Abstract
BACKGROUND: Hip displacement (HD), common in cerebral palsy (CP), is reportedly less prevalent for spastic hemiplegia. Patients with a Winter-Gage-Hicks (WGH) type IV gait pattern are believed at increased risk of HD, but true prevalence is unknown. This study aimed to analyze the rates of HD according to the sagittal plane-based WGH classification and identify associated risk factors. METHODS: Patients with hemiplegic CP, ≥1 instrumented gait analysis (IGA), hip surveillance radiograph(s), and minimum 2-year follow-up were included. The primary outcome was presence of an "unsuccessful hip" defined as a migration percentage ≥30% and/or undergoing reconstructive osteotomies for HD. Secondary outcome variables included WGH type, previous surgery, sex, scoliosis, epilepsy, ventriculoperitoneal shunt, gastrostomy tube, and IGA-derived hip kinematics. RESULTS: Included were 144 patients (39.6% female), classified as Gross Motor Function Classification System I (45.1%) or II (54.9%), mean follow-up 9.6 ± 4.6 years. Seventeen patients (11.8%) had an unsuccessful hip outcome (age 11.6 ± 3.6 years). Stratified by WGH type, unsuccessful hip outcome rates were I: 9.5% (2/21), II: 9.4% (6/64), III: 6.7% (2/30), and IV: 24.1% (7/29); age at onset was not different between WGH types (p = 0.8). Multivariate analysis identified hip internal rotation (odds ratio [OR]: 4.7, confidence interval [CI]: 1.2-18.1, p = 0.02) and hip adduction (OR: 5.2, CI: 1.2-22.1, p = 0.02) as significant independent risk factors. CONCLUSION: The rates of HD in spastic hemiplegia were higher than expected for all WGH types, particularly IV. A high index of suspicion and regular hip surveillance radiographs is required for patients with hip internal rotation and adduction, starting during preadolescence. LEVEL OF EVIDENCE: III-Retrospective cohort observational study. See Instructions for Authors for a complete description of levels of evidence.