Fracture healing

Despite of large strength of bones, they can break. In older people fractures occur as bones weaken and become thin. In young people most fractures occur due to trauma that smashes or twits the bones for example during sports or accidents. Type of fractures can be classified in complete fractures or incomplete fractures open or closed fractures and non-displaced fractures or displaced fractures. When the bone is broken through, it is a complete fracture otherwise it is an incomplete fracture. A fracture is an open fracture when the bone ends penetrate the skin. In non-displaced fractures are the ends of the bone in normal position, when they are out of alignment it is a displaced fracture. In young adults a small simple fracture heals in six or eight weeks, for elderly people or weight-bearing bone it takes much longer. The most common form of fracture healing is secondary fracture healing. The repair of secondary fractures healing consist of three phases, these three phase overlap each other. First the inflammatory phase occurs, the bone fracture damaged the bone matrix, the cells, the blood vessels and the surrounding soft tissue. As a result there is a mass of clotted blood at the fracture site called a hematoma. Bone cells will die due to lack of nutrition. An inflammatory response is induced and helps to immobilize the fracture due to protecting the injury by pain causing and swelling to keep the fracture from moving. Grow factors are released by the platelet degranulation and chemotactic signals are triggered.^1,16,18 The second phase is the reparative phase that occurs in the first few days, overlapping the inflammatory phase. In this phase soft granulation tissue also called soft callus will form. First capillaries will grow into the hematoma and the phagocytic cells will remove the debris. Fibroblasts cells invade the fracture and produce collagen fibers connecting the broken bones ends and therefore span the fracture. From the nearby endosteum and periosteum, cartilage and osteogenic cells enter the fracture site. Spongy bone will be formed by osteoblasts. The repair tissue is called fibrocartilaginous callus. This fibrocartilaginous callus will be convert into bony hard callus, eventually the bony hard callus is composed of woven bone and connects the fracture ends. The third phase is the final phase in fracture healing and called the remodeling phase. Hereby the woven bone is replaced by lamellar bone. Normal remodeling activity of the bone is represented. Remodeling of fracture repair consist of resorption of poorly located trabeculae by osteoclasts and along lines of stress new bone formation will occur.^1,16,18 Primary fracture healing occurs only when bone to bone nicely fit together or there is a gap less than 800 ?? to 1 mm. ¹⁶ Hereby there is no space for callus formation. Primary fracture healing can occur by direct remodeling of the Haversian canals, blood vessels and lamellar bone.