Comparison of Mobile-Bearing and Fixed-Bearing Designs in High Flexion Total Knee Arthroplasty: Using a Navigation System

PURPOSE: We compared and analyzed the short term results of high flexion total knee arthroplasty (TKA) with mobile-bearing and fixed bearing designs. MATERIALS AND METHODS: We studied 32 patients that had undergone TKA with LPS-Flex Mobile and 34 patients with LPS-Flex Fixed using an electromagnetic navigation system between January 2010 and June 2010, and were followed up for at least 1 year. RESULTS: Knee Society Functional Score (KSFS) and Knee Society Knee Score (KSKS) of the mobile-bearing group were 94.5 and 93.8 points, respectively, and were 48.2 and 45.3 points preoperatively, whereas those of the fixed-bearing group were 95.1 and 94.2 points, respectively, and were 49.5 and 46.9 points preoperatively. Postoperative mechanical axis deviation and implant position of the femoral and tibial component both on the coronal and sigittal planes showed no significant differences between the two groups. Range of motion (ROM) and maximal flexion angle (MFA) of the knee joint also showed no significant differences between the two groups. The possibility of crossed-legged sitting and kneeling position also showed no significant differences between the two groups. CONCLUSIONS: Clinical and radiologic parameters, ROM and MFA of knee joints showed no significant differences in both the groups, but long term follow-up results may be necessary, including survival rate.

High Flex Knee Arthroplasty and Range of Motion / 대한정형외과학회잡지

PURPOSE: The aim of this prospective study was to determine which factors are predictive of the post operative range of motion and to evaluate the short-term clinical results after total knee arthroplasty using The Nexgen Legacy Knee LPS-Flex fixed bearing knee system replacement. MATERIALS AND METHODS: A total of 67 patients (101 knees) were enrolled in this study. 101 knees were operated on using the LPS-Flex fixed bearing knee system replacement. The same surgeon performed the surgery between December 2001 and March 2002. The patients' ages ranged from 52 to 77 years, with an average of 68.4 years. Preoperatively the factors considered were the age of the patient, gender, the body mass index, the flexion contracture and further flexion possible. The factors considered postoperatively were patellar tilting and displacement, the postoperative knee and functional score, and a varus deformity. The patients were followed up once every 3 month for up to 2 years. RESULTS: At the latest follow-up, the average flexion in this series was 130.8degrees (range, 90degrees-150degrees). Thirty knees could attain more than 140degrees flexion. Twenty patients could comfortably kneel down. The 53 patients could sit cross-legged. The eleven knees could attain less than 120degrees of flexion at the final follow-up. There was a significant improvement in flexion at each successive review 12 months after surgery. The most important factor that influenced the range of motion after an arthroplasty was the preoperative range of flexion. The average Knee Society knee score was 90 points (range, 80-100), and the function score was 91 points (range, 45-100). CONCLUSION: A total knee arthroplasty with LPS-flex showed an excellent range of motion and satisfactory early clinical results. The most important factor that influences the range of motion after an arthroplasty is the preoperative range of flexion.