Brady Kirk Huang MD, Presenter: Nothing to Disclose

Eric Y. Chang MD, Abstract Co-Author: Nothing to Disclose

We aim to describe the imaging features of infraspinatus tendon tears that occur adjacent to an intact footprint. Isolated injuries of the infraspinatus tendon have been designated in the literature as a "novel lesion" from a tendon versus myotendinous injury (Lunn JV, et al. J Shoulder Elbow Surg. 2008). Based on retrospective review of our own cases, we postulate that these injuries may be related to a layered anatomy of the infraspinatus tendon, with a superficial (transverse) tendon inserting onto a deeper (oblique) tendon, the latter of which inserts on the greater tuberosity (Kato A et al. Surg Radiol Anat. 2012).

This retrospective chart review study was performed performed over a 3 year period from January 2010 to December 2012. A key word search for the term “novel lesion” was applied to the search algorithm, as we began to document these cases in our reporting lexicon. MR images of all patient were retrospectivly reviewed in addition to the clinical and surgical data, if available.

The average age at presentation was 50.8 years (range=24.2-69.3). 2 patients had a traumatic fall prior to presentation and 8 recalled a single event that lead to symptoms, such as lifting or throwing. The remaining 7 patients presented with pain without preceding injury. All patients showed myotendinous junction edema of the infraspinatus muscle and variable degrees of retraction of bursal-sided fibers, with an intact footprint. 8 patients eventually underwent arthroscopic surgery with an average time of 116 days from initial presentation. Average follow-up time after surgery was 141.8 days. Tendon repairs were performed in 6 patients and debridement in 2 patients. Only 2 patients shows bursal-sided tendon tearing potentially corresponding to the MRI. One repair failed. 3 patients underwent follow-up MRI, with 2 showing progression of infraspinatus muscle atrophy.

Partial tears of the infraspinatus tendon, especially when affecting the bursal surface fibers with an intact footprint, are likely the result of delamination of the superior (transverse) part from the inferior (oblique) part of the tendon, resulting in characteristic imaging appearances.

Infraspinatus tendon injuries with an intact footprint are unusual injuries with a characteristic imaging appearance, and may be missed on arthroscopy, even when prospectively identified on pre-operative imaging.

Huang, B, Chang, E, Infraspinatus Tendon Tears with an Intact Footprint: Imaging Features and Anatomic and Clinical Relevance.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14010099.html