Association Between Rotator Cuff Tears and Superior Migration of the Humeral Head: An MRI-Based Anatomic Study

BACKGROUND: Superior humeral migration has been established as a component of rotator cuff disease, as it disrupts normal glenohumeral kinematics. Decreased acromiohumeral interval (AHI) as measured on radiographs has been used to indicate rotator cuff tendinopathy. Currently, the data are mixed regarding the specific rotator cuff pathology that contributes the most to humeral head migration. PURPOSE: To determine the relationship between severity of rotator cuff tears (RCTs) and AHI via a large sample of magnetic resonance imaging (MRI) shoulder examinations. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A search was performed for 3-T shoulder MRI performed in adults for any indication between January 2010 and June 2019 at a single institution. Three orthopaedic surgeons and 1 musculoskeletal radiologist measured AHI on 2 separate occasions for patients who met the inclusion criteria. Rotator cuff pathologies were recorded from imaging reports made by fellowship-trained musculoskeletal radiologists. RESULTS: A total of 257 patients (mean age, 52 years) met the inclusion criteria. Of these, 199 (77%) had at least 1 RCT, involving the supraspinatus in 174 (67.7%), infraspinatus in 119 (46.3%), subscapularis in 80 (31.1%), and teres minor in 3 (0.1%). Full-thickness tears of the supraspinatus, infraspinatus, or subscapularis tendon were associated with significantly decreased AHI (7.1, 5.3, and 6.8 mm, respectively) compared with other tear severities (P < .001). Having a larger number of RCTs was also associated with decreased AHI (ρ = –0.157; P = .012). Isolated infraspinatus tears had the lowest AHI (7.7 mm), which was significantly lower than isolated supraspinatus tears (8.9 mm; P = .047). CONCLUSION: Although various types of RCTs have been associated with superior humeral head migration, this study demonstrated a significant correlation between a complete RCT and superior humeral migration. Tears of the infraspinatus tendon seemed to have the greatest effect on maintaining the native position of the humeral head. Further studies are needed to determine whether early repair of these tears can slow the progression of rotator cuff disease.