(Also known as a Partial Dislocation)
The shoulder is the junction of three bones: the humerus (upper arm bone), the clavicle (collarbone), and scapula (shoulder blade). A group of four muscles and their respective tendons, known as the rotator cuff, connects the humerus to the shoulder socket, or glenoid, stabilizes the joint, and allows the upper arm to be lifted and rotated. In a subluxation, the humerus slips out of the glenoid cavity as a result of weakness in the rotator cuff or a blow to the shoulder area. A subluxation can occur in one of three types: anterior (forward), posterior (backward), and inferior (downward).
Extreme pain, possible abnormality of shoulder when compared to other, and a possible loss of feeling if nerves are damaged may accompany a subluxation. Swelling, bruising and tenderness will always follow the injury.Causes and Risk Factors
Causes
Subluxation is most often caused by laxity or instability within the shoulder joint, which allow the head of the humerus to slip partially out of the glenoid.
Risk Factors
Shoulder subluxation is often a recurrent problem caused by weakness in the rotator cuff or laxity in the tendons that stabilize the shoulder. Therefore, people with previous shoulder dislocation or subluxation stand at the highest risk for future subluxation. Wrestlers, basketball players and football players compose the biggest risk group. Twisting, lifting and hitting, as well as throwing sports, also pose a higher risk of injury of this type. Those with arthritis, degeneration of the rotator cuff, or poor muscle tone are also at great risk.
Treatment
Immediate Action:
If a subluxation is suspected, gently place the arm in the most comfortable position across the chest. If this is not possible, use medical tape or bandages to secure the arm gently to the side of the body. Do not try to force the bones back into place, as this will often worsen the condition. Seek a doctor or emergency room immediately.Procedures
The condition is often treated conservatively right away with a sling and pain medication, followed by physical therapy to strengthen the muscles around the joint and tighten the allowances within the glenoid. For recurrent dislocations or subluxations, open-shoulder stabilization, arthroscopic stabilization, or thermal stabilization may be ordered.
Medications
Non-steroidal anti-inflammatory drugs (as directed), local and general anesthetic for reduction.
Prevention
Strong rotator cuff muscles remain the strongest defense against shoulder subluxation. Exercises that build up these muscles around the shoulder should be done. Those with great joint laxity should build a training regimen with a doctor or physical therapist to tighten and stabilize the joint.
Last updated: 10-Oct-00
