Gait Characteristics Associated with Walking Speed in Postoperative Patients with Adult Spinal Deformity Extracted by Machine Learning.

Purpose: Patients with adult spinal deformity (ASD) are unable to walk faster even after spinal fixation. Gait rehabilitation that focuses on movements associated with reduced speed may help improve gait function. This study aimed to identify the gait characteristics associated with walking velocity in postoperative patients with ASD.

Methods: Three-dimensional gait analysis was performed in 62 postoperative patients with ASD and 105 healthy volunteers. A dimensionality reduction method, based on data from the healthy cohort, was applied to 194 gait characteristics of the patients. Then, the Markov Chain Monte Carlo method sampled the gait characteristics related to speed, and k-means clustering categorized the gait patterns. The relationships between the extracted gait characteristics and velocity were assessed using multiple regression analysis within each cluster.

Results: Hip sagittal angle and moment (β = - 0.47 to 0.42) were significantly associated with postoperative velocity in all the patients (R² = 0.834). Two clusters were identified, and hip sagittal moments at contralateral contact and toe-off (β = - 0.58 and 0.68, respectively) were associated with velocity in the group that walked faster (R² = 0.634). Maximum ankle plantarflexion moment and hip flexion power (β = 0.53 and 0.33, respectively) were associated with velocity in the group that walked slowly (R² = 0.448).

Conclusion: Larger hip joint movement may play a crucial role in enhancing gait velocity because the spinal fixation limits spino-pelvic movement. To improve gait speed, postoperative older adults with ASD who walk slowly may require new rehabilitation strategies that exert more ankle plantarflexion moment and develop an adequate stance phase to facilitate hip extension.