Incidence and Risk Factors for Hip Displacement in Thai Children with Cerebral Palsy under a 10-Year Surveillance Program: A retrospective analytical study at Queen Sirikit National Institute of Child Health

Vollständiger Abstract

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Objectives: To evaluate the cumulative incidence of significant hip displacement, defined as a migration percentage (MP) > 40% or the requirement for hip reconstructive surgery among children with cerebral palsy (CP) enrolled in a 10-year institutional hip surveillance program, and to identify independent clinical predictors of displacement. Study design: Retrospective cohort study Setting: Queen Sirikit National Institute of Child Health Participants: Children with cerebral palsy (CP) undergoing their first surveillance radiograph with baseline MP ≤ 40.0%. Methods: This retrospective cohort study at Queen Sirikit National Institute of Child Health, a national tertiary referral center in Thailand (2016 to 2025), analyzed children with CP having baseline MP ≤ 40.0%. The primary outcome was the cumulative incidence of hip displacement (MP > 40% or surgery), estimated using Kaplan-Meier analysis. Multivariable Cox regression was used to identify risk factors, adjusting for Gross Motor Function Classification System (GMFCS) level, CP subtype, and epilepsy. Results: A total of 265 patients were included. The cumulative incidence of significant hip displacement of the patients progressively increased over time: 17.8% at 2 years of follow-up, 30.5% at 4 years of follow-up, reaching 41.0% at 6 years of follow-up. Among the children who developed significant hip displacement during the surveillance period, the mean age at the time of initial documentation of displacement was 5.0 (SD = 2.2) years. Multivariable analysis identified GMFCS levels IV-V as the strongest independent predictor (adjusted Hazard Ratio [aHR] 3.09; 95% CI: 1.24, 7.70; p = 0.015) compared to levels I-III. Non-spastic CP subtypes were associated with a significantly lower risk (aHR 0.22; p = 0.017) compared to spastic diplegia. Epilepsy was not found to be an independent risk factor after adjusting for motor severity (aHR = 0.76; p = 0.407). Conclusions: The cumulative risk of hip displacement in this surveillance cohort is high, particularly among children with severe motor impairment (GMFCS IV-V), reaching 41.0% at 6 years of follow-up. These findings underscore the necessity for rigorous, long-term surveillance stratified by GMFCS level and provide crucial data for prognostic counseling to facilitate timely interventions.