Three-dimensional shoulder kinematics in individuals with C5-C6 spinal cord injury

The shoulder kinematics of five able-bodied subjects and those of five arms in three subjects with spinal cord injuries at C5 or C6 levels were measur ed as the subjects elevated their arms in three different planes: coronal, scapular and sagittal. The range of humeral elevation was significantly red uced in all spinal cord injury (SCI) subjects relative to able-bodied subje cts. Over this restricted range of humeral motion, the scapula of SCI subje cts tended to be medially rotated, relative to able-bodied subjects, and th e protraction and spinal tilt angles of the scapula of the SCI subjects ind icated scapular winging. These results are consistent with paralysis or at least with significant weakness of the serratus anterior muscle. If further study confirms this hypothesis, functional neuromuscular stimulation of th e serratus anterior muscle via a nerve cuff electrode may be an effective i ntervention for improving shoulder function in C5-C6 SCI.