A dislocation is an injury to a joint in which the ends of the bones are forced from their normal positions. The shoulder is a “ball-and-socket” joint where the “ball” is the rounded top of the arm bone (humerus) and the “socket” is the cup (glenoid) of the shoulder blade. A layer of cartilage called the labrum cushions and deepens the socket. A shoulder dislocation occurs when the humerus pops out of its socket, either partially or completely. As the body’s most mobile joint, able to move in many directions, the shoulder is most vulnerable to dislocation. A shoulder dislocation may be caused by a sports injury, trauma from a motor vehicle accident or a fall.
Symptoms of Shoulder Dislocation
Dislocation causes pain and unsteadiness in the shoulder. The shoulder may be visibly deformed or look out of normal placement. Other symptoms of a dislocated shoulder may include:
The muscles in the shoulder may spasm and cause tingling sensations in the neck and down the arm. Complications of a shoulder dislocation may also include muscle tears, tendon or ligament injuries, and blood vessel or nerve damage.
Diagnosis of Shoulder Dislocation
A shoulder dislocation is diagnosed through a physical examination and a review of symptoms. Additional diagnostic tests may include:
- MRI scan
The electromyography test is used to determine whether there is any nerve damage as a result of the shoulder dislocation.
Treatment of Shoulder Dislocation
In most cases, the dislocated shoulder can be manipulated back into place by a doctor in a process known as closed reduction. When the shoulder bone is back in place, severe pain normally subsides. The arm and shoulder are then immobilized in a special splint or sling for several weeks as the shoulder heals. Medication may also be prescribed for pain. A shoulder that is severely dislocated or in cases where surrounding ligaments or nerves have been damaged, surgery may be necessary to tighten stretched ligaments or reattach torn ones.
After treatment for a shoulder dislocation, when pain and swelling have subsided, physical therapy is recommended to restore the range of motion of the shoulder, strengthen the muscles, and prevent future dislocations. After treatment and recovery, a previously dislocated shoulder may remain more susceptible to reinjury, potentially resulting in chronic shoulder instability and weakness.
Shoulder impingement occurs when the front of the shoulder blade rubs against the rotator cuff causing irritation and pain. The rotator cuff is a group of muscles and tendons that stabilizes the shoulder and permits lifting and rotating movements. If the rotator cuff weakens or is injured, the bone of the upper arm (humerus) can lift up, pinching the rotator cuff against the shoulder blade. The muscles can then swell further, creating a cycle of pain and weakness that worsens over time. Shoulder impingement is one of the most common causes of shoulder pain and occurs more frequently in athletes who lift their arms overhead, such as swimmers, baseball players and tennis players.
Causes of Shoulder Impingement
Shoulder impingement is often caused by the weakening of, or injury to, the shoulder tendons which may be due to:
- Rotator cuff injuries
Shoulder impingement may also be caused by overuse of the rotator cuff, and may be more common in people who do repetitive lifting or activities that include frequent raising of the arm, such as construction workers, painters or athletes. In some cases, impingement may occur without a discernible cause.
Symptoms of Shoulder Impingement
The symptoms of shoulder impingement often worsen over time. Initial symptoms may include mild pain in the shoulder, and may progress to
- Pain radiating from the front of the shoulder to the side of the arm
- Sudden pain when lifting and reaching the arm
- Swelling and tenderness in the shoulder
- Loss of strength and motion
As impingement progresses, pain and stiffness may worsen until it becomes difficult to lift or lower the arm. Left untreated, shoulder impingement may severely limit arm motion to the point that the shoulder becomes “frozen.”
Diagnosis of Shoulder Impingement
Shoulder impingement may be diagnosed after a review of symptoms and a physical examination of the shoulder. Additional tests may include X-rays or an MRI scan to rule out any other conditions that may be causing symptoms. A doctor may also test the individual’s range of motion and arm strength by asking the patient to perform different actions with the arm and shoulder.
Treatment of Shoulder Impingement
Treatment for shoulder impingement focuses on managing pain and restoring function of the shoulder. Initial treatment may include rest and modifying physical activities as well as:
- Anti-inflammatory medication
- Steroid injections
- Physical therapy
Surgery is rarely recommended for shoulder impingement, however, in severe cases that do not respond to other treatment, arthroscopic surgery may be performed to remove the tissue that may be irritating the rotator cuff.