Risk factors for hip redislocation in surgically treated children with cerebral palsy: A multicenter study with follow-up until skeletal maturity

Abstract

Purpose: To identify clinical and radiographic risk factors associated with hip redislocation in children with cerebral palsy (CP) who underwent surgical treatment for hip dislocation. Methods: This multicenter retrospective study included children with CP who underwent reconstructive osteotomy for hip dislocation and were followed until triradiate cartilage closure. Demographic, clinical, and radiographic variables were evaluated. Univariate and multivariate logistic regression analyses were performed to identify independent risk factors for redislocation. Additionally, a classification and regression tree (CART) model was developed to stratify redislocation risk. Results: Hip redislocation occurred in 25 of 115 hips (21.7%). Redislocation was significantly more frequent in hips treated with femoral osteotomy alone (40%) compared to combined femoral and pelvic osteotomies (16.7%), (p = 0.026). Multivariate analysis identified younger age at surgery (Odds ratio (OR) = 0.981, p = 0.010), higher postoperative Sharp\"s angle (OR = 1.082, p = 0.034), and lower postoperative Mose hip ratio (MHR) (OR = 0.007, p = 0.033) as independent predictors of redislocation. Radiographic ratios, including medial joint space to cranial joint space (MJS/CJS) and MJS to maximum capital femoral epiphysis diameter (MJS/MCFED), were also significantly higher in redislocated hips. The CART model classified patients into high- and low-risk groups based on surgical age = 48 degrees, and MHR < 0.69. Conclusions: Younger surgical age, insufficient correction as indicated by a higher postoperative Sharp angle and lower MHR were independently associated with hip redislocation in CP patients undergoing surgery. MJS/CJS and MJS/MCFED ratios were also associated with redislocation, indicating incomplete reduction.