Acromioclavicular (AC) Joint Separation
What is this Acromioclavicular joint in the shoulder?
The Acromioclavicular joint (AC) in the shoulder is where the collar bone (clavicle) articulates or connects to the acromion of the scapula (shoulder bone). The AC joint moves and shifts as the shoulder goes through various motions. Like any other joint in the body the bones of the AC joint are covered with articular cartilage that provides a slick, rubbery surface that allows bones to glide over each other.
What are the causes of an Acromioclavicular joint separation?
The AC joint is often injured from a fall directly onto the shoulder, or a forceful impact like from a motor vehicle accident. This causes the top of the shoulder (the acromion) to separate from the clavicle by disrupting the surrounding ligaments, capsule, and muscle that maintain joint stability. In a mild injury, the ligaments are strained and not torn. In more severe cases the ligaments can be partially or completely torn. AC separations are graded from 1-3 depending on which ligaments are sprained or torn, 3 being the most severe.
Diagnosis and Symptoms
Patients commonly complain of tenderness over the AC joint, pain, and a deformity at the top of the shoulder near the AC joint. The diagnosis is often confirmed with an x-ray.
Treatment
Nonsurgical
In most cases, nonsurgical treatment can be utilized. The utilization of anti-inflammatory medications as well as ice helps to decrease inflammation and swelling. The use of sling may be recommended to help minimize the weight of the arm on the AC joint. Gentle passive range of motion exercises will be given to prevent stiffness, however active range of motion exercises and weight bearing are restricted for a few weeks while healing occurs.
Surgical
Surgical intervention is reserved for patients with persistent pain and an unacceptable deformity. If the deformity is severe enough, a patient may be a surgical candidate immediately after the injury, however in most cases, surgical repair is delay. Operative treatment of an AC separation is an AC joint reconstruction. This procedure involves a small incision along the front of the shoulder. The clavicle is secured to the coracoid bone and the acromion with heavy grade stitches, or sutures. In order to replace the torn CC ligaments, another ligament in the shoulder can be transferred to the clavicle, or cadaver tissue (allograft) can be used to restore stability to the AC joint. If the patient is deemed a surgical candidate immediately after injury, sometimes the injury can be fixed arthroscopically using a small incision and camera inside the joint.
