Aim. Total knee arthroplasty (TKA) in valgus knee is more difficult than in well aligned or varus knee, The correction of deformities and ligament balancing are the priority. The aim of this study was to evaluate our experience on 20 knees treated with Advance TKA. Methods. The study group is based on 20 consecutive patients who underwent primary TKA using cemented prosthesis fixation and a medial pivot implant. Study participants included 14 women and 6 men with a mean age of 69.6 years (range, 60 to 82 years). Osteoarthritis (80%) was the most common diagnosis rheumatoid arthritis (16%), and other findings (4%). All patients received the Advance TKA (cruciate ligament sacrificing) prosthesis (Wright) using cemented fixation. Results. Twelve knees were rated excellent, 8 as good. The femorotibial mechanical axis was corrected from a valgus of 15 to 5 in postoperative. There was no varus-valgus instability in 18 knees, and 2 knees had approximately 50 varus-valgus instability in extension. There was palpable, non-painful, patellofemoral crepitus noted in one knee. Conclusion. The Advance TKA (with cruciate ligament sacrificing) prosthesis (Wright) with cemented fixation was successful in primary arthroplasty in valgus knees, also in severe deformities with incompetent medial collateral ligament.

PROSTHETIC DESIGN AND KNEE KINEMATICS. RELATIONS AND RESULTS The clinical outcome and survival of a prosthetic implant depends on several factors, such as surgical technique, materials' quality and design of articular surfaces. The latter is specifically related to recent insights regarding articular kinematics. These showed that medial and lateral femoro-tibial compartments have a considerably different articular geometry. This leads to a flexion-extension movement (occurring about the trans-epicondylar axis) that is accompanied by a rotation around the vertical axis passing through the center of the medial tibial plate (tibial internal rotation) and a femoral condyle roll-back which is more prominent in the lateral compartment. It means that a medial-pivot mechanism is occurring, i.e., the convergence on the medial half of the knee between the lines connecting the medial and lateral condyle contact positions. A total knee arthroplasty that favors the medial-pivot mechanism must have an asymmetric surface of the tibial insert, so that the medial plate presents a high congruence with the femoral condyle to guarantee stability. On the contrary, the lateral plate must have a radius bigger than that of the lateral condyle to facilitate posterior roll-back and allow rotation movements between the components. Key words: Prosthesis design - Knee prosthesis Biomechanics.

Aim. The need to resurface or not the patella during total knee arthroplasty is still an open problem. Some surgeons always recommend to replace the patella, others suggest to not replace routinely the patella and others to replace it only in selected cases. The purpose of this study was to compare clinical results of knee prosthesis with or without patella replacement in a series of 30 patients treated for bilateral knee arthritis using a medial pivot prosthesis (Advance Wright, Arlington TN). Methods. Between January 2003 and October 2004 in our Hospital a consecutive series of 30 patients were treated for bilateral knee arthritis. All patients underwent a bilateral total knee replacement with a mean interval of 152 days between the two procedures. All patients were randomized to resurface or not the patella during the first procedure and to receive the opposite treatment during the second intervention. Results. At a mean follow-up of 4.1 years no complications occurred in the treated knees. We did not observe statistically significant differences in the Functional Score, Knee Score and patient's satisfaction. Conclusions. On the basis of our experience we believe that patella resurfacing should not he performed routinely when Advance prostheses are used.