Hip joint subluxation after selective dorsal rhizotomy for spastic cerebral palsy

OBJECT: The effects of selective dorsal rhizotomy (SDR) procedures on the hip joints of children with spastic cerebral palsy (CP) are not well described. This study was performed to determine the incidence of hip subluxation in children with CP who underwent SDR at a single institution. METHODS: The study group comprised 82 patients (164 hip joints) with a mean follow up of 3.9 years. Forty-four patients had spastic diplegia (53.6%), 35 had spastic quadriplegia (42.7%), two had spastic triplegia (2.4%), and one had spastic hemiplegia (1.2%). The mean patient age at SDR was 5.2 +/- 2.4 years. Preoperative and postoperative hip radiographs were reviewed and the femoral head center edge (CE) angles were recorded. The mean pre- and postoperative right CE angles were 14.1 and 17.2 degrees, respectively, and those of the left were 13.6 and 15.1 degrees, respectively. Considering a change in CE angle greater than 5 degrees as clinically significant, 72 hips (43.5%) remained unchanged, 63 (38.4%) improved, and 29 (17.7%) worsened. Of a number of preoperative variables, including age at time of surgery, Gross Motor Function Classification System (GMFCS) level, ambulatory status, extent of hip subluxation, preoperative scoliosis, and asymmetry of hip subluxation, only GMFCS level was associated with worsening of hip subluxation. CONCLUSIONS: Selective dorsal rhizotomy is more likely to have a positive effect or no effect on hip joint subluxation rather than to have a negative effect. More severe involvement, as measured using the GMFCS, may predispose to worsening of hip subluxation after SDR.