Redefining superior escape of the humeral head: A radiographic and magnetic resonance imaging study

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.