What Is a Rotator Cuff Injury?
The rotator cuff is made up of four muscles that help move and stabilize the shoulder joint. Damage to any or all of the four muscles and the ligaments that attach these muscles to bone can occur because of acute injury, chronic overuse, or gradual aging. This damage can cause significant pain and disability with decreased range of motion and use of the shoulder joint.
The shoulder is a ball-socket joint that allows the arm to move in many directions. It is made up of the humeral head (the upper end of the bone of the upper arm) fitting into the glenoid fossa of the scapula (shoulder blade). The humeral head is kept in place by the joint capsule and labrum, thick bands of cartilage that form an elongated cone where the humeral head fits. The rotator cuff muscles are the dynamic stabilizers and movers of the shoulder joint and adjust the position of the humeral head and scapula during shoulder movement.
The rotator cuff muscles are anatomically associated with the scapula. Any changes in the movement of the scapula with shoulder range of motion can cause impingement of the rotator cuff muscles, causing problems with the movement of the shoulder itself.
The four rotator cuff muscles include the
- subscapularis, and
- teres minor.
Other muscles that help move and stabilize the shoulder include the deltoid, teres major, corachobrachialis, latissimus dorsi, and pectoralis major.
When the rotator cuff is damaged, a variety of issues arise:
- Pain and spasm limit the range of motion of the shoulder.
- The muscles do not make the small adjustments within the joint to allow the humeral head to move smoothly.
- Fluid accumulation within the joint due to inflammation limits movement.
- There can be impingement on the rotator cuff muscles or the tendons that attach them to the bones. The tendons run through narrow bony spaces, and if there is a change in how the humerus and scapula move, these spaces can become even narrower.
- Arthritis and calcium deposits that form over time limit range of motion. These calcifications may occur along the bony edges of the joint or within the tendons of the rotator cuff muscles.
The severity of injury may range from a mild strain and inflammation of the muscle or tendon, that will lead to no permanent damage, to a partial or complete tear of one of the rotator cuff muscles that might require surgery for rotator cuff repair.