E4822. Instability of the Shoulder: Imaging Predictors and Clinical Implications
  1. Rohan Manickam; University of Texas Health Science at Houston
  2. Ahmed Elsayes; No Affiliation
  3. Vikram Vijayarajan; University of Texas Health Science at Houston
  4. Manickam Kumaravel; University of Texas Health Science at Houston
  5. Serag Attia; University of Texas Health Science at Houston
  6. Alexis Nguyen; University of Texas Health Science at Houston
The shoulder joint, also known as the glenohumeral joint, holds the distinction of being the most frequently dislocated joint in the human body, and recurrent dislocations are prevalent. Among individuals aged 12–22, the recurrence rate can be as high as 72%, and around 27% in individuals over the age of 30. This propensity for dislocation is attributed to the joint's exceptional range of motion and the relatively shallow structure of its socket, known as the glenoid. The pervasiveness of recurrent dislocations amongst patients highlights the importance of avoiding misdiagnosis on radiography and applying appropriate management, to limit recurrence and mitigate long-term shoulder instability. Various anomalies have been linked to shoulder instability, including Bankart lesions, anterior labral periosteal sleeve avulsion (ALPSA), and Hill-Sachs lesions. Additionally, the understanding of on track vs. off track types of Hill-Sachs lesions provides insight into the likelihood of shoulder dislocation and subsequent shoulder instability. By recognizing radiological signs and understanding the appropriate use of medical imaging modalities to diagnose high-risk lesions of the shoulder, management can be optimized to minimize long-term shoulder instability.

Educational Goals / Teaching Points
The reviewer will have an overview of the assessment of shoulder instability-related lesions, such as Bankart, ALPSA, and Hill-Sachs, utilizing various imaging methods. Moreover, the concept of on track versus off track lesions will be elucidated in the context of shoulder instability. The categorization of instability extends to two main types: posterior and multidirectional, contingent on the anatomical positioning of the lesions. The association specifically between shoulder dislocations and the factors that link shoulder instability development will be demonstrated. These categorizations will be delineated, and the relevance of lesions and dislocations will be explored within the exhibit, accompanied by an illustration of the sensitivity of MRI arthrography in pinpointing shoulder instability.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Multiple imaging modalities will be used including CT, MRI, and arthrograms to diagnose shoulder instability and associated lesions.

Assessment of shoulder instability is essential in the field of radiology for management and prevention of recurrent shoulder dislocations. Accurate determination of lesions associated to instability, whether they are on track or off track, and determination of the directionality of instability is essential in guiding the management of patients with a history of glenohumeral dislocation.