Publications (36)51.7 Total impact
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Article: Reduction of Pullout Strength Caused by Reinsertion of 3.5-mm Cortical Screws.
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ABSTRACT: INTRODUCTION:: Osteosynthesis of the tibia, tibial plafond, and calcaneus is commonly performed with plates and 3.5-mm self-tapping cortical screws. Screw insertion and reinsertion within the same hole in the bone may occur during surgery. Therefore, the purpose of this study was to evaluate the pullout strength of 3.5-mm self-tapping screws with up to 5 re-insertions in the diaphysis of the tibia, metaphysis of the distal tibia, calcaneus, and a polyurethane synthetic bone model. METHODS:: Screws were inserted into a synthetic bone model and 5 pairs of human cadaveric diaphyseal tibiae, distal tibiae, and calcanei. The bone was predrilled, and then 3.5-mm cortical self-tapping 316 L stainless steel screws with a washer were inserted bicortically. Screws were inserted from 1 to 5 times at each location. The screws were grasped and subjected to 5-mm/min tensional force via the biaxial material testing systems machine. Statistical significance was determined using a paired 2-tailed t test. RESULTS:: There was a significant difference in the pullout strength of the tibial diaphysis (1710 ± 550 N), tibial metaphysis (471 ± 266 N), and calcaneus (238 ± 90 N; P < 0.01). The tibial diaphysis pullout strength was 1710 ± 550 N for one insertion differing significantly relative to the groups with 4 (average 1030 ± 543 N, P = 0.004) or 5 (average 364 ± 209 N, P < 0.001) insertions. The tibial metaphyseal pullout strength for the single insertion group was 471 ± 266 N and differed significantly relative to the 3 (P = 0.026), 4 (P = 0.044), and 5 (P = 0.042) insertion groups. The calcaneal pullout strength for the single insertion group was 238 ± 90 N with a significant difference of the 1, 3, and 4, versus the 5 insertion group (P = 0.027, 0.040, and 0.033, respectively). The synthetic bone model pullout strength decreased significantly from the one insertion group relative to all other insertion groups (group 1, 1167 ± 263 N; group 2, 768 ± 199 N; group 3, 694 ± 295 N; group 4, 662 ± 356 N; and group 5, 154 ± 183 N; P < 0.02). CONCLUSIONS:: There is a significant decrease in relative pullout strength of 3.5-mm self-tapping cortical screws when comparing the tibial diaphysis, tibial metaphysis, and calcaneus. There is also a significant decrease in 3.5-mm self-tapping screw pullout strength after repeated reinsertions in the synthetic bone model, mid-shaft tibia, metaphyseal tibia, and calcaneus. We recommend that during osteosynthesis, careful screw insertion, and minimal reinsertion be performed.Journal of orthopaedic trauma 04/2012; · 1.78 Impact Factor -
Article: Bone remodeling after total hip arthroplasty with a short stemmed metaphyseal loading implant: Finite element analysis validated by a prospective DEXA investigation.
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ABSTRACT: In total hip arthroplasty (THA), short stemmed cementless implants are used because they are thought to stimulate physiological bone remodeling and reduce stress shielding. We performed a numerical investigation on bone remodeling after implantation of a specific short stemmed implant using finite element analysis (FEA). Overall bone mass loss was 2.8% in the entire femur. Bone mass decrease was mostly found in the proximal part of the calcar and in the greater trochanter due to the vast cross section of the implant, probably leading to stress shielding. In the diaphysis, no change in the apparent bone density was proven. The assumptions made agreed well with bone remodeling data from THA recipients who underwent dual-energy X-ray absorptiometry. However, the clinical investigation revealed a bone mass increase in the minor trochanter region that was less pronounced in the FEA. Further comparisons to other stem designs must be done to verify if the relative advantages of the investigated implant can be accepted. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 30:1822-1829, 2012.Journal of Orthopaedic Research 04/2012; 30(11):1822-9. · 2.81 Impact Factor -
Article: Minimally invasive osteotomy for symptomatic bunionette deformity is not advisable for severe deformities: a critical retrospective analysis of the results.
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ABSTRACT: Bunionette, or tailor's bunion, is a painful protrusion on the plantar and/or lateral aspect of the fifth metatarsal head. Until recently, there have been very good results reported in literature when minimally invasive therapy is used to treat this deformity. In this study, the authors critically review the outcome of patients operated by the minimal invasive technique. A total of 31 feet were retrospectively reviewed with a mean follow-up of 52 months (range 14-106 months). The results were related to the preoperative severity of the bunionette deformity. The mean intermetatarsal angle IV/V was reduced from 12° to 7.5° postoperatively. The American Orthopaedic Foot and Ankle Society score showed good and excellent values (80-100 points) at follow-up in 16 (12 type I, 4 type III) feet. Fourteen (2 type I, 5 type II, 7 type III) feet were rated as satisfactory (60-80 points) and one (type III) foot with fair (56 points). Nine patients (5 type II and 4 type III) indicated that they would not undergo the operative procedure again. Our results show inclusive evidence that minimal invasive osteotomies have a good clinical outcome in the treatment of high-grade deformities. The best future option is to consider the classification of the deformity before a minimally invasive operation is to take place.Foot & Ankle Specialist 01/2012; 5(2):91-6. -
Article: Biomechanical in vitro - stability testing on human specimens of a locking plate system against conventional screw fixation of a proximal first metatarsal lateral displacement osteotomy.
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ABSTRACT: The aim of this study was to examine resistance to angulation and displacement of the internal fixation of a proximal first metatarsal lateral displacement osteotomy, using a locking plate system compared with a conventional crossed screw fixation. Seven anatomical human specimens were tested. Each specimen was tested with a locking screw plate as well as a crossed cancellous srew fixation. The statistical analysis was performed by the Friedman test. The level of significance was p = 0.05. We found larger stability about all three axes of movement analyzed for the PLATE than the crossed screws osteosynthesis (CSO). The Friedman test showed statistical significance at a level of p = 0.05 for all groups and both translational and rotational movements. The results of our study confirm that the fixation of the lateral proximal first metatarsal displacement osteotomy with a locking plate fixation is a technically simple procedure of superior stability.The Open Orthopaedics Journal 01/2012; 6:133-9. -
Article: Reply to comments on the article: Bone remodelling around the Metha short stem in total hip arthroplasty: a prospective dual-energy X-ray absorptiometry study.
International Orthopaedics 12/2011; 36(3):681-2. · 2.03 Impact Factor -
Article: Reconstruction of the patella with an autogenous iliac graft: clinical and radiologic results in thirteen patients.
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ABSTRACT: Extension lag, quadriceps weakness and subluxation of the extensor apparatus are known complications of patellectomy. In the case of total knee joint replacement with a nonconstrained system an instability may be encountered. Reconstruction of the patella allows restoration of the moment arm to improve quadriceps leverage. The goal of our study was to analyse the clinical and radiological results after reconstruction of the patella with an autogenous iliac graft. 13 previously patellectomized patients had reconstruction of the patella with an autogenous iliac graft and were retrospectively studied by clinical and radiographic examination. For evaluation we used the scores of Feller and the Knee Society. Also, all complications were recorded. After an average follow-up of 40.1 months, nine patients had full strength of the quadriceps, while six had an improved function of the extensor apparatus. The mean Feller score was 21.8 and the Knee Society score was 67.3 for knee and 57.5 for function. Six complications occurred including three infections, two problems with the replaced patella and one fracture of the anterior superior iliac spine. Reconstruction of the patella with an autogenous iliac graft enables the strength of the extensor apparatus with restoration of the knee joint.International Orthopaedics 05/2011; 36(3):545-52. · 2.03 Impact Factor -
Article: Quadriceps force after TKA with femoral single radiusAn in vitro study
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ABSTRACT: Background and purpose New implant designs have incorporated a single radius instead of a multiple radius to the femoral component in order to improve the mechanical function after TKA. We investigated the amount of quadriceps force required to extend the knee during an isokinetic extension cycle of different total knee designs, focusing on the radius of the femoral component (single vs. multiple). Methods Human knee specimens (n = 12, median patient age 68 (63–70) years) were tested in a kinematic knee-simulating machine untreated and after implantation of 2 types of knee prosthesis systems, one with a single femoral radius design and one with a multiple femoral radius design. During the test cycle, a hydraulic cylinder, which simulated the quadriceps muscle, applied sufficient force to the quadriceps tendon to produce a constant extension moment of 31 Nm. The quadriceps extension force was measured from 120° to full knee extension. Results The shape of the quadriceps force curve was typically sinusoidal before and after TKA, reaching a maximum value of 1,493 N at 110°. With the single femoral radius design, quadriceps force was similar to that of the normal knee: 1,509 N at 110° flexion (p = 0.4). In contrast, the multiple femoral radius design showed an increase in quadriceps extension force relative to the normal knee, with a maximum of 1,721 N at 90° flexion (p = 0.03). Interpretation The single femoral radius design showed lower maximum extension forces than the multiple femoral radius design. In addition, with the single femoral radius design maximum quadriceps force needed to extend a constant extension force shifted to higher degrees of knee flexion, representing a more physiological quadriceps force pattern, which could have a positive effect on knee function after TKA.05/2011; 82(3):339-343. -
Article: Taylor spatial frame in severe foot deformities using double osteotomy: technical approach and primary results.
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ABSTRACT: The treatment of severe foot deformities in children or adolescents is complex and demanding to the surgeon. This paper describes the technical strategy of using a Taylor spatial frame and reports on the functional outcome. The Taylor spatial frame was used by a single surgeon in patients with severe foot deformities. Seven patients with eight severe deformities were treated. Mean patient age at surgery was 15.1 (9-29) years. A double Taylor spatial frame reconstruction was mounted to the limb. All patients had a midtarsal osteotomy and an additional inverse dome-shaped calcaneus osteotomy. Assessed measures were pre- and postoperative deformity and associated complications and clinical results according to Ferreira et al. Mean follow-up was 576.5 (359-987) days. The final functional outcome according to Ferreira was good in seven cases, fair in none, and poor in one. Early complications included pin-tract infection, temporary hypoesthesia, and temporary shortening of the tendon of the M. flexor digitorum. At follow-up there was no deformity recurrence. In children or adolescents, the innovative treatment using the Taylor spatial frame and a double osteotomy allows joint-preserving correction of severe foot deformities. However, the complication rate is relatively high due to the severely deformed feet. Furthermore, the Taylor spatial frame is expensive. Thus, this treatment is only recommended for severe foot deformities and should be handled by experienced orthopedic surgeons.International Orthopaedics 05/2011; 35(10):1489-95. · 2.03 Impact Factor -
Article: Quadriceps force after TKA with femoral single radius.
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ABSTRACT: New implant designs have incorporated a single radius instead of a multiple radius to the femoral component in order to improve the mechanical function after TKA. We investigated the amount of quadriceps force required to extend the knee during an isokinetic extension cycle of different total knee designs, focusing on the radius of the femoral component (single vs. multiple). Human knee specimens (n = 12, median patient age 68 (63-70) years) were tested in a kinematic knee-simulating machine untreated and after implantation of 2 types of knee prosthesis systems, one with a single femoral radius design and one with a multiple femoral radius design. During the test cycle, a hydraulic cylinder, which simulated the quadriceps muscle, applied sufficient force to the quadriceps tendon to produce a constant extension moment of 31 Nm. The quadriceps extension force was measured from 120° to full knee extension. The shape of the quadriceps force curve was typically sinusoidal before and after TKA, reaching a maximum value of 1,493 N at 110°. With the single femoral radius design, quadriceps force was similar to that of the normal knee: 1,509 N at 110° flexion (p = 0.4). In contrast, the multiple femoral radius design showed an increase in quadriceps extension force relative to the normal knee, with a maximum of 1,721 N at 90° flexion (p = 0.03). The single femoral radius design showed lower maximum extension forces than the multiple femoral radius design. In addition, with the single femoral radius design maximum quadriceps force needed to extend a constant extension force shifted to higher degrees of knee flexion, representing a more physiological quadriceps force pattern, which could have a positive effect on knee function after TKA.Acta Orthopaedica 05/2011; 82(3):339-43. · 2.17 Impact Factor -
Article: Correction of severe foot deformities using the Taylor spatial frame.
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ABSTRACT: This study was conducted to evaluate the treatment of severe foot deformities using the Taylor spatial frame. The treatment of seven patients with nine severe foot deformities was reviewed. The mean age of the patients at surgery was 16 years with a mean followup of 21.5 months. The following parameters were assessed: etiology of deformity, date of surgery, surgical procedure, age at surgery, previous surgical or conservative treatments, preoperative symptoms, preoperative and postoperative deformity and affected side, complications during correction, duration of TSF, duration of hospital stay, occurrence of secondary osteoarthritis, recurrence of deformity, surgical revisions or subsequent surgeries. The pre- and postoperative deformity was assessed clinically. The final outcome was categorized as good, fair, or poor. The results were good in eight feet and poor in one foot. Early complications included pin tract infection, temporary hypoesthesia and temporary shortening of the tendon of the flexor digitorum longus. Recurrence of deformity occurred in no patient. One patient required a subtalar arthrodesis for symptomatic, secondary osteoarthritis in one foot. The present study showed that TSF is a viable solution to correct severe foot deformities but we believe a surgeon should be aware of the possible complications.The Foot and Ankle Online Journal 02/2011; 32(2):176-82. · 1.22 Impact Factor -
Article: Numerical simulation of strain-adaptive bone remodelling in the ankle joint.
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ABSTRACT: The use of artificial endoprostheses has become a routine procedure for knee and hip joints while ankle arthritis has traditionally been treated by means of arthrodesis. Due to its advantages, the implantation of endoprostheses is constantly increasing. While finite element analyses (FEA) of strain-adaptive bone remodelling have been carried out for the hip joint in previous studies, to our knowledge there are no investigations that have considered remodelling processes of the ankle joint. In order to evaluate and optimise new generation implants of the ankle joint, as well as to gain additional knowledge regarding the biomechanics, strain-adaptive bone remodelling has been calculated separately for the tibia and the talus after providing them with an implant. FE models of the bone-implant assembly for both the tibia and the talus have been developed. Bone characteristics such as the density distribution have been applied corresponding to CT scans. A force of 5,200 N, which corresponds to the compression force during normal walking of a person with a weight of 100 kg according to Stauffer et al., has been used in the simulation. The bone adaptation law, previously developed by our research team, has been used for the calculation of the remodelling processes. A total bone mass loss of 2% in the tibia and 13% in the talus was calculated. The greater decline of density in the talus is due to its smaller size compared to the relatively large implant dimensions causing remodelling processes in the whole bone tissue. In the tibia, bone remodelling processes are only calculated in areas adjacent to the implant. Thus, a smaller bone mass loss than in the talus can be expected. There is a high agreement between the simulation results in the distal tibia and the literature regarding. In this study, strain-adaptive bone remodelling processes are simulated using the FE method. The results contribute to a better understanding of the biomechanical behaviour of the ankle joint and hence are useful for the optimisation of the implant geometry in the future.BioMedical Engineering OnLine 01/2011; 10:58. · 1.40 Impact Factor -
Article: Digital stereophotogrammetry based on circular markers and zooming cameras: evaluation of a method for 3D analysis of small motions in orthopaedic research.
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ABSTRACT: Orthopaedic research projects focusing on small displacements in a small measurement volume require a radiation free, three dimensional motion analysis system. A stereophotogrammetrical motion analysis system can track wireless, small, light-weight markers attached to the objects. Thereby the disturbance of the measured objects through the marker tracking can be kept at minimum. The purpose of this study was to develop and evaluate a non-position fixed compact motion analysis system configured for a small measurement volume and able to zoom while tracking small round flat markers in respect to a fiducial marker which was used for the camera pose estimation. The system consisted of two web cameras and the fiducial marker placed in front of them. The markers to track were black circles on a white background. The algorithm to detect a centre of the projected circle on the image plane was described and applied. In order to evaluate the accuracy (mean measurement error) and precision (standard deviation of the measurement error) of the optical measurement system, two experiments were performed: 1) inter-marker distance measurement and 2) marker displacement measurement. The first experiment of the 10 mm distances measurement showed a total accuracy of 0.0086 mm and precision of ± 0.1002 mm. In the second experiment, translations from 0.5 mm to 5 mm were measured with total accuracy of 0.0038 mm and precision of ± 0.0461 mm. The rotations of 2.25° amount were measured with the entire accuracy of 0.058° and the precision was of ± 0.172°. The description of the non-proprietary measurement device with very good levels of accuracy and precision may provide opportunities for new, cost effective applications of stereophotogrammetrical analysis in musculoskeletal research projects, focusing on kinematics of small displacements in a small measurement volume.BioMedical Engineering OnLine 01/2011; 10:12. · 1.40 Impact Factor -
Article: A rotating inlay decreases contact pressure on inlay post after posterior cruciate substituting total knee arthroplasty.
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ABSTRACT: The post/cam mechanism of posterior cruciate substituting total knee arthroplasty, which is intended to achieve maximum range of flexion, offers the risk of failure due to mechanical overload. The purpose of this in vitro study was to investigate load and contact pressure on the inlay post of posterior substituting knee prosthesis with different designs. Isokinetic extension/flexion motions of seven fresh frozen left knee specimens were simulated dynamically in a specially designed knee simulator with an extension moment of 31 Nm. After implantation of the knee prosthesis system, which provides a fixed and a rotating posterior cruciate substituting inlay, a pressure sensitive film was fixed on the inlay post surface to measure maximum load and contact pressure. Both types of inlays showed nearly the same contact load of up to 480 N on the posterior surface of the inlay post at 120 degrees knee flexion. Contact pressure was measured to be up to 19.7 MPa at 120 degrees flexion on the posterior surface of the post of the fixed inlay, whereas contact pressure was measured to be significantly lower (6.8 MPa, p=0.04) on the inlay post of the rotating inlay. The modification of a rotating posterior cruciate substituting inlay could not decrease the horizontal load, but offers the possibility to decrease contact pressure on the inlay post to avoid mechanical overload of the polyethylene inlay.Clinical biomechanics (Bristol, Avon) 05/2009; 24(5):446-50. · 1.76 Impact Factor -
Article: Numerical investigations on the strain-adaptive bone remodelling in the periprosthetic femur: influence of the boundary conditions.
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ABSTRACT: There are several numerical investigations on bone remodelling after total hip arthroplasty (THA) on the basis of the finite element analysis (FEA). For such computations certain boundary conditions have to be defined. The authors chose a maximum of three static load situations, usually taken from the gait cycle because this is the most frequent dynamic activity of a patient after THA. The numerical study presented here investigates whether it is useful to consider only one static load situation of the gait cycle in the FE calculation of the bone remodelling. For this purpose, 5 different loading cases were examined in order to determine their influence on the change in the physiological load distribution within the femur and on the resulting strain-adaptive bone remodelling. First, four different static loading cases at 25%, 45%, 65% and 85% of the gait cycle, respectively, and then the whole gait cycle in a loading regime were examined in order to regard all the different loadings of the cycle in the simulation. The computed evolution of the apparent bone density (ABD) and the calculated mass losses in the periprosthetic femur show that the simulation results are highly dependent on the chosen boundary conditions. These numerical investigations prove that a static load situation is insufficient for representing the whole gait cycle. This causes severe deviations in the FE calculation of the bone remodelling. However, accompanying clinical examinations are necessary to calibrate the bone adaptation law and thus to validate the FE calculations.BioMedical Engineering OnLine 05/2009; 8:7. · 1.40 Impact Factor -
Chapter: Finite Element Analysis of Bone Remodeling after Hip Resurfacing Arthroplasty
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ABSTRACT: Hip resurfacing arthroplasty (HRA) is a bone-saving treatment of degenerative or traumatic damages of hip joints, and it is more and more used for younger patients. However, numerous clinical studies have shown that HRA can cause a fracture of the femoral neck. This has been widely attributed to the large contact area in the coupling of prosthesis head and socket. Another factor, though, which is probably more crucial for possible fractures, is bone resorption due to stress shielding in the periprosthetic femur. This is investigated in the study presented here by computation of the bone remodeling after HRA on the basis of the finite element analysis (FEA). The FE results show that there is bone mass loss at the femoral head underneath the prosthesis cap and at the stem, and this can cause a femoral neck fracture.12/2008: pages 2288-2291; -
Article: Differences in patellofemoral contact stresses between mobile-bearing and fixed-bearing total knee arthroplasties: a dynamic in vitro measurement.
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ABSTRACT: Anterior knee pain is one of the most common problems after total knee arthroplasty (TKA). Mobile-bearing designs should improve patella tracking with a reduced rate of patella tilt as well as reduced patellofemoral contact stresses and improve knee flexion. The aim of this dynamic in vitro investigation was to evaluate the changes of patellofemoral contact stresses after TKA using fixed and mobile-bearing designs. Seven knee specimens were mounted into a knee simulator imitating an isokinetic extension of the knee. The patellofemoral contact was measured before and after tricompartimental TKA with fixed and mobile-bearing designs using pressure-sensitive films. Contact stresses were measured from 120 degrees knee flexion to full extension with a simulated force of the quadriceps muscle up to 1,200 N. Additionally all measurements were performed with simulated co-contraction of the hamstrings muscles. Fixed-bearing TKA increases patellofemoral contact stresses compared to physiologic conditions. After patella resurfacing, contact stresses increase even more. By changing the prosthesis design to mobile bearing, maximum contact stress was measured to be punctual higher than in fixed-bearing implants. In the interval between 0 degrees -30 degrees and 70 degrees -105 degrees of flexion, obviously lower pressures were evaluated for the mobile-bearing design. With cocontraction of the hamstrings, a lower contact stress of the mobile-bearing design was evident for the complete measurement of the knee extension. An increase of patellofemoral contact stresses after patellar resurfacing in TKA could be demonstrated. This outcome implicates a higher risk of patellofemoral complications. The mobile-bearing design showed evidently lower patellofemoral contact stresses than the fixed-bearing design.Archives of Orthopaedic and Trauma Surgery 10/2008; 129(7):901-7. · 1.37 Impact Factor -
Article: Revision total hip arthroplasty with an uncemented primary stem in 79 patients.
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ABSTRACT: Revision in THA continues to be a technical challenge because of difficulties in fixation of the femoral component in mostly deficient bone in the proximal femur. In cases with minor cortical defects, the use of primary stems in revision surgery has also been described by some authors. Seventy-nine patients with minor femoral bone defects were reviewed retrospectively (mean follow-up 6.8 +/- 3.9 years), who underwent a femoral component revision surgery using the uncemented primary Bicontact stem (Aesculap, Tuttlingen, Germany). Furthermore, the radiographs (anteroposterior and lateral) before, after surgery and at latest follow-up were analysed concerning femoral defects, proximal bone loss, and to determine the quality of bony fixation. The average Harris hip score (HHS) was 42.2 +/- 20.8 preoperative and improved to 78.9 +/- 12.5 at latest follow-up (p < 0.001). Motion Score increased significantly from 2.7 +/- 1.9 to 3.5 +/- 1.4 (p < 0.05) and pain score decreased significantly from 5.7 +/- 2.9 to 3.6 +/- 2.4 (p = 0.005). During follow-up there were only four re-revisions within 2 years after revision. The results and clinical outcome of this study correspond to those published before, using primary cementless stems in cases of revision. Therefore, the primary uncemented Bicontact stem appears to be a good alternative to other revision systems in well-selected femoral revision cases with minor defects.Archives of Orthopaedic and Trauma Surgery 07/2008; 128(7):673-8. · 1.37 Impact Factor -
Article: Quadriceps force during knee extension after non-hinged and hinged TKA: an in vitro study.
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ABSTRACT: Problems during knee extension, due to kinematic alterations, are not uncommon after total knee arthroplasty. Hinged prostheses provide higher stability than non-hinged designs and may minimize these alterations. Thus, in this in vitro study we investigated the quadriceps force required to extend the knee during an isokinetic extension cycle generating a constant extension moment after non-hinged and hinged total knee arthroplasty. Human knee specimens were tested in a kinematic knee simulator under physiological conditions, after implantation of two types of non-hinged cruciate retaining prosthesis (Gemini; Link, Germany and Interax I.S.A.; Stryker, Ireland) and a hinged prosthesis (Rotations-Knie; Link, Germany). During simulation of an extension cycle from 120 degrees knee flexion to full extension, the change in quadriceps force to produce the constant extension moment of 31 Nm was dynamically measured using a load cell attached to the quadriceps tendon. After implantation of the non-hinged pros-theses, there was no alteration in maximum quadriceps force in knee flexion compared to physiological conditions, but alteration occurred at lower flexion angle (p=0.002) and increased up to 1,257 (SD 273) N (p=0.04) in knee extension. Following implantation of the hinged prosthesis, there was no alteration in quadriceps extension force in flexion but it decreased to 690 (SD 81) N (p=0.003) in extension. Hinged knee prostheses restore the quadriceps lever arm in knee flexion and improve the lever arm in knee extension due to higher constraint and knee joint stability. This would offer a potential advantage for patients with weak quadriceps strength by making it easier to stabilize the knee in full extension during walking.Acta Orthopaedica 03/2008; 79(1):34-8. · 2.17 Impact Factor -
Article: The effect of tourniquet release timing on perioperative blood loss in simultaneous bilateral cemented total knee arthroplasty: a prospective randomized study.
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ABSTRACT: Today the use of pneumatic tourniquet is commonly accepted in total knee arthroplasty (TKA) to reduce perioperative blood loss. There are a few prospective randomised and nonrandomised studies that compare the effect of tourniquet release timing in cementless or cemented unilateral TKA. However, many of these studies show an inadequate reporting and methodology. This randomized prospective study was designed to investigate the efficiency of tourniquet release timing in preventing perioperative blood loss in a simultaneous bilateral TKA study design. To our knowledge, this is the first study of its kind, in which the effect of tourniquet release timing on perioperative blood loss was investigated in simultaneous bilateral cemented TKA to compare both techniques intraindividually. In 20 patients (40 knees) one knee was operated with tourniquet release and hemostasis before wound closure, and the other knee with tourniquet release after wound closure and pressure dressing. We found no significant difference in total blood loss between both techniques (p=0.930), but a significant difference in operating time (p=0.035). There were no postoperative complications at a follow-up of 6 month. Other studies report an increase the blood loss in early tourniquet release and an increase the risk of early postoperative complications in deflation of tourniquet after wound closure. In this study we found no significant difference in perioperative blood loss and no increase of postoperative complications. Therefore, we recommend a tourniquet release after wound closure to reduce the duration of TKA procedure and to avoid possible risks of extended anaesthesia.Technology and health care: official journal of the European Society for Engineering and Medicine 02/2008; 16(2):85-92. -
Article: [Reconstruction of the medial patellofemoral ligament by tunnel transfer of the semitendinosus tendon].
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ABSTRACT: Stabilization of the patella by reconstruction of the medial patellofemoral ligament. Chronic recurrent lateral dislocation or subluxation of the patella. Habitual lateral dislocation of the patella. Primary dislocation of the patella. Genu valgum with a Q-angle > 15 degrees . Status following semitendinosus tendon transfer to reconstruct the anterior cruciate ligament. Joint infection. Neurogenic instability, ischiocrural muscle deficiency. Division of the distal insertion of the semitendinosus muscle at the pes anserinus. Subligamentous tunneling at the proximal insertion of the medial collateral ligament. The distal end of the semitendinosus tendon is transferred through the subligamentous tunnel to the medial patellar margin. Fixation of the tendon to the medioproximal patellar margin by passing it through an oblique transpatellar drill hole. The patella was stabilized by dynamic reconstruction of the medial patellofemoral ligament in 14 patients with chronic recurrent or habitual lateral patellar dislocation. Ten patients were available for clinical follow-up assessment at an average of 13 months (8-27 months) postoperatively. The postoperative Kujala Index (maximum 100 points) increased on average from 56 to 95 points.Operative Orthopädie und Traumatologie 01/2008; 19(5-6):489-501. · 0.46 Impact Factor
Top co-authors
Top Journals
Institutions
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2011
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Diakoniekrankenhaus Friederikenstift gGmbH
Hannover, Lower Saxony, Germany -
Leibniz Universität Hannover
- Institute of Metal Forming and Metal Forming Machines
Hannover, Lower Saxony, Germany
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2003–2011
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Medizinische Hochschule Hannover
- Trauma Department
Hannover, Lower Saxony, Germany
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