear failure forces of 12965.4 N and 9341.1 N, respectively, being statistically higher (p < 0.05) compared with most other subgroups tested. Specimens failed primarily by plate bending as the humeral head was pushed down medially and distally. Anatomic reduction with the medial cortical contact was the stiffest construct after a simulated two-part fracture. This study affirms the concept of medial cortical support by fixing proximal humeral fractures in varus, if absolutely necessary. This may be preferable to fixing the fracture in anatomic alignment when there is a medial fracture gap.
Article
The goal of this study is to evaluate the incidence of complications and the functional outcome after open reduction and internal fixation with the proximal humeral locking plate (Philos). Prospective case series. Multicenter study in 8 trauma units (levels I, II, and III) with recruitment between September 12, 2002, and January 9, 2005. One hundred fifty-seven patients with 158 fractures. Open reduction and internal fixation with a Philos plate. Occurrence of postoperative complications up to 1 year and active follow-up for 1 year with radiologic assessment to observe fracture healing, alignment, reduction, avascular necrosis, and functional outcome measurements including Constant, Disabilities of the Arm, Shoulder, and Hand, and Neer scores. One-year follow-up rate was 84%. The incidence of experiencing any implant-related complication was 9% and 35% for nonimplant-related complications. Primary screw perforation was the most frequent problem (14%) followed by secondary screw perforation (8%) and avascular necrosis (8%). After 1 year, a mean Constant score of 72 points (87% of the contralateral noninjured side), a mean Neer score of 76 points, and a mean Disabilities of the Arm, Shoulder, and Hand score of 16 points were achieved. Fixation with Philos plates preserves achieved reduction, and a good functional outcome can be expected. However, complication incidence proportions are high, particularly due to primary and secondary screw perforations into the glenohumeral joint, with an overall complication rate of 35%. More accurate length measurement and shorter screw selection should prevent primary screw perforation. Awareness of obtaining anatomic reduction of the tubercles and restoring the medial support should reduce the incidence of secondary screw perforations, even in osteopenic bone.
Article
The treatment of unstable displaced proximal humeral fractures, especially in the elderly, remains controversial. The objective of the present prospective, multicenter, observational study was to evaluate the functional outcome and the complication rate after open reduction and internal fixation of proximal humeral fractures with use of a locking proximal humeral plate. One hundred and eighty-seven patients (mean age, 62.9 +/- 15.7 years) with an acute proximal humeral fracture were managed with open reduction and internal fixation with a locking proximal humeral plate. At the three-month, six-month, and one-year follow-up examinations, 165 (88%), 158 (84%), and 155 (83%) of the 187 patients were assessed with regard to pain, shoulder mobility, and strength. The Constant score was determined at each interval, and the Disabilities of the Arm, Shoulder and Hand (DASH) score was determined for the injured and contralateral extremities at the time of the one-year follow-up. Between three months and one year, the mean range of motion and the mean Constant score for the injured shoulders improved substantially. Twelve months after surgery, the mean Constant score for the injured side was 70.6 +/- 13.7 points, corresponding to 85.1% +/- 14.0% of the score for the contralateral side. The mean DASH score at the time of the one-year follow-up was 15.2 +/- 16.8 points. Sixty-two complications were encountered in fifty-two (34%) of 155 patients at the time of the one-year follow-up. Twenty-five complications (40%) were related to incorrect surgical technique and were present at the end of the operative procedure. The most common complication, noted in twenty-one (14%) of 155 patients, was intraoperative screw perforation of the humeral head. Twenty-nine patients (19%) had an unplanned second operation within twelve months after the fracture. Surgical treatment of displaced proximal humeral fractures with use of the locking proximal humeral plate that was evaluated in the present study can lead to a good functional outcome provided that the correct surgical technique is used. Because many of the complications were related to incorrect surgical technique, it behooves the treating surgeon to perform the operation correctly to avoid iatrogenic errors.
Article
To determine the outcome after indirect reduction and buttress plate fixation of displaced and unstable proximal humeral fractures, we retrospectively evaluated 98 patients, an average of 34 months (range 24-72 months) after fracture fixation. The patients were reviewed and results were evaluated clinically according to the Neer, UCLA and Constant score. A radiographic evaluation of fracture healing, avascular necrosis and degenerative changes of the shoulder joint was performed in all patients. Any complications of treatment were assessed. Results were, according to the UCLA-rating system, good to excellent in 76% of fractures. According to the Constant-score and the Neer score, good to excellent results were obtained in 69 and 59% of fractures, respectively. Poor results were mainly due to secondary malunion. The avascular necrosis rate was 4%. Non-union was seen in one case. Secondary varus deformity and retroversion of the humeral head as a result of lack of rotational and angular stability of the plate developed in twelve (12%) and eight (8%) cases, respectively. Plate fixation is an adequate procedure for treating unstable and displaced two- to four-part fractures of the proximal humerus, enabling early functional after-treatment. The incidence of avascular necrosis and nonunion are low, when fracture reduction is performed indirectly. Poor rotational and angular instability can lead to a loss of reduction.
Article
Proximal humeral fractures are common injuries, and numerous surgical methods have been described for their treatment. The biomechanical characteristics of various internal fixation devices that are used to treat these fractures have not been extensively studied, nor has the potential beneficial effect of calcium phosphate cement supplementation. We used a cadaveric three-part proximal humeral osteotomy model to perform a biomechanical evaluation of three types of internal fixation devices: a cloverleaf plate, an angled blade-plate, and Kirschner wires. The effect of supplementing the fixation with SRS (Skeletal Repair System) calcium phosphate cement was evaluated as well. Eighteen pairs of fresh-frozen humeri were obtained, and the bone-mineral density of each specimen was measured. In each pair, one specimen was secured with internal fixation alone and the contralateral specimen was secured with internal fixation combined with calcium phosphate cement. The specimens were tested cyclically in abduction and in external rotation for 250 cycles to evaluate interfragmentary motion. The specimens were then loaded to failure in external rotation to measure torsional load to failure and torsional stiffness. Overall, there were no significant differences between the specimens treated with the blade and cloverleaf plates, whereas the specimens treated with Kirschner wires demonstrated more interfragmentary motion, less stiffness, and lower torque to failure. In general, supplementation with calcium phosphate cement led to significant improvements in the mechanical performance of all three forms of internal fixation as demonstrated by a significant decrease in interfragmentary motion, a significant increase in torque to failure, and a significant increase in torsional stiffness. The addition of calcium phosphate cement increased the stiffness of even the most osteoporotic specimens to levels that were higher than those of the most osteodense specimens that had been treated with internal fixation alone. The initial biomechanical properties of internal fixation as measured with use of a proximal humeral osteotomy model and three methods of fixation were significantly improved by the addition of calcium phosphate cement.
Article
To determine histomorphometric and bone strength distribution of the proximal humerus, analyses were done on 24 freshly harvested human cadaveric humeri. Median ages of 46 and 69 years were recorded respectively for the male group (n = 11; minimum, 34 years; maximum, 76 years) and the female group (n = 13; minimum, 46 years; maximum, 90 years). The humeral head was sliced into four equal horizontal levels (Levels 1-4). Five regions of interest were defined in each cutting plane: anterior, posterior, lateral, medial, and central. Histomorphometric analyses evaluated structural parameters (tissue volume to bone volume ratio, trabecular thickness), connectivity (number of nodes, node to node length), and trabecular orientation (mean bone length). The peak values of histomorphometric parameters and bone strength were identified for the cranial section and decreased caudally. The medial and dorsal aspects of the proximal humeral head were found to be the areas of highest bone strength. The trabecular network formed a pattern that connected the center of the gleaned cavity. The structural and connectivity parameters, bone strength, and trabecular orientation showed region- and level-related characteristics. Knowledge of distribution, microstructure, and quality of bone in the humeral head allows the remaining bone stock to be used effectively, even in elderly patients, with a minimally invasive approach and maximum mechanical stability.
Article
The shoulder joint represents an indeterminate mechanical system, making it difficult to predict individual muscle forces required to equilibrate a given arbitrary external force. Although considerable work has been published on this matter, no model exhibits the adaptability required for the analysis involving different positions of the humerus and for any external load. An algorithm involving decision-making loops is developed to predict forces exerted by muscles that cross the shoulder joint in equilibrating a given external force acting in an arbitrary direction, with the humerus in any one of 12 selected positions. Muscle lever arms and directions of action collected from a full-size epoxy model of the shoulder joint are used together with the external force as input. The algorithm selects an appropriate group of muscles and step by step attributes small force increments to withstand the external moment while aiming at minimising the forces involved. Each muscle force increment is stored after every loop and eventually summed up. Stability of the glenohumeral joint is the final determining factor. Six worked-out examples show interesting features of probable muscular activity. Muscle segmentation is of paramount importance for spatial control. Although stability can be achieved by increasing the overall rotator cuff activity (co-contraction), this is rarely necessary. The strategy of force sharing among the muscles opens up the possibility to examine the outcome of muscle deficiencies and to investigate causes of joint instability as encountered in clinical practice. Further validation of the model is still needed, but certain clinical observations can be explained.
Article
The increasing number of fractures of the proximal humerus, especially in the elderly, carries with it the unsolved problem of the optimal treatment for the displaced or unstable fractures. The authors' goal was to analyze whether fixation with a bent valgus angled blade plate could improve the outcomes reported in the literature to date. Prospective clinical study. Urban level 1 university trauma center. Over a 27-month period, 42 consecutive patients were treated for an unstable or displaced proximal humerus fracture. Open reduction and internal fixation with a 90-degree cannulated angled blade plate prebent to 110 degrees. Active follow-up for 1 year with assessment of objective and subjective functional results (ie, motion; strength; Constant score; Disabilities of the Arm, Shoulder, and Hand (DASH) score; and visual analog scale (VAS)) and radiographic assessment (reduction, alignment, necrosis, and nonunion). Follow-up was completed for 86% of the patients, who achieved a mean Constant score of 66 points (82% of the contralateral side) with a mean forward flexion of 125 degrees and an average strength of 72% of the contralateral side. Low disability (mean DASH score 22) and pain values (mean VAS 2) were demonstrated after this type of stabilization. The overall complication rate was 33% (12/36), with protrusion of the blade into the glenohumeral articulation as the most frequent problem (8/36, 22%). The negative impact of an adverse event on subjective and objective outcomes was only significant for forward flexion (P = 0.02). Neither clinical outcome nor complication rate was different when compared to patients with regard to fracture type (3 versus 4 parts) or age (younger or older than 70 years). Fixation of displaced proximal humeral fractures with an angled blade plate provided sufficient stability. Blade perforation into the humeral joint occurred in every fourth patient and was found to be the major reason for a high complication rate. In view of this major problem, the technique described here cannot be recommended, even though the absence of nonunions in our series seems to support the low invasiveness of this surgical approach.
Article
Locked plating techniques recently have gained popularity and offer a different biomechanical approach for fracture fixation compared with traditional compression plating. In certain clinical situations, it may be preferable to employ a "hybrid" construct, in which an unlocked screw is used to assist with reduction and locked screws are subsequently used to protect the initial reduction. In the present study, we used an unstable osteoporotic fracture model of the humerus to determine (1) whether a hybrid construct behaved more like a locked construct or a conventional unlocked construct and (2) whether there was a difference between locked and unlocked constructs. Thirty third-generation Sawbones humeri were divided into three groups of ten humeri each. A locking plate with combination holes was applied to each bone with use of either a locked construct, an unlocked construct, or a hybrid construct. To simulate purchase in osteoporotic bone, all screw-holes were drilled to 0.3 mm less than the diameter of the screw used. Each specimen was then osteotomized in the middle part of the shaft, and a 5-mm segment was removed. Oscillating cyclic torsion testing was performed to +/-10 N-m for 1000 cycles, torsional stiffness was determined at periodic cyclic intervals, and the groups were compared. The locked and hybrid constructs demonstrated similar behavior. The initial stiffness was similar in these two groups. At ten cycles, the locked and hybrid constructs retained 96.3% and 95.4% of their initial stiffness, respectively. During the remainder of cycling the stiffness of the locked and hybrid constructs decreased in a linear fashion (R(2) = 0.89 and 0.88, respectively), and at 1000 cycles the stiffness of the locked and hybrid constructs averaged 80.0% and 79.2% of the initial values, respectively (p = 1.0). In contrast, the unlocked constructs initially were significantly less stiff than both the locked and hybrid constructs (p < 0.001). At ten cycles the unlocked constructs retained 80.4% of their initial stiffness, and at 1000 cycles they retained only 22.3% of their initial stiffness. Hybrid constructs are mechanically similar to locked constructs, and both are significantly more stable than unlocked constructs under torsional cyclic loading. Combining screws in the hybrid configuration used in the present study did not compromise the mechanical performance of the construct. Hybrid constructs may decrease cost and may provide additional clinical value when treating fractures in osteoporotic bone.
Article
Successful internal fixation of fractures of the surgical neck of the humerus can be difficult to achieve because of osteopenia of the proximal aspect of the humerus. The purpose of this study was to compare the biomechanical stability of a proximal humeral intramedullary nail and a locking plate for the treatment of a comminuted two-part fracture of the surgical neck in a human cadaver model. Twenty-four cadaveric humeri were instrumented with use of either a titanium proximal humeral nail (PHN) or a 3.5-mm locking compression plate for the proximal part of the humerus (LCP-PH). The specimens were matched by bone mineral density and were separated into four experimental groups with six humeri in each: PHN bending, LCP-PH bending, PHN torsion, or LCP-PH torsion. Comminuted fractures of the surgical neck were simulated by excising a 10-mm wedge of bone. Bending specimens were cyclically loaded from 0 to 7.5 Nm of varus bending moment at the fracture site. Torsion specimens were cyclically loaded to +/-2 Nm of axial torque. The mean and maximum displacement in bending, mean and maximum angular rotation in torsion, and stiffness of the bone-implant constructs were compared. In bending, the LCP-PH group demonstrated significantly less mean displacement of the distal fragment than did the PHN group over 5000 cycles (p = 0.002). In torsion, the LCP-PH group demonstrated significantly less mean angular rotation than did the PHN group over 5000 cycles (p = 0.04). A significant number of specimens in the PHN group failed prior to reaching 5000 cycles (p = 0.04). The LCP-PH implant created a significantly stiffer bone-implant construct than did the PHN implant (p = 0.007). The LCP proximal humeral plate demonstrated superior biomechanical characteristics compared with the proximal humeral nail when tested cyclically in both cantilevered varus bending and torsion. The rate of early failure of the proximal humeral nail could reflect the high moment transmitted to the locking proximal screw-bone interface in this implant. The high failure rate in torsion of the proximal humeral nail-bone construct is concerning, and, with relatively osteoporotic bone and early motion, the results could be poor.
Article
The aim of the study was to quantify the decrease in glenohumeral stability following a global rotator cuff tear and to evaluate the effect of a decreased glenoid inclination angle through analysis of muscle force vectors in a computer model. The lines of action of eight shoulder muscles were integrated into a standard geometric model. Muscle force magnitudes were estimated based on physiological cross-sectional area and normalized electromyographic activity. The magnitude and elevation angle of the resultant force vector was calculated at 0, 30, 60, and 90 degrees of abduction. A rotator cuff tear was simulated by reduction of the corresponding muscle force vectors. At 0 and 30 degrees of glenohumeral abduction a global rotator cuff tear showed a resultant force vector pointing outside the glenoid. In the computer model, decreasing the inclination angle of the glenoid by 30 degrees increased the stability in rotator cuff-deficient shoulders. The results of this study provide a biomechanical rationale for clinical complications of global rotator cuff tear such as superior humeral head translation. The decreased glenoid inclination simulated in the computer model may represent a biomechanical basis for the development of new operative techniques to treat global rotator cuff tears.
Article
Proximal fracture of the humeral head is the third most frequent fracture in humans. Most (70%) of those affected are over 60 years old. It is hoped that advanced locking medullary screws or plates will reduce the risk of secondary dislocation of screws or fracture segments when the bone of the humeral head is osteoporotic. From January 2002 to August 2005, 225 displaced humeral head fractures in 223 patients aged on average 66+/-15 years were treated with a new locking proximal humeral plate. In 176 patients in whom follow-up was possible, the average Constant Score after 9 months was 70+/-19 points (raw data), or 81+/-22% in the normalized score. No significant difference was detected between the younger group up to 65 years of age (73% points) and those over 65 years of age (80% points). Axial deviations by more than 30 degrees were noted in 11 (5%), and of 159 displaced tubercles, malreduction by more than 5 mm was noted in 14 (9%). Two infections and two haematomas had to be treated so far. Primary screw perforations were seen in 24 (11%) cases as well as further implant dislocations in 3 (1,7%). Plate dislocations out of the shaft existed in 4 (2,4%) and 14 collapses of the humeral head with secondary screw perforations were recorded. All other complications arose out of technical faults, such as 24 screw perforations (11%) into the glenohumeral joint and 3 (1.7%) cases of secondary implant dislocation from the humeral head and 5 (3%) from the shaft, and 14 (8%) sinterings with glenohumeral screw perforation. So far, in addition to 1 case of pseudarthrosis with a broken plate, 5 (3%) cases of total and 9 (5%) of partial avascular humeral head necrosis have been observed. The new implant provides superior stability in the fixation of humeral head fragments and has proved its worth in everyday clinical practice when additional indirect fixation of the tubercle is needed, as it frequently is in elderly patients.
Article
Locked plates (internal fixators) have been found to be an optimal method for the fixation in proximal humeral fractures. In a biomechanical cadaver study the difference between locked and non-locked osteosyntheses was investigated. Paired humeri were harvested, bone density measured. Locked internal fixators were mounted on one specimen; identical plate-screw-systems without locking mechanism applied to the contralateral specimen for comparison. After that, a transverse subcapital osteotomy was performed. With 7 pairs of humeri static tests with increasing axial loads and with 5 pairs dynamic tests with 10 N preload and 80 N maximal axial load for up to 1 million cycles were performed. In the static experiments the elastic stiffness of the construct was 74% higher in the locked group (median 80 N/mm, quartile range 77-86 N/mm) compared with the non-locked group (46 N/mm, 35.5-56.5 N/mm). The difference was statistically significant (Wilcoxon test for paired samples, P<0.05). Similarly, the linear range until failure was definitely extended in the locked group by 64% (92 N, 89-98 N vs. 56 N, 36.5-73.5 N, P<0.05). Under dynamic loading the non-locked group showed fixation failures between 97,000 and 500,000 cycles. In the locked group no failure was observed until the end of the experiment at 1 million cycles (P<0.0.5). The final deformation was found to be 1 mm (median, quartil range 1.0-1.2 mm) in the non-locked group and 0.3 mm (0.2-0.3 mm) in the locked group (P<0.05). The differences were found equally in lower as well as in higher bone density specimen. Because of the optimal load transfer between implant and cancellous bone, a locked screw plate interface will reduce fixation failure in proximal humeral fractures.
Article
The aim of this study was to describe early results of a new internal locking system, PHILOS, used for the treatment of proximal humeral fractures. A chart and radiographic review of 25 cases that had proximal humeral internal locking system (PHILOS) plate for the treatment of proximal humeral fractures was performed. Of the 25 cases, 20 went to union with a mean neck/shaft angle of 127.2 degrees . Five cases required or were considered for revision surgery for non-union or implant failure. Of the 25 implants, 4 had screw protrusion into the gleno-humeral joint, 4 had screw loosening and backing out, and 1 plate broke without further trauma. Our results suggest that PHILOS is an effective system for providing fracture stabilisation to bony union but awareness of potential hardware complications is essential.
Article
Fractures of the proximal humerus are common in elderly patients, especially in osteoporotic bone. Requirements for surgical treatment are high primary stability to allow early functional physiotherapy. The Non-Contact Bridging (NCB) Plate for the proximal humerus (PH) is a new head locking system for treating fractures of the proximal humerus which allows minimally invasive surgery (MIS). In this contribution, the implant and technique are described, as well as the analysis of the first clinical results after 61 procedures. In a mainly elderly patient population (mean: 73 years, range: 50-91 years) 61 minimally-invasive procedures were performed. The placement of screws led to a high primary stability. Primary implant failure occurred in one case (1.69%). The average constant score after 6 months was 62 points (age related mean 72). Using the MIS-technique, the NCB-PH plate provides high primary stability, allowing functional treatment without postoperative limitations. The first clinical results show a good functional outcome in a mainly elderly patient population.
Article
The purpose of this study was to determine what factors influence the maintenance of fracture reduction after locked plating of proximal humerus fractures, and particularly the role of medial column support. University medical center. Thirty-five patients who underwent locked plating for a proximal humerus fracture were followed up until healing. For the initial and final radiographs, 2 lines were drawn perpendicular to the shaft of the plate, one at the top of the plate and one at the top of the humeral head, and the distance between them was measured as an indicator of loss of reduction. Medial support was considered to be present if the medial cortex was anatomically reduced, if the proximal fragment was impacted laterally in the distal shaft fragment, or if an oblique locking screw was positioned inferomedially in the proximal humeral head fragment. Multivariate linear regressions were performed to determine the effects that age, sex, fracture type, cement augmentation, and medial support had on loss of reduction. The presence of medial support had a significant effect on the magnitude of subsequent reduction loss (P < 0.001). Age, sex, fracture type, or cement augmentation had no effect on maintenance of reduction. Eighteen patients were determined to have adequate mechanical medial support (+MS group), and the remaining 17 patients did not have medial support (-MS group). In the +MS group, the average loss of humeral head height was 1.2 mm, and 1 case of articular screw penetration occurred that required removal. In the -MS group (without an appropriately placed inferomedial oblique screw and either nonanatomic humeral head malreduction with lateral displacement of the shaft or medial comminution), loss of humeral height averaged 5.8 mm (P < 0.001). There were 5 cases in this group in which screw penetration of the articular surface occurred (P = 0.02), 2 of which required reoperation for removal. All fractures in both groups healed without delay, and none required revision to arthroplasty. Achieving mechanical support of the inferomedial region of the proximal humerus seems to be important for maintaining fracture reduction. Locked plates in general do not appear to be a panacea for these fractures and are unable to support the humeral head alone from a lateral tension-band position. However, there are several factors that are in the surgeon's control that may improve the mechanical environment. Achieving an anatomic or slightly impacted stable reduction, as well as meticulously placing a superiorly directed oblique locked screw in the inferomedial region of the proximal fragment, may achieve more stable medial column support and allow for better maintenance of reduction.