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Jangwon Park - One of the best experts on this subject based on the ideXlab platform.
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simultaneous cemented and Cementless total knee replacement in the same patients a prospective comparison of long term outcomes using an identical design of nexgen Prosthesis
Journal of Bone and Joint Surgery-british Volume, 2011Co-Authors: Jangwon ParkAbstract:The purpose of this prospective, randomised study was to evaluate the clinical and radiological results comparing the identical cemented or Cementless NexGen total knee prostheses implanted bilaterally in the same patient. Sequential simultaneous bilateral total knee replacements were performed in 50 patients (100 knees). There were 39 women and 11 men with a mean age of 58.4 years (51 to 67) who received a cemented Prosthesis in one knee and a Cementless Prosthesis in the other. The mean follow-up was 13.6 years (13 to 14). At final review, the mean Knee Society scores (96.2 (82 to 100) versus 97.7 (90 to 100)), the mean Western Ontario and McMaster Universities osteoarthritis index (34.5 (4 to 59) versus 35.6 (5 to 51)), the mean ranges of knee movement (124° (100° to 140°) versus 128° (110° to 140°)), mean patient satisfaction (8.1 (sd 1.9) versus 8.3 (sd 1.7)), and radiological results were similar in both groups. The rate of survival of the femoral components was 100% in both groups at 14 years. The rate of survival of the cemented tibial component was 100% and 98% in the Cementless tibial component. No osteolysis was identified in either group. Our data have shown no advantage of Cementless over cemented components in total knee replacement.
A Giunti - One of the best experts on this subject based on the ideXlab platform.
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ion release in patients with metal on metal hip bearings in total joint replacement a comparison with metal on polyethylene bearings
Journal of Biomedical Materials Research, 2002Co-Authors: L Savarino, Donatella Granchi, G Ciapetti, E Cenni, Nardi A Pantoli, Roberto Rotini, C A Veronesi, Nicola Baldini, A GiuntiAbstract:Polyethylene (PE) wear has been shown to be a problem in long-term joint replacement using metal-on-PE bearing. The use of metallic heads articulating with metallic cups could solve this problem: success will be enhanced if wear and corrosion of the articulating surfaces are maintained at a low level. New models with metal-on-metal bearing have been proposed, to be used mainly for young subjects: such coupling seems to have a reduced release, but it is unclear yet if the medium-term corrosion rate is really negligible or, on the contrary, it is significantly higher than in the metal-on-PE bearing. Aim of our study was the comparison of ion release in the serum of two groups of patients who had the same type of stable Cementless Prosthesis, but different bearing: twenty-six patients with metal-on-metal (Group A) and fifteen patients with metal-on-PE bearing (Group B) were examined. The follow-up was 14-38 months for group A and 18-34 months for group B. The serum concentration of chromium (Cr), cobalt (Co) and molybdenum (Mo) was measured. Twenty-two patients before surgery were used for comparison (Group C). The reference values were obtained from a population of twenty-two healthy subjects (Group D). Our findings indicate that metal-on-metal bearings produce a significantly higher systemic release of cobalt and chromium (ng/ml) when compared with levels found in metal-on-PE, pre-surgery and reference groups. Such a high release should induce to improve the bearing materials or, at least, to study the biologic fate of metal ions and consequently their long-term effects. In such a way a risk-to-benefit ratio for the patient could be established.
S H Oh - One of the best experts on this subject based on the ideXlab platform.
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primary total hip arthroplasty with a second generation Cementless total hip Prosthesis in patients younger than fifty years of age
Journal of Bone and Joint Surgery American Volume, 2003Co-Authors: S H OhAbstract:Background: The early experience with Cementless total hip replacement led to design modifications to increase the initial press-fit and stability of the femoral component, to reduce the diameter of the femoral head, and to improve the acetabular component, including the locking mechanism of the shell and the quality of the polyethylene liner. We performed a prospective study to assess the results in young patients who had been followed for a minimum of eight years after treatment with a primary total hip arthroplasty with a second-generation Cementless Prosthesis. Methods: Eighty patients (118 hips) were included in the study. There were fifty-eight men and twenty-two women; the mean age at the time of the operation was 46.8 years (range, twenty-one to forty-nine years). We used a Cementless Duraloc series-100 or 1200 acetabular component with or without screw fixation, a polyethylene liner with a 22-mm inner diameter, and a Cementless Profile femoral component in all hips. The average duration of follow-up was 9.8 years (range, eight to eleven years). Clinical follow-up (with use of the Harris hip score) and radiographic follow-up were performed at six weeks; at three, six, and twelve months; and yearly thereafter. Linear and volumetric wear were measured, and bone-remodeling and osteolysis were assessed. Results: The average Harris hip score improved from 48.8 points preoperatively to 92 points at the final follow-up examination. The prevalence of transitory thigh pain was 10% (twelve of 118 hips). There was no aseptic loosening. One hip was revised because of recurrent dislocation. The average amount of linear wear was 1.18 mm, and the average wear rate was 0.12 mm/yr. Fourteen hips (12%) had osteolysis in the calcar femorale and eleven hips (9%) had acetabular osteolysis, but all of the osteolytic lesions were <1 cm 2. Conclusions: The mechanical fixation of the anatomic fit Cementless Profile stem was excellent in this study of young patients who were particularly difficult to treat because of a high prevalence of osteonecrosis and developmental dysplasia. Although there was no aseptic loosening of the components and a relatively low prevalence of osteolysis, there was a high rate of linear wear of the polyethylene liner. Level of Evidence: Therapeutic study, Level IV (case series [no, or historical, control group]). See p. 2 for complete description of levels of evidence.
Adalbert I Kapandji - One of the best experts on this subject based on the ideXlab platform.
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primary total hip arthroplasty with the karl zweymuller first generation Cementless Prosthesis a 5 to 9 year retrospective study
Journal of Arthroplasty, 1996Co-Authors: Christian P Delaunay, Adalbert I KapandjiAbstract:Abstract A consecutive series of 72 primary total hip arthroplasties were performed in 70 patients using the first-generation Zweymuller Cementless titanium press-fit femoral and threaded acetabular components (AlloPro, Baar, Switzerland). Twelve hips were excluded from the study because of insufficient follow-up evaluation, including one patient who underwent a socket revision within the first 2 weeks. Sixty total hip arthroplasties with an average follow-up period of 80 months (range, 60–108 months) were retrospectively reviewed. Clinical results were graded excellent or good in 54 cases (90%), fair in 3 (5%), and poor in 3 (5%) with 2 early implant failures (1 acetabular cup and 1 femoral stem in 2 hips). Cumulative survival rates at the 6- to 7-year interval, with failure defined as revision and/or loosening are 98.47% (SD, 2.0%) for the femoral component (1 single septic and loose stem, revised at 5 years), 97.08% (SD, 2.72%) for the screw ring (2 unstable but only 1 revised), and 95.56% (SD, 3.36%) for both components. This encouraging experience with the first-generation Prosthesis supports the rationale for continued use of the new Zweymuller Alloclassic stem and open-back screw ring available since 1988.
Bjorn Skallerud - One of the best experts on this subject based on the ideXlab platform.
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subject specific finite element analysis of stress shielding around a Cementless femoral stem
Clinical Biomechanics, 2009Co-Authors: Sune H Pettersen, Bjorn SkallerudAbstract:Abstract Background Stress shielding around a femoral stem is usually assessed experimentally using composite or human cadaver femurs. In the present study we have explored the feasibility of using subject specific finite element models to determine stress shielding in operated femurs. Methods Cortical strain was measured experimentally on seven human cadaver femurs, intact and implanted with a straight Cementless Prosthesis. Two load configurations were considered: single leg stance and stair climbing. Subject specific finite element models derived from computed tomography of the same femurs were analysed intact and with an implant. Principal cortical strain was used to validate the finite element models. Stress shielding was defined as the change in equivalent (von Mises) strain between pre- and post-operative femurs. Findings Cortical strain predicted by the finite element analyses showed to be close to unity with the experimental observations for both intact ( R 2 = 0.94, slope = 0.99), operated femurs ( R 2 = 0.86, slope = 0.86) and stress shielding ( R 2 = 0.70, slope = 0.90). In the proximal calcar area, the region most prone to periprosthetic remodelling, the finite element models were found to successfully reproduce the stress shielding observed experimentally. Interpretation The study shows that subject specific finite element models manage to describe the stress shielding pattern measured in vitro in the different femurs. Finite element models based on actual human femurs (cadaver and/or patient) could thus be a useful tool in the pre-clinical evaluation of new implants.