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Separated Shoulder

Anatomy

The AC joint is the connection between the clavicle and the acromion (a portion of the scapula). The clavicle is secured to the scapula by three different ligaments. One ligament originates from the acromion and attaches to the clavicle. In addition, two ligaments called coracoclavicular (C.C.) originate from a different portion of the scapula (the coracoid process) and help to stabilize the clavicle. To further support the AC joint a ligament called the coracoacromial ligament connects the coracoid process and the acromion thus stabilizing the acromion (15) When the junction between the clavicle and scapula is disrupted itis referred to as a separated shoulder or AC joint separation.

How Injury Occurs

A shoulder separation almost always occurs due to a sudden traumatic event. The most common mechanism of separation is a direct blow to the top of the shoulder. This means of injury usually occurs in contact sports, such as football or rugby, when a participant lands directly on the apex of their shoulder. Another common mechanism of separation occurs when trying to brace a fall. The AC joint can be disrupted if a person falls on an outstretched hand, like falling off of a bike or horse (9).

If a patient has a grade II or I separation, surgical intervention is unnecessary. Instead, the patient will be put in a protective sling for one week and use ice for the first few days. After that time, range-of-motion (R.O.M.) and strengthening exercises are performed to regain motion and strength. It is toughest to regain shoulder motion that involves overhead activity so it is essential that these sorts of exercises be emphasized during rehabilitation. In four to six weeks, tissue scarring will have stabilized the injured joint and the patient can return to normal activity (6).

If a grade III separation occurs some orthopedic surgeons will perform surgery. To align the clavicle, the surgeon normally detaches the coracoacromal ligament (the ligament that stretches from the coracoid of the scapula to the acromion of the scapula) from the acromion and reattaches it to the clavicle. This ligament by itself is not strong enough so in addition, a screw or mersilene tape (a very strong tape) is used to help secure the clavicle (6). Not all orthopedic surgeons will perform surgery for grade III separations. Having the clavicle displaced from the scapula infrequently has repercussions; so many orthopedists will treat a grade III just as a grade II or I.

In grade II and I separated shoulders, the clavicle retains its alignment however the ligaments may be strained or partially torn. As a result, bone-to-bone contact is possible leaving a patient more susceptible to arthritis 10-15 years after the injury (6). Patients who have grade III separated shoulders and do not have surgery, have a 15-20% chance of developing chronic pain (6). In this situation, the patient can have surgery to alleviate any discomfort. If patients are not diligent about their rehab program they could develop an immovable shoulder referred to as a frozen shoulder.

Different Grades The magnitude of separation can vary between cases, so physicians have categorized shoulder separations into three different grades. -Grade I separation- is a mild separation that involves a strain of the acromioclavicular ligament and does not displace the clavicle. -Grade II separation- is a more serious injury that completely tears the AC ligament and may tear or partially tear the C.C. ligaments. In this case, the clavicle is slightly out of place. -Grade III separation- is a severe injury that completely tears the AC ligament and both C.C. ligaments. Also the clavicle is noticeable out of alignment (16)