ACR Codes: 4.9
Rotator cuff partial tears can be classified into articular surface
and bursal surface tears.
A rim rent tear, also called "partial articular supraspinatus tendon avulsions" or PASTA lesion, is a partial-thickness articular surface tear at the insertion of the supraspinatus (or less commonly infraspinatus) tendon on the greater tuberosity. The rotator cuff is vulnerable in this location because collagen fibers make an abrupt 90 degree turn as they attach to the greater tuberocity. The most common rim rent occurs on the anterior leading edge of the supraspinatus. These are a relatively common tear partial tear frequently seen in younger patients. Rim rent tears comprise 25% of tears seen in patients under 36 years of age. They are better appreciated by performing an MRI in the ABER (abduction and external rotation) position. The most sensitive method of detecting articular-sided partial tears is MRI direct arthrogram with ABER. They can be easily over looked on MR without contrast, particularly if there is significant internal rotation of the shoulder.
Reference(s): 1. Beltran, Salvador. Magnetic Resonance Imaging in Orthopaedics and Sports Medicine, 3rd Edition. 1262-1263.
2. Vinson EN, Helms CA, Higgins LD. Rim-rent tear of the rotator cuff: a common and easily overlooked partial tear. AJR Am J Roentgenol. 2007 Oct;189(4):943-6.
3. Tuite MJ, Turnbull JR, Orwin JF. Anterior versus posterior, and rim-rent rotator cuff tears: prevalence and MR sensitivity. Skeletal Radiol. 1998 May;27(5):237-43.