Distal tibial rotation osteotomies normalize frontal plane knee moments.

BACKGROUND: Torsional deformities of the lower extremity are common in children and are often corrected with rotational osteotomy. The effects of torsional abnormalities, and the effects of corrective osteotomy, are not well understood. A study of children with isolated idiopathic tibial torsional pathology undergoing a single corrective procedure may assist in understanding the biomechanics of torsional deformities and the effect of surgical correction.

METHODS: Preoperative and postoperative gait analyses were performed for eight subjects (eleven sides) with idiopathic excessive inward tibial torsion and ten subjects (fourteen sides) with excessive outward tibial torsion. Sagittal ankle and frontal knee moments were assessed and compared with those for age-matched controls.

RESULTS: Preoperatively, subjects exhibited abnormal frontal knee moments at push-off. Subjects with inward tibial torsion demonstrated excessive internal valgus moments, and subjects with outward tibial torsion demonstrated reduced internal valgus or relative internal varus moments compared with the control subjects. Ankle power was significantly reduced in the inward torsion group but not in the outward torsion group. Surgical correction of the torsional deformities normalized frontal plane knee moments in both inward and outward torsion groups and restored ankle power in the inward torsion group.

CONCLUSIONS: In the present study, excessive tibial torsion adversely affected frontal knee moments and was associated with other kinematic and kinetic abnormalities. Corrective osteotomies improved all variables studied here and restored many to the values found in the control group.