What Are Rotator Cuff Injuries?
Rotator cuff problems are among the most frequent reasons adults experience shoulder pain and loss of function. Each year, nearly 2 million people in the United States seek medical care for rotator cuff issues. The rotator cuff is made up of 4 muscles that wrap around the rim of the shoulder's "ball" (the humeral head). One muscle sits at the front, the subscapularis. One sits on top, the supraspinatus. Two sit at the back, the infraspinatus and teres minor. Together these muscles cradle the ball and help hold it centered within the socket. They also assist with shoulder motion, including raising the arm overhead and rotating it side to side. The rotator cuff muscles begin on the shoulder blade and turn into tendons as they attach around the humeral head. The tendon portion (shown in white in the image below) is the area most often injured. A lubricating sac called a bursa rests over the tendon, helping the rotator cuff glide smoothly beneath the bony ridge of the shoulder blade known as the acromion.
Tendinitis, Bursitis and Impingement of the Rotator Cuff
Inflammation of the rotator cuff tendons is one of the most frequent causes of shoulder pain. The bursa lying over the tendons is often inflamed as well. Because it is usually hard to tell which of these two structures is generating the inflammatory pain, the terms rotator cuff tendinitis and bursitis are used interchangeably. Impingement describes a narrowing of the space between the rotator cuff and the acromion bone above it. That narrowed space leads to inflammation in both the bursa and the rotator cuff. Rotator cuff tendinitis can arise at any age. In younger athletes it typically stems from overuse and is most often linked to overhead sports such as swimming, baseball and tennis. Impingement may be present, but it is not caused by a bony spur forming on the acromion. Instead, the space between the acromion and the rotator cuff narrows because the humeral head migrates upward. Weakness in the rotator cuff and looseness of the shoulder ligaments can allow the humeral head to drift off center within the socket. This is known as secondary impingement. In middle-aged adults, tendinitis often results from repetitive lifting or overhead work on the job. Ongoing overhead use of the shoulder is thought to cause a bony spur to form on the underside of the acromion. This can produce primary impingement as the spur rubs against the bursa and rotator cuff tendon beneath it. Primary impingement is the leading source of rotator cuff inflammation and bursitis in older adults.
If you are dealing with rotator cuff pain, understanding which structures are involved is the first step toward relief. Whether your symptoms stem from tendinitis, bursitis or impingement, an accurate diagnosis helps guide the right treatment plan for your shoulder.