Effect of derotation osteotomy of the femur on hip and pelvis rotations in hemiplegic and diplegic children.

The purpose of this study was to evaluate hip and pelvis rotations in groups of hemiplegic and diplegic children before and after surgical correction of fixed internal rotation deformity of the hip. Twenty-two children with cerebral palsy (eight diplegia, 14 hemiplegia) having fixed internal rotation deformity at the hip were treated by multilevel surgery which included derotation osteotomy of the femur. Evaluation was done before and at a mean of 3.1 years after surgery using three-dimensional computerized gait analysis. Preoperatively, the patients in the hemiplegia group had a significantly greater compensatory external rotation of the pelvis than those in the diplegic group. Post-operatively there were no significant differences between the two groups. In the hemiplegia group the external rotation of the pelvis was corrected after correction of hip rotation by derotation osteotomy. Patients in the diplegia group showed significant improvements in the hip rotation with no significant change in the pelvis rotation after multilevel surgery.