A shoulder separation is not truly an injury to the shoulder joint. The injury
actually involves the acromioclavicular joint (also called the AC joint). The
AC joint is where the collarbone (clavicle) meets the highest point of the
shoulder blade (acromion).
Mechanism of injury
The most common cause for a separation of the AC joint is from a fall
directly onto the
shoulder. The fall injures the
ligaments that surround and
stabilize the AC joint.
If the force is severe enough, the
ligaments attaching to the underside of the
clavicle are torn. This causes the "separation" of the collarbone and shoulder
blade or scapula. The shoulder blade actually moves downward from the weight of
the arm. This creates a "bump" or bulge above the shoulder.
This figure shows the intact ligaments around
the acromioclavicular joint.
The injury can range from a little change in configuration with mild pain, to
quite deforming and very painful. Good pain-free function often returns even
with a lot of deformity. The greater the deformity, the longer it takes for
pain-free function to return.
• A mild shoulder separation involves a sprain of the AC ligament that does not
move the collarbone and looks normal on X-rays.
• A more serious injury tears the AC ligament and sprains or slightly tears the
coracoclavicular (CC) ligament, putting the collarbone out of alignment to some
• The most severe shoulder separation completely tears both the AC and CC
ligaments and puts the AC joint noticeably out of position
The injury is easy to identify when it causes
deformity. When there is less deformity, the location of pain and X-rays help
the doctor make the diagnosis. Sometimes having the patient hold a weight in
the hand can increase the deformity, which makes the injury more obvious on
Nonsurgical treatments, such as a sling, cold packs, and medications can often
help manage the pain. Sometimes, a doctor may use more complicated supports to
help lessen AC joint motion and lessen pain.
Most people return to near full function with this injury, even if there is a
persistent, significant deformity. Some people have continued pain in the area
of the AC joint, even with only a mild deformity. This may be due to:
• Abnormal contact between the bone ends when the joint is in motion
• Development of arthritis
• Injury to a disk-like piece of cushioning cartilage that is often found
between the bone ends of this joint
It is often worthwhile to wait and see if reasonable function returns without
Surgery can be considered if pain persists or the deformity is severe. A
surgeon might recommend trimming back the end of the collarbone so that it does
not rub against the acromion.
Where there is significant deformity, reconstructing the ligaments that attach
to the underside of the collarbone is helpful. This type of surgery works well
even if it is done long after the problem started.
Whether treated conservatively or with surgery, the shoulder will require
rehabilitation to restore and rebuild motion, strength, and flexibility.