What Is The Rotator Cuff?

The term "rotator cuff" refers to a group of four tendons that attach four shoulder muscles to the upper arm. Tendons are stringy tissues that attach muscle to bone.

A healthy shoulder is the most versatile joint in the human body. It has a wider "range of motion," which means it can move more freely, and in more directions, than any other joint. The shoulder's versatility enables us to retrieve soup cans from the cupboard, to hammer nails, swing golf clubs, roll bowling balls, and perform thousands of other activities.

The shoulder's flexibility is due to its unique structure. Like the hip, the shoulder is a "ball-and-socket" joint - a "ball" at the top of the upper arm bone (the humerus) fits neatly into a "socket" formed by the shoulder blade (scapula).

But unlike hip joints, where the ball sits in a deep, well-protected socket, the shoulder socket is very shallow. As a result, the shoulder is the most frequently dislocated major joint in the body. It's also prone to a variety of other injuries and chronic problems that can be painful and hinder a person's ability to perform ordinary tasks.

What Is A Rotator Cuff Tear?

Many shoulder problems are caused by injuries to the rotator cuff - the tendons that attach the shoulder muscles to the arm.

If a rotator cuff tendon becomes inflamed or is partially torn, it can cause pain and limit shoulder movement. If a tendon tears completely, the corresponding muscle can no longer affect movement of the arm. This type of injury usually causes severe limitations in shoulder movement as a result of pain and weakness.

What Is Shoulder Impingement?

The most common cause of rotator cuff problems is a disorder known as impingement.

Ordinarily, the rotator cuff moves freely in the space between the top of the upper arm and a part of the shoulder blade known as the acromion, which overhangs the rotator cuff. But in some people, this space is inadequate to allow the normal smooth gliding movements of the rotator cuff as it moves the arm. Every time they raise an arm, the rotator cuff is pinched between the two bones.

In other cases, impingement is caused by accident or injury. Most often, it occurs with aging. As people grow older, their shoulder muscles and tendons weaken, causing the shoulder joint to become less stable. The space between the upper arm and the acromion narrows. The rotator cuff has less room to move. The increased pressure gradually damages the rotator cuff.

Although the rotator cuff can tear suddenly as a result of a serious injury, most rotator cuff problems develop over time. Over a period of months or years, impingement causes the rotator cuff to become irritated, to tear partially, or to tear completely.

What Is Rotator Cuff Tendinitis?

The term tendinitis refers to chronic irritation, inflammation, or tearing of the rotator cuff that occurs as a result of impingement or overuse. Tendinitis bothers some people for a time and then seems to disappear. Their symptoms vary greatly, depending on several factors, the most important of which is how they use the affected shoulder or shoulders.

Some people with tendinitis also develop calcium deposits or abnormal bone growths called bone spurs. Both can aggravate tendons, contributing to the weakening, partial, or complete tearing of the rotator cuff.

What Is Shoulder Bursitis?

A bursa (plural bursae) is a soft, fluid-filled sac that helps to cushion and lubricate joints. In the shoulder, there are bursae located between the rotator cuff and the shoulder blade. When a bursa becomes irritated or inflamed, it causes bursitis. Pain and swelling of the joint often accompany bursitis.

What Causes Rotator Cuff Problems?

The most common cause of rotator cuff problems is shoulder impingement, in which there is a narrowing of the gap between a portion of the shoulder blade known as the acromion and the top of the upper arm bone. This causes increased friction and gradually damages the rotator cuff.

Rotator cuff tears can also happen suddenly; for example, when a person tries to lift a heavy object above the head. Repeatedly performing a strenuous task such as throwing a baseball can also damage the rotator cuff. In such cases, the excess strain on the rotator cuff causes one or more tendons to tear.