CHANGES IN HIP MIGRATION AFTER SELECTIVE DORSAL RHIZOTOMY FOR SPASTICQUADRIPLEGIA IN CEREBRAL-PALSY

Selective dorsal rhizotomy is increasingly used for management of spas tic quadriplegic cerebral palsy but rates of hip stability following t he operation have not been reported. Determining hip stability by radi ographic measurement of lateral migration of the femoral head beyond a lateral edge of the acetabulum after dorsal rhizotomy allows an objec tive assessment of the outcome of the operation. This prospective stud y examined the effect of selective dorsal rhizotomy on lateral migrati on of the femoral head in 45 children with spastic quadriplegic cerebr al palsy. The children ranged in age from 2 to 9 years (average 5 year s 1 month) and were grouped according to their ages with 23 children i n the 2- to 4-year-old group and 22 children in the 5- to 9-year-old g roup. Postoperative follow up ranged from 7 to 50 months (average 20 m onths). The Reimers migration percentage (MP), a measure of the latera l migration of the femoral head, was calculated from anteroposterior h ip radiographs taken prior to the operation and at the last followup e xamination. Of the 90 hips involved, 9% improved, 80% remained unchang ed, and 11% worsened, yielding a radiographic stability rate of 89%. T he hips with postrhizotomy worsening of the MP had an average preopera tive MP of 14% (range 9% to 38%) and an average postoperative increase in MP of 18% (range 11% to 37%). Of the 45 children, four subsequentl y underwent unilateral derotational femoral osteotomies for persistent or worsening hip subluxation. There was a significant tendency for th e MP to worsen in patients with lower prerhizotomy MP values (chi(2) = 20.74, df = 4, p = 0.001), but the age of patients and their ambulato ry status at the time of rhizotomy had no bearing on postoperative hip stability. The data indicate that selective dorsal rhizotomy prevents progressive lateral migration of the femoral head in the majority of children who undergo the operation for spastic quadriplegia.