A clavicle fracture is a break in the collarbone, one of the main bones in the shoulder. Most clavicle fractures occur when you fall directly onto the shoulder or an outstretched arm. A broken collarbone can be very painful and can make it hard to move your arm. Most clavicle fractures can be treated by wearing a sling to keep the arm and shoulder from moving while the bone heals. With some clavicle fractures, however, the pieces of bone shift out of alignment when the injury occurs. For these fractures, surgery may be needed to realign the collarbone.