Coronal Plane Knee Moments Improve After Correcting External Tibial Torsion in Patients With Cerebral Palsy

Background External tibial torsion causes an abnormal axis of joint motion relative to the line of progression with resultant abnormal coronal plane knee moments and affects lever arm function of the foot in power generation at the ankle. However, it is unclear whether surgical correction of the tibial torsion corrects the moments and power. Questions/purposes We evaluated whether surgical correction of external tibial torsion in patients with cerebral palsy would correct the abnormal coronal plane knee moments and improve ankle power generation. Methods We studied 22 patients (26 limbs) with cerebral palsy (Gross Motor Function Classification System Level I or II) who underwent distal internal rotation osteotomies for correction of external tibial torsion as part of a multi-level surgical intervention. There were 10 males and 12 females with a mean age at surgery of 14 years (range, 6.8-20.9 years). All patients had pre- and postoperative standardized clinical evaluation and computerized three-dimensional gait analysis. Minimum followup was 9 months (average, 13 months; range, 9-19 months). Results On physical examination, the mean (+/- SD) transmalleolar axis improved from 43 degrees +/- 10 degrees preoperatively to 20 degrees +/- 7 degrees postoperatively. Mean knee rotation improved kinematically from 40 degrees +/- 9 degrees preoperatively to 21 degrees +/- 9 degrees postoperatively. Twenty-two of 26 limbs (88%) improved in one or both peaks of the abnormal coronal plane knee moments. Ankle power generation did not change from preoperative (1.6 +/- 0.7 W/kg) to postoperative (1.6 W/kg). Conclusions Correction of external tibial torsion in ambulatory patients with cerebral palsy improves the kinematic and kinetic deviations identified by gait analysis.