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A bone fracture is a medical condition in which a bone has been cracked or broken. While many fractures are the result of high force impact or stress, bone fracture can also occur as a result of certain medical conditions that weaken the bones, such as osteoporosis, certain types of cancer or osteogenesis imperfecta.
Any type of bone break is a fracture. The word break is not used in a formal orthopaedic terminology.
Another type of bone fracture is a compression fracture. An example of a compression fracture is when the front portion of a vertebra in the spine collapses due to osteoporosis, a medical condition which causes bones to become brittle and susceptible to fracture (with or without trauma).
Other types of fracture are:
The Orthopaedic Trauma Association, an association for Orthopaedic surgeons, devised an elaborate classification system to describe the injury accurately and guide treatment. There are five parts to the code:
Other classification systems
There are other systems used to classify different types of bone fractures:
The natural process of healing a fracture starts when the injured bone and surrounding tissues bleed. 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 white blood cells 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 (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 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.
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.
First aid for fractures includes stabilizing the break with a splint in order to prevent movement of the injured part, which could sever blood vessels and cause further tissue damage. Waxed cardboard splints are inexpensive, lightweight, waterproof and strong. Compound fractures are treated as open wounds in addition to fractures.
At the hospital, closed fractures are diagnosed by taking an X-ray photograph of the injury.
Since bone healing is a natural process which will most often occur, fracture treatment aims to ensure the best possible function of the injured part after healing. Bone fractures are typically treated by restoring the fractured pieces of bone to their natural positions (if necessary), and maintaining those positions while the bone heals. To put them back into the natural positions, the doctor often "snaps" the bones back into place. This process is extremely painful without anesthesia, about as painful as breaking the bone itself. To this end, a fractured limb is usually immobilized with a plaster or fiberglass cast which holds the bones in position and immobilizes the joints above and below the fracture. If being treated with surgery, surgical nails, screws, plates and wires are used to hold the fractured bone together more directly. Alternatively, fractured bones may be treated by the Ilizarov method which is a form of external fixator.
Occasionally smaller bones, such as toes, may be treated without the cast, by buddy wrapping them, which serves a similar function to making a cast. By allowing only limited movement, fixation helps preserve anatomical alignment while enabling callus formation, towards the target of achieving union.
Surgical methods of treating fractures have their own risks and benefits, but usually surgery is done only if conservative treatment has failed or is very likely to fail. With some fractures such as hip fractures (usually caused by osteoporosis or Osteogenesis Imperfecta), surgery is offered routinely, because the complications of non-operative treatment include deep vein thrombosis (DVT) and pulmonary embolism, which are more dangerous than surgery. When a joint surface is damaged by a fracture, surgery is also commonly recommended to make an accurate anatomical reduction and restore the smoothness of the joint.
Infection is especially dangerous in bones, due to their limited blood flow. Bone tissue is predominantly extracellular matrix, rather than living cells, and the few blood vessels needed to support this low metabolism are only able to bring a limited number of immune cells to an injury to fight infection. For this reason, open fractures and osteotomies call for very careful antiseptic procedures and prophylactic antibiotics.
Sometimes bones are reinforced with metal, but these fracture implants must be designed and installed with care. Stress shielding occurs when plates or screws carry too large of a portion of the bone's load, causing atrophy. This problem is reduced, but not eliminated, by the use of low-modulus materials, including titanium and its alloys. The heat generated by the friction of installing hardware can easily accumulate and damage bone tissue, reducing the strength of the connections. If dissimilar metals are installed in contact with one another (i.e., a titanium plate with cobalt-chromium alloy or stainless steel screws), galvanic corrosion will result. The metal ions produced can damage the bone locally and may cause systemic effects as well.
In children, whose bones are still developing, there are risks of either a growth plate injury or a greenstick fracture.
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Bone_fracture". A list of authors is available in Wikipedia.|