There are several common reasons for a piece of bone protrusion: First, the protrusion of normal bone, at the ends of the bone near the joint, often need to have the attachment point of the joint capsule, ligaments, tendons, the bone in the area will be protruding and rough to provide better adhesion, the protrusion can be felt on the body surface. However, it is not accompanied by any pain or discomfort and does not affect the function of the joint. Secondly, it can be seen in degeneration of the joint or hyperplasia due to bone injury and strain. The hyperplasia of bone can be felt on the surface of the body, and mild hyperplasia can be asymptomatic, but if arthritis occurs, it can lead to pain or dysfunction. Thirdly, it is seen in bone tumors, which will appear to grow outward to the bony structures, including benign bone tumors and malignant bone tumors. Benign tumors progress slowly and have few obvious pressure symptoms except for mild pain symptoms, unless benign bone tumors grow very large to produce pressure symptoms. Malignant bone tumors are associated with significant pain and nocturnal pain, and they progress rapidly, becoming large or even invading other tissues within a short period of time.