Changes in gait parameters after femoral derotational osteotomy in cerebral palsy patients with medial femoral torsion

Medial femoral torsion (MFT) is a common pathologic gait in cerebral palsy (CP) children that can be corrected by femoral derotational osteotomy (FDO). It is not clearly known as to how much various gait parameters change after FDO. The aim of this study was to quantify changes in gait parameters after FDO. The study group included 19 young CP patients (28 limbs, age<20 years, average age: 13.2 years) with symptomatic MFT, treated with distal FDO. The study group was divided into two groups: the unilateral FDO group (UG) and the bilateral FDO group (BG). The mean degree of derotation was 24.6° (25.0° for UG, 24.4° for BG). Pre-FDO and post-FDO values of Staheli’s rotational profiles and kinematic data were compared. A paired t-test and Pearson’s correlation were used for statistical analysis. The mean internal hip rotation was 71.4±6.9° before surgery and 48.6±10.7° after surgery in the UG (P<0.05) and it was 63.8±15.8° before surgery and 40.9±9.2° after FDO in the BG (P<0.05). The change in the foot progression angle (FPA) was 12.9° in the UG group (P<0.05) and 12.6° in the BG group (P<0.05). The degree of FPA had changed by about a half of the surgical derotation angle. Changes in the mean hip rotation during gait were 14.8° in the UG (P<0.05) and 6.7° in the BG (P<0.05) groups. The overall pelvic rotation was not changed after surgery. However, in patients with preoperative compensatory pelvic rotation of more than 5°, there was a change of 5.3±4.8° in the UG and 6.6±1.54° in the BG after surgery (P<0.05). There was also a trend showing that the younger the patient, the more the pelvic rotation changed (P=0.069). In-toeing gait because of MFT improved with FDO in CP patients. The expected degree of postoperative correction of FPA and hip rotation is about a half of the FDO degree. The degree of compensatory pelvic rotation should be considered to determine the correction angle of FDO, especially in young patients with preoperative pelvic rotation of more than 5°.