Anatomy Msk · Year 1 · from Anatomy Msk
Case 1: Rotator Cuff Tear
Clinical Image
Source: Wikimedia Commons - Rotator Cuff Tear MRI - CC BY-SA 3.0
Case Presentation
A 58-year-old house painter presents with 4 months of progressive right shoulder pain and weakness. He initially noticed pain when reaching overhead while painting ceilings, which has now progressed to difficulty lifting his arm to wash his hair. He reports night pain that disrupts sleep, particularly when lying on the affected side. He denies any acute injury or trauma. Physical examination reveals atrophy of the supraspinatus and infraspinatus fossae. Active range of motion is limited with painful arc between 60-120 degrees of abduction. Passive range of motion is full but painful. He has weakness with resisted external rotation and abduction. Empty can test (Jobe test) is positive with weakness and pain. Drop arm test is positive - he cannot slowly lower his arm from 90 degrees of abduction. Neer and Hawkins impingement signs are positive. Radiographs show superior migration of the humeral head with decreased acromiohumeral distance. MRI confirms a full-thickness tear of the supraspinatus tendon with retraction to the level of the glenoid, as well as partial thickness infraspinatus tear and moderate fatty infiltration of the supraspinatus muscle. Given the chronic tear with muscle atrophy, he undergoes arthroscopic rotator cuff repair with subacromial decompression.
Key Learning Points
- The rotator cuff consists of four muscles: supraspinatus, infraspinatus, teres minor, and subscapularis (SITS)
- Supraspinatus initiates abduction (first 15 degrees) and passes through the narrow subacromial space
- The supraspinatus tendon has a watershed zone of relative hypovascularity predisposing to degeneration
- Full-thickness tears cause weakness and positive drop arm test; partial tears may have pain without weakness
- Fatty infiltration of muscle and tendon retraction indicate chronicity and affect surgical outcomes