An Analysis of Reoperations Following Proximal Femoral Varus Derotational Osteotomy in Children with Cerebral Palsy.

Background: Hip displacement is common in children with cerebral palsy (CP). The existing literature has focused on native-hip longevity in patients with CP. This study investigated the reoperation-free rate of hips in children with CP following index proximal femoral varus derotational osteotomy (VDRO).

Methods: We conducted a retrospective cohort study of patients with CP who were <18 years of age and underwent VDRO surgery at a tertiary referral center between January 2004 and January 2022, and who were followed for at least 2 years after the index surgery. Two hundred and eighty-nine patients (518 hips) met the inclusion criteria. Any return to the operating room for a same-site procedure counted as a reoperation, apart from elective hardware removal undertaken while the patient underwent a distinctly separate procedure. Reoperation rates and odds ratios (ORs) were calculated. Analyses were carried out using logistic regression and Cox proportional hazard models.

Results: We found a 29.2% rate of reoperation (151 reoperations among 518 hips). The reoperation rate was greatest for patients functioning at Gross Motor Function Classification System (GMFCS) level V (32.2% for level V, 27.8% for level IV, and 25.5% for level II/III), although the difference did not reach significance (p = 0.73). Hips in patients ≥6 years of age were significantly less likely to require reoperation than in those <6 years of age (23.1% versus 46.0%; p < 0.01). Bilateral index procedures (OR, 3.68 [95% confidence interval (CI), 1.68 to 8.04]; p < 0.01) significantly increased the risk of reoperation, regardless of operative side (31.1% right versus 32.3% left; p = 0.84). Additionally, operations on the left hip (OR, 1.24; 95% CI, 1.04 to 1.48; p = 0.02) had an increased risk of reoperation compared with those on the right.

Conclusions: The frequency of reoperation in this large cohort was 29.2%, which is similar to previously published rates. An age of <6 years at the index surgery, operation on the left hip, and bilateral VDRO were the only significant risk factors for reoperation; however, there was a nonsignificant stepwise increase in the reoperation rate with increasing GMFCS level. These findings enhance a surgical team's ability to optimize counseling for families and patients with CP regarding the frequency and timing of additional hip surgery.

Level of evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.