The provided material is a clinical case review involving medical imaging. The appropriate persona is a Senior Musculoskeletal (MSK) Radiologist.
Abstract:
This clinical case review evaluates an MR arthrogram of a 20-year-old male presenting with shoulder pain following a traumatic fall. The study utilizes intra-articular contrast to achieve joint capsule distension, facilitating the visualization of the glenohumeral internal structures. Imaging confirms a significant posterior labral tear characterized by a detached and displaced labral fragment residing in the dependent posterior joint space. The analysis highlights the diagnostic utility of contrast-enhanced MRI in identifying donor sites and outlining labral pathology through high-contrast fluid-tissue interfaces.
MSK Radiology Case Review: Posterior Labral Tear and Displacement
0:00 Clinical Presentation: A 20-year-old male presents with persistent shoulder pain following a fall. Orthopedic assessment suspected a labral injury, prompting an MRI with intra-articular contrast (MR arthrogram).
0:17 Radiographic Anatomy: The study identifies the humeral head (circular structure), the glenoid process of the scapula (appearing as a "golf tee"), and the surrounding musculature.
0:34 Joint Capsule Distension: The intra-articular contrast appears hyperintense (white) on the sequence, distending the joint capsule both anteriorly and posteriorly. This distension is critical for outlining the rotator cuff and labral margins.
1:02 Anatomical Landmarks: The biceps tendon is visualized within the bicipital groove. The middle glenohumeral ligament is noted as a normal anterior structure.
1:17 Pathological Identification: Imaging reveals a free, hyperintense-outlined fragment in the posterior joint space. This is a torn labral fragment that has detached and migrated to the dependent portion of the joint.
1:44 Donor Site Localization: The donor site for the displaced fragment is identified at the posterior labrum. While the anterior labrum remains intact and dark (hypointense), the posterior labrum is truncated and undermined by hyperintense joint fluid.
2:25 Diagnostic Takeaway: The definitive diagnosis is a posterior labral tear with a displaced fragment. While non-contrast imaging may show joint effusions, MR arthrography provides superior contrast between fluid and labral tissues, precisely delineating the extent of the detachment for surgical planning.