Effects of combined soft-tissue surgery on adaptability of the patellofemoral joint in treatment of habitual patellar dislocation in children

Abstract

Objective To explore adaptability of the patellofemoral joint after combined soft-tissue surgery in treatment of habitual patellar dislocation at different age. Methods Seventy-three children with habitual patellar dislocation were retrospectively reviewed from 2000 to 2007. There were 24 males and 49 females, with a mean age of 7.1 years(ranged 3-15). The mean follow-up period was 38 months (ranged 25-98). There were 24 patients with 30 knees aged from 3 to 8 years in A group and 49 cases with 69 knees aged from 8 to 15 years in B group. The combined soft-tissue surgery procedure consists of lateral capsular release, medial retinacular tightening of the knee, vastus medialis muscle transfer to the patella, medial and distal transfer of the half patellar tendon. Patella axial and knee lateral X-ray examination were obtained.Femoral trochlear angle,patellar height changes, patellofemoral congruence angle and patellar tilt angle (Laurin angle) were measured to evaluate adaptability of the patellofemoral joint. Results The data of 73 cases were complete. At the last visit, no recurrence of patellar lateral dislocation was found and two cases had patella medial dislocation. Femoral trochlear angle improved from 150.1°±5.1° preoperatively to 144.3°±6.0° postoperatively (P ＜0.05) in A group, while similar changes had not found (P ＞ 0.05) in B group. There were no difference in A and B group in regard to patellar height, congruence angle and Laurin angle. Conclusion The combined soft-tissue surgery had effect on patellofemoral joint remodel in children with habitual patellar dislocation. These procedures can significantly promote development of the femoral condyle, decrease femoral trochlear angle and improve adaptability of the patellofemoral joint in children under the age of 8 years. But it had no obvious influence on older than 8-year-old children. Key words: Patellar dislocation;  Knee joint;  Surgical procedures, operative