Bones may thicken in adulthood. In adulthood, although the epiphyseal cartilage of the metaphyseal end of the long bone has ossified, the long bone has lost its ability to continue to grow, but the periosteum of the long bone still exists. At this time, through the continuous proliferation of periosteum, the cortical bone of long bone will thicken, and then the bone will thicken. There are mainly the following conditions of bone thickening in adults: 1. Thicken bones through constant physical exercise or labor. This situation is often due to the constant stimulation of external forces, which leads to the continuous proliferation of periosteum, which in turn leads to bone thickening. The purpose of bone thickening is to adapt to this increasing external load; 2. This situation may be caused by hyperosteogeny. For example, if the patient suffers from cold around the bone for a long time, or has trauma such as fracture and contusion, abnormal calcium salt deposition will gradually appear in this part, leading to bone thickening; 3. This situation may also be caused by space occupying diseases of bones. For example, if a tumor appears in or around a bone, it may thicken the bone.