Bone is an active living tissue that is constantly being renewed through a process known as remodelling. Cells called osteoclasts break down old, damaged bone to make way for new bone laid down by cells called osteoblasts. Over time, this bone is mineralised, forming a hard and strong skeleton. Under normal circumstances, the amount of bone removed is balanced by the amount of bone laid down. In Paget’s disease, the processes of bone resorption and bone formation are markedly increased. The osteoclasts are larger than normal and break down bone faster than normal. The osteoblasts respond to this by depositing new bone at an increased rate. This dysregulation of bone turnover in Paget’s disease results in abnormalities of the bone structure, weakening of the bone and enlargement or deformity of the affected bones. Pagetic bone often appears misshapen and enlarged. You can learn more by watching this video on our Youtube channel.