Effect of Intertrochanteric Femoral Derotational Osteotomy on Sagittal Plane Kinematic and Kinetic Study of the Hip and Pelvis in Spastic Cerebral Palsy: A Preliminary Report

Chung, Chin Youb; Kim, Hye Oh; Choi, In Ho; Cho, Tae Joon; Sohn, Chi Soo

Abstract

To evaluate the effect of intertrochanteric femoral derotational osteotomy(IFDO) on the sagittal plane kinematics and kinetics of the hip and pelvis in spastic cerebral palsy, we compared the preoperative and post-operative results of 3 dimensional gait analysis. Intertrochanteric femoral derotational osteotomy alone without psoas procedure was performed in 34 hips of cerebral palsy patients with increased femoral anterversion regardless of preoperative dynamic or static hip flexion contracture. Those who had other concomitant hip procedures were excluded. There were 24 diplegics and 10 hemiplegics. Mean age of the patients at the time of operation was 9.1 years (range, 4.9 to 22). They were divided into three subgroups according to the degree of dynamic hip flexion contracture; 13 patients with normal hip extension in terminal stance (group I), 13 patients with maximum hip extension in terminal stance between 0 and 15 degrees (group II), and 8 patients with maximum hip extension in terminal stance of more than 15 degrees (group III). The gait analysis included clinical assessment, video-taping, 3D-kinematics and kinetics, and dynamic EMG. Linear parameters of gait, kinematic parameters, sagittal plane hip moment parameters, and total hip energy parameters were compared. Postoperatively, cadence and double support time decreased, whereas walking velocity and stride length increased in all groups. Maximum and minimum pelvic tilt were improved in all groups. The range of pelvic tilt improved in all groups except group I. Hip flexion-extension curve shifted into extension in all groups. Marked improvement in maximum hip extension in stance and the range of hip motion were observed in all groups. The sum of extensor moment decreased, whereas that of flexor moment increased significantly in all groups. The conversion timing from extensor to flexor moment significantly improved in group I and II. The decrease of power generations of Hl and the increase of power absorptions of H2 were significant in all groups. However, there were no significant changes in power generation of H3 in all groups. The changes of peak power generation timing of H3 was not consistent among the groups. Femoral derotational osteotomy at the intertrochanteric level brings the lesser trochanter forward resulting in iliopsoas lengthening effect. We found significant improvement of the sagittal plane kinematics and kinetics of the hip and pelvis when IFDO alone was performed without psoas tenotomy. The psoas lengthening procedure may be considered secondarily at the time of hardware removal after full evaluation of the psoas lengthening effect.