The impact of glenohumeral bone loss on range of motion in patients with anterior shoulder instability.

BACKGROUND Loss of shoulder range of motion (ROM) is common after surgical management of anterior shoulder instability; however, it remains unclear to what degree this is related to their injury. AIM The purpose of this study was to compare passive shoulder ROM in patients with ASI to a normal contralateral shoulder. METHODS A total of 121 patients undergoing stabilization surgery were prospectively enrolled. Preoperative advanced imaging was used to assess for glenoid bone loss and the presence of off-track Hill-Sachs lesions. Passive ROM was measured in both shoulders while under anaesthesia prior to surgery. RESULTS In all directions, there was a significant loss of ROM in shoulders with instability. Regression analysis showed that neither a glenoid bone defect nor greater glenoid bone loss were associated with a loss of ROM in any plane. The presence of a Hill-Sachs lesion was significantly associated with a loss of external rotation, while off-track lesions were associated with a loss of ROM in all planes (p < 0.05). CONCLUSION Patients with anterior shoulder instability lost motion in all directions, with a profound loss of external rotation. The presence of a glenoid bone defect nor greater bone loss did not reliably predict a loss of range of motion. A Hill-Sachs lesion was predictive of a loss of external rotation, while an off-track lesion was predictive of a loss of range in all directions.