Femoral derotation osteotomy (FDO) is a treatment option in children and adolescents with cerebral palsy who have transverse plane deviations in their lower limbs. When the transverse kinematic deviations are asymmetric, the osteotomy indication can be unilateral.

Unilateral FDO has a kinematic effect on ipsilateral transverse plane deviations along with those of the pelvis and contralateral side.

Among the 170 diplegic children that our team has operated on, 34 underwent unilateral FDO. Their mean age was 12.5±2.7 years; 12 were GMFCS level I and 22 were level II. The kinematic changes 18 months after surgery were evaluated with a paired Student's t test and correlations were determined with the Spearman test (p<0.05). The mean preoperative femoral anteversion was 45°±8°. In terms of kinematics, on the operated side, the children had a mean internal hip rotation of 26°±7°, external pelvis rotation of −8°±6° and inward foot progression angle of 8°±12°.

The anteversion was corrected surgically by −28°±5°. Postoperatively, the ipsilateral hip rotation (10°±10°), pelvis rotation (−2°±5°) and foot rotation (6°±12°) were significantly improved. No correlations were identified between the resulting kinematic parameters and surgical correction. The five feet that had inward rotation (13°±9°) were improved to (−5°±7°).

Unilateral FDO of the hip in patients with asymmetry not only reduces the internal rotation of the operated hip, it also normalizes the rotation of the pelvis and both feet. However, these improvements are not directly related to the amount of surgical correction.

IV: case series.