Recurrence of knee flexion contracture after surgical correction in children with cerebral palsy

Purpose: Knee flexion contracture (FC) and crouch gait are challenging to treat in children with cerebral palsy (CCP), and recurrent knee FC after surgery is a severe complication. The aim was to identify factors associated with recurrent knee FC after surgery.

Methods: The records of 62 CCP (age 10.6±2.6 years) who underwent surgery and were followed for > six months were reviewed. Knee FC was treated by hamstring lengthening, posterior knee capsulotomy, and femoral shortening/extension osteotomy until full extension was obtained. Kaplan-Meier analysis was used to estimate the probability of the correction being maintained. Cox proportional hazard modeling was used to compare parameters between patients with and without recurrent knee FC, with the time to recurrence as the endpoint. Potential confounding factors were included in the multivariate analysis.

Results: In total, the procedure was performed on 122 knees. The average weight-for-age z score was -1.3±1.2. The average follow-up period was 5.4±4.2 years. Knee FC recurrence was observed in 37 knees (30%). The average recurrence-free time was 4.9 years, with most cases of recurrence (33 knees) occurring within six years after surgery. The factors associated with recurrence were age (HR, 1.19) and a required posterior knee capsulotomy procedure (HR, 4.53).

Conclusion: Recurrent knee FC after correction is associated with CCP who are older at the time of operation and when posterior knee capsulotomy is performed. The age at operation should be optimized. The sequence of procedures should be performed only as necessary to minimize the chance of post-operative muscle weakness and recurrence.