Hi everybody, this is Rob Swatsky from the York Campus of Hack and in this podcast I'll be reviewing the different types of bone fractures and the way bone is repaired after injury. Any break in a bone is called a fracture. There are different types of fractures that are classified and named based upon their shape, location and severity. Some common types of fractures include green stick, impacted, open, commonuded, pots, collies and stress fractures. A green stick fracture is a partial incomplete fracture in children that involves a break in one side of the bone and a bend in the other side. This fracture is named after the way a young twig breaks on a plant. The bones of children are still developing and are not fully ossified, so the extra protein their bones contain make them a bit more bendable compared to adult bone. An impacted fracture is where one end of a broken bone is forcefully pushed into the interior of the other. An open or compound fracture is when the ends of the broken bone pierce through the skin and are exposed. A closed or simple fracture in contrast does not break through the skin. A commonuded fracture is where the bone is heavily damaged at the location of a high energy impact with lots of splintering and broken or crushed bone fragments in the area. A pots fracture is a specific break at the distal end of the fibula near the ankle with significant injury to the distal tibia where it articulates with the foot here at the talus. A collie's fracture is a break at the distal end of the radius near the wrist. Stress fractures are microscopic breaks and bone, often quite painful, which are usually the result of repetitive strenuous activities such as running or jumping, but they can also be caused by osteoporosis and other bone calcification disorders. Bone fracture repair goes through four phases, the reactive phase which involves the formation of a fracture hematoma over a blood clot, a reparative phase involving the formation of a fibrocardalaginous or soft calis, another reparative phase involving the formation of a bone or hard calis and a bone remodeling phase. During the first phase, the reactive phase, inflammation is triggered as a result of the injury and the damage inflicted on severed blood vessels. A massive clotted blood called the fracture hematoma builds up around the fracture usually six to eight hours after the injury occurred. As bone cells die in the area of the fracture, due to them being cut off from the blood circulation, lots of swelling and inflammation takes place in the area. The debris that accumulates along with dead and damaged cellular tissue is removed by phagocytic white blood cells and osteoclasts. This phase can extend over several weeks time. The next phase is a reparative phase that forms a fibrocardalaginous calis, also called a soft calis. As blood vessels begin to regrow and move into the fracture hematoma, fibroblasts from the periosteum start secreting collagen fibers in the damaged area. Condroblasts also develop and start producing fibrocardalage, which is a tough, dense, protein-rich cartilage tissue. Over a three-week period, the fibrocardalaginous calis forms, which binds together the ends of the broken bone. Following the formation of the soft calis, another reparative phase occurs. This phase involves osteoblasts from nearby healthy bone tissue that start making spongy bone tribeculi in the area of the soft calis. The tribeculi connects the healthy and damaged ends and fragments of bone tissue. Over a three to four-month period, the soft calis is transformed into a bony or hard calis. During the final phase of bone remodeling, the osteoclasts resort remaining bone fragments, while osteoblasts build up the compact bone matrix from the spongy bone around the fracture. The original shape of the bones is restored as closely as possible to their original appearance.