9.04 Acromio-clavicular joint separation
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agk's Library of Common Simple Emergencies

Presentation
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The patient fell on the point of the shoulder. 
He may come in right away because it hurts even 
without movement (first or second degree tear), 
or he may come in days later without pain, 
having noted that the injured shoulder hangs 
lower or the clavicle (collar bone) rides 
higher (third degree).

What to do:
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- Examine the shoulder. The diagnosis is 
    supported by tenderness at the lateral end 
    of the clavicle where it joins the acromion 
    process coming up from the scapula and by 
    pain on pulling the humerus down towards 
    the feet, distracting the acromio-clavicul- 
    ar joint. Strength may be decreased because 
    of pain, but other bones, joints, range of 
    motion, sensation and circulation should be 
    documented as intact.
- X-ray the shoulder to be sure there is no 
    associated fracture of the lateral clavicle 
    or fracture or dislocation of the humerus.
- Support the injured joint with a sling.
- Provide additional analgesia. Ibuprofen or 
    naproxen usually suffices. 
- Arrange for re-evaluation by an orthopedic 
    surgeon and physical therapy to begin 
    shoulder range of motion excercises within 
    a week.

What not to do:
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- Do not bother with weight-bearing x-ray views 
    to differentiate first, second and 
    third-degree separations based on the 
    widening of the distance between the 
    clavicle and scapula. These are painful and 
    do not change the initial treatment.
- Do not allow the patient to wear a sling and 
    immobilize the shoulder for more than a 
    week without at least beginning pendulum 
    exercises. The shoulder capsule will 
    contract and restrict the range of motion.

Discussion
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A partial tear of the ligaments between 
acromion and clavicle produces pain but no 
widening of the joint (first degree tear). A 
second-degree A-C separation shows up on x-ray 
a widened joint, but is otherwise the same on 
examination and treatment. In a third-degree or 
complete separation, the ligament from the 
coracoid process to the clavicle is probably 
also torn, allowing the collarbone to be pulled 
superior by the sternocleidomastoid muscle, but 
often releiving the pain of the stretched A-C 
joint. Long-term shoulder joint stability and 
strength remain almost normal, but patients may 
desire sugical repair to regain the appearance 
of the normal shoulder or the last few percent 
of function for athletics.

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 from Buttaravoli & Stair: COMMON SIMPLE EMERGENCIES
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