Sensorimotor deficits contributing to glenohumeral instability.

The conventional perspective has been that capsuloligamentous structures act as a mechanical restraint to humeral translation at the shoulder. Although this is true, the capsuloligamentous structures also have a sensorimotor influence on the musculoskeletal system, providing stability at the shoulder. The purpose of the current study was to discuss the sensorimotor role that the capsuloligamentous structures play in providing stability, how these mechanisms are disrupted with glenohumeral instability, and how surgical intervention restores such mechanisms. Proprioceptive information transmitted from the mechanoreceptors embedded within the capsuloligamentous structures influence the coordinated motor patterns, reflex activity, and joint stiffness to provide enhanced joint stability. The capsuloligamentous injury that occurs with shoulder instability not only affects mechanical restraint, but also alters this proprioceptive input to the central nervous system. As a result of these deficits in proprioception, alterations in reflex activity and motor programs as evident by muscle firing pattern alterations manifest. Although the main goal of surgical intervention is to restore the mechanical restraint that is lost with joint dislocation or subluxation, surgical intervention whether through open, arthroscopic, or thermal techniques seem to restore the proprioceptive deficits that exist after joint injury.