Bankart Lesion

Diagnosis Definition

Bankart lesion refers to anteroinferior, glenolabral, and associated capsuloligamentous, injury of shoulder. This is one of the most common complications of anterior shoulder dislocation, and a common cause of anterior shoulder instability. It commonly occurs spontaneously with posterosuperior humeral head Hill-Sachs lesion secondary to a direct impact. There are “bony” or “soft tissue” Bankart lesions. A Bankart must have either a fracture of the anteroinferior glenoid, a full-depth labral tear, and / or periosteal rupture.

Imaging Findings

• On water-weighted axial PDFS or T2FS, a fluid cleft between anteroinferior labrum and glenoid, or frank separation and displacement, is seen.
• In chronic cases, the labrum could be diminutive or deficient due to microinstability wear, and repeated impaction.
• On MRI arthrogram and water-weighted MRI, there is a cleft of fluid-contrast interposed between anteroinferior glenoid margin and labrum results in so-called “double axillary pouch sign”.

KEY IMAGES

Pearls

• Bankart equivalent lesions are Perthe’s lesion, glenolabral articular disruption (GLAD lesion), humeral attachment glenohumeral ligament (HAGL lesion), RAGL, GAGL, and anterior inferior glenohumeral ligament (AIGL) injury.
• Bony Bankart lesions could be a bony defect caused by initial fracture-dislocation event (usually with a variable size adjacent detached bony fragment), or an erosion and rounding of glenoid edge caused by repetitive (anterior to posterior) subluxations or dislocations.
• Assessment of a bone loss is crucial for surgical management plan. At least 25% loss of inferior width of glenoid is required to cause “inverted pear shape” bony glenoid which is associated with shoulder instability, mostly when accompanying engaging Hill-Sacks lesions, so-called “off-track bipolar lesion”.
• 3-D reconstructed CT scan is considered a gold standard for bone defect measurement, but MRI has been shown equally valuable usually by using the “best fitted circle method”.

References