Osteosarcoma commonly occurs in the long tubular bones of the limbs, such as the femur, tibia, and humerus, especially near the joints of these long bones where the incidence is highest. In children, the distal femur and proximal tibia account for about three-quarters of all bone tumors. Osteosarcoma can also occur in the proximal humerus, the spine, and the ribs, although it is less common in these locations. The most frequent sites remain the long tubular bones in the limbs.