Sprains and Strains, Acromioclavicular Joint

Risk: Individuals at greatest risk for an AC dislocation include athletes in contact or collision sports (e.g., downhill skiing, rugby, ice hockey, football), or workers participating in activities that could result in falls onto the shoulder or contact with an object while moving; much less commonly, having an object fall on the shoulder or falling onto the outstretched hand and arm may result in an AC joint sprain.

History: Individuals usually report a direct blow to the tip of the shoulder, either from a fall (e.g., landing on the side of the shoulder in a football tackle), or from a push or stumble (e.g., being checked into a wall when playing ice hockey). Individuals may complain of pain and weakness, and note a bump on the top of the shoulder. The bump is caused by depression of the scapula relative to the clavicle and swelling (edema) of the joint itself. Pain may radiate into the base of the neck or down the arm. The individual often carries the arm across the chest, cradling it under the elbow.

Physical exam: Direct visual comparison with the uninjured shoulder reveals an asymmetry of the two joints. Often abrasions can be observed across and somewhat behind the joint. Moving the shoulder-joint complex reveals weakness of the shoulder, limited active shoulder range of motion, and painful assisted range of motion. Close observation of range of motion and elicited pain helps to distinguish AC sprains and strains from other common shoulder pathologies. The bump or high-riding tip of the clavicle may be repositioned (reduced) into its normal anatomical position by the individual or the doctor, but this maneuver can be painful.

Tests: X-rays of the AC joint are taken to establish position of the acromion and clavicle and to rule out associated fractures. In rare severe trauma cases, an MRI, CT scan, or nerve conduction studies may be needed to evaluate damage to the surrounding tissue. Ultrasound may be used in some cases to further evaluate or confirm findings obtained by physical exam or x-ray.

Rehabilitation of acromioclavicular sprain or strain depends greatly on the severity of the injury. For example, in some cases, individuals may require immobilization in a sling for a short period to control pain (Buss), whereas in other cases, individuals may require prolonged use of a sling, in conjunction with supervised exercise.

Individuals with a grade I injury may be instructed in range of motion exercises for the hand, wrist, and elbow. Once the acute pain is relieved, the individual is instructed in shoulder range of motion exercises and shoulder strengthening exercises (Clarke; Lemos; Moushine). The rehabilitation process may warrant the observation and guidance of a physical therapist or occupational therapist until the individual progresses to an independent exercise program.

Individuals with a grade II or III injury may be managed operatively or nonoperatively (Rockwood). If managed nonoperatively, the individual may be instructed in range of motion exercise for the hand, wrist, and elbow during a period of immobilization. After the initial immobilization period, the individual is instructed in shoulder range of motion exercises and exercises to strengthen the arm and shoulder. All exercises need to be limited to the pain-free arc of motion. Strengthening exercises progress in intensity as the individual's pain decreases and strength improves. Individuals are instructed in a home program that reflects the exercise regimen prescribed during rehabilitation. If managed operatively, rehabilitation will proceed as described for grades IV, V and VI.

Individuals with a grade IV, V, or VI injury are generally treated surgically (Buss; Lemos). Rehabilitation protocols are guided by the treating physician. The general focus of rehabilitation is to reduce pain and regain full function of the shoulder girdle.