Percutaneous hamstring lengthening in cerebral palsy: Technique and gait outcomes based on GMFCS level

Background Increased knee flexion at initial contact and in stance is a common problem for children with cerebral palsy. Surgical correction with percutaneous hamstring lengthening is an alternative to open hamstring lengthening; however, outcomes are less well documented, and there is concern about increasing anterior pelvic tilt. The purpose of this study was to evaluate the short-term outcomes of percutaneous hamstring lengthenings in children with cerebral palsy using comprehensive gait analysis techniques. Research Question Does percutaneous hamstring lengthening improve knee function, and do knee and anterior pelvic tilt outcomes vary by GMFCS level? Methods A convenience sample of 52 patients with both pre and post-surgical gait analyses was evaluated retrospectively for changes in gait function in terms of temporal-spatial parameters, kinematics and kinetics. Patients were divided into two GMFCS subgroups: GMFCS level I/II and III. Results The percutaneous hamstring lengthening results in statistically significant improvements in knee function during gait with increased knee extension at initial contact (mean 32° SD 13° to mean 21° SD 11°, p = 0.000) and improved mean knee flexion in stance (mean 23° SD 12° to mean 16° SD 11°, p = 0.000) for the total study cohort. Beneficial changes were found for knee function in both GMFCS level subgroups; however, there was an increase in pelvic tilt pre to post-surgery in the GMFCS level III subgroup (mean 21° SD 8° to mean 26° SD 6°, p = 0.012) but not the GMFCS level I/II subgroup (mean 18° SD 7° to mean 20° SD 8°, p = 0.427). Significance Percutaneous hamstring lengthening can improve knee function for all patients; however, the impact on anterior pelvic tilt varies by GMFCS level, with increasing anterior tilt for GMFCS level III only. This study highlights the importance of understanding differences in surgical outcomes by GMFCS level to better predict post-surgical function.