The shoulder is the most moveable joint in your body. It helps you to lift your arm, to rotate it, and to reach up over your head. It is able to turn in many directions. This greater range of motion, however, can cause instability.
Shoulder instability occurs when the head of the upper arm bone is forced out of the shoulder socket. This can happen as a result of a sudden injury or from overuse.
Once a shoulder has dislocated, it is vulnerable to repeat episodes. When the shoulder is loose and slips out of place repeatedly, it is called chronic shoulder instability.
The articulation of the shoulder joint is between the head of the humerus and the shallow glenoid cavity of the scapula. The glenoid cavity is deepened by the glenoid labrum (a fibro cartilaginous rim). The joint capsule surrounds the shoulder joint. The rotator cuff muscles around the shoulder are very important for protecting the joint and adding to stability.
There are three common ways that a shoulder can become unstable:
Severe injury, or trauma, is often the cause of an initial shoulder dislocation. When the head of the humerus dislocates, the socket bone (glenoid) and the ligaments in the front of the shoulder are often injured. The labrum — the cartilage rim around the edge of the glenoid — may also tear. This is commonly called a Bankart lesion. A severe first dislocation can lead to continued dislocations, giving out, or a feeling of instability.
Some people with shoulder instability have never had a dislocation. Most of these patients have looser ligaments in their shoulders. This increased looseness is sometimes just their normal anatomy. Sometimes, it is the result of repetitive overhead motion.
Swimming, tennis, and volleyball are among the sports requiring repetitive overhead motion that can stretch out the shoulder ligaments. Many jobs also require repetitive overhead work.
Looser ligaments can make it hard to maintain shoulder stability. Repetitive or stressful activities can challenge a weakened shoulder. This can result in a painful, unstable shoulder.
In a small minority of patients, the shoulder can become unstable without a history of injury or repetitive strain. In such patients, the shoulder may feel loose or dislocate in multiple directions, meaning the ball may dislocate out the front, out the back, or out the bottom of the shoulder. This is called multidirectional instability. These patients have naturally loose ligaments throughout the body.
Common symptoms of chronic shoulder instability include:
- Pain caused by shoulder injury
- Repeated shoulder dislocations
- Repeated instances of the shoulder giving out
- A persistent sensation of the shoulder feeling loose, slipping in and out of the joint
Recurrence rates for nonoperative treatment
People over 40 have a 30% recurrence risk with nonoperative treatment, and people around 20 have an 82% recurrence risk with nonoperative treatment.
Younger the patient higher is probability of recurrent dislocation.
Chronic shoulder instability is often requires surgery, non-surgical treatment is not successful.Goal is to repair torn or stretched ligaments so that they are better able to hold the shoulder joint in place.
There are several stabilization procedures, dependent upon the nature of the lesion
When to do the surgery?
Earlier the surgery better the results, the problem with recurrent dislocation is bone loss on the glenoid which will change further course to open surgery from arthroscopic surgery
Bankart lesions and hillsach lesions can be repaired arthroscopically . Sutures and anchors are used to reattach the ligament, labrum and soft tissues to the bone
Some patients may need an open surgical procedure - bony stabilization [laterjet]. This involves making a larger incision over the shoulder and performing the repair under direct visualization.
After surgery, your shoulder may be immobilized temporarily with a sling.
When the sling is removed, exercises to rehabilitate the ligaments will be started. These will improve the range of motion in your shoulder and prevent scarring as the ligaments heal. Exercises to strengthen your shoulder will gradually be added to your rehabilitation plan.