Biomedical subjects
Publications and source records attributed to F Mazoochian.
The implantation of a knee arthroplasty is still a demanding operation. There is still no "golden standard" available, although a lot of guidelines have been declared. Because of this fact this article should provide the radiologist with an overview of and some background knowledge for the radiological evaluation of knee arthroplasty.
Bone cements based on polymethylmethacrylate are typically used for fixation of artificial joints. Intolerance reactions to endoprostheses not explained by infection or mechanical failure may lead to allergological diagnostics, which mostly focuses on metal allergy. However, also bone cement components may provoke hypersensitivity reactions leading to eczema, implant loosening, or fistula formation. Elicitors of such reactions encompass acrylates and additives such as benzoyl peroxide, N,N-dimethyl-p-toluidine, hydroquinone, or antibiotics (particularly gentamicin). Upon repeated contact with bone cement components, e.g., acrylate monomers, also in medical personnel occasionally hand eczema or even asthma may develop. Therefore, in the case of suspected hypersensitivity reactions to arthroplasty, the allergological diagnostics should include bone cement components.
BACKGROUND: Patellofemoral osteoarthritis is generally considered a contraindication for unicondylar knee arthroplasty. Therefore, even with an intact lateral compartment, bicondylar surface replacement is preferred when patellofemoral osteoarthritis is present, despite comparatively worse functional results. In the present study, the influence of patellofemoral osteoarthritis on the outcome of the Oxford III unicondylar implant was investigated. MATERIAL AND METHODS: The HSS and the patella score according to Turba were used to retrospectively evaluate the outcome of 44 Oxford III unicondylar implants at an average follow-up of 35 months. The degree of patellofemoral osteoarthritis was radiographically graded according to the Sperner score. RESULTS: The HSS score improved to an average of 92.3 points (68-99; p<0.001 vs preoperative score). With the patella score, only good and very good results were observed. At follow-up examination almost 70% of the knees showed patellofemoral osteoarthritis of degree III-IV. No correlation was found between the functional scores and the degree of patellofemoral osteoarthritis. CONCLUSION: Radiographic patellofemoral osteoarthritis seems to have no influence on the functional outcome of the Oxford III unicondylar knee arthroplasty. Therefore, unicondylar surface replacement is indicated even with radiographic evidence of patellofemoral osteoarthritis, provided that it is clinically asymptomatic.
AIM: The aim of the study was to validate macerated human acetabuli as replacement for fresh frozen preparations for testing primary stability and the screwing in moments of cementless threaded hip cups. METHOD: Three fresh frozen human pelvis were tested. One half of each pelvis was macerated whereas the other half was preserved as fresh frozen preparation. In the side of every pelvis the moments of screwing-in, the micromotions, the maximum expressing force and the maximum pull-out torque were determined. RESULTS: The screwing in moments, the maximum expressing forces and the maximum pull-out torques did not change. The micromotions were reduced to half. CONCLUSION: Considering the reduction of the micromotions, macerated human acetabuli are valid replacements for fresh frozen preparations for testing the primary stability and the screwing-in behaviour of screwed pans.
INTRODUCTION: The influence of implant size on the results in unconstrained total knee arthroplasty has never been investigated before. PATIENTS AND METHODS: 133 patients with unconstrained total knee arthroplasty were examined (HSS Score, Knee Society Score) with consideration of the different sizes of femoral and tibial components and the thicknesses of the tibial inlays. The medium follow up was 41.2 months (8 months to 74 months). RESULTS: Although the different component sizes gained different results, the differences were not significant. The combination of two component sizes did not lead to a significant change of the results. The results of the Knee Society Score seemed to become worse with thinner polyethylene tibial inlays although these differences were not significant. CONCLUSIONS: In conclusion, implant size had no significant influence on the outcome of total knee arthroplasty. The combination of two implant sizes showed no disadvantage.