Osteosarcoma can be detected with an X-ray, which is a very important method for diagnosing osteosarcoma. Since osteosarcoma typically comes in three types—osteoblastic, osteolytic, and mixed—the appearances on the X-rays are generally different. Osteolytic osteosarcoma mainly involves bone destruction, osteoblastic is characterized by bone regeneration, and the mixed type has both bone destruction and regeneration. Secondly, osteosarcoma primarily erodes the bone quality, and the periosteal reaction is very apparent. Typical osteosarcomas often show signs like Codman's triangle or the sunburst appearance. Therefore, if symptoms such as redness and increased temperature of the skin, along with a bony lump, occur around the distal femur, proximal tibia, or proximal humerus, it is best to first go to the hospital for an X-ray. X-rays are currently the most economical and necessary diagnostic tool for osteosarcoma.