Progression of Contralateral Hip Displacement After Unilateral Reconstruction in Children with Cerebral Palsy: A Single-Center Retrospective Study of 42 Patients

The management of the stable contralateral hip after unilateral reconstruction in children with cerebral palsy (CP) remains controversial. This single-center retrospective study included 42 children at Gross Motor Function Classification System (GMFCS) levels III–V (mean age, 8.1 ± 2.9 years) who underwent unilateral hip reconstruction between 2019 and 2026; the median follow-up was 51.9 months. Progression was defined as a contralateral migration percentage (MP) increase of ≥10 percentage points or crossing 30% from below. Progression occurred in 8 of 42 children (19.0%; 95% confidence interval [CI], 10.0–33.3%), all at GMFCS levels IV–V (level V, 38.5%; level IV, 11.1%; P = 0.086). Children who progressed more often had an index-hip MP of 100% (50.0% vs. 5.9%; odds ratio, 16.00; P = 0.008) and baseline disruption of Shenton’s line (62.5% vs. 20.6%; P = 0.031). They also had a higher contralateral neck–shaft angle (150° vs. 145°; P = 0.046), a larger increase in pelvic obliquity (+5.0° vs. 0°; P = 0.014), and less standing time (1.5 vs. 3 hours/week; P = 0.029). All events occurred within 27 months of surgery. With eight events, these findings are descriptive: they support denser surveillance during the first two to three postoperative years but not prophylactic contralateral surgery.