The Insall-Burstein posterior stabilized total knee replacement in the valgus knee.

Sixty-seven Insall-Burstein (Zimmer Inc, Warsaw, Indiana) posteriorly stabilized total knee replacements were implanted in knees with a preoperative alignment > 10 degrees of valgus (average: 19.5 degrees). An anteromedial approach with release of the lateral ligaments of the femur was used. A lateral patellar release was necessary in 49\% of cases. Fifty-one knees (76\%) were reviewed with an average follow-up of 6 years. Pain at follow-up was absent or mild in all of the knees except one with aseptic loosening of the tibial and patellar components. The average flexion was 105 degrees. The results according to the Knee Society Rating System were excellent in 53\%, good in 39\%, fair in 6\%, and poor in 2\%. A patellofemoral "clunk" was present in three knees (6\%), and one knee required arthroscopic debridment. The mechanical axis was within 5 degrees of neutral in 88\%. A survivorship analysis was performed using failure requiring reoperation as the end point. There were four failures due to aseptic loosening, symptomatic lateral ligamentous instability, deep infection, and recurrent patellar dislocation. The patellar component had not been implanted in the knee with recurrent patellar dislocation due to severe bony erosion. The cumulative success rate was 95\% at 10 years. These results indicate that release of the contracted lateral structures and implantation of a posteriorly stabilized prosthesis achieve a stable and well-aligned knee in 66 out of 67 knees. Attention must be paid to patellar tracking and realignment of the extensor mechanism.