Rotator cuff injuries result from trauma, overuse

The rotator cuff consists of four muscles that go from the shoulder blade to the upper arm: the supraspinatus, infraspinatus, teres minor and subscapularis.

These muscles and their tendon attachments work as a team to provide stability and motion to the shoulder joint. Because the shoulder joint is used in so many activities, injuries are not uncommon. If one or more of the rotator cuff muscles are weakened or injured, moving the shoulder can become very painful. Everyday tasks, such as reaching upward or behind your body or combing your hair, can become difficult or even impossible. Although pain is the most common symptom of a rotator cuff tear, it is also possible to have a tear without significant pain.

A healthy rotator cuff functions in many ways. With the thumbs pointing down and toward the back of the body, the shoulder is rotated internally, which automatically limits your range of motion when trying to raise the arms to the sides. In this position, at best, you may be able to bring the arms just past shoulder level. This is because, as the arms are raised, the upper part of the humerus begins to impinge upon the shoulder joint, stopping your arms from moving any further. When the thumbs are pointed up, however, the shoulder is rotated externally (outward), and range of motion is no longer limited. Two of the four rotator cuff muscles — the infraspinatus and teres minor — perform external rotation.

The bones that make up the ball and socket shoulder joint are the scapula, humerus and clavicle. The scapula provides the socket for the top of the humerus, which allows your arms to move in many different directions. This socket is very shallow and gets its stability from the muscles and tendons that surround it. The rotator cuff acts as a support, each of the muscles pulling from a different direction to hold the joint together while it is moving.

The deltoid muscles run from the collarbone to the humerus. In movements such as raising your arms, they pull the humerus upward. One of the functions of the rotator cuff is to prevent the humerus from moving too far up and hitting the top of the shoulder joint.

As the arm moves away from the body, as when throwing a baseball or football, the rotator cuff muscles help keep the arm from detaching or dislocating from the body. Because throwing involves both internal and external rotation of the shoulder, the rotator cuff muscles are involved in varying degrees during different stages of the throw. Overhead motions of the arm, used in racquetball, swimming, volleyball, weight lifting and tennis also require a healthy rotator cuff to help prevent injury.

Problems with the rotator cuff can occur for a number of reasons. Impingement occurs with motion, as when the arms are raised in a forward or upward position. There is not enough space, and the tendons become pinched between bones. In some people, it is the shape and thickness of the bone that doesn't leave sufficient space, or there may be bone spurs. Repeated impingement causes pain and inflammation/swelling, leaving even less space for normal movement to occur. Symptoms include shoulder weakness, pain on the outer side of the upper arm or front of the shoulder and lack of full range of motion. Over time, repetitive use and/or chronic physical stress, as with heavy weight lifting, sports-related activities or even everyday tasks, can cause damage to the rotator cuff area, causing it to weaken and tear.

Although less common than injuries from repetitive use, the rotator cuff can also be injured from trauma, such as falling onto an outstretched arm. Rotator cuff injuries can be seen at any age, but are much more common among older individuals. With age, muscle and overall strength decreases, and we also lose some of our flexibility, making joints more prone to injuries.

In younger people, injury is usually the result of trauma or overuse of the shoulder in sports. Although symptoms of rotator cuff problems may include weakness, pain and loss of motion, as stated, not every rotator cuff injury causes significant pain or disability. Estimates are that rotator cuff tears occur in up to 70 percent of people over the age of 80 and 30 percent of people younger than 70. If you suspect rotator cuff problems, prompt diagnosis is important.

Marjie Gilliam is an International Sports Sciences Association Master certified personal trainer and fitness consultant. She owns Custom Fitness Personal Training Services. Write to her in care of the Dayton Daily News, call her at (938) 878-9018 or by e-mail at OHTrainer@aol.com. Her Web site is www.ohtrainer.com.