Partial-thickness rotator cuff tears can be divided into three categories based on their anatomic location: bursal-sided, interstitial, or articular-sided. Because of their concealed nature within the tendon substance, interstitial rotator cuff tears are frequently misdiagnosed and may be more common than previously thought. Although the exact pathogenesis of interstitial rotator cuff tears remains unknown, the consensus is that they result from shearing forces between the superficial and deep layers of a degenerated supraspinatus tendon. The role of trauma in the development of interstitial rotator cuff tears is controversial.

Patients with an interstitial rotator cuff tear typically are in their forties to seventies and report shoulder pain that is bothersome, especially at night, and exacerbated with overhead activities. Physical examination often reveals weakness in abduction and signs of subacromial impingement. MRI is the most sensitive and specific imaging study for the detection of an interstitial rotator cuff tear, which appears as an increased signal intensity within the supraspinatus tendon on T2-weighted MRI.

Typically, first-line treatment for patients with an interstitial rotator cuff tear consists of 4 to 6 months of activity modification, the use of NSAIDs, subacromial steroid injections, and physical therapy. For patients in whom nonsurgical treatment fails, several surgical options have been described, with no technique being clearly superior to another.

This video demonstrates arthroscopic débridement and repair of a high-grade interstitial rotator cuff tear. During diagnostic arthroscopy, an area of abnormal tendon is identified along the bursal side of the supraspinatus tendon. This area of tendon is injected with 5 cm³ of normal saline, and a positive bubble sign is observed, confirming the location of an interstitial tear. An inverted t-shaped incision is made over the interstitial tear, the tendon is débrided down to cancellous bone, and the tendon is repaired with the use of medial and lateral rows of suture anchors. The video also reviews patient presentation, physical examination findings, MRIs, and the postoperative rehabilitation protocol.