The appropriate audience for this material consists of Board-Certified Musculoskeletal (MSK) Radiologists, Orthopedic Surgeons, and Sports Medicine Fellows.
As a Senior MSK Imaging Consultant, I have synthesized the technical findings and diagnostic pearls from this clinical lecture below.
Abstract
This clinical presentation provides a rigorous diagnostic framework for interpreting MRI shoulder arthrography, with a specific focus on labral pathology and normal anatomical variants. Dr. Scott Shipman outlines optimized imaging protocols—emphasizing the utility of the Abduction External Rotation (A-BEAR) view for stressing the anterior inferior glenohumeral ligament (AIGL)—and details the morphology of the glenoid labrum. The lecture systematically categorizes Superior Labrum Anterior to Posterior (SLAP) tears using the Snyder classification, discusses the "peel-back" mechanism in overhead athletes, and differentiates true pathology from common variants such as the sub-labral foramen and Buford complex. Furthermore, the presentation covers the sequelae of macro-instability, including Bankart variants (ALPSA, Perthes, GLAD) and humeral avulsions of the glenohumeral ligaments (HAGL). Advanced concepts such as internal impingement, Bennett lesions, and the diagnostic criteria for adhesive capsulitis on arthrography are also addressed to ensure a comprehensive evaluation of the glenohumeral joint.
0:00:45 Optimized MRI Protocols: Standard arthrography utilizes intermediate and T1 fat-saturated sequences across three planes. The A-BEAR view is critical for detecting anteroinferior labral tears by placing tension on the anterior band of the IGHL. Sagittal T1/PD sequences are mandatory to quantify glenoid bone loss (e.g., Bony Bankart).
0:02:24 Technical Pitfalls in Interpretation: Accurate labral assessment requires planes perpendicular to the labral surface to maintain a "black triangle" morphology. Oblique slicing leads to volume averaging and pseudo-blurring, which can be mistaken for pathology.
0:05:33 SLAP Tear Pathomechanics: The labrum acts as a "labro-ligamentous seal" (analogous to a pressure cooker O-ring). In throwing athletes, the "peel-back" mechanism—driven by extreme external rotation and abduction—creates a posterior-directed torque on the biceps tendon, fatiguing the superior labrum.
0:08:33 Snyder Classification & SLAP Variants: Surgeons prioritize Types 1–4. Type 2 (detachment of the bicipital-labral anchor) is most common. Types 5–10 typically represent extensions of Type 2.
0:10:16 SLAP Tear vs. Sub-labral Recess: A true SLAP tear is characterized by irregular margins, a width >2–3mm, lateral propagation into the labral substance, and extension posterior to the biceps anchor. Normal recesses typically parallel the glenoid and extend medially.
0:14:29 Internal Impingement in Overhead Athletes: Repetitive collision between the greater tuberosity and posterosuperior glenoid results in a triad: posterosuperior labral fraying, synovial herniation cysts in the greater tuberosity, and articular-sided infraspinatus tears.
0:16:13 Paralabral Cysts & Nerve Entrapment: Superior labral tears can feed ganglion cysts in the suprascapular or spinoglenoid notches. Cysts in the spinoglenoid notch specifically compress the nerve branch to the infraspinatus, leading to isolated denervation edema/atrophy.
0:18:07 Anterior-Superior Variants: The Sub-labral Foramen (isolated to the 11–1 o’clock position) and the Buford Complex (absent anterosuperior labrum with a cord-like middle glenohumeral ligament) must not be misdiagnosed as tears.
0:21:55 Macro-instability & Bone Loss: Hill-Sachs defects are evaluated as "On-Track" vs. "Off-Track." Off-track lesions (lateral to the humeral apex) carry a higher risk of re-engagement and recurrent dislocation. Bony Bankart fractures involving >20-25% of the glenoid width typically require surgical augmentation (e.g., Latarjet procedure).
Perthes: Non-displaced labral tear with stripped but intact medially-attached periosteum.
GLAD: Focal articular cartilage defect with an associated non-displaced labral tear.
ALPSA: The labrum is avulsed and displaced medially/inferiorly along the glenoid neck, "sleeved" by the periosteum.
0:28:15 HAGL and the "J Sign": Humeral Avulsion of the Glenohumeral Ligament (HAGL) presents as a "J" shaped redundancy of the axillary pouch due to retraction from the humeral neck. It must be differentiated from benign contrast extravasation, which typically occurs posteriorly.
0:31:48 Posterior Pathology: Reverse Hill-Sachs (anteromedial humerus impaction) and Reverse Bankart lesions are common in "linebacker" injuries or seizures. Overhead athletes may also develop a Bennett Lesion—extra-articular ossification of the posterior capsule/IGHL.
0:37:50 Adhesive Capsulitis: Key arthrographic indicators include a contracted, thickened axillary pouch, edema within the rotator interval fat, and high resistance during contrast injection (often limited to <10cc).
0:39:55 Rotator Cuff Enhancement: Arthrography improves the detection of Rim-Rent (interstitial) tears and delaminating components by allowing contrast to imbibe into articular-sided defects. It also clarifies the diagnosis of subacromial bursitis by confirming the lack of communication between the joint and the bursa.