Varus derotational osteotomy for spastic hip instability: the roles of femoral shortening and obturator neurectomy.

Varus derotational osteotomy (VDRO) was used to treat 69 unstable hips in 38 patients with spastic quadriplegia. After a mean follow-up of 5.3 years, the total rate of failure as judged by either need for revision or persistent radiographic instability or dislocation was 26%. Overall outcomes were better for hips that had been more congruent (preoperative migration index < 60%) than for hips that had experienced more migration (P = .027), and more-congruent hips were 9 times more likely to be stable radiographically at follow-up (P < .001). The failure rate for VDRO combined with femoral shortening or obturator neurectomy was lower than that for VDRO alone (P = .035). VDRO is an appropriate option for treating less advanced hip subluxation and may be more reliable when combined with femoral shortening and/or obturator neurectomy. VDRO alone, however, may be insufficient for treating more advanced instability.