• Question: how does the bone actually repair itself ?

    Asked by cammynkyle to Alastair on 13 Jun 2010 in Categories: .
    • Photo: Alastair Sloan

      Alastair Sloan answered on 13 Jun 2010:

      Good question. It repairs itself because it is not a static tissue, but is continually remodelling itself. Two cell types are always working together to keep breaking down bone and making new bone. Cells called OSTEOBLASTS make bone and cells called OSTEOCLASTS break down bone. When bone in damaged this process is just speeded up and more focussed. After bone is damaged, a large number of immature cells called PROGENITOR cells arrive a the site of damage through the bloodstream or from the bone marrow. They get there by following chemical signals released at the area of damage – a sort of emergency homing beacon. When the progenitor cells get to the site of damage, they specialise and become bone making cells (osteoblasts) or bone breaking cells (osteoclasts). The osteoclasts remove the damaged tissue and the osteoblasts make new bone to replace that which is lost. All this is controlled by bioactive proteins called growth factors and cytokines so that the process is very carefully controlled and monitored. They also make sure that new blood vessels are formed around the new bone so that nutrients from the blood can keep the new bone healthy