Grade 5 AC Separation
A grade 5 AC Joint Separation occurs when the clavicle is severely displaced superiorly. It represents the most severe type of AC joint injury. The separation between the clavicle and the coracoid part of the scapula has to more than 100% (more than double) the normal side in order to fit the x-ray definition of a type 5 joint separation. When the injury is this severe there is a very obvious deformity with the distal end of the clavicle now very prominently protruding under the skin. In these injuries it is actually the scapula that has pulled away from the clavicle.
Severe AC Joint Separation
When it is this severe the detachment from the clavicle not only involves the “acromioclavicular” and the “coracoclavicular” ligaments but even involves tearing of the periosteum of the bone on the clavicle as well. In some cases the bone actually punctures all of the soft tissue and is sitting in the subcutaneous tissues. This severity of injury is very uncomfortable for most patients and requires surgery to stabilize the joint in almost all cases. There is no effective non-operative treatment as the downward force of gravity ensures that there can be no possibility of reducing the joint back into position.