Acromioclaviclar Joint (ACJ) – Separation and Arthritis

What is the AC joint in the shoulder?

Where the collar bone (clavicle) connects to the scapula (or shoulder blade) is termed the acromioclavicular joint, or the ACJ. The acromion is a bony process that arises from the scapula and articulates (or connects) with the clavicle. The ACJ moves and shifts as the shoulder goes through various motions. Positioned in the joint between the clavicle and acromion is a cartilage disk that cushion the joint along with cartilage that covers the end of the clavicle. The AC joint is held together by a strong fibrous capsule and surrounding muscle that crosses the joint including the deltoid and trapezius muscles. Two important ligaments, called the coracoclavicular (CC) ligaments, link the clavicle to the coracoid process of the scapula and are the most important stabilizers of the ACJ.

How is the AC joint usually injured?

AC joint injuries are common and typically occur from a fall directly onto the shoulder. This causes the top of the shoulder (acromion) to separate from the clavicle by disrupting the surrounding ligaments, capsule, and muscle that maintain joint stability. In a mild injury, the coracoclavicular ligaments that support the AC joint are simply strained, but not torn. However, with more severe injury, these ligaments can either partially or completely tear. In the most severe injury, the ligaments and muscle attachments are also torn and the end of the clavicle may protrude directly beneath the skin resulting in a prominent bump.

How is an AC joint separation diagnosed?

Typically, patients complain of tenderness and a deformity (bump) at the top of the shoulder near the AC joint. This diagnosis can be confirmed with an X-ray that compares the injured shoulder to the noninjured side.

What is the proper treatment for a sprained AC joint?

In most cases, nonsurgical treatment can be utilized. The application of ice directly on the AC joint helps to limit swelling and relieve pain. The arm can be supported with a sling to minimize the weight of the arm pulling on the injured AC joint. Gentle motion of the arm is initiated to limit stiffness; however, active motion of the shoulder and weight bearing are restricted for a short time to allow for healing to occur.

How long does it take for a shoulder separation to heal?

This depends on the severity of the injury. Minor injuries may improve dramatically in only two to three weeks. However, more severe cases may require surgery in order to restore the correct alignment of the ACJ.

When and why is surgery necessary for AC joint separations?

Usually surgery is reserved for patients with pain or an unacceptable deformity. If the deformity is severe enough, a patient may be a surgical candidate immediately after injury. Other patients may complain of pain or deformity many months after injury, which requires delayed surgical repair. Commonly, pain occurs as a result of direct pressure on the joint, such as with straps from clothing or undergarments. Other patients complain of catching, clicking, or pain with overhead activities, such as lifting, throwing, or reaching. In some patients, the prominent bump after the separation may appear unattractive and feel unbalanced.

What type of surgery can repair AC Joint separation?

The goal of surgery is to restore the position of the shoulder girdle with that of the clavicle. This can be accomplished with several techniques. The most common 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.

What is the post-operative treatment after surgery for AC joint separation?

Patients are usually able to go home on the same day as the surgery. Patients are positioned in a sling and an ice pack is used to limit post-operative swelling. Patients remain in a sling for 6 weeks after surgery in order to allow the ligaments to heal. After 6 weeks, gentle motion exercises for the shoulder are initiated and waist level activity is allowed. Weight bearing is limited until around 3-4 months after surgery.

What are common symptoms for patients with ACJ arthritis?

Arthritis is a chronic disease commonly seen in the ACJ. Although many patients have signs of ACJ arthritis on x-ray, these findings do not always correlate with symptoms. Many patients may be asymptomatic. Patients with symptomatic arthritis commonly complain of stiffness, aching and swelling in the shoulder joint.

What type of surgery can repair ACJ problems?

The simplest type of surgery for ACJ arthritis involves removal of the end of the clavicle using arthroscopy, or a small incision over the ACJ. If removal is performed with an open incision rather than arthroscopy, the underlying capsule and muscle attachments are tightened and repaired during the surgery.

What is the post-operative treatment following resection of the end of the clavicle?

Post-operatively, the arm is placed into a sling and the soft tissues are allowed to heal for 1-2 weeks. Elbow, wrist, and hand exercises are begun immediately. Lifting is limited for three weeks, but following that, progressive exercise and motion activities are initiated.