Role of femoral derotation on gait after selective dorsal rhizotomy in children with spastic cerebral palsy

AIM: To evaluate the long-term outcome of selective dorsal rhizotomy (SDR) on gait and the influence of previous femoral derotation osteotomy (FDO). METHOD: In a retrospective cohort study of 29 children (16 females, 13 males) with spastic diplegic cerebral palsy, 14 children received FDO before SDR, whereas 15 children with moderate or near-normal internal femoral rotation during gait received only SDR. Three-dimensional gait data were obtained pre-FDO, pre-SDR, 1 year post-SDR, and 3 to 5 years post-SDR, to study the Gait Profile Score (GPS), pelvic tilt, and knee and hip kinematics. A mixed analysis of variance with the repeated measure 'time' was performed between different time points for each group. RESULTS: Children who first underwent FDO and then SDR started with a more complex gait pathology but showed fewer gait deviations 3 to 5 years post-SDR, compared to children who only underwent SDR. This was reflected by a lower GPS and pelvic tilt, as well as less knee flexion in stance. INTERPRETATION: The effect of SDR on gait is only significant in the mid- to long-term if the bony lever arms are also corrected. Thus, the clinical outcome after SDR is dependent on good proximal alignment. WHAT THIS PAPER ADDS: Pelvic tilt remains stable after femoral derotation osteotomy (FDO)+selective dorsal rhizotomy (SDR). But pelvic tilt deteriorates after SDR only. Hip and knee extension is better after FDO+SDR than after SDR only. Spasticity reduction (by SDR) combined with bony lever arm correction (by FDO) improves gait.