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Fixation considerations in osteoporotic bone fractures
Abstract
Purpose of review: Osteoporosis compromises the structural strength of bone, making fracture fixation a surgical challenge. Special strategies and newly designed locking plate fixation enhance the surgeon's ability to treat these fractures. This essay reviews these developments.
Recent findings: Conventional plate and screw fixation achieves stability by creation of a friction force between the plate and bone. Osteoporotic bone, especially in metaphyseal areas, is too weak to allow sufficient screw torque to be generated for development of stability in plated fractures. Modified techniques that achieve load sharing improve the results of fracture repair in these cases. Locking plate fixation, which creates a single beam construct not relying on the generation of a friction force, is a significant advantage in osteoporotic fracture care. Early experience with the use of locking plates designed for various specific fractures suggests that this new technology results in enhanced fixation and better clinical outcomes.
Summary: Surgeons must apply specific techniques that incorporate load sharing when surgically managing osteoporotic fractures. Locking plates will offer a significant advantage compared with conventional plates when treating fractures in osteoporotic bone.
... It is recommended using longer plates with fewer screws spread over a longer working distance from the fracture to increase the bending resistance and flexibility [17,18]. Rigidity of the construct and a large gap between the fragments are the limitations in using of locking plates, which are leading especially to non-union [6][7][8][9][10][11][12][13][14][15][16][17][18][19]. ...
... Internal fixation of secondary osteoporotic fractures using intramedullary nails, allows the patients to start early weight bearing movement avoiding important complications due to prolonged immobilization [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. This osteosynthesis method also protects the soft tissues around the fracture site [20,21]. ...
... Another new type of nails with the option of using interlocking screws in multiple planes helped improve fracture stability and decrease the risk of malunion [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]. ...
... The new technology results in enhanced fixation and better clinical outcome, Locking plates will offer a significant advantage compared with conventional plates when treating fractures in osteoporotic bone. 10 In 2007 Stern R concludes in a study that While the rate of failure following hip fracture surgery for extracapsular hip fractures in the elderly is low In general, a well-executed osteosynthesis is the best assurance of a good outcome with few complications, and typically a less than ideal placement of the implant in the femoral head is the reason for cut-out and failure of the operation. However, what is less clear is whether there are newer ideas and/or implant designs that represent true advances in the treatment of extracapsular fractures in the elderly. ...
Background: The hip joint transmits weight several times that of the body weight particularly during running, functioning as both a highly mobile and very stable joint. In weight bearing the pressure forces are transmitted to the head and neck of the femur at an angle of 1650 to 1700, regardless of the position of pelvis. The planes of force coincide with strongly developed trabeculae. The reacting force normally runs perpendicular to the cartilaginous epiphyseal plate. The mechanism of bone failure in a structure will fail if it suffers an overload situation. An overload situation will occur if the system is unable to absorb the energy that is applied to it. In the hip joint area this overload situation can occur as a result of number of independent but often interrelated factors. The present work is conducted to study the; profiles of patients with extra capsular fracture neck of femur, efficiency and outcome of fractures treated with Proximal Femoral Locking Compression Plate (PFLCP), intra - operative & post-operative complication following management of extra capsular fracture neck of femur with Proximal Femoral Locking Compression Plate. Methods: This is a prospective study of 21 cases of extra capsular fracture neck of femur admitted to Victoria and Bowring and Lady Curzon Hospitals, Bangalore, treated with PFLCP. Results: In our study of 21 cases, cases 13 cases were intertrochanteric fracture and remaining 8 were subtrochanteric fracture with the mean age was 51.47 years. Minimum age was 19 years and maximum age was 85 years. 14 patients (67%) were males and 7 patients (33%) were females, 13 IX patients (62%) had right-sided fracture and 8 patients (38%) had left-sided fracture. with right side being more common side affected. The average duration of stay in the hospital was 25.31 days. The average follow up was 18 months [11 to 23 months]. Out of 21 patients in our study 16 patients (76%) are able to sit cross-legged and can squat on ground without any problem. The functional results were graded according to Harris Hip Scoring, In our study, 10 patients (48%)had excellent results, 8 patients (38%)had good results, 2 patients (10%)had poor result, and 1 failed case (5%) as she is an elderly female of 85 years with limited activity both preoperatively due to physiological age and general weakness. Conclusions: In conclusion the potentiality of the Proximal Femoral Locking Compression Plate (PF-LCP) in varied indications, shows its versatility. Although not free of complications our study has demonstrated excellent results. The procedure offers, faster mobilization, rapid return to activities of daily living, improves the quality of life and gave a long term solution in patients with extracapsular fracture neck of femur. Larger studies with longer follow up will further validate the procedure.
... Such forces and stresses are not developed in the nail constructs because of the implants position in the IM canal and its ability to act as a load sharing device. These findings support the hypothesis of Perren (2002) and Cornell (2005) which stated that when a large fracture gap or absent far cortex is present, a rigid plate fixation will focus the strain and increase the risk of failure in bending. A recent biomechanical study by Bottlang et al. (2009) investigated failure loads and failure modes in conventional plating, locked plating and hybrid plating designs. ...
The following is Part B of a two-part study. Part A evaluated, biomechanically, intramedullary (IM) nails versus locking plates for fixation of an extra-articular, metaphyseal wedge fracture in synthetic osteoporotic bone. Part B of this study introduces deterministic finite element (FE) models of each construct type in synthetic osteoporotic bone and investigates the probability of periprosthetic fracture of the locking plate compared with the retrograde IM nail using Monte Carlo simulation. Deterministic FE models of the fractured femur implanted with IM nail and locking plate, respectively, were developed and validated using experimental data presented in Part A of this study. The models were validated by comparing the load-displacement curve of the experimental data with the load-displacement curve of the FE simulation with a root-mean square error of less than 3 mm. The validated FE models were then modified by defining the cortical and cancellous bone modulus of elasticity as uncertain variables that could be assumed to vary randomly. Monte Carlo simulation was used to evaluate the probability of fracture (POF) of each fixation. The POF represents the cumulative probability that the predicted shear stresses in the cortical bone will exceed the expected shear strength of the cortical bone. This investigation provides information regarding the significance of post-operative damage accumulation on the POF of the implanted bones when the two fixations are used. The probabilistic analysis found the locking plate fixation to have a higher POF than the IM nail fixation under the applied loading conditions (locking plate 21.8% versus IM nail 0.019%).
Background: Dynamic hip screw (DHS) is a standard internal fixation for intertrochanteric fracture, whereas the patient combined with osteoporosis, cut-out incidence of lag screw is common. The articles in China and abroad indicate bone cement augmentation of DHS to achieve firni fixation. As for normal bone, no reports is published that whether bone cement augmentation is effective. Objective: To investigate the biomechanics of DHS with bone cement augmentation for the fixation of intertrochanteric fracture specimen that has a normal bone density. Design, Time and Setting: Bilateral contrast observation study of the same sample was performed in the Laboratory of Biomechanics, Hebei Orthopaedic Research Institute (Shijiazhuang, Hebei Province, China) between March and April in 2005. Materials: Bilateral upper femora from the embalmed male cadaver were provided by Anatomy Department of Hebei Medical University (China). X-ray scan results proved the absence of tuberculosis, anatomical deformity and tumor. Methods: Twenty-four matched pairs of the upper femora (48 sides) were used to make the specimens of the intertrochanteric fracture of type A2. The right femur specimens were fixed with DHS augmented by bone cement, as the augmentation group (The screw track of femoral neck was expended by curette, and the femoral bead facing upwards were injected with 2 mL low viscosity bone cement. Then lag screw was wrested to keep the position unchanged till the bone cement coagulated. Placing barrel, compressing through tighten tail screw, and cortical screw fixing side-plate were followed). And the left femur specimen was fixed with DHS conventional fixation, as the control group. The bending and torsional tests were performed in the two groups. Main Outcome Measures: The maximum load and the maximum torque in the two groups. Results: The maximum load and the maximum torque were (3 852.160 2±143.603 1) N and (15.5±2.6) Nm in the augmentation group, and (3 702.966 7±133.860 1) N and (14.7±3.4) Nm in the control group. There was no significant difference in the biomechanical effects between the two groups (P > 0.05). Conclusion: The augmenting fixation with bone cement for intertrochanteric fracture specimen has no significant effect on the strength of DHS fixation or on the overall stability of the fractured bone in normal bone density.
Musculoskeletal problems, including bone and joint pathologies are among the main causes of chronic pain, physical disability, and work absenteeism in both developed and developing countries, and they affect millions of people worldwide. This is the reason why biomaterials play a key role in bone repair and regeneration. In this chapter, the societal impact of musculoskeletal diseases, as well as other bone problems is discussed in terms of their costs and the degree of physical disability that they generate. In addition, some of the most relevant clinical challenges in bone repair are presented.
Introduction
Osteoporotic fractures in the elderly are often complicated by delayed union, pseudarthrosis or implant failure and are associated with considerable morbidity and prolonged reconvalescence. At present there is cumulating recommendation to treat this kind of fractures with angular stable implants.
Case presentation
Herein, we report on the successful definitive treatment of a displaced comminuted spiral-fracture of the distal humerus shaft in an 89-year-old woman after two attempts of internal fixation with angular stable implants had failed in severely osteoporotic bone.
Conclusion
The present case illustrates the problems we have faced with after
a single locking plate fixation, especially in poor bone, and shows a possible
solution by performing a double(-locking)-plate fixation.
Osteoporotic fractures represent one of the most common cause of disability and one of the major voice in the health economic budget in many countries of the world. Fragility fractures are especially meta-epiphyseal fractures, in skeletal sites with particular biomechanic characteristic (hip, vertebrae), complex and with more fragments, with slow healing process (mineralization and remodeling) and co-morbidity. The healing of a fracture in osteoporotic bone passes through the normal stages and concludes with union of the fracture although the healing process is prolonged. Fractures in the elderly osteoporotic patients represent a challenge to the orthopaedic surgeons. Osteoporosis does not only increase the risk of fracture but also represents a problem in osteofixation of fractures in fracture treatment. The major technical problem that surgeons face, is the difficulty to obtain a stable fixation of an implant due to osteoporotic bone. The load transmitted at the bone-implant interface can often exceed the reduced strain tolerance of osteoporotic bone.IN THE TREATMENT OF OSTEOPOROTIC FRACTURES IT IS IMPORTANT TO CONSIDER DIFFERENT ASPECTS: general conditions of elderly patient and comorbidity, the reduced muscular and bone mass and the increased bone fragility, structural modifications as medullary expansion.The aim of surgical treatment is to obtain a stable fixation that reduces pain and permits an early mobilization.
Osteoporosis is a public health issue that leads to increased morbidity and dependency in an increasing population. Fractures in osteoporotic bone have been a contraindication to internal fixation due to their past poor results. Various treatment methods and innovations have been attempted that have met with some success. This paper reviews one such innovation, locking-plate osteosynthesis, looking at its technology and success and its role in osteoporotic patients. As this is an evolving technology, surgeon's experience with these plates and screws are in advance of clinical studies and therefore the surgeons should proceed with caution when choosing locking plate technology in the treatment of osteoporotic fractures.
We determined the current trends in the number and incidence of osteoporotic fractures of the proximal humerus in Finland by collecting from the National Hospital Discharge Register all patients 60 years of age or more who were admitted to Finnish hospitals in 1970-1998 for primary treatment of such fractures. The fracture was defined osteoporotic if it was caused by a low-energy trauma only, i.e., a fall from standing height or less. The number and incidence (per 10(5) persons) of fractures increased sharply from 208 (number) and 32 (incidence) in 1970 to 1,105 and 110 in 1998. Even after the age-adjustment, the incidence of fractures showed a clear increase: in women from 50 in 1970 to 133 in 1998, and in men from 14 in 1970 to 49 in 1998. If this trend continues, there will be three times more osteoporotic fractures of the proximal humerus in Finland in the year 2030 than there were in 1998.
Controversy in the treatment of displaced femoral neck fractures in the elderly focuses on the use of fixation versus the use of a prosthesis. Beginning in 1980, at The New York Hospital-Cornell Medical Center, it became routine to treat elderly patients for displaced fractures with bipolar hemiarthroplasty. This retrospective study evaluates the morbidity, mortality, and clinical and social functioning of 246 consecutive patients treated with bipolar hemiarthroplasty for Garden III and Garden IV nonpathological fractures. Follow-up ranged from 1 to 6 years. Of the 246 patients with 247 femoral neck fractures, 201 were female and 45 were male; the average age was 78 years. Fourteen patients (5.7%) died during the postoperative hospitalization. Thirty-one patients (13.3%) died within the first year following surgery. Mortality was related to the number of preexisting medical conditions: patients with four or more preexisting conditions had a significantly higher mortality than others (p less than 0.001: chi 2). The overall wound infection rate was 3.2%. There were only two failures (0.9%), both for deep infection, requiring Girdlestone debridement. One patient was revised for infection with successful reimplantation. There were two postoperative dislocations (0.9%), both reduced closed. Only one bipolar (0.4%) required conversion to a total hip replacement for a fractured acetabulum, none for arthritic wear. No radiographic evidence of significant acetabular erosion or protrusion nor femoral component loosening was noted. Clinical results were evaluated using the Hospital for Special Surgery Hip Rating Scale.(ABSTRACT TRUNCATED AT 250 WORDS)
Our purpose was to study the relationship between the number of plate holes filled and the spacing between the screws and the resultant strength of plated constructs. Broad regular DC plates were anchored with 4.5-mm cortical screws to blocks of polyurethane foam. Six constructs were tested: (a) screws in holes 1, 2, and 3; (b) screws in holes 1 and 3; (c) screws in holes 1 and 4; (d) screws in holes 1 and 5; (e) screws in holes 1 and 6; (f) screws in holes 1, 3, and 5. The strength was quantified using a material-testing system. In cantilever and four-point bending, the constructs were loaded in both gap-closing and gap-opening modes. Screws in holes 1, 2, and 3 were tested against other constructs. For cantilever bending (gap opening and gap closing), construct (a) was stronger than construct (b), as strong as construct (c), but weaker than the constructs with more widely spaced screws (p < 0.0001). In terms of four-point bending, for gap opening, the standard fixation (construct (a) was stronger than construct (b) but weaker than the more widely spaced constructs. For gap closing, construct (a) was stronger than constructs (b) and (c) but weaker than the rest. Regardless of the spacing of screws and the plate length, strength in torsion was dependent on the number of screws securing the plate. In a laboratory fracture model of plate-bone constructs tested to failure by screw pullout, wider spacing of bone screws increases the bending strength of screw-plate fixation and can be more effective than increasing the number of screws. Torsional strength is independent of screw placement in plates of a given width and depends on the number of screws used.
This investigation considers the effect of a variety of screw positions on plate strain in three fracture models.
Dynamic compression plate fixation of in vitro fracture models.
To model a fracture, a plastic pipe was cut transversely and a twenty-hole dynamic compression plate was attached by screws. Eighteen stacked, rectangular, rosette strain gauges were installed on the plate to evaluate strain. Three models were evaluated: two constructs in which there was no contact between the cut ends of the pipe under the fixation plate (small-and large-gap models) and a construct in which there was direct apposition of the cut ends (no-gap model). The pattern and magnitude of strains were assessed as a function of varying combinations of screw position for each model.
Maximal plate strain in the gap models was lowest with screws placed closest to the gap, compared with screws placed away from the gap or spaced apart. The no-gap model showed significantly lower strains when screws were placed further from the osteotomy site than when screws were positioned close together or spaced apart. In all cases, maximal plate strain occurred adjacent to the most central screw holes and rapidly dissipated along the length of the plate.
In a model simulating a comminuted fracture (gap), this study found that screws should be placed as close to the fracture site as possible to minimize plate strain. In an anatomically reduced two-part fracture model (no gap), widely spaced screws or those placed away from the fracture resulted in lower strains.
We investigated the biomechanical performance of a compression hip screw with four reversibly deployable talons. We hypothesized that the talons would increase purchase strength of the lag screw and prevent rotation of the femoral head by resisting torsional forces between the lag screw and the femoral head.
Reproducible, stable two-part intertrochanteric fractures were created on matched pairs of embalmed human femurs. Fractures were fixed using the compression hip screw with either the talons deployed (talon) or not deployed (screw) configuration. Pre- and postimplantation radiographs and dual energy x-ray absorptiometry scans were used to ensure geometric and balanced equivalency between contralateral limbs. Torsional tests were performed on femoral pairs at 1 Hz for 5000 cycles prior to torque failure. Compression tests were performed on femoral pairs with the screw in the inferior or central position.
Peak torque and torque at 15 degrees of rotation were significantly greater for the talon versus screw device (6.5 +/- 1.7 Nm vs. 1.9 +/- 1.7 Nm for peak torque, P = 0.0002; and 4.2 +/- 2.0 Nm vs. 1.2 +/- 1.2 Nm for torque at 15 degrees rotation, P = 0.003). The peak compressive forces generated by the talon device were significantly greater than for the screw device in the inferior position (P = 0.005), with compression values of 1398 +/- 467 N and 713 +/- 323 N, respectively. Peak compression forces did not differ significantly between talon and screw devices in the central position.
Talon deployment significantly improved interfragment compression and torsional strength. Engagement or penetration into or through the cortical bone at the base of the femoral head-neck junction in the inferior lag screw position is the critical technical step to maximize the talon purchase.
The Locking Compression Plate (LCP), in combination with the LISS and the PHILOS, is part of a new plate generation requiring an adapted surgical technique and new thinking about commonly used concepts of internal fixation using plates. The following guidelines are needed to avoid failures and possible complications in the hands of surgeons not yet confident with the new implant philosophy. The importance of the reduction technique and minimal-invasive plate insertion and fixation is addressed to keep bone viability undisturbed. Understanding of mechanical background for choosing the proper implant length and the type and number of screws is essential to obtain a sound fixation with a high plate span ratio and a low plate screw density. A high plate span ration decreases the load onto the plate. A high working length of the plate in turn reduces the screw loading, thus fewer screws need to be inserted and the plate screw density can be kept low. Knowledge of the working length of the screw is helpful for the proper choice of monocortical or bicortical screws. Selection is done according to the quality of the bone structure and is important to avoid problems at the screw thread bone interface with potential pullout of screws and secondary displacement. Conclusive rules are given at the end of this chapter.
A retrospective analysis of a compression hip screw with four reversibly deployable talons was done. Fifty-four patients had sufficient radiographs to be included in this analysis. One-year mortality was 17% and increased to 41% by 2 years. No lag screws cut out, and postoperative slide was reduced compared with that in many published series. Three patients had revision of a failed alternate-type hip pin with the Talon hip compression screw. Previous studies showed the talons provide the definitive difference in allowing enhanced compression at the time of surgery, preventing cut-out by enhanced rotational stability, and allowing immediate postoperative weightbearing without excessive limb shortening. The failure mode of the Talon compression hip screw seems to be side-plate loosening rather than varus deformity and lag screw cut-out. The Talon compression hip screw especially is effective with weak, osteoporotic bone and in unstable, three-part and four-part fractures. A previous study showed that Talon deployment notably improved interfragment compression and torsional strength, and that engagement or penetration into or through the cortical bone at the base of the femoral head-neck junction in the inferior lag screw position was the critical technical step to maximize the talon lag screw purchase.
Osteoporosis is a major public health problem that is characterized by low bone mass and structural deterioration of bone tissue, leading to bone fragility and an increased susceptibility to fractures of the hip, spine, and wrist. Poor bone quality in patients with osteoporosis presents the surgeon with difficult treatment decisions. Bone fracture repair has more pathways with combinations of bone formation mechanisms, which depend on the type of fracture fixation to be applied to achieve the desirable immobilization. There only may be one remodeling principle and in less than ideal conditions, mechanical and biophysical stimuli may provide effective augmentation of fracture healing in elderly patients. A different stimulus may limit its association to a specific healing mechanism. However, no matter which fixation method is used, an accurate reduction is a requisite for bone healing. Failure to realign the fracture site would result in delayed union, malunion, or nonunion. Therefore, a basic understanding of the biomechanics of osteoporotic bone and its treatment is necessary for clinicians to establish appropriate clinical treatment principles to minimize complications and enhance the patient's quality of life. We describe the biomechanical considerations of osteoporosis and fracture treatment from various aspects. First, bone structure and strength characterization are discussed using a hierarchical approach, followed by an innovative knowledge-based approach for fracture reduction planning and execution, which particularly is beneficial to osteoporotic fracture. Finally, a brief review of the results of several experimental animal models under different fracture types, gap morphologic features, rigidity of fixation devices, subsequent loading conditions, and biophysical stimulation is given to elucidate adverse mechanical conditions associated with different bone immobilization techniques that can compromise normal bone fracture healing significantly.
To review the biomechanical principles that guide fracture fixation with plates and screws; specifically to compare and contrast the function and roles of conventional unlocked plates to locked plates in fracture fixation. We review basic plate and screw function, discuss the design rationale for the new implants, and examine the biomechanical evidence that supports the use of such implants.
Systematic review of the per reviewed English language orthopaedic literature listed on PubMed (National Library of Medicine online service).
Papers selected for this review were drawn from peer review orthopaedic journals. All selected papers specifically discussed plate and screw biomechanics with regard to fracture fixation. PubMed search terms were: plates and screws, biomechanics, locked plates, PC-Fix, LISS, LCP, MIPO, and fracture fixation.
The following topics are discussed: plate and screw function-neutralization plates and buttress plates, bridge plates; fracture stability-specifically how this effects gap strain and fracture union, conventional plate biomechanics, and locking plate biomechanics.
Locked plates and conventional plates rely on completely different mechanical principles to provide fracture fixation and in so doing they provide different biological environments for healing. Locked plates may increasingly be indicated for indirect fracture reduction, diaphyseal/metaphyseal fractures in osteoporotic bone, bridging severely comminuted fractures, and the plating of fractures where anatomical constraints prevent plating on the tension side of the bone. Conventional plates may continue to be the fixation method of choice for periarticular fractures which demand perfect anatomical reduction and to certain types of nonunions which require increased stability for union.
Unlabelled:
In a prospective study, 28 patients with 29 proximal humeral fractures were treated with the Locking Proximal Humerus Plate from 2001-2002. Most of these fractures were complex, Type B (n = 15) and Type C (n = 9) fractures, according to the AO classification. Followups included radiographs, clinical examinations, and recording Constant scores. After 1 year, the average Constant score for all fractures was 74.6 (range, 37-96). For Type A fractures, it was 82.6 (range, 60-96), for Type B it was 78.3 (range, 37-95), and for Type C it was 64.6 (range, 40-91). Complications related to the implant included breakage of the plate in one patient and redislocation of the fracture in four patients (one fracture was associated with deep infection), which required reoperation in two patients. Partial osteonecrosis was seen in two patients, once after deep infection. There were no nonunions. Our data show that using the Locking Proximal Humerus Plate for treatment of proximal humeral fractures of all types is a reliable procedure, with good results being obtained with careful planning and familiarity with the special features of the operative technique.
Level of evidence:
Therapeutic study, Level II-1 (prospective cohort study).