Your shoulder joint is composed of three bones: the clavicle (collarbone), the scapula (shoulder blade), and the humerus (upper arm bone). Your shoulders are the most movable joints in your body. They can also be unstable because the ball of the upper arm is larger than the shoulder socket that holds it. To remain in a stable or normal position, the shoulder must be anchored by muscles, tendons and ligaments. Because the shoulder can be unstable, it is the site of many common problems. They include sprains, strains, dislocations, separations, tendonitis, bursitis, torn rotator cuffs, frozen shoulder, fractures and arthritis.
What is a shoulder dislocation?
A shoulder dislocation occurs when the head of the humerus moves out of it’s normal position in the socket of the shoulder complex (the glenoid fossa). As a result the ligaments that stabilize the glenohumeral joint are injured or torn.
There are different types of shoulder dislocations. Classification of the different types depends on the direction in which the head of the humerus dislocates. The most common type of shoulder dislocation is one where the head of the humerus dislocates in front of and below the glenoid fossa. This is called and anterior (in front of) – inferior (below) shoulder dislocation.
Anterior-inferior shoulder dislocations make up over 95% of shoulder dislocations.
What is a rotator cuff tear?
When the rotator cuff becomes injured or torn, it is described as a rotator cuff tear. These tears may be classified as partial-thickness tears or full-thickness tears. A partial thickness rotator cuff tear is the term used when the tendon is not completely torn. A full-thickness rotator cuff tear is the term used when the tendon is completely torn.
What can cause a rotator cuff tear?
A rotator cuff tear may occur suddenly or develop gradually. Sudden rotator cuff tears usually occur during falls or while lifting heavy objects. A rotator cuff tear may develop gradually for a variety of reasons, including: :
– Repetitive overhead lifting.
– Degeneration of the rotator cuff due to aging.
– Poor blood supply to the rotator cuff.
– Narrowing of the space between the humerus and the acromion (subacromial arch). This can cause progressive “fraying” of the rotator cuff.
What is an AC joint separation?
An AC joint separation occurs when the ligaments that stabilize the clavicle to the acromion process are injured or torn. As a result the clavicle can be displaced (moved) upwards. This condition is commonly known as a shoulder separation.
There are different severities of AC joint separation. Classification of the different severities depends on the ligaments that are torn. One classification is as follows:
Type I: A sprain (without a complete tear) of either of the ligaments holding the joint together. The clavicle is not displaced.
Type II: A complete tear of the acromioclavicular ligament and a partial tear of the coracoclavicular ligaments. The clavicle is slightly displaced.
Type III: A complete tear of both the acromioclavicular ligament and the coracoclavicular ligaments. When this occurs the clavicle is severely displaced (dislocated).
Types IV, V, VI: A complete tear of the acromioclavicular ligament and the coracoclavicular ligaments. The clavicle is severely dislocated and usually requires surgical intervention.
What can cause an AC joint separation?
Injuries to the AC joint are usually caused by a direct blow to the shoulder. Traumatic contact from the side or from above the shoulder can tear the AC ligaments. Hockey players and football players commonly injure this joint when they make contact with the boards, ground or an opponent with their shoulder striking first.
Injuries to the AC joint can also be caused by overstressing the joint with heavy weightlifting (i.e. deep bench-press techniques). This mechanism of injury is rare.
Usually shoulder problems are treated with RICE. This stands for Rest, Ice, Compression and Elevation. Other treatments include exercise, medicines to reduce pain and swelling, and surgery if other treatments don’t work.