O2119: Beyond the First Procedure: An Analysis of Reoperations Following Femoral Osteotomy in Patients with Cerebral Palsy

Background: Hip displacement occurs commonly in children with cerebral palsy (CP), with reported rates of 30-35%. Displacement risk is directly related to increased gross motor function classification system (GMFCS) level. “At-Risk”, subluxated or dislocated hips are indicated for surgical intervention to avoid pain later in life. Existing literature focuses on the survival of a native hip in patients with CP. We undertook this study to define the survival of hips after undergoing an index procedure.

Methods: We conducted a retrospective cohort study of patients ≤18 years old with CP who underwent a proximal femoral derotational varus osteotomy (VDRO) surgery at a tertiary referral center from 2004 to 2022. 350 patients (130 female; mean age: 8.6 years, SD: 3.4, range: 1.5-18; 2 GMFCS I, 35 GMFCS II, 39 GMFCS III, 119 GMFCS IV, 135 GMFCS V, 22 unavailable) met inclusion criteria. Demographic information, index surgery, and reoperation surgery data were collected. Reoperation surgery was defined as any return to the operating room for same-surgical-site procedures, including hardware complications, peri-implant fracture, infection, pain, soft tissue, and further hip subluxation. Analyses were carried out using logistic regression models in STATA. Reoperation surgery rates and odds ratios were calculated.

Results: In total, 664 hips (267 bilateral) were included for analysis (54 GMFCS II, 72 GMFCS III, 244 GMFCS IV, 256 GMFCS V, 38 unavailable), with a mean follow-up of 3.8 years (SD 3.4 years ). Neither patient functioning at GMFCS I had a reoperation surgery, and these patients were thus excluded from analysis. We report a 27% rate of reoperation surgery (178 reoperations). Increasing age at initial surgery was protective against reoperation surgery (OR=0.83, 95% CI [0.78-0.89], p< 0.01). Among hips with available GMFCS information, reoperation surgery rates were greatest in GMFCS V hips (28.9% GMFCS V, 26.2% GMFCS IV, 23.0% GMFCS II/III,). Hips in patients operated on at age ≥8 years old are significantly less likely to require a reoperation surgery than in those operated on at < 8 years old (36% vs 17%, OR 0.37, 95% CI [0.25-0.53], p< 0.01).

Conclusion: This is the largest series of VDRO reoperations in CP reported to date. Age at index surgery was the only significant variable in this analysis with a stepwise decrease in GMFCS level that did not reach statistical significance. These findings are a tool to aid in counseling regarding a child with CP’s hip surgical trajectory.