Risk of recurrent dislocation and avascular necrosis after proximal femoral varus osteotomy in children with cerebral palsy.

A retrospective review was conducted on 50 children with cerebral palsy, having 89 femoral varus osteotomy at an average age of 7.4 years, trying to identify risk factors for complications, particularly redislocation and avascular necrosis. Among the well-reduced hips, new subluxation developed in 12 cases; postoperative radiographic measurements showed a mean neck-shaft angle of 135 degrees and an acetabular slope of 32 degrees . Main risk factors for secondary dislocation seem to be insufficient correction of preexisting valgus and uncorrected acetabular dysplasia. Avascular necrosis was observed in 33 hips (37%): 26 minor and seven severe. Older age at surgery and high preoperative Reimer's migration index seem statistically significant risk factors.