Although tears near the musculotendinous junction (MTJ) are common in some areas of the body, they infrequently involve the rotator cuff where the majority of tears present with detachment of the foot- print from the greater tuberosity. Only a small number of case reports of have described the treatment of rotator cuff tears near the MTJdmany of these reports specifically refer to the infraspinatus whereas others refer specifically to the supraspinatus. Although the precise etiologies of medial cuff tears are not fully understood, they are likely to be multifactorial and may include any combination of acute or chronic trauma with established subacromial impingement.

In general, rotator cuff tendon repair techniques aim to restore the anatomic rotator cuff footprint, achieve adequate footprint compression,8 minimize gap formation, and maximize ultimate load-to-failure. With tears at the MTJ, repair techniques rely more on soft tissueetoesoft tissue fixation as opposed to soft tissue to bone. Although we have seen an overall reduction in repair failures with anatomic constructs that follow the aforementioned biomechanical criteria, there are still some retears. One of the mechanisms of failure may be related to biologic insufficiency of the repaired cuff tendon (e.g., failure at the suture-tendon interface). Specifically, repair constructs that have sutures at the MTJ have introduced a new failure mechanism characterized by suture cut-out at or near the MTJ.

Medial tears of the rotator cuff that occur at the MTJ can occur primarily (without prior surgery), or secondarily after previous rotator cuff repair (secondary or type 2 failures). Both pose relevant treatment challenges. Primary failure usually occurs from a traumatic injury to the shoulder. Secondary injuries occur after previous surgery. Cho described this type of failure and classified it as a type 2 failure where the tendon fails medially, close to the MTJ. Secondary medial cuff failure near the MTJ after repair (type 2 failure) has been associated with the placement of knots and abrasive suture materials near the MTJ, thus potentially resulting in acute or chronic subacromial knot impingement, medial stress concentration, tendon strangulation, and/or suture cut-out in this area. When failure occurs, the tendon/muscle is found to be torn medial to the previous repair site whereas the cuff tendon insertion remains intact and well fixed to the greater tuberosity.

Surgical treatment of these tears is challenging because of the short or absent medial tendon stump; the lack of sufficient tendon medially, the susceptibility of sutures to tear through degenerated tissues or the medial muscle fibers at the MTJ, the difficulty in restoring the length-tension relation of the cuff tendon without overtensioning the repair site, and the lack of sufficient clinical outcomes data to guide surgical deci- sion making. As a result, when surgeons encounter these types of tears, there is little information to guide them. The purpose of this report is to highlight that (1) medial cuff failure can occur both primarily and secondarily after previous repair; (2) to define and classify the 3 major tear patterns that are encountered, and (3) to describe our preferred techniques for medial cuff repair that specifically address each of the major tear patterns.

Full Article: Rotator Cuff Tears at the Musculotendinous Junction: Classification and Surgical Options for Repair and Reconstruction