Rapid progression of hip subluxation in cerebral palsy after selective posterior rhizotomy.

Rapid progression of hip subluxation was noted in the year after selective dorsal rhizotomy in seven hips (six patients). The hips that subluxed progressed from a lateral extrusion index averaging 25% preoperatively as compared with 50% after rhizotomy. Although preexistent hip dysplasia was a predisposing factor, hips with an intermediate degree of preoperative lateral extrusion (12-25%) had variable results. Ongoing and more frequent evaluation of hip stability is necessary after dorsal rhizotomy.