Crankshaft effect after posterior spinal fusion and unit rod instrumentation in children with cerebral palsy.

Radiographs and charts were reviewed for all children with cerebral palsy who underwent posterior-only spinal fusion with the unit rod for neuromuscular scoliosis by the senior author from 1989 through 1996. Fifty patients were found to have an open triradiate cartilage at the time of fusion. A single observer obtained measurements of the preoperative, postoperative, and most recent spine films using the standard Cobb angle. Amount of change was calculated over the respective periods. Forty-three patients had at least 2 years of clinical follow-up. Twenty-nine patients had more than 2 years of both radiographic (mean, 4.6 years) and clinical follow-up (mean, 4.8 years) with a closed triradiate cartilage on their most recent films. In this group, the mean absolute curve change over the length of radiographic follow-up was 0.6 degrees (range, -9-14). None of the 43 patients with at least 2 years of clinical follow-up (mean, 4.5 years) had any radiographic change that was clinically significant on chart review. Therefore posterior spinal fusion alone with unit rod instrumentation is adequate treatment to control crankshaft deformity in skeletally immature children with neuromuscular scoliosis due to cerebral palsy.