Revision Total Knee Arthroplasty Using the PFC Sigma Knee System

PURPOSE: We wanted to analyze the causes of revision and the clinical and radiographic results after revision total knee arthroplasty. MATERIALS AND METHODS: Thirty-eight knees in 34 patients underwent revision total knee arthroplasty using the PFC(R) Sigma revision system between March 1999 and May 2005. The average patient age was 71.2 years, and the average follow-up period was 6 years 7 months (range: 4 years~10 years 2 months). We evaluated the time interval between the primary and revision arthroplasty and the causes of revision. The clinical outcomes were assessed using the knee score and the functional score of the Knee Society Scoring system (KSS system), and the radiographic measurements were assessed using the roentgenographic method of the American Knee Society. RESULTS: The mean interval between primary and revision arthroplasty was 6 years 3 months. The causes of revision included 25 cases of aseptic loosening and osteolysis, 7 cases of infection, 3 cases of joint stiffness and 3 cases of polyethylene problems. At the follow up, the mean preoperative knee and functional scores improved from 45.1 points to 84.5 and 37.2 to 78.2, respectively. Radiographycally, the average femorotibial angle was corrected from 2.2degrees in valgus to 6.5degrees. The radiolucency score was below 4 in all the cases. The complications after revision arthroplasty were 2 cases of superficial infection and 1 case of wound dehiscence with a skin defect. CONCLUSION: The main causes of revision arthroplasty were aseptic loosening and osteolysis. Satisfactory results were obtained using the posterior cruciate ligament and substituting the PFC(R) Sigma knee system with appropriately selected metal augmentation and an allograft. This study showed favorable results on long term follow-up.

Bilateral Total Knee Arthroplasty using the Fixed Bearing Platform and the Rotating Platform in the Same Patient

PURPOSE: We wanted to evaluate the clinical and radiological results after total knee arthoplasty using the Press Fit Condylar (PFC) Sigma fixed bearing platform knee and the rotating platform knee in the same patient. MATERIALS AND METHODS: We enrolled 44 patients who had undergone bilateral total knee arthroplasties due to osteoarthritis of both knees from November 2001 to December 2004, using the fixed bearing platform and the rotating platform, respectively. The mean age of the study group was 71.5 years (range: 65~85 years). The mean follow up period was 74.3 months (range: 62~86 months). The clinical results were evaluated according to the knee score, the functional score, the presence of flexion contracture, the range of motion and the complications, and the visual analog scale system was used for the patients' satisfaction. The radiological results using the American Knee Society criteria and the tibiofemoral angle were also evaluated. RESULTS: The average knee score improved from 36.5 to 87.3 in the fixed bearing group and from 38.8 to 87.9 in the rotating platform group, respectively. The average functional score improved from 28.4 to 83.5 in the fixed bearing group and from 32.6 to 85.8 in the rotating platform group, respectively. The average range of knee motion improved from 85.5degrees to 115.5degrees in the fixed bearing group and from 86.6degrees to 116.8degrees in the rotating platform group. The average tibiofemoral angle improved from varus 8.2degrees to valgus 5.5degrees in the fixed bearing group and from varus 7.1degrees to valgus 5.3degrees in the rotating platform group. We did not observe any clinically significant osteolysis or wear. However, there were 3 cases of instability out of the 13 cases in rotating platform group, and this was accompanied by varus deformities of over 15 degree and 6 cases of friction sound during walking. CONCLUSION: We could find no clinical and radiological differences between the fixed bearing platform and the rotating platform in this study. However, we should regard the fixed bearing prosthesis as a good option for the patients with severe varus deformities, with considering performing bulky soft tissue release for obtaining a balanced gap, for preventing spin-out and to correct deformity.