What is shoulder dislocation?
If your shoulder is wrenched upward and backward, you may
dislocate it out of its socket. This condition is both
painful and incapacitating. The force required is often that
of a fall or a collision with another person or object (both
of which can occur during many sports).
Most shoulder dislocations happen at the lower front of
the shoulder, because of the particular anatomy of the
shoulder joint. The bones of the shoulder are the socket of
the shoulder blade (scapula) and the ball at the upper end
of the arm bone (humerus). The socket on the shoulder blade
is fairly shallow, but a lip or rim of cartilage makes it
deeper. The joint is supported on all sides by ligaments
called the joint capsule, and the whole thing is covered by
the rotator cuff. The rotator cuff is made up of four
tendons attached to muscles that start on the scapula and
end on the upper humerus. They reinforce the shoulder joint
from above, in front, and in back, which makes the weakest
point in the rotator cuff in the lower front.
Subluxation refers to a partial dislocation. A
subluxation occurs when the two joint (articular) surfaces
have lost their usual contact. A 50% subluxation means the
normally opposing articular surfaces have lost half their
usual contact and the joint is partially dislocated. A 100%
subluxation means the articular surfaces have lost all of
their contact. A dislocation is the same as a 100%
What causes shoulder dislocation?
The shoulder joint is the most frequently dislocated
joint of the body. Because it can move in many directions,
your shoulder can dislocate forward, backward or downward,
completely or partially. In addition, fibrous tissue that
joins the bones of your shoulder (ligaments) can be
stretched or torn, often complicating the dislocation.
When your shoulder dislocates, a strong force, such as a
sudden blow to your shoulder, pulls the bones in your
shoulder out of place (dislocation). Extreme rotation of
your shoulder joint can pop the ball of your upper arm bone
(humerus) out of your shoulder socket (glenoid), which is
part of your shoulder blade (scapula). Partial dislocation (subluxation)
— in which your upper arm bone is partially in and partially
out of your shoulder socket — also may occur.
A dislocated shoulder may be caused by:
- Sports injuries. Shoulder dislocation is a common
injury in contact sports, such as football and hockey,
and in sports that may involve falls, such as downhill
skiing, gymnastics and volleyball.
- Trauma not related to sports. A hard blow to your
shoulder during a motor vehicle accident is a common
source of dislocation.
- Falls. You may dislocate your shoulder during a
fall, such as from a ladder or from tripping on a loose
Shoulder dislocation symptoms:
Patients with a shoulder dislocation are usually in
significant pain. They know something is wrong, but may not
know they have sustained a shoulder dislocation. Symptoms of
shoulder dislocation include:
- Shoulder pain
- Arm held at the side, usually slightly away from
the body with the forearm turned outward
- Loss of the normal rounded contour of the deltoid
Diagnosing Shoulder Dislocation:
Diagnosis of a shoulder dislocation is usually quite
apparent just by talking to a patient and examining their
joint. Patients must be examined to determine if there is
any nerve or blood vessel damage. This should be done prior
to reduction (repositioning) of the shoulder dislocation.
X-rays should be obtained to check for any fracture around
the joint, and to determine the pattern of the shoulder
Shoulder Dislocation Surgery:
Surgery is sometimes necessary following a shoulder
dislocation if there has been extensive damage to muscles,
tendons, nerves, blood vessels or the labrum. Surgery is
then usually performed as soon as possible after the injury.
In cases of recurrent shoulder dislocations, surgery may
be offered in an attempt to stabilise the joint. There are a
number of procedures which can be performed. The decision
over which procedure to use depends largely on the patients
lifestyle and activity. Some procedures result in reduced
shoulder external rotation and so are not suitable for
athletes involved in throwing or racket sports as this would