The lateral clavicle hook-an acquired as well as a congenital anomaly.

The lateral clavicle hook (LCH), an excessive upward convexity of the lateral clavicle, was formally defined by Igual and Giedion, and reported as always present in thrombocytopenia-radial aplasia syndrome and sometimes in other congenital malformations. Additional malformation syndromes including camptomelia are added. In addition, the hook may be seen in acquired upper extremity weakness such as in persistent brachial plexus injury after birth trauma and in severe osteogenesis imperfecta.