The shoulder joint is the most mobile joint in the body and consequently one of the most commonly dislocated joints.
An article published in the March 2010 issue of The Journal of Bone and Joint Surgery (JBJS) reveals that the majority of all shoulder dislocations occur during sports activities and young males are at a higher risk. The study also shows a high rate of shoulder dislocation in elderly women.
The overall incidence rate was 23.9 shoulder dislocations per 100,000 person years (the product of the number of years times the number of members of a population who have been affected by a certain condition). While this is more than double the previous rate reported for shoulder dislocations for the U.S. general population, it is still less than the rates of other common musculoskeletal injuries seen in emergency rooms, such as injuries to the lower back, knee and foot.
"Shoulder instability is one of the most common reasons young athletes see orthopaedic surgeons," explained Brett Owens, MD, study co-author, orthopaedic surgeon at Keller Army Hospital in West Point, New York and Associate Professor at the Uniformed Services University of the Health Sciences. "However little has been reported about the incidence of this injury."
Dr. Owens and his colleagues studied 8,940 shoulder dislocations in patients presenting to 100 hospital emergency rooms across the United States from 2002 to 2006. The purpose of the study was to identify the specific groups of individuals at risk, to help direct prevention efforts.
Of all dislocations, the study found:
Dislocations most frequently resulted from a fall (58.8 percent), of which 47.7 percent of these falls occurring at home and 33.6 percent occurring at recreation or sports sites.
In women, higher dislocation rates were seen among those aged 80 to 90 years old. This increase was mostly due to falls at home.
"We were not too surprised to find the high number of young males dislocating their shoulders during athletic activity," commented Dr. Owens. "However, the rate of shoulder dislocations among elderly women was higher than we had previously assumed."
The shoulder joint can dislocate forward, backward or downward. The most common shoulder dislocation happens when the shoulder slips forward (anterior instability). The arm bone is moved forward and down and out of its joint.
Dislocated shoulder symptoms include:
Often the dislocation will tear ligaments or tendons in the shoulder or even damage nearby nerves. To treat the dislocation, the doctor must manipulate the arm bone (the humerus) and replace it in the shoulder socket. This stops the severe pain and allows for the injured tissues to heal.
"Individuals who dislocate their shoulders should see an orthopaedic surgeon. While not all patients require surgery, an orthopaedist can best counsel patients on the treatment options and expected outcomes," said Dr. Owens.
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