Failure of Hip Reconstruction in Children With Cerebral Palsy: What Are the Risk Factors?

Abstract

The rates and risk factors contributing to failure after hip reconstruction among patients with cerebral palsy (CP) are not well established. In analyzing a large cohort of children with CP who underwent hip reconstruction, the objectives of this study are to establish (1) the failure rates and (2) associated risk factors. This retrospective study included chart and radiographic review of patients between the ages of 1 to 18, with a diagnosis of CP, who underwent a hip reconstructive procedure at a single children's hospital over a 9-year period (2010 to 2018). Patients without at least 2 years of follow-up were excluded. Age at time of surgery, sex, Gross Motor Function Classification System (GMFCS), procedure(s) performed, preoperative migration percentage (MP), neck-shaft angle, and acetabular index (AI) were recorded. Failure was defined as need for revision surgery or a MP >50% on follow-up radiographs. Logistic regression and multiple-variable regression-type models were used to test for significance of risk factors. Of the 291 hips in 179 patients (102 males, 77 females) that met inclusion criteria, 38 hips (13%) failed. Significant differences in the failure group were seen in age at time of surgery (6.2±3.2 vs. 8.1±3.2; P<0.001), preoperative MP (62.3±28.7 vs. 39.9±24.1%; P<0.001) and preoperative neck-shaft angle (164.9±8.2 vs. 157.3±15.6 degrees; P<0.001). Age below 6 at time of surgery significantly increased failure rate (26% vs. 6.3%, P<0.001) as did preoperative MP >70% (28.9% vs. 9.9%, P<0.001). Receiving an acetabular osteotomy was protective against failure (9.1% vs. 16.9%, P=0.048), particularly in patients with a preoperative AI >25° (odds ratio=0.236; confidence interval: 0.090-0.549). In this case series, failure after hip reconstruction for children with CP was determined to be 13.1%. There was a higher risk associated with age under 6 at time of surgery or a preoperative MP >70%. Correction of acetabular dysplasia when AI is more than 25 degrees with acetabular osteotomy at time of hip reconstruction, exerted a protective effect against subsequent failure. Level III-retrospective case series.