[Chronic anterior laxity of the knee treated with free patellar graft and extra-articular lateral plasty: 10-year follow-up of 148 cases].

PURPOSE OF THE STUDY: Assess long-term subjective, functional and radiographic outcome after free patellar graft and extra-articular lateral plasty for chronic anterior laxity of the knee. PATIENTS AND METHODS: 148 cases of chronic anterior laxity of the knee treated by free patellar graft and extra-articular lateral Lemaire plasy were reviewed after a mean follow-up of 11.5 years (range 10-15 years). A complete work-up was performed in all cases at 4 years postsurgery to assess objective, sport, function and radiographic outcome (objective laxity and osteoarthritic status).
RESULTS: Subjectively, 65 p. 100 of the patients were very satisfied and 24 p. 100 were satisfied. According to the IKDC classification, functional outcome was in class A in 22 p. 100 and in class B in 49 p. 100. All failures (14 p. 100) except one occurred during the first year. When the meniscus was healthy or repaired, the failure rate was only 4 p. 100. Two principal factors favoring failure were severe laxity (meniscectomy) and poor femoral position. Residual laxity measured on the lateral view in the one-leg weight bearing position was 3.3 mm in the overall series, 2.4 mm for cases with isolated anterior laxity, and 4 mm for chronic laxities. Residual laxity was higher if the medial meniscus was totally or partially removed. There was no change between the 4th and 11th year of follow-up. A secondary meniscectomy was performed in 5 p. 100 of the cases despite renewed sports activity in 80 p. 100 of the cases. Osteoarthritic degeneration was the most important factor for less favorable outcome: 42 p. 100 of the cases developed preosteoarthitis or osteoarthritis. Joint degeneration occurred almost exclusively in patients who had undergone medial meniscectomy. Only 2 p. 100 of the patients with a healthy or repaired meniscus developed osteoarthritis. When the anterior laxity was the only anomaly, the functional result was very excellent, with renewed sports activity. Even in cases with persistent residual laxity, there were almost no failures or secondary meniscal lesions if the femoral position was correct. DISCUSSION: For chronic laxity, free patellar graft alone cannot avoid a high rate of failure and/or joint degeneration, particularly favored by an incorrect femoral position. Improved results can only be achieved by preserving the meniscus and possibly associating a lateral or medial plasty whose effect remains to be evaluated.