Fracture (bone)
| Bone fracture | |
|---|---|
| Synonyms | broken bone, bone break |
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| Internal and external views of an arm with a compound fracture, both before and after surgery. | |
| Classification and external resources | |
| Specialty | Orthopedics |
| ICD-10 | Sx2 (where x=0–9 depending on the location of the fracture) |
| ICD-9-CM | 829 |
| DiseasesDB | 4939 |
| MedlinePlus | 000001 |
| MeSH | D050723 |
A bone fracture (sometimes abbreviated FRX or Fx, Fx, or #) is a medical condition in which there is a damage in the continuity of the bone. A bone fracture can be the result of high force impact or stress, or a minimal trauma injury as a result of certain medical conditions that weaken the bones, such as osteoporosis, bone cancer, or osteogenesis imperfecta, where the fracture is then properly termed a pathologic fracture.
Although bone tissue itself contains no nociceptors, bone fracture is painful for several reasons:
Damage to adjacent structures such as nerves or vessels, spinal cord and nerve roots (for spine fractures), or cranial contents (for skull fractures) can cause other specific signs and symptoms.
The natural process of healing a fracture starts when the injured bone and surrounding tissues bleed, forming 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 the 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 the vessels and these multiply and produce 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 in the form of collagen monomers. These monomers spontaneously assemble to form the bone matrix, for which bone crystals (calcium hydroxyapatite) are deposited in amongst, 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 average sufficiently mineralized to show up on X-ray within 6 weeks in adults and less 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 up to 18 months, but in adults the strength of the healing bone is usually 80% of normal by 3 months after the injury.
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