Abstract
BACKGROUND: The underlying shoulder pathology in radiographic superior escape of the humeral head and association between acromiohumeral interval (AHI) on radiographs and magnetic resonance imaging (MRI) are poorly understood. METHODS: A retrospective review of shoulder radiographs and MRI scans was undertaken. AHI was measured using both modalities. Deltoid bulk, long head of biceps brachii subluxation/tear, and rotator cuff disease (tendon involvement, severity, fatty infiltration) were noted using MRI. RESULTS: A total of 167 patients were included. MRI measurements of AHI were significantly smaller than radiographic measurements (p = 0.010). AHI was significantly smaller in patients with at least one partial or full thickness rotator cuff tear (p < 0.0001) and in patients with increased fatty infiltration based on Goutallier grade (p = 0.004). In the presence of two or more tendon tears, long head of biceps brachii rupture was associated with superior escape (p < 0.001). In patients with superior escape (AHI <6 mm), the number of rotator cuff tendon tears ranged from 0 to 3 and Goutallier grades from 0 to 4 representing a wide disease spectrum. DISCUSSION: Radiographic superior escape of the humeral head is correlated with full thickness rotator cuff tears, fatty infiltration, and long head of biceps brachii rupture. However, superior escape can occur with a single or no tendon injury with minimal fatty infiltration. LEVEL OF EVIDENCE: Level III; Retrospective Case-Control Design; Prognosis Study.