prevalence of concomitant injuries with hill–sachs lesion in traumatic shoulder dislocations

INTRODUCTION: The shoulder joint (comprising the glenohumeral and scapulothoracic joints) displays the greatest range of motion of all joints in the human body, and preservation of its stability is essential to its function. The Hill–Sachs defect is a compression fracture of the humeral head associated with instability. The Hill–Sachs lesion may be limited to the articular cartilage or may extend to the subchondral bone. PURPOSE: To identify and characterize the magnetic resonance imaging (MRI) findings in patients with Hill–Sachs lesion and to look for concomitant injuries. MATERIALS AND METHODS: This retrospective case series included 35 patients identified by search through the senior authors' databases, with cross-reference to our institutional radiologic communication system for MRI review. Baseline patient demographic data were collected, including age and sex. We retrospectively assessed all patients who were diagnosed with shoulder dislocation at our institution between 2012 and 2016. RESULTS: We identified 35 patients with a posterior Hill–Sachs lesion. The average age was 33.6 years (range, 22–70 years) and 31 patients were male (89%). There were 18 right shoulders and 17 left shoulders. Eleven patients (31.4%) had evidence of engaging Hill–Sachs lesion and 24 did not. Posterior humeral avulsion of the glenohumeral ligament (HAGL) injuries were found to be partial tears (30%) and complete tears (70%). Additional shoulder injury with the lesion occurred in 96% of identified cases. The most common concomitant injuries were recurrent shoulder joint dislocations (85.7%), posterior HAGL (71%), anterior Bankart lesions (74%), glenoid bone loss (11%), and anterior glenohumeral ligament injuries (5%). CONCLUSION: Engaging Hill–Sachs lesion on physical examination shows a trend toward more medially oriented lesion measured using modified biceps angle on MRI, and the size of engaging Hill–Sachs lesion appears significantly larger than that of nonengaging lesions on both axial and coronal images.