Sports Tips - Dislocated Shoulder
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1) WHY IS THE SHOULDER THE MOST
FREQUENTLY DISLOCATED LARGE JOINT?
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The shoulder is actually several joints, the main
joint, the glenohumeral joint (which is most frequently
dislocated) has the greatest range of motion of all joints in
the body. There is a large ball (humeral head) and a small
shallow socket (glenoid). The glenoid is made deeper by a rim
of fibrocartilage called the labrum. There are several loose
ligaments that form the shoulder capsule. These ligaments are
attached to both the humeral head and glenoid. Each ligament
tightens in different arm positions, thus keeping the humeral
head attached to the glenoid. These ligaments are responsible
for “static stability”. Rotator cuff muscles that originate
on the scapula (wing bone) form a cuff of tendons that
surround the humeral head. These rotator cuff muscles and
tendons provide for “dynamic stability” of the glenohumeral
joint.
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2) WHAT STRUCTURES ARE INJURED
WITH SHOULDER DISLOCATIONS?
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When
the shoulder dislocates (the humeral head becomes dissociated
from the glenoid) usually the ligamentous structures are
stretched and/or torn. The fibrocartilage (labrum) that
surrounds the glenoid can be torn away from the labrum.
Occasionally the front of the glenoid will actually fracture.
At other times, the humeral head, once it slips forward, will
become impacted on the glenoid and will develop an impaction
fracture called a “Hill-Sachs lesion”.
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3) WHAT IS THE MECHANISM OF
SHOULDER DISLOCATIONS?
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Usually the
shoulder dislocates anteriorally when the arm is caught above
and behind the patient, such as a football player reaching out
to his side to tackle a runner. It is common for athletes to
dislocate their shoulders while playing football, hockey or
sliding into a base head first with arms stretched out ahead
of them. Occasionally the humeral head can be pushed
posteriorly out of the glenoid, which can happen from a direct
blow to the front of the shoulder.
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For the first true
dislocation, the patient must usually be taken to an emergency
room facility where medication is given to relieve pain and
muscle spasm. Once this is done, a physician can apply gentle
traction and relocate the humeral head back into the glenoid.
With a recurrent dislocating shoulder, sometimes a patient can
use their own muscles to pull the humeral head back into the
socket; however, if it is dislocated for more than a minute or
so, the muscles around the shoulder will go into spasm and the
patient will need medication to help reduce the shoulder.
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There are various reports
in the medical literature stating that a patient under 20
years old will have a high recurrence rate for dislocating the
shoulder (various studies report re-dislocation rates from 30-
90%). There are newer studies showing when an acute
dislocation is treated with arthroscopic stabilization, this
will greatly reduce the re-dislocation rate.
Currently, the typical treatment involves rehabilitation
programs that start with a short period of immobilization,
isometric exercises, and progress to exercises involving
motion of the shoulder. These exercises are aimed at
strengthening the rotator cuff muscles. Over time, the
exercises are to increase coordination of the shoulder and
help return the patient to sports.
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Surgery for acute shoulder dislocations
seems to prevent recurrent dislocations. However, the need
for surgery depends on the functional demands of the patient
and degree of instability and disability. If the patient does
not wish to return to sports or it is their non-dominant arm,
the need for surgery is less than if it is the dominant arm of
an athlete who participates in collision or contact sports.
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Surgery for recurrent dislocations
of the shoulder can be performed by the traditional open
approach or via arthroscopy. The repair is focused on
tightening the stretched ligaments and/or repairing the labrum
if it was torn at the time of injury. Generally, if the
patient is going to return to a collision sport, such as
hockey or football, an open repair is favored over an
arthroscopic repair. The goal of surgery is to restore
stability while maintaining motion of the glenohumeral joint.
The success rate of open surgery vary from 90-95% and success
rate for arthroscopic surgery vary from 85-90%
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