What is a Shoulder Dislocation?
A shoulder dislocation occurs when the humeral head (ball of the shoulder) is completely dislodged from the glenoid (socket). A subluxation occurs when the ball comes part of the way out of the socket, and then returns to the center without intervention.
What causes a Shoulder Dislocation?
Falls onto the shoulder or an outstretched hand, collision sports such as football and rugby, and sports where a sudden twisting injury may occur, such as skiing, are common causes of shoulder dislocations. Most of these injuries will cause the humeral head to be dislocated out of the front of the shoulder. Seizures and electrocutions can cause the humeral head to be dislocated out of the back of the shoulder.
What are the symptoms?
Patients complain of shoulder pain, and the inability to move the arm. A deformity will be present in the shoulder. Numbness and tingling may be present in the arm.
How is a Shoulder Dislocation diagnosed?
On physical exam, your surgeon will press on the shoulder and find a depression where the humeral head should be. Range of motion will be greatly reduced, and the shoulder will have a visible deformity. X-rays should be obtained to evaluate for associated injuries, such as fractures of the humeral head or glenoid. The labrum, or shoulder cartilage and the ligaments holding the humeral head in place are torn as a result of the dislocation. In older patients, the rotator cuff may be torn. An MRI should be obtained if a rotator cuff tear is suspected.
How is it treated?
The shoulder is reduced by providing traction to the arm, or elevating and rotating the arm. After the shoulder is back in place, it is initially immobilized in a sling. Consideration was recently given to immobilization of the shoulder in external rotation, but as of this time, scientific literature has not proven this to be of long-term benefit. Physical therapy should begin as soon as the patient can tolerate it to regain motion and strength in the shoulder. Anti-inflammatory medication and ice may be used to help with the initial pain and swelling. Return to activity may be allowed when the shoulder's motion and strength has returned to normal.
In young patients, consideration should be given to surgical repair of the labrum and shoulder ligaments that are injured at the time of the dislocation. These structures are detached from the socket, and do not heal. This leaves the shoulder 'loose' and prone to further dislocations. The risk of future dislocation is inversely proportional to the patient's age, with the risk of recurrent dislocation in young, active patients approaching 100%. With each dislocation, an indentation may form in the back of the humeral head, or the front of the glenoid as a result of the bones rubbing against each other. These indentations become larger with each subsequent dislocation, and further increase the risk of recurrent instability in the shoulder.
Surgery is performed arthroscopically(Bankart repair). The labrum and the shoulder ligaments are reattached to the glenoid using small, plastic devices called anchors. These devices have suture imbedded in them that allows the surgeon to sew the cartilage and ligaments down to the bone. A sling is worn postoperatively to protect the repair, and physical therapy is started to regain motion and strength.
If dislocations persist despite surgery or if the indentations on the humeral head and glenoid are too large to allow conventional repair, then the surgeon will transfer a bone block from the shoulder blade to the front of the glenoid to act as a bumper. This is called a Latarjet procedure.