Acromioclavicular Joint Dislocations

What is the Acromioclavicular Joint?

The Acromioclavicular joint (AC joint) is located at the tip of the shoulder where the shoulder blade (scapula) and collarbone (clavicle) come together at a point-called the acromion-on the upper surface of the shoulder blade. These two bones are held together by tough, sinewy tissues-ligaments-that tie the bones together. There is a pad, known as the meniscus, in the joint between the two bones that allows them to move on each other. As a person moves his/her shoulder, the AC joint shifts slightly to allow the shoulder to move freely but to continue to be supported by the clavicle.

CAUSES:

The Acromioclavicular Joint is usually injured by a direct fall onto the point of the shoulder. The shoulder is forced downwards and the clavicle (collarbone) appears prominent.

The degree of damage to the joint is classified by the joint displacement:

Type 1 injury = joint sprain
Type 2 injury = partial joint dislocation (subluxation)
Type 3 injury = complete joint dislocation

TREATMENT:

Most ACJ dislocations do not require surgery and almost all can be managed with:
1. Physiotherapy - to 'retrain' the shoulder muscles.
2. Painkillers and anti-inflammatories

Most people fully recover without any problems, however overhead athletes and manual workers may have persistent symptoms and require surgery.

Surgery is indicated if the shoulder is still painful and there is some functional loss at about 3-6 months after the injury.

For Type 1 and 2 injuries removal of the damaged joint is performed. This is done by keyhole surgery (arthroscopically) and is known as an Arthroscopic ACJ Excision.
A Subacromial Decompression is usually done at the same time.

For Type 3 injuries the collarbone needs to be reduced to the acromion and the procedure to do this is known as a Modified Weaver-Dunn Procedure. Your surgeon will discuss this in more detail with you.

23/03/2004