Pathophysiology of anterior shoulder instability.

OBJECTIVE: To review some of the important biomechanical factors that provide glenohumeral stability, along with the pathologic mechanisms involved in glenohumeral instability of the shoulder. DATA SOURCES: Current English medical literature concerning the multiple pathologic factors involved in glenohumeral instability was reviewed. DATA SYNTHESIS: Multiple dynamic and static factors control glenohumeral instability. Knowledge of normal shoulder anatomy and biomechanics is necessary to interpret pathologic events. CONCLUSIONS/RECOMMENDATIONS: Dynamic and static factors collectively provide stability to the glenohumeral joint. Disruption or malfunction of these factors causes dysfunction in the shoulder.