Anatomy

The shoulder is a complex joint comprising; a deeply sited "gleno-humeral" joint (the proper shoulder joint), a joint between the outer end of the clavicle and the "acromium" bone (the acromium is the flat bone on the lateral aspect of the shoulder) "rotator cuff" which is the muscle tendon which lies beneath the acromium. The bony surfaces of the joint are covered with a smooth articular cartilage layer. The gleno-humeral joint or shoulder joint proper is enhanced by a thick fibro-cartilaginous rim or "labrum" which deepens the shallow shoulder joint and improves its stability. There are numerous ligaments around the shoulder joint which can generally be divided into the anterior, inferior and posterior "capsular" ligaments and a superior "coraco-acromial" ligament. These ligaments also have a stabilising effect on the joint. The shoulder and its ligaments are surrounded by strong muscles.

Aetiology Of Shoulder Injuries

Dislocation or subluxation of the shoulder usually occurs due to a forceful injury. The partial dislocation or subluxation will spontaneously reduce. However a dislocation may not spontaneously reduce and a reduction in hospital may be necessary. Alternately an injury may cause damage to the capsule or inner labrum of the shoulder joint making it prone to recurrent dislocation or subluxation. Some patients may have a genetic predisposition to shoulder dislocation because of a congenital laxity or looseness of their shoulder ligaments. In such patients shoulder dislocation may occur after trivial injury. A rotator cuff tear may also follow a traumatic injury. Alternately it may occur with repetitive activity such as tennis serving or as a degenerative condition in the aging adult or golfer. In the ageing athlete minor trauma may be enough to produce a significant degree of tendonitis. It is not uncommon for shoulder pain to be associated with cervical spine or neck pain or pain around the scapula or shoulder blade.

Shoulder Dislocation

Dislocation of the shoulder usually occurs following a violent fall. The injury usually tears the ligaments at the front of the shoulder. The cartilaginous labrum may also be torn. The torn ligaments and labrum may make the shoulder liable to dislocate again if the shoulder is injured again. The torn labrum may also cause persistent pain when the arm is used in a raised up position.

The first episode of dislocation is uncomplicated and may be treated by immobilisation in a sling for 1-2 weeks followed by physiotherapy to strengthen the muscles around the shoulder. If a second or subsequent dislocation occurs surgery to stabilise the shoulder should be considered. Arthroscopy of the shoulder may be necessary to determine the amount of shoulder instability and to identify and treat any tear of the labrum or damage to the glenoid itself. If the shoulder is very unstable or the labral tear requires to be repaired, although sometimes this may be undertaken arthroscopically an open surgical repair of these structures will sometimes be necessary.

Shoulder Subluxation

Subluxation of the shoulder occurs when the joint partially dislocates due to ligamentous stretching. Shoulder subluxation may produce a feeling of looseness and instability of the shoulder, particularly when throwing. Alternatively, pain deep within the shoulder when throwing can occur.

If strengthening exercises for the shoulder do not help, arthroscopic assessment of the instability is necessary. If subluxation of the shoulder is confirmed, repair of the damaged ligaments may be necessary.

Shoulder Tendonitis

Tendonitis or inflammation and pain within the rotator cuff is a very common shoulder problem. The tendonitis may follow an injury or be produced by gradual wear within the tendon following many years of shoulder activity. The pain is usually felt to the front or outside of the shoulder and is worse when the arm is used above the head in activities such as washing windows. The arm may also be painful when raised out to the side. The arm may feel heavy and tire easily. The shoulder may also become stiff, such that placing the hand behind the head or behind the back becomes difficult.

Rotator cuff tendonitis should be treated by physiotherapy and strengthening exercises. Anti- inflammatory drugs can be of great help in reducing the pain and inflammation. Injection of steroid and local anaesthetic into the inflamed tendon can help the inflammatory process to settle down.

If the symptoms of tendonitis are severe, if the tendon has ruptured or if the symptoms are not helped by the other measures described, surgery may be advisable.

Arthroscopy of the shoulder is usually undertaken to inspect the interior of the joint and to remove any damage within the shoulder joint. The rotator cuff is then inspected and any damaged area removed through the arthroscope, the acromium bone can be partially removed to allow the rotator cuff more room in which to move.

Calcific tendonitis or supraspinatus syndrome is a second separate type of shoulder tendonitis. The pain is felt in a similar manner to that of rotator cuff tendonitis. If physiotherapy and injection with steroid is unsuccessful, removal of the calcified nodule in the supraspinatus tendon is necessary. This may be undertaken through the arthroscope without opening the shoulder joint. A rapid recovery usually results.

Biceps tendonitis is the third type of tendonitis around the shoulder. The biceps tendon runs up from the arm over the front of the shoulder and through the joint. The tendon may become inflamed as a separate entity or as part of a rotator cuff tendonitis. Biceps tendonitis usually responds to physiotherapy and steroid injection. Occasionally the tendon may rupture or tear and surgery may be necessary to repair the tendon.

Frozen Shoulder

Frozen shoulder refers to a shoulder which becomes stiff usually without a great amount of pain and without any rotator cuff or shoulder joint damage. The condition usually occurs gradually over several months. A frozen shoulder requires intensive physiotherapy to restore the range of motion. Injection of steroid into the shoulder joint may help reduce any inflammation within the joint. If a rapid response is not achieved a manipulation of the shoulder whilst under anaesthetic is required to restore the range of motion. Shoulder arthroscopy may also be advised if additional damage within the joint is suspected.

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