On top of the shoulder blade (scapula) sits a bony mass called the acromion. This composes the top of the shoulder and serves as the headquarters for the deltoid muscle - connecting to the collarbone (clavicle) to form the acromioclavicular joint or AC Joint. The AC joint is an important part of the shoulder as it connects the shoulder to the rest of the body.

This joint frequently incurs damage as a result of an impact to the outside of the shoulder - as often seen in contact sports as well as in biking and skiing accidents. When this happens it is called an AC joint separation.

As a result, patients may notice a visible bump on the top of the shoulder. While not extremely painful, this happens when the end of the collarbone becomes detached from the acromion and the arm correspondingly sags - making the bump more pronounced. The initial injury may cause pain in the AC joint area and may be accompanied by some bruising and swelling.

When a severe displacement occurs, patients experience a tremendous amount of weakness in the deltoid muscle - indicating more serious ligament damage.

An AC joint separation, or shoulder separation, is often confused with a shoulder dislocation. The primary differences lie in the bones affected. In a shoulder separation, the area where the clavicle and scapula connect is disrupted, but in a shoulder dislocation the humerus is displaced from the socket, which is formed by the scapula.

Those at Risk
Those involved in extreme biking, motocross racing and other action sports are frequently diagnosed with AC joint separation.

Diagnosis
The prominent bump at the top of the shoulder is a good indictor of AC joint separation. Patient history and detail of how the injury occurred followed by an assessment of pain and tenderness at the joint will also help in the diagnosis. An X-ray may be performed in order to confirm that there is no bone fracture.

Treatment
Most AC joint separation problems can be addressed conservatively and will include a period of rest, cold compression and anti-inflammatory medication in order to relieve pain and reduce swelling. Range of motion exercises begin shortly thereafter in order to rebuild shoulder strength and flexibility.

In the case of severe displacement and corresponding weakness of the deltoid muscle, an outpatient surgical repair may be performed in order to restore the ligaments, which maintain the AC region. Rest, cold compression and range of motion exercises follow the procedure.

With the greatest range of motion than any other joint in the body, the shoulder is vulnerable to injury as well as many problems that can cause pain, tenderness and weakness. The shoulder is surrounded by four muscles (the infraspinatus, teres minor, supraspinatus, and subscapularis) and accompanying tendons, which are collectively called the Rotator Cuff and serve as part of a delicate balance of strength, flexibility and stability.

Rotator Cuff tears can result from a single action or the cumulative affect of gradual degenerative stress caused by long term involvement in overhead sports such as throwing, tennis and swimming - possibly following rotator cuff tendonitis, impingement, or dysfunction. Tears can also result from the degenerative affects of aging. Damage is classified as either extrinsic (initiated from the outside and resultant of a trauma or overuse), or intrinsic (initiated from the inside and resultant of degeneration with aging and calcific presence).

Symptoms generally include pain, weakness and loss of motion. Pain intensifies during overhead or above the shoulder activities. There may also be night pain that disrupts sleep.

Those at Risk
Athletes involved in overhead sports and the elderly experiencing tissue degeneration in the shoulder joint are most often diagnosed with a rotator cuff tear. Though, calcific tendonitis, which can eventually lead to a rotator cuff tear, may occur in those ranging in age from 30 to 50 years.

Diagnosis
Patient history and physical examination is key in establishing any diagnosis, but particularly for a rotator cuff tear. Pain is assessed as patients move through a series of passive shoulder movements involving forward flexion, as well as internal and external rotation at various rotations.

Radiographic testing is also helpful in eliminating the presence of calcific deposits and other contributing factors. In patients with a history of severe trauma or who experience extreme weakness, magnetic resonance imaging or an arthrogram may be indicated in order to determine appropriate treatment.

Treatment
Most rotator cuff injuries can be addressed nonsurgically and may respond to a course of conservative treatment that includes anti-inflammatory medication and rehabilitative exercises - involving all muscle groups instrumental in shoulder function, with both positive and negative force. If pain persists, cortisone injection treatment may be indicated.

And in more serious cases non responsive to conservative treatment, arthroscopic surgery may be indicated and instrumental in removing damaged portions of the bursa and repairing the torn rotator cuff tendons with suture anchors. Arthritis of the AC joint and other shoulder pathology can also be addressed at the same time.

The shoulder joint is a ball and socket joint similar to the hip, though it is extremely shallow and, therefore, unstable. Ligaments help hold the shoulder bone in its socket. If the ligaments become stretched or torn from trauma, or overloading, the required stability of the ligaments throughout the shoulder’s large range of motion is compromised. This is called instability.

Shoulder instability problems are the second most common type of shoulder problems after Rotator Cuff tears. These instabilities can range from subluxation (a malalignment subject to dislocation), to dislocation (actual separation of the humerus from the scapula).

Shoulder instability problems generally result from forceful contact and overhead sports or activities. Patients report an uncomfortable sensation and feeling that their shoulder may slide out of place - which is called apprehension. An unstable shoulder is globally tender and causes a reduction in range of motion - particularly in overhead activities.

Those at Risk
Shoulder instability is most frequently diagnosed in patients who have sustained a prior shoulder dislocation that resulted in torn ligaments. Loose healing of the tendons will result in chronic instability. In patients under the age of 35 sustaining a traumatic dislocation, shoulder instability generally follows in approximately 80 percent of the patients.

Athletes competing in overhead and forceful contact sports, such as swimmers, pitchers and volleyball players, are also at risk for shoulder instability problems.

In young patients, a shoulder dislocation frequently results in future instability and dislocations ultimately requiring surgery. For those in their 30s, future dislocation and instability is rare following a first-time episode. For patients over 40 years of age, a dislocation usually results in a rotator cuff tear as well.

Diagnosis
Patient history, a listing of symptoms experienced, and a physical examination are generally all that is necessary to diagnose shoulder instability. An X-ray may be indicated in order to determine which way the shoulder comes in and out of its socket - anterior (front), posterior (back) or both (multidirectional). And magnetic resonance imaging (MRI) can help identify possible causes for the instability or dislocation, such as the presence of torn cartilage or stretched ligaments.

Treatment
Depending on the severity of the instability, conservative nonsurgical treatment is generally the first course of action and generally involves refraining from overhead activities, cold compression to control pain and swelling and targeted range of motion exercises that strengthen the rotator cuff, the deltoid, and the scapula rotators. Also established are exercises providing both positive and negative force on the muscles while improving cooperation of muscle groups.

If the instability results in a labrum tear, sutures may be required for reattachment. A dislocation may simply require immobilization with a shoulder sling. Arthroscopy or other outpatient procedure may be indicated to assist in stabilizing the shoulder joint.

A winged scapula is a shoulder injury or condition causing the scapula or shoulder blade to protrude out at the back, which is exaggerated when pushing against an object. It is the result of damage or a contusion to the long thoracic nerve of the shoulder or area muscle weakness. This nerve damage may also be the result of a direct trauma to the shoulder.

Aside from the protrusion of the scapula at the back, those suffering from winged scapula also experience pain, a reduction in shoulder movement, difficulty lifting and pressure on the scapula when sitting or leaning against a solid surface such as a chair.

Those at Risk
Athletes involved in contact sports placing the shoulder in jeopardy of a direct blow are often diagnosed with winged scapula.

Diagnosis
The protrusion at the back is a strong indicator of winged scapula. Patient history and physical examination are generally all that is necessary for diagnosis. Though, an X-ray may be indicated to thoroughly assess the area of impact and rule out other damage.

Treatment
Initial treatment for winged scapula is conservative and involves a complete rehabilitation program designed to strengthen the shoulder and surrounding muscles. If the condition is not improved with conservative treatment, surgery may be required to correct the problem and restore full shoulder function.