The Acromioclavicular joint can be injured by a fall on that part of the shoulder. This results in the shoulder blade or scapula being forced downwards and making the clavicle or collarbone appearing to be prominent.
The extent of the AC joint injury is classified by the displacement of the joint and the injury to the ligaments that support the AC joint. There are six grades of AC joint injuries depending on the severity of damage, as shown below:
Only the AC joint ligament is sprained.
There is a tear in the AC joint ligaments only with partial dislocation of the clavicle.
The AC joint is dislocated with the clavicle displaced superiorly (above) and the clavicle and the acromion loses contact completely.
The AC joint is dislocated and the clavicle is displaced posteriorly or backward.
The AC joint is dislocated and the clavicle is displaced to extreme superior elevation (100% to 300% of the normal)
The AC joint is dislocated with the clavicle displaced inferior (lower) to the acromion and coracoid process.
The chronic AC joint dislocations are usually from grades 3 to 6. Usually the severity of the grade 1 & 2 are overlooked and if left untreated can cause some chronic disability.
The chronic AC joint Dislocations normally can be treated only through surgical interventions.
The surgical treatment is opted for by the doctor for the following:
When the patient is under severe pain
When the patient has an onset of weakness and extreme loss of motion.
The usual approach to treating chronic AC joint dislocations is the Anatomic Coracolavicular Reconstruction (ACCR). The different anatomic principles that help guide the surgical procedures include:
In order to avoid further joint instability, no significant resection of the distal clavicle is performed.
To regain the original stability of the joint, some of the ligaments have to be reconstructed.
The ACCR technique has more advantages when compared to the modified Weaver-Dunn technique that include:
Decreased Anterior – posterior translation
Better outcomes in terms of subjective and radiographic.
This procedure is performed using open surgery approach in order to get a better visualization and to reduce the CC interval and AC joint. The CC ligaments are anatomically reconstructed using hamstring auto graft from patients own leg , which is secured with small drill tunnels on the clavicle and coracoid respectively.