The impact of asymmetry on the radiographical outcomes following hip reconstruction in patients with cerebral palsy

PURPOSE: The purpose of this study was to evaluate the impact of asymmetric hip dysplasia on the outcome of hip reconstruction in patients with cerebral palsy according to preoperative migration percentage (MP). METHODS: This study was institutional review board-approved for retrospective cohort review. From 2008 to 2018, 65 patients met inclusion criteria: Gross Motor Function Scale Classification (GMFSC) III to V with spastic hips (MP > 30%) who underwent bilateral hip reconstruction, with a follow-up > 24 months. Main exclusion criteria: children with associated syndromes or chromosomal disorders. The cohort was subdivided into three groups according to preoperative MP difference between hips: Group A > 50%, group B 20% to 50% and Group C < 20%. Subsequently, the groups were analyzed individually and then compared. The asymmetry of extended abduction of the hip was also evaluated and separated into three groups: no asymmetry (< 20° difference), mild asymmetry (20° to 50° difference) and severe (> 50° difference). RESULTS: In total, 65 patients underwent bilateral bony reconstructive surgery (130 hips). Mean age at surgery was 10.1 years (sd 3.6; 3.6 to 18.4). Mean age at follow-up was 14.7 years (sd 3.8; 8 to 21). Preoperative GMFSC distribution was grade III (four, 6%), IV (15, 23%) and V (46, 71%). In all, 21 symmetric hips (< 20% MP difference) had a preoperative MP difference of 9% and a follow-up MP difference of 18% (p > 0.05); 32 had a preoperative MP difference of 34% and a follow-up MP difference of 16% (p < 0.0001); 12 had a preoperative MP difference of 80% and a follow-up difference of 6% (p < 0.0001). According to pre- and postoperative abduction values, the mean high hip abduction preoperatively was 34° (sd 17°), whereas low hip abduction was 23° (sd 17°). CONCLUSION: Hips with asymmetrical dysplasia and/or abduction undergoing bilateral reconstructive surgery focused on symmetric abduction, and corrected dysplasia in patients with cerebral palsy has improved symmetry in hip abduction and MP. Obtaining this goal immediately postoperatively is maintained to medium-term follow-up. LEVEL OF EVIDENCE: IV