Performing Clinical Exams at Specific Joint Positions May Help Identify Injured Regions of the Glenohumeral Capsule Following Anterior Dislocation

The anteroinferior glenohumeral capsule (anterior band of the inferior glenohumeral ligament (AB-IGHL), axillary pouch) limits anterior translation, particularly in positions of external rotation. [1, 2] Permanent tissue deformation that occurs as a result of dislocation contributes to anterior instability, but, the extent and effects of this injury are difficult to evaluate as the deformation cannot be seen using diagnostic imaging. Clinical exams are used to identify the appropriate location of tissue damage and current arthroscopic procedures allow for selective tightening of localized capsule regions; however, identifying the specific location for optimal treatment of each patient is challenging. Although the reliability of clinical exams has been shown to change with joint position [3] a standardized procedure has yet to be established. This lack of standardization is particularly problematic since capsule function is highly dependent upon joint position [4–7], and could be responsible for failed repairs attributed to plication of the wrong capsular region [8]. Understanding the relationship between the location of tissue damage and changes in capsule function following anterior dislocation could aid clinicians in diagnosing and treating anterior instability. Therefore, the objective of this work was to compare strain distributions in the anteroinferior capsule before and after anterior dislocation in order to identify joint positions at which clinical exams would be capable of detecting damage (nonrecoverable strain) in specific locations.