Paralytic pelvic obliquity. Its prognosis and management and the development of a technique for full correction of the deformity.

Thirty-nine patients with post-poliomyelitic scoliosis and pelvic obliquity were treated and followed for up to four years. The dominant pathological mechanism causing the pelvic obliquity was trunk-muscle imbalance. The natural history of untreated pelvic obliquity is progression, leading ultimately to dislocation of the hip. The functional abilities of the patient are then severely restricted. Our aim in treatment was to obtain the maximum possible correction of pelvic tilt and so to prevent subluxation of the femoral head. Total correction was obtained in fifteen patients; no loss of correction was seen in twenty-four patients. The best results were achieved by preliminary traction, Dwyer instrumentation distally to the fifth lumbar vertebra, and extensive posterior fusion extendind distally to the sacrum.