Acromioclavicular (AC) Joint Dislocations
What is the Acromioclavicular (AC) Joint?
The AC joint is the connection between the collarbone (clavicle) and the tip of the shoulder blade (acromion). Located at the top outer corner of the shoulder, the AC joint enables gliding and rotational motion between the shoulder blade and the collarbone.
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The AC joint is stabilized by the AC joint capsules, four AC ligaments, and a pair of CC (coracoclavicular) ligaments.
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What causes AC Joint Dislocation?
AC joint can be injured due to a direct blow to the shoulder or, more commonly, from a fall with a direct impact on the shoulder. This trauma can result in the sprain or complete rupture of the ligaments stabilizing the AC joint, leading to the separation or dislocation of the AC joint. The collarbone (clavicle) can dislocate in several directions concerning the tip of the shoulder blade (acromion), with upward (superior) migration being the most common type.
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What Are the Symptoms of AC Joint Dislocation?
Patients with AC joint injury may experience pain, swelling, and/or deformity on the tip of the shoulder where the AC joint is located.
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How is it Diagnosed?
AC joint injury can be diagnosed by your doctor after assessing your symptoms, conducting a shoulder examination, and performing simple X-ray imaging.
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What Are the Treatments for AC Joint Dislocation?
The treatment of AC joint injury depends on its severity, usually graded based on the amount and direction of AC joint dislocation observed on X-ray.
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Low-grade injuries can be treated non-operatively, typically involving a short period of arm sling usage to allow the injury to settle. This is followed by physiotherapy and a gradual return to sports or activities. Patients are usually advised to avoid excessive overhead weight during the early phase of recovery to allow the ligaments to heal.
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Patients with high-grade injuries might require an operation to restore the stability of the AC joint.
What are the Surgeries for AC Joint Dislocation?
The goal of the surgery is to reduce the dislocation and restore stability to the AC joint. This can be achieved through a mini-open incision or keyhole (arthroscopic) techniques. Various implants, such as hook plates, fibertape, tightrope, or suture anchors, might be used to maintain stability while allowing the native AC and CC ligaments to heal.
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In cases of chronic injury (> 3 weeks old), a tendon graft reconstruction is usually necessary due to concerns about the healing potential of the native ligaments.
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The surgery is commonly performed as a day procedure. You might be advised to wear an arm sling in the early post-operative period to facilitate the healing of the native or reconstructed ligaments. Rehabilitation is necessary thereafter to regain range of motion and strength.