Femoral neck anteversion of the less involved side in unilateral cerebral palsy: kinematics and radiological considerations.

This research aims to investigate femoral neck anteversion (FNA) on the less involved side in unilateral cerebral palsy (CP) and examine its impact on hip rotation during gait. Sixty-nine patients with unilateral CP, with a mean of 21 years, were included study. Static and dynamic hip rotation ranges were quantified via physical examination and three-dimensional motion analysis. Patients were stratified into five levels of involvement according to modified Winters' classification. FNA differences between modified Winters' classification types and correlation with static and dynamic hip rotation were analyzed. Hip morphology was classified based on the Melbourne Cerebral Palsy Hip Classification Scale E&R. Regarding FNA, our analysis suggested a moderate correlation (r = 0.61, P < 0.05) between both sides. Hip dysplasia was found in 20.5 and 23.1% of the less involved and more involved sides, respectively, in 39 patients. Increased FNA was associated with increased static hip internal and decreased external rotation for both sides (P < 0.05). A positive correlation was observed between FNA and dynamic hip rotation on the more involved side (P < 0.05). Conversely, on the less involved side, FNA showed no significant correlation with pelvic, hip, or knee rotation. This study demonstrates that in unilateral CP, the less involved side is also significantly affected, a moderate correlation exists between the two sides, and both hips may exhibit dysplasia. These findings underscore the necessity for a comprehensive bilateral clinical assessment. Long-term surveillance of both hips and consideration of the less involved side for surgical planning may be warranted.