A fracture is defined as a break in the continuity of a bone. A fracture can be the result of high force impact or stress,or by just a trivial injury in weak bones, such as osteoporosis, bone cancer or osteogenesis imperfecta.
Fractures can be classified in the following ways :
The natural process of healing of a fracture starts when the injured bone and surrounding tissues bleed to form a fracture hematoma. The blood coagulates to form a blood clot situated between the broken fragments. Within a few days blood vessels grow into the jelly-like matrix of this blood clot. The new blood vessels bring phagocytes to the area, which gradually remove the non-viable material. The blood vessels also bring fibroblasts in the walls of these vessels and this then multiplies and produces collagen fibres. In this way the blood clot is replaced by a matrix of collagen. Collagen's rubbery consistency allows bone fragments to move only a small amount unless severe or persistent force is applied.
At this stage, some of the fibroblasts begin to lay down bone matrix (calcium hydroxyapatite) in the form of insoluble crystals. This mineralization of the collagen matrix stiffens it and transforms it into bone. In fact, bone is a mineralized collagen matrix. If the mineral is dissolved out of bone, it becomes rubbery. Healing bone callus is on an average sufficiently mineralized to show up on X-ray within 6 weeks in adults and about 4 weeks in children. This initial "woven" bone does not have the strong mechanical properties of mature bone. By a process of remodeling, the woven bone is replaced by mature "lamellar" bone. The whole process can take upto 18 months, but in adults, the strength of the healing bone is usually 80% of normal by 3 months after the injury.
Several factors can help or hinder the bone healing process. For example, any form of nicotine hinders the process of bone healing, and adequate nutrition (including calcium intake) will help the bone healing process.Weight-bearing stress on bone, after the bone has healed sufficiently to bear the weight, also builds bone strength. Although there are theoretical concerns about NSAID's slowing the rate of healing, but there is not enough evidence to warrant withholding the use of this type of analgesic a in simple fractures.