Anterior Shoulder Instability in the Aging Population: MRI Injury Pattern and Management.

BACKGROUND. Literature on glenohumeral dislocations has focused on younger patient populations because of high recurrence rates. However, the spectrum of injuries sustained in younger versus older patient populations is reported to be quite different. OBJECTIVE. The purpose of this article is to describe MRI findings and management of anterior shoulder instability in the aging (≥ 60 years) population. METHODS. Shoulder MRI examinations of anterior glenohumeral dislocations in patients 40 years old and older were subdivided into groups younger than 60 years old or 60 years old and older and reviewed by two musculoskeletal radiologists for a Hill-Sachs lesion, other fracture, glenoid injury, capsulolabral injury, rotator cuff tear, muscle atrophy, and axillary nerve injury. Fischer exact test and logistic regression was evaluated for significant differences between cohorts, and interreader agreement was assessed. Surgical management was recorded, if available. RESULTS. A total of 104 shoulder MRI examinations (age range, 40-79 years; mean age, 58.3 years; 52 women, 52 men) were reviewed (54 examinations < 60 years; 50 examinations ≥ 60 years). Acute high-grade or full-thickness supraspinatus (64.0% vs 37.0%; p = .001), infraspinatus (28.0% vs 14.8%; p = .03), and subscapularis (22.0% vs 3.7%; p = .003) tears were more common in the group 60 years old and older. Hill-Sachs lesions were more common in the younger group (81.5% vs 62.0%; p = .046). Greater tuberosity fractures were seen in 15.4% of the overall cohort, coracoid fractures in 4.8%, and acute axillary nerve injuries in 9.6%. Interreader concordance was 88.5-89.4% for rotator cuff tears and 89.4-97.1% for osseous injury. In the group younger than 60 years old, 11 of 37 subjects (29.7%) had rotator cuff repair and 11 of 37 (29.7%) had labral repair, whereas 17 of 36 (47.2%) of the older group underwent rotator cuff repair, six of 36 (16.7%) underwent reverse shoulder arthroplasty, and six of 36 (16.7%) underwent labral repair. CONCLUSION. Radiologists should have a high index of suspicion for acute rotator cuff tears in anterior shoulder instability, especially in aging populations. Greater tuberosity or coracoid fractures and axillary nerve injury occur across all ages, whereas Hill-Sachs injuries are more common in younger patients. CLINICAL IMPACT. Acute high-grade or full-thickness rotator cuff tears are seen with higher frequency in older populations after anterior glenohumeral dislocation. Osseous and nerve injuries are important causes of patient morbidity that if not carefully sought out may be overlooked by the interpreting radiologist on routine imaging.