Femoral neck abnormalities in spina bifida.

Femoral neck abnormalities in spina bifida can be of two types: Type A, consisting of widening of the physis and often associated with varus deformity, and Type B, characterized by marked narrowing of the femoral neck, resulting in a typical mushroom appearance. The Type A deformity is usually associated with an abduction contracture of the hip. This physeal lysis seems to be secondary to microtrauma sustained during persistent exercise done by the parents and therapist to overcome the abduction contracture. No treatment is required, even when varus deformity is present. These patients require an orthosis with a pelvic band for ambulation, and their mobility will not be affected by the deformity.