injuries poisoning
Clavicle Fractures
Etiology of Clavicle Fractures
Clavicle fractures usually result from a fall on the lateral shoulder or, less often, a direct blow. Traditionally, treatment has been based on the following classification. Class Afractures involve the middle third of the bone and account for about 80% of clavicle fractures. The proximal fragment is often displaced upward because it is pulled by the sternocleidomastoid muscle. Subclavian vessels are rarely damaged. Class Bfractures involve the distal third of the bone and account for about 15% of clavicle fractures. They usually result from a direct blow. 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 Involving the intra-articular surface of the acromioclavicular joint, thus increasing the risk of osteoarthritis (see figure Class B clavicular fractures ) Class Cfractures involve the proximal third of the bone and account for about 5% of clavicle fractures. These fractures usually result from great force and thus may be accompanied by intrathoracic injuries or sternoclavicular joint damage. 