ABSTRACT

The primary classification system divides fractures into those of the medial (5%), middle (85%) and distal (10%) thirds (Allman).

Fractures of the lateral third are subclassified into types I to V, based upon integrity of the coracoclavicular ligament (CCL) complex:

• Type I: non-displaced. • Type IIA: fracture proximal to conoid and trapezoid ligaments. • Type IIB: fracture between the conoid (proximal) and trapezoid ligaments. • Type III: fracture into ACJ. • Type IV: epiphyseal separation (children). • Type V: three-part fracture, with intact ligaments connected to the middle fragment.