Kinematic characteristics of multi-directional reaching movement in degenerative cervical myelopathy

Study Design: Prospective cross-sectional study Objectives: To objectively evaluate kinematic characteristics of multi-directional reaching movement in individuals with degenerative cervical myelopathy (DCM). Setting: East Maebashi Orthopedic Hospital, Japan. Methods: Twenty-five individuals with DCM participated in this study. Participants performed single- and multi-directional reaching tasks before and after cervical decompression surgery. Kinematic parameters, including Acceleration (ACC), Movement time, and Movement distance, were recorded in three-dimensional (3D) space during the two reaching tasks. Correlations between the improvement rates of kinematic parameters and other clinical tests were evaluated. Furthermore, a multiple stepwise regression analysis was performed to investigate the contribution of multi-directional reaching to the postoperative improvement of upper limb performance. Results: The 3D trajectories during multi-directional reaching became smoother with reduced variability after surgery, and significant postoperative improvements were observed in kinematic parameters. Multiple regression analysis revealed that improvement of upper limb performance was predicted by the improvement of ACC during multi-directional reaching (β = 0.50, p < 0.05) and the 10-second grip-and-release test (β = 0.49, p < 0.05), explaining 45% of variance. Conclusions: Evaluation of multi-directional reaching movement, which more accurately reflects multi-joint coordination of the proximal arm, could serve as a valuable indicator for assessing postoperative recovery in reaching function in DCM. Moreover, these findings suggest that reaching function affects overall upper limb performance and the importance of separately assessing proximal and distal arm functions in individuals with DCM.