SHOULDER SEPARATION (ACROMIOCLAVICULAR SPRAIN)
Tom C. Haney, M.D.
Team Physician
Florida State University
Shoulder injuries in football are very common. Frequently, there is confusion between a
shoulder dislocation and a shoulder separation. A shoulder dislocation is an injury during
which the ball of the joint slips out of the socket. A shoulder separation is an injury to
the small joint at the top of the shoulder called the acromioclavicular or AC joint.
Although the AC joint can be dislocated, the injury is usually called a separation.
ANATOMY
The AC joint is formed by the end of the collarbone (clavicle) and a broad bone forming
the top edge of the shoulder called the acromion, which is part of the shoulder blade. The
soft tissue ligament which holds the joint together is called the acromioclavicular
ligament. The joint is also supported by a second ligament which connects the clavicle to
a small prominence, which is also part of the shoulder blade, called the coracoid process.
This ligament is called the coracoclavicular ligament. The severity of the injuries to the
acromioclavicular joint is determined by the extent to which these two ligaments are
injured.
CORACOCLAVICULAR
LIGAMENT
ACROMION
CORACOIDLIGAMENT
PROCESS
ACROMIOCLAVICULAR
ACROMIOCLAVICULAR JOINT
SHOULDER BLADE
Figure 1 - The structures supporting the acromioclavicular joint.
1
THE INJURY
The AC joint is usually injured by a direct blow to the tip of the shoulder when it strikes
the ground. It frequently occurs when a running back, receiver or other athlete strikes the
shoulder against the ground while the arm is at the athlete’s side.
Figure 2 - The usual mechanism of injury to the AC joint is direct impact to the tip of the
shoulder.
This injury forces the acromion of the shoulder down as the muscles of the neck tighten
pulling the clavicle up. The direct blow causes enough stress to tear the ligaments that
hold the joint together.
DIAGNOSIS
The acromioclavicular joint will always be painful immediately following the injury.
There will be tenderness of the acromioclavicular joint. There may or may not be
deformity of the joint depending on the severity of the separation. The severity of the
shoulder separations can be described by various classifications. However, the most
commonly used descriptions are grade I, grade II and grade III. When an AC separation
is suspected, x-rays can be taken with a 10-pound weight suspended to each wrist of the
athlete while the athlete is standing. The weights may spread apart the injured the AC
joint while compared to the AC joint in the opposite shoulder. This helps to determine
the severity of the injury.
2
MILD SPRAIN, GRADE I
Figure 3A
Milder AC separations are the result of partial tears to the acromioclavicular ligament.
This is called a grade I sprain. The joint is tender and swollen, but not deformed. X-rays
show no offset of the clavicle relative to the acromion. The treatment for mild sprains is
restricted activities, ice, anti-inflammatory medications such as ibuprofen, and the use of
a sling as needed. Most athletes can recover in one to three weeks with a mild sprain.
Protective padding can be used following the sprain.
MODERATE SPRAIN, GRADE II
Figure 3B
Moderate sprains of the AC joint occur when the acromioclavicular ligament is
completely torn, as well as at least a partial tear of the coracoacromial ligament. X-rays
reveal incomplete offset of the end of the clavicle relative to the acromion. However,
3
there is still some approximation of the clavicle with the acromion. This results in some
deformity, more swelling, and increased pain. The treatment is restricted activities, ice,
anti-inflammatory medications, and the use of a sling. Surgery is usually not necessary.
Most athletes can recover within three to six weeks with a moderate separation.
Protected padding is frequently used following this injury. If pain occurs later,
arthroscopic surgery can be used to remove the end of the clavicle to relieve chronic
symptoms.
SEVERE SPRAIN, GRADE III
Figure 3C
Severe sprains occur when both ligaments holding the end of the clavicle are completely
torn. This includes both the acromioclavicular ligament and the coracoclavicular
ligament. X-rays show complete offset of the end of the clavicle from the acromion.
Severe sprains result in marked deformity, more pain, and increased disability. Severe
sprains can be treated with a special sling device which holds the clavicle down for two
to four weeks to allow some healing, followed by the usual treatment for moderate
sprains. Recovery time is usually six to twelve weeks. Some severe AC separations
require surgery to repair the torn ligaments. Surgery is frequently needed in athletes with
high demands on their shoulder such as quarterbacks, pitchers and other throwing
athletes. Recovery from surgery usually takes at least twelve weeks.
Regardless of the classification of the shoulder separation, some athletes return to action
sooner than expected and still have satisfactory results. The trainers and team physicians
can monitor the athlete’s progress and return the athletes to action based on the degree of
pain and motion, rather than absolute time standards.
Most athletes return to full
activities when the shoulder is nontender, has full motion, and is not painful when the
arm is placed under traction.
4
ILLUSTRATIONS:
Figure 2 – From Rockwood, C. A., and Green, D. P. (Eds.), Fractures in Adults, 2nd ed.
Philadelphia, J. B. Lippincott, 1984
Figure 3A, 3B, 3C – From Zarins, B., Andrews, J., and Carson, W., Injuries To The
Throwing Arm, The United States Olympic Committee Sports Medicine Council, W. B.
Saunders Company, 1985
5