Summary of Rotator cuff tear
Transcript for Rotator cuff tear
Content Reviewers:Rishi Desai, MD, MPH, Evode Iradufasha, Justin Ling, MD, MS, Evan Debevec-McKenney
Rotator cuff tear
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 humerus to make it stable and help it move, specifically in abduction, 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, called the acute tear, 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.
Now, the tears may be partial, which is where the tendon is damaged but not completely torn, and may even go unnoticed.
Alternatively, the tear may be a full thickness tear, where the tendon is completely detached from the humerus.
In contrast to an acute tear, there may also be a chronic tear due to regular wear and tear, which usually occurs in the elderly.
That’s because the blood supply to the rotator cuff tendons reduces over time making it harder for them to heal after an injury.
As a result, injuries can go unrepaired, and successive injuries can weaken the tendon.