Anterior shoulder instability, also known as anterior glenohumeral instability, is a condition in which the head of the humerus (upper arm bone) is able to dislocate or sublux from the glenoid fossa (socket), compromising the function of the shoulder. Dislocation is where the ball comes completely out of the socket and often needs to be reduced (manipulated) back into position. Subluxation is where the ball only partially comes out of the joint and then spontaneously reduces. Both are usually caused by trauma or injury to the glenohumeral joint. Anterior shoulder instability accounts for 95 per cent of all acute traumatic shoulder dislocations.
When a dislocation occurs the patient usually is aware that the shoulder has come out of joint, and it is very painful. Sometimes the arm can just go “dead” for a period of time and instability may not be recognized. Damage usually occurs in the shoulder, with the classic pathology being the “Bankart lesion” where the anterior glenoid labrum and capsule is torn off the front of the socket. Very occasionally the damage occurs on the ball (humeral head side). This is called a HAGL lesion (humeral avulsion of the glenohumeral ligaments). Often when the shoulder has been out of joint a dent occurs in the back of the humeral head. This is called a Hill-Sachs defect.
Diagnosis of Anterior Shoulder Instability
Anterior shoulder instability is usually diagnosed from the history and a physical examination. During examination, specific tests such as load and shift test; apprehension, relocation, and anterior release tests; and anterior drawer test may be undertaken to assess the degree of shoulder instability. Imaging studies such as X-rays are usually ordered to obtain additional information about the potential causes of the instability and to rule out other causes of shoulder pain. Additionally, a CT scan and/or an MRI may also be ordered for a detailed evaluation of the bones and soft tissues of the shoulder joint.
Treatment for Anterior Shoulder Instability
The treatment options for anterior shoulder instability involve both conservative as well as surgical treatment.
Conservative Treatment
Closed reduction: Following a dislocation, your surgeon can often externally manipulate the shoulder joint, usually under anaesthesia, realigning it into proper position.
Medications: Over-the-counter pain medications and NSAIDs can help reduce the pain and swelling.
Rest: Rest the injured shoulder and avoid activities that require overhead motion. A sling should be worn for 2 to 3 weeks to facilitate healing.
Ice: Ice packs should be applied to the affected area for 20 minutes every hour.
Exercise:
This is very important after a period of healing has been allowed to occur. Initially range of motion is restored. Then a progressive strengthening program for the rotator cuff and scapula stabilisers is undertaken.
Return to activity:
This is ideally delayed for 6 weeks or more to allow the soft tissues to heal. Normally return to sport should not occur until pain has gone, range of motion has been restored, strength in the arm is close to normal, and apprehension in use of the arm has diminished
Surgical Treatment
When conservative treatment fail to relieve shoulder instability, your surgeon may recommend shoulder stabilization surgery. Anterior shoulder stabilization surgery is performed to improve the stability and function of the shoulder joint and prevent recurrent dislocations. It can be performed arthroscopically or through open surgery, depending on your condition.
Arthroscopy is a surgical procedure in which an arthroscope, a small tube with a light and video camera at the end, is inserted into a joint to evaluate and treat the condition. It is a minimally invasive surgery and is performed through two or more tiny incisions (portals), about half-inch in length, made around the joint area. Through one of the incisions, an arthroscope is passed. The camera attached to the arthroscope displays the images of the inside of the joint on the television monitor, which allows your surgeon to carry out the required repair through tiny surgical instruments that are passed through the other incisions.
Open surgery is mostly required to correct severe instability. During this surgery, a surgical cut is made on the shoulder and the muscles under it are moved apart to obtain access to the joint capsule, labrum, and ligaments. These soft tissue structures are then reattached, tightened, or repaired accordingly depending on the extent of tissue injury and closed with sutures. Sometimes if bone loss has occurred as a result of recurrent instability a bony procedure may be required. This usually involves taking some bone from the coracoid process of the shoulder and attaching it to the front of the socket with screws. This is called the Latarjet procedure.
Any surgery is followed by rehabilitation to restore range of motion and strength of the shoulder joint.