A comparison of shoulder joint forces during ambulation with crutches versus a walker in persons with incomplete spinal cord injury.

OBJECTIVE To compare 3-dimensional (3D) shoulder joint reaction forces and stride characteristics during bilateral forearm crutches and front-wheeled walker ambulation in persons with incomplete spinal cord injury (SCI). DESIGN Cross-sectional cohort study. SETTING Biomechanics laboratory. PARTICIPANTS Fourteen adult volunteers with incomplete SCI recruited from outpatient rehabilitation hospital services. INTERVENTIONS Not applicable. MAIN OUTCOME MEASURE Peak force, rate of loading, and force-time integral were compared for each component of the net 3D shoulder joint reaction force during ambulation with crutches and a walker. Stride characteristics were also compared between assistive device conditions. RESULTS The largest weight-bearing force was superiorly directed, followed by the posterior force. The superior joint force demonstrated a significantly higher peak and rate of loading during crutch walking (48.9N and 311.6N/s, respectively, vs 45.3N and 199.8N/s, respectively). The largest non-weight-bearing force was inferiorly directed with a significantly greater peak occurring during crutch ambulation (43.2N vs 23.6N during walker gait). Walking velocity and cadence were similar; however, stride length was significantly greater during crutch walking (62% vs 58% of normal). CONCLUSIONS Shoulder joint forces during assisted ambulation were large. Crutch use increased the superior force but did not increase walking velocity.