Morphological Changes in Femoral Trochlea After Extensor Realignment Surgery in Children With Congenital Patellar Dislocation

Background: Femoral trochlear dysplasia (FTD) is a major factor affecting the stability of the knee joint. Congenital patellar dislocation (CPD) is usually accompanied by distal FTD. Few studies have investigated trochlear development following surgery in skeletally immature patients. Purpose: To observe trochlear remodeling following surgical extensor realignment and stabilization in children with CPD and to analyze the factors associated with this remodeling. Study Design: Case series; Level of evidence, 4. Methods: A retrospective analysis was conducted on surgical cases of CPD treated at 2 centers between January 2014 and June 2023. The recorded data comprised patient age, sex, side, presence of syndromic CPD, genetic testing results, and magnetic resonance imaging (MRI) findings, including the trochlear depth index (TDI), lateral trochlear inclination (LTI), and medial condylar trochlear offset (MCTO). Pre- and postoperative knee joint range of motion and Lysholm scores were also collected. The surgical procedure involved lateral retinacular release, resection of the redundant medial capsule, lengthening suture of the quadriceps femoris, and a Roux-Goldthwait procedure. Results: In total, 58 cases (80 knees) of pediatric FTD (a modified MRI classification of FTD: 19 mild (type A), 28 moderate (type B), 4 severe (type C), 7 special type) with a mean ± SD age of 34.4 ± 3.68 months (range, 14-64 months) were followed up for 2.46 ± 0.73 years. A total of 40 cases (52 knees) were of the idiopathic type and 18 cases (28 knees) were of the syndromic type. Pre- and postoperative TDI, MCTO, and LTI improved significantly (all P < .0001). The patellar redislocation rate was 1.7%; all had full knee motion, with a mean Lysholm score of 96. Conclusion: The dysplastic trochlea in CPD postoperation can remodel in skeletally immature patients.