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Rotator cuff tear

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Rotator cuff tear

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A 44-year-old man presents to his primary care physician with worsening left shoulder pain. He can no longer do bench presses or shoulder presses at the gym due to weakness and pain. The pain is primarily located over the lateral shoulder, is worse at night, and is preventing him from obtaining adequate rest. Past medical history is otherwise unremarkable. He has no history of recent trauma or surgeries to the left shoulder. The patient subsequently undergoes a MRI of the left shoulder, which reveals the following:  


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Which of the following physical examination maneuvers is most likely to yield a positive test, given this patient’s clinical findings?  

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Rishi Desai, MD, MPH,Evode Iradufasha, MD

The rotator cuff refers to a group of four muscles and their tendons, which help to stabilize the shoulder when it’s moving particularly during rotational motion. So, a rotator cuff tear is when one or more of the tendons of the muscles of the rotator cuff are torn.

The shoulder is a complex of bones, ligaments, muscles and their tendons that all work together to connect the upper limb to the chest, allowing necessary movement and providing stability.

The round head of the humerus fits and rotates inside the shallow glenoid cavity of the scapula. Just above the glenoid cavity, the scapula extends two bony processes; the acromion and the coracoid processes which serve as attachment for ligaments and muscle tendons.

The ligaments of the capsule of the glenohumeral joint hold the head of the humerus inside the glenoid cavity. The coracoacromial ligament forms an arch between the coracoid process and the acromion and it prevents the head of the humerus from upward dislocation.

In addition to these ligaments, the shoulder is supported by the four rotator cuff muscles, also called the SITS muscles, for Supraspinatus, Infraspinatus, Teres minor, and Subscapularis.

The SITS muscles form a cuff that surrounds the head of the humerus to make it stable and help it move, specifically in abduction, as well as internal and external rotation. Below the acromion lies the acromial bursa, which is a small sac filled with rubbery synovial fluid, that provides lubrication and prevents the rotator cuff tendons, especially the supraspinatus tendon, from rubbing against the acromion as the joint moves.

A rotator cuff tear may occur when the tendons are violently stretched like when you jerkily lift up something which is too heavy, or accidentally fall on an outstretched arm. This most commonly affects the supraspinatus tendon at its insertion on the greater tubercle of the head of the humerus, because it’s under a lot of tension when the shoulder is abducted.

Summary

A rotator cuff tear occurs when one or more tendons of the SITS muscles - Supraspinatus, Infraspinatus, Teres minor, and Subscapularis - of the rotator cuff are torn. Acute tears happen when the tendons are violently stretched, like falling on an outstretched arm. Chronic tears result from cumulative wear and tear of the tendon, and it usually occurs in the elderly.

The cuff is responsible for stabilizing the glenohumeral joint, abducting, externally rotating, and internally rotating the humerus. When shoulder trauma occurs, these functions can be compromised. The diagnosis is clinical, mainly based on pain and weakness, specifically with abduction or rotation, and can be confirmed with an MRI. Treatment involves rest, ice, and pain control, but if it fails, surgery may be needed.

Sources

  1. "Robbins Basic Pathology" Elsevier (2017)
  2. "Harrison's Principles of Internal Medicine, Twentieth Edition (Vol.1 & Vol.2)" McGraw-Hill Education / Medical (2018)
  3. "Pathophysiology of Disease: An Introduction to Clinical Medicine 8E" McGraw-Hill Education / Medical (2018)
  4. "CURRENT Medical Diagnosis and Treatment 2020" McGraw-Hill Education / Medical (2019)
  5. "MR Imaging of Rotator Cuff Injury: What the Clinician Needs to Know" RadioGraphics (2006)
  6. "Delineation of diagnostic criteria and a rehabilitation program for rotator cuff injuries" The American Journal of Sports Medicine (1982)
  7. "Compressive cryotherapy versus ice—a prospective, randomized study on postoperative pain in patients undergoing arthroscopic rotator cuff repair or subacromial decompression" Journal of Shoulder and Elbow Surgery (2015)