Results of Recurrent Patellar Instability after Trauma According to Anatomical Predisposing Factors

ABSTRACT

PURPOSE: We analyzed the results of lateral retinacular release(LRR) and proximal realignment for recurrent patellar instability after trauma according to the anatomical predisposing factors. MATERIALS AND METHODS: Twelve patients of fifteen cases of recurrent patellar instability had been evaluated. Clinical assessment were performed by Q-angle, apprehension test, passive patellar tilt test and general joint laxity. The anatomical predisposing factors assessed by plain radiographs included patella alta, sulcus angle, femoral trochlear dysplasia, genu valgum and patellar dysplasia. Clinical results were assessed by Kujala scoring system. Radiographic results were assessed by congruence angle. The results were analyzed according to the predisposing factors. RESULTS: Patella alta was observed in eight, increased sulcus angle in six, trochlear dysplasia in twelve, genu valgum in five and patella dysplasia in four cases. The result of treatment (Kujala score / congruence angle) was 85.8 / 9.7degrees in group A(predisposing factors > or = 3) and 91.4 / -5.3degrees in group B (predisposing factors<3)(p=0.036). We had 4 cases of recurrence after operation and genu valgum was related with recurrence rate. CONCLUSION: The clinical results of LRR and proximal realignment for recurrent patellar instability developed after trauma were worse in cases with more anatomical predisposing factors.