Use of 3D gait analysis as predictor of achilles tendon lengthening surgery outcomes in children with cerebral palsy

BACKGROUND: In children with spastic Cerebral Palsy (CP), the treatment of equinus foot with Achilles tendon lengthening (ATL) surgery is associated with high incidence of overcorrection, which may result in crouch gait. AIM: We aimed to assess if gait pattern in preoperative time could be a predictor of the surgery outcome. DESIGN: Cross-sectional retrospective study. SETTING: Movement Analysis Lab, IRCCS San Raffaele Pisana Hospital, Rome (ITALY). POPULATION: Eighteen children (mean age 9.64.7 years) with spastic diplegia CP who underwent bilateral ATL surgery to correct equinus foot were involved. METHODS: Participants underwent 3D gait analysis before and approximately 12 months after surgery. Primary measures were spatiotemporal, kinematic (summarized by Gait Variable Scores, GVSs) and kinetic parameters. The gait patterns for each leg was defined from kinematic data, using a quantitative classification: Plantar Flexor Knee Extension (PFKE) index. The CP group was split into true equinus and jump gait. RESULTS: The equinus foot was successfully corrected as demonstrated by the improvement of GVS ankle dorsi-plantarflexion. However, there was a high rate of overcorrection in the true equinus, characterized by increases in knee flexion- extension GVS (8.7° pre vs. 16.7° post P<0.05) and knee flexion angle at initial contact (5.2° vs. 20.6° P<0.05) and by a decrease in the maximum ankle power generated at push-off (1.49 vs. 0.83 W/kg P <0.05). CONCLUSIONS: Assessment of motor phenotype in preoperative time are good predictors of the results of ATL surgery. In children with true equinus gait, the increase of knee flexion subsequent to ATL is an early indicator that this technique will lead to crouch gait. These results show the influence of true equinus and jump gait patterns on the outcomes of the ATL. CLINICAL REHABILITATION IMPACT: Therefore, we propose that this approach could have clinical value to evaluate and prescribe rehabilitation in children with CP disease, proposing different solutions depending on motor phenotype.