The bone ends that constitute a joint are covered with a firm smooth cartilage. In the shoulder joint it involves a humeral head and glenoid process. At the acromioclavicular joint it involves the lateral end of the clavicle and the acromion process and at the elbow it involves the distal humerus and the proximal end of the radius and ulna. The articular cartilage eliminates friction nearly completely, protects the underlying cartilage against damage and allows for smooth sliding motion between bone ends. Wear and tear of the articular cartilage leads to osteo arthritis also called degenerative arthritis. This is the most common type of arthritis that occurs in the shoulder and elbow.
The process of osteo arthritis takes place over time. It might be caused by wear and tear over a period of years, repeated strain on the joint, previous injuries, mal-alignment, metabolic defects or genetic conditions. In weight-bearing joints being overweight also plays a part. Osteo arthritis in shoulder and elbow is more common in patients over 50 years of age but younger patients can develop this after dislocation of the joint or in people with a genetic tendency to develop osteo arthritis.
It causes a dull aching pain that alternates with acute pain episodes, stiffness and swelling of the joint and limited range of motion. Bony outgrowth or osteofytes develop over time together with gradual erosion of the articular cartilage. It may cause symptoms in the soft tissue like swelling or stiffness. Pain is typically centered over the posterior aspect of the shoulder and elbow but in the acromio-clavicular joint it is usually on top or in front of the shoulder. Osteoarthritis can occur simultaniously in joints lying close together like the acromioclavicular and glenohumeral joints.
When no specific cause can be identified or when it occurs due to genetic or metabolic factors it is called primary osteo arthritis. In the case of trauma with an underlying defect of the cartilage or bone, secondary osteo arthritis will develop. Specific diseases of cartilage can also influence the classification.
Pain relief and improvement of function is the aim of treatment. Analgesic medication, anti-inflammatory medication and adjustment of physical activities are first line of treatment. Exercises to improve range of motion and to strengthen surrounding muscle groups might be of help.
Surgical debridement might be indicated for patients that are not candidates for more extensive surgery.
Severe acromio-clavicular joint involvement may require complete removal of the acromio- clavicular joint which will lead to development of scar tissue in place of the diseased joint. For advanced osteo arthritis of the glenohumeral joint replacement of the humeral head and glenoid provides good pain relief. Joint replacement of the elbow is performed less often.
The collar bone connects the scapula via the acromion process and coracoid process with the sternum. The collar bone or clavicle is attached to the acromion through the acromion clavicular ligaments and to the coracoid through the coracoid clavicular ligaments. The ligamentous connections allow small amounts of movement and supplies stability with which the person can elevate his arm above his head. For reasons that are not yet clearly understood, the lateral end of the clavicle can start losing calcium, become soft and disintegrates. This condition is known as lateral clavicle osteolysis but is more commonly known as weight lifters shoulder.
It probably is related to single or repeated injury of the acromio clavicular joint. Repeated movement with heavy weights over head can contribute to this or a direct fall on the lateral side of the shoulder. Underlying conditions like infection, rheumatoid arthritis and other chronic conditions can also contribute to its development.
Lifting heavy weights above head height places large amounts of strain over the acromio clavicular joint and leads to micro trauma that is not allowed enough time to heal in-between sessions. This eventually leads to softening and dissolving of the bone in this area. There are studies that show that the bone tends to regenerate as the body tries to repair it, but eventually re-absorption of the lateral end of the clavicle takes place.
It is a condition that develops slowly and starts with a dull ache over the acromion clavicular area, local tenderness and stiffness of the shoulder. These symptoms intensify over time. Pain is typically over the front and the upper part of the shoulder and intensifies during activity, especially lifting of weight above shoulder height, pushing of objects or throwing of objects. Two to 3 cm of bone loss can occur.
It is classified according to the amount of bone involved, the specific anatomical structure involved as well as any associated pathology.
The aim of treatment is to reduce pain and consists of limitation of activities that exacerbates the condition. Adjustment of activities, rest, ice and anti-inflammatory medication are employed as first line treatment and can be followed by corticosteroid injection if inflammation continues. Smoking must be stopped to help remineralisation of bone. It can take many months for the bone to repair. If remmeralisation does not take place and pain continues, excision of the lateral clavicle is indicated.