Imaging modalities for atraumatic shoulder hypermobility: a scoping review.

Background: Objective measures from imaging studies have the potential to assist in timely diagnosis of atraumatic shoulder hypermobility to better guide management. The aim of this scoping review is to examine imaging modalities and techniques used to characterize atraumatic shoulder hypermobility.

Methods: MEDLINE, EMBASE, SPORTDiscus, Cochrane Library, and Web of Science were searched up to May 2024 for any primary study investigating imaging findings seen in atraumatic shoulder hypermobility. Patients with unilateral instability were excluded given its frequent association with traumatic origin.

Results: Eighteen observational studies met inclusion criteria. Results were divided into outcomes relating to capsular redundancy, glenohumeral anatomy, and muscle activation. Five studies using magnetic resonance arthrography (MRA) demonstrated statistically significant increases in capsular cross-sectional area (CSA), while a significant superior capsular elongation was reported by two studies in patients with multidirectional instability (MDI). Labrocapsular distance, glenocapsular ratio, and the presence of a combined sail and triangle sign on MRA were highly sensitive and specific parameters for identifying MDI. There were inconsistent findings for alterations of glenohumeral anatomy. Ultrasound assessments of acromiohumeral distance (AHD) were significantly increased in patients with MDI, but not in shoulders with hypermobility alone. Similarly, muscle activity measured by electromyography or glenohumeral translations differed significantly in patients with MDI, but not in those with hypermobility alone.

Conclusion: Radiographic markers of capsular redundancy (e.g., CSA, labrocapsular distance, glenocapsular ratio), AHD, and muscular activity are useful in the diagnosis of MDI. However, there are no definitive imaging markers for diagnosing atraumatic shoulder hypermobility without MDI.