There are 3 subtypes: Type I: Extra-articular and nondisplaced, generally indicating a functionally intact coracoclavicular ligament (a strong and structurally important ligament) Type II: Extra-articular and displaced, generally indicating rupture of the coracoclavicular ligament, with the proximal fragment typically displaced upward because it is pulled by the sternocleidomastoid muscle Type III: Involving the intra-articular surface of the acromioclavicular joint, thus increasing the risk of osteoarthritis (see figure Class B clavicular fractures) Class C fractures involve the proximal third of the bone and account for about 5% of clavicle fractures.