Robert J. Snyder, MD
The human shoulder is a joint which allows an incredible amount of flexibility and movement. The shoulder has the most mobility of all of the joints in the body. This wide range of motion also makes it the joint most vulnerable to dislocation. Why do shoulders dislocate, how are they treated and what can be done to prevent shoulder dislocation?
The shoulder joint connects the upper arm bone (humerus) to the shoulder blade socket (scapula). The shallow cup that holds the bone is called the glenoid. Cartilage forms a rim around the shallow cup (labrum) and ligaments comprise the joint capsule which support the joint. This is surrounded by the rotator cuff, a set of four tendons which support and mobilize the shoulder joint.
Risk factors for shoulder dislocation include:
- Overuse/repetitive activities
- Previous dislocation(s)
- Stretched or loose shoulder ligaments
- Genetic predisposition to have lax tendons making the shoulder unstable
Shoulders dislocate usually during violent sports activities, falls, motor vehicle or work accidents. A large force across the shoulder causes the humerus bone to dislodge from the glenoid. Shoulders can partially dislocate (subluxation) or totally dislocate. Almost all dislocations occur with the bone moving forward out of the socket, called an anterior dislocation. During dislocations, the labrum tears off the glenoid, sometimes with a piece of bone. The humeral head impacts the edge of the glenoid, creating a break in the humeral head (Hill-Sachs lesion).
Symptoms of a dislocated shoulder include:
- Extreme pain at the shoulder
- Difficulty moving the arm
- Swelling or bruising
- Possible physical deformity
- Tingling, numbness or weakness in the upper arm
Shoulder dislocations should be treated at the ER by an Orthopaedic specialist or ER Physician. Treatment involves putting the arm bone (humerus) back into the socket and most primary or urgent care providers are not equipped to perform this procedure.
X-rays will be taken to ensure that a fracture has not occurred and the patient will be asked how the dislocation occurred and if it have ever happened before. Patients usually have severe pain and muscle spasm around the shoulder joint after a dislocation, so IV medications are given to ease pain and relax the muscles before the shoulder is put back in the socket, called reduction. In extreme cases, a patient may require a reduction surgery under general anesthetic.
Patients are sent home from the hospital with their arm in a sling. Oral pain medications will be given to control the pain and soreness from the dislocation. Ice can be used to help lessen swelling.
For an initial dislocation, follow-up with an orthopaedist is important. A MRI scan may be ordered. Non-operated dislocations have a high recurrence rate, particularly in a younger, athletic patient. Certain studies support arthroscopic stabilization of initial dislocation. For patients being treated without surgery, physical therapy is important and is begun as soon as possible.
Recurrence of shoulder dislocation can occur and patients should be aware of this during activities. This usually occurs if surgery is not performed. A 20 year old has an 80% chance of redislocating without surgery. An 80 year-old has less than a 10% chance. If it happens again, the patient may require surgery to stabilize the shoulder and repair damage.
Anyone who has had a shoulder dislocation knows how painful it can be. Prompt follow-up with an orthopaedic surgeon is important with all shoulder dislocations.