Worthing Physiotherapy & Sports Injury Clinic
The shoulder joint is composed of three bones: the clavicle (collarbone), the scapula (shoulder blade), and the humerus (upper arm bone).
Two joints facilitate shoulder movement. The acromioclavicular joint is located between the acromion and the clavicle. The glenohumeral joint, commonly called the shoulder joint, is a ball-and-socket-type joint that helps move the shoulder forward and backward and allows the arm to rotate in a circular fashion or hinge out and up away from the body. (The "ball," or humerus, is the top, rounded portion of the upper arm bone; the "socket," or glenoid, is a dish-shaped part of the outer edge of the scapula into which the ball fits.)
The capsule is a soft tissue envelope that encircles the glenohumeral joint. It is lined by a thin, smooth synovial membrane.
The shoulder joint is the most frequently dislocated major joint of the body. In a typical case of a dislocated shoulder, either a strong force pulls the shoulder outward (abduction) or extreme rotation of the joint pops the ball of the humerus out of the shoulder socket. Dislocation commonly occurs when there is a backward pull on the arm that either catches the muscles unprepared to resist or overwhelms the muscles. When a shoulder dislocates frequently, the condition is referred to as shoulder instability. A partial dislocation in which the upper arm bone is partially in and partially out of the socket is called a subluxation.
● Rotator Cuff Disease, Tendonitis and Bursitis.
These conditions are closely related and may occur alone or in combination. Tendonitis is inflammation (redness, soreness, and swelling) of a tendon. In tendonitis of the shoulder, the rotator cuff and/or biceps tendon become inflamed, usually as a result of being pinched by surrounding structures. The injury may vary from mild inflammation to involvement of most of the rotator cuff. When the rotator cuff tendon becomes inflamed and thickened, it may get trapped under the acromion. Squeezing of the rotator cuff is called impingement syndrome. Bursitis, or inflammation of the bursa sacs that protect the shoulder, may accompany tendonitis and impingement syndrome. Inflammation caused by a disease such as rheumatoid arthritis may cause rotator cuff tendonitis and bursitis. Sports involving overuse of the shoulder and occupations requiring frequent overhead reaching are other potential causes of irritation to the rotator cuff or bursa and may lead to inflammation and impingement. If the rotator cuff and bursa are irritated, inflamed, and swollen, they may become squeezed between the head of the humerus and the acromion. Repeated motion involving the arms, or the effects of the aging process on shoulder movement over many years may also irritate and wear down the tendons, muscles, and surrounding structure
● Torn Rotator Cuff.
Rotator cuff tendons often become inflamed from overuse, aging, or a fall on an outstretched hand or another traumatic cause. Sports or occupations requiring repetitive overhead motion or heavy lifting can also place a significant strain on rotator cuff muscles and tendons. Over time, as a function of aging, tendons become weaker and degenerate. Eventually, this degeneration can lead to complete tears of both muscles and tendons. These tears are surprisingly common. In fact, a tear of the rotator cuff is not necessarily an abnormal situation in older individuals if there is no significant pain or disability. Fortunately, these tears do not lead to any pain or disability in most people. However, some individuals can develop very significant pain as a result of these tears and they may require treatment.
● Frozen Shoulder (Adhesive Capsulitis)
As the name implies, movement of the shoulder is severely restricted in people with a "frozen shoulder." This condition, which doctors call adhesive capsulitis, is frequently caused by injury that leads to lack of use due to pain. Rheumatic disease progression and recent shoulder surgery can also cause frozen shoulder. Intermittent periods of use may cause inflammation. Adhesions (abnormal bands of tissue) grow between the joint surfaces, restricting motion. There is also a lack of synovial fluid, which normally lubricates the gap between the arm bone and socket to help the shoulder joint move. It is this restricted space between the capsule and ball of the humerus that distinguishes adhesive capsulitis from a less complicated painful, stiff shoulder. People with diabetes, stroke, lung disease, rheumatoid arthritis, and heart disease, or those who have been in an accident, are at a higher risk for frozen shoulder. Frozen shoulder is more common among women than men. People between the ages of 40 and 70 are most likely to experience it.
© 2008 Worthing Physiotherapy & Sports Injury Clinic: Chartered Physiotherapists in Worthing, West Sussex