Mechanical compensation for weak triceps in C5/C6 tetraplegia

Persons with spinal cord injury at the C5/C6 cervical level typically have relatively well preserved biceps function, but minimal or no voluntary control of triceps. The authors´ previous work demonstrated that this results in deficiencies in speed and accuracy of elbow movements. The authors´ goal is to design a simple mechanical orthosis, worn at the elbow, to correct these deficiencies and also to improve reaching capacity. In this study, the authors have specified the mechanical components necessary for this orthosis by performing computer simulations of movements at the elbow joint and experiments with C5/C6 tetraplegic subjects in which their triceps function was assisted with electronically emulated mechanical springs and damping elements. Results indicate that provision of an elbow orthosis consisting of a constant torque spring and a viscous damping element should obtain the best improvement in arm function of tetraplegic subjects with weak triceps