Radiological outcome of reconstructive hip surgery in children with gross motor function classification system IV and V cerebral palsy.

Hip subluxation is common in children with cerebral palsy (CP). The aim of this study was to describe the radiological outcome of reconstructive hip surgery in children with CP, gross motor function classification system (GMFCS) level IV and V, and determine whether the GMFCS level plays a predictive role in outcome. This was a retrospective cohort study conducted at a tertiary-level pediatric hospital with a CP hip surveillance program. Of 110 children with GMFCS IV and V CP registered for hip surveillance, 45 underwent reconstructive hip surgery between 1997 and 2009, defined as varus derotational proximal femoral osteotomy with or without additional pelvic osteotomy. Eleven children were excluded because of lack of 12-month follow-up (n=10) or missing clinical records (n=1). Thus, 21 GMFCS IV children (median age 6 years at surgery) and 13 GMFCS V children (median age 5 years at surgery), who underwent 58 index surgeries, were included in the study. Clinical records and radiology were reviewed. The two surgical groups were femoral osteotomy (varus derotational femoral osteotomy with an AO blade plate or femoral locking plate fixation), or femoral ostetotomy with additional pelvic osteotomy. Reimer's migration percentage (MP) was calculated from anteroposterior pelvis radiographs to determine the outcome for each hip independently. Failure was defined as MP of greater than 60% or further operation on the hip. Reconstructive surgeries were performed for 58 hips with a median preoperative MP of 55%. There were 15 failures at a median of 62 months, including nine failures in 35 GMFCS IV hips and six failures in 23 GMFCS V hips. Overall, GMFCS V hips tended to fail earlier, (hazard ratio 2.3) with a median time to failure of 78 and 39 months for GMFCS IV and V hips, respectively. Combined femoral and pelvic osteotomies had the lowest failure rates in both groups of patients. The GMFCS classification may have some predictive value for outcomes following reconstructive hip surgery, with surgery for GMFCS V hips tending to fail earlier.