Biomechanical analysis of a posterior transfer maneuver on a level surface in individuals with high and low-level spinal cord injuries

Objective. The purpose of this study was to determine the movement patterns and the muscular demand during a posterior transfer maneuver on a level surface in individuals with spinal cord injuries. Design. Six participants with high-level spinal cord injury (C7 to T6) were compared to five participants with low-level spinal cord injury (T11 to L2) with partial or complete control of abdominal musculature. Background. Developing an optimal level of independence for transfer activities figures among the rehabilitation goals of individuals with spinal cord injury. There has been no biomechanical study which specifically describes the posterior transfer maneuver. Methods. Tridimensional kinematics at the elbow, shoulder, head and trunk, as well as surface electromyographic data of the biceps, triceps, anterior deltoid, posterior deltoid, pectoralis major, latissimus dorsi, trapezius and rectus abdominus muscles were recorded during the posterior transfer. To quantify the muscular demand, the electromyographic data were amplitude normalized to the peak value obtained from maximum voluntary contractions. The transfer was divided into pre-lift, lift, and post-lift phases for analysis. Results. The duration of the lift phase was significantly shorter (P<0.05) for the high-level spinal cord injury (1.24; SD, 0.37 s) when compared to the low-level spinal cord injury (1.74; SD, 0.39 s). The patterns and magnitudes of the angular displacements were found similar between groups (P values: 0.45–0.98). However, the high-level spinal cord injury initiated the task from a forward flexed posture, whereas the low-level spinal cord injury adopted an almost upright alignment of the trunk. Higher muscular demands were calculated for all muscles among high-level spinal cord injury participants during the transfer when compared to the low-level spinal cord injury. However, only the anterior deltoid (high level = 92.4%; low level = 34.2%) and the pectoralis major (high level = 109.8%; low level = 25.6%) reached statistical significance during the lift phase. Conclusions. Participants with high-level spinal cord injury presented different movement characteristics and higher muscular demands during the posterior transfer than low-level spinal cord injury ones. This is probably to compensate for the additional trunk and upper limb musculature impairment.