NationMaster - Encyclopedia: Bone healing

Bone healing or fracture healing is a proliferative physiological process, in which the body facilitates repair of Bone fractures. Image File history File links Merge-arrow. ... Internal and external views of an arm with a compound fracture, both before and after surgery A bone fracture is a medical condition in which a bone breaks. ... Image File history File links Bone_fracture_metal_plate. ... Image File history File links Bone_fracture_metal_plate. ... In the NATO phonetic alphabet, X-ray represents the letter X. An X-ray picture (radiograph) taken by Röntgen An X-ray is a form of electromagnetic radiation with a wavelength approximately in the range of 5 pm to 10 nanometers (corresponding to frequencies in the range 30 PHz... The term cell growth is used in two different ways in biology. ... Physiology (in Greek physis = nature and logos = word) is the study of the mechanical, physical, and biochemical functions of living organisms. ... Internal and external views of an arm with a compound fracture, both before and after surgery A bone fracture is a medical condition in which a bone breaks. ...

Physiology and process of healing

In the process of fracture healing, several phases of recovery facilitate the proliferation and protection of the areas surrounding fractures and dislocations. The length of the process is relevant to the extent of the injury, and usual margins of two to three weeks are given for the reparation of the majority of upper bodily fractures; anywhere above four weeks given for lower bodily injury.

The process of the entire regeneration of the bone can depend upon the angle of dislocation or fracture, and dislocated bones are generally pushed back into place via relocation with or without anaesthetic. While the bone formation usually spans the entire duration of the healing process, in some instances, bone marrow within the fracture having healed two or fewer weeks before the final remodeling phase.

While immobilization and surgery may facilitate healing, a fracture ultimately heals through physiological processes. The healing process is mainly determined by the periosteum (the connective tissue membrane covering the bone). The periosteum is the primary source of precursor cells which develop into chondroblasts and osteoblasts that are essential to the healing of bone. The bone marrow (when present), endosteum, small blood vessels, and fibroblasts are secondary sources of precursor cells. The periosteum is an envelope of fibrous connective tissue that is wrapped around the bone in all places except at joints (which are protected by cartilage). ... Connective tissue is one of the four types of tissue in traditional classifications (the others being epithelial, muscle, and nervous tissue. ... A chondroblast is a cell, which originates from a mesenchymal stem cell and forms Chondrocytes, commonly known as cartilage cells. ... An osteoblast (from the Greek words for bone and to build) is a mononucleate cell that produces a protein that produces osteoid. ... For the Todd Rundgren album, see Healing (Todd Rundgren). ... This article does not cite any references or sources. ... Endosteum is the inner lining of the bone. ... The blood vessels are part of the circulatory system and function to transport blood throughout the body. ... A fibroblast is a cell that makes the structural fibers and ground substance of connective tissue. ...

Phases of fracture healing

There are three major phases of fracture healing, two of which can be further sub-divided to make a total of five phases;

Reactive Phase

After fracture, the first change seen by light and electron microscopy is the presence of blood cells within the tissues which are adjacent to the injury site. Soon after fracture, the blood vessels constrict, stopping any further bleeding.^[1] Within a few hours after fracture, the extravascular blood cells, known as a "hematoma", form a blood clot. All of the cells within the blood clot degenerate and die.^[2] Some of the cells outside of the blood clot, but adjacent to the injury site, also degenerate and die.^[3] Within this same area, the fibroblasts survive and replicate. They form a loose aggregate of cells, interspersed with small blood vessels, known as granulation tissue.^[4] A fractured bone in a living person is typically treated by restoring the fractured pieces of bone to their natural positions (if necessary), and maintaining those positions while the bone heals. ... Hematoma on thigh after a beating. ... A fibroblast is a cell that makes the structural fibers and ground substance of connective tissue. ... Granulation tissue is the perfused, fibrous connective tissue that replaces a fibrin clot in healing wounds. ...

Reparative Phase

Days after fracture, the cells of the periosteum replicate and transform. The periosteal cells proximal to the fracture gap develop into chondroblasts and form hyaline cartilage. The periosteal cells distal to the fracture gap develop into osteoblasts and form woven bone. The fibroblasts within the granulation tissue also develop into chondroblasts and form hyaline cartilage.^[5] These two new tissues grow in size until they unite with their counterparts from other pieces of the fracture. This process forms the fracture callus.^[6] Eventually, the fracture gap is bridged by the hyaline cartilage and woven bone, restoring some of its original strength. A chondroblast is a cell, which originates from a mesenchymal stem cell and forms Chondrocytes, commonly known as cartilage cells. ... Cartilage is a type of dense connective tissue. ... An osteoblast (from the Greek words for bone and to build) is a mononucleate cell that produces a protein that produces osteoid. ... This article is about the skeletal organs. ...

The next phase is the replacement of the hyaline cartilage and woven bone with "lamellar bone". The replacement process is known as "endochondral ossification" with respect to the hyaline cartilage and "bony substitution" with respect to the woven bone. Substitution of the woven bone with lamellar bone precedes the substitution of the hyaline cartilage with lamellar bone. The lamellar bone begins forming soon after the collagen matrix of either tissue becomes mineralized. At this point, "vascular channels" with many accompanying osteoblasts penetrate the mineralized matrix. The osteoblasts form new lamellar bone upon the recently exposed surface of the mineralized matrix. This new lamellar bone is in the form of "trabecular bone".^[7] Eventually, all of the woven bone and cartilage of the original fracture callus is replaced by trabecular bone, restoring much, if not all, of the bone's original strength. This article is about the skeletal organs. ... Section of fetal bone of cat. ... This article is about the skeletal organs. ...

Remodeling Phase

The remodeling process substitutes the trabecular bone with "compact bone". The trabecular bone is first resorbed by osteoclasts, creating a shallow resorption pit known as a "Howship's lacuna". Then osteoblasts deposit compact bone within the resorption pit. Eventually, the fracture callus is remodelled into a new shape which closely duplicates the bone's original shape and strength.^[8] This article is about the skeletal organs. ... An osteoclast (from the Greek words for bone and broken) is a type of bone cell that removes bone tissue by removing the bones mineralized matrix. ...

Other forms and complications

Inadequate healing or formation

Inadequate bone healing is known as an "incomplete" form of bone healing, in which the regeneration of bone through natural processes is impeded due to other factors, such as malnutrition or immune disorders, which may prevent the reparation of bone due to the lack of nutrient intake, such as that seen in the case of osteomalacia and osteoporosis. Percentage of population affected by malnutrition by country, according to United Nations statistics. ... Osteomalacia is a softening of the bones, resulting from defective bone mineralisation. ... Osteoporosis is a disease of bone in which the bone mineral density (BMD) is reduced, bone microarchitecture is disrupted, and the amount and variety of non-collagenous proteins in bone is altered. ...

Similarly, factors such as the intake of carcinogens, such as nicotine (edit; nicotine is not a carcinogen...is it carcinogens or nicotine that cause these problems??) or exposure to radiation may lead to the malformation or incomplete healing of bones, which can further facilitate the formation of newer fractures, due to the already weakened site of injury being more easily affected by impact or strain, as well pseudarthrosis, undesired mobility in what appears to have become a new joint. This article is about the chemical compound. ... Pseudarthrosis is the movement of a bone at the location of a fracture resulting from inadequate healing of the fracture. ...

Medical Treatments

In terms of medical treatments and procedures, several options are available which facilitate faster reparation of bone if the specific patient has an aforementioned bone disorder. The use of Bone morphogenetic proteins is incurred in small amounts, and is also used in clinical practice, alongside immobilising surgical procedures involving vertebroplasty or percutaneous kyphoplasty in the case of bone malformation, and stimulate the growth of bone in areas which require "strengthening", such as in the case of spinal fusion. Bone morphogenetic proteins (BMPs) are growth factors belonging to the TGF-Î² (Transforming Growth Factor-beta) super family with a strong ability to induce new bone and/or cartilage formation. ... A diagram of a thoracic vertebra. ... In surgery, percutaneous pertains to any medical procedure where access to inner organs or other tissue is done via needle-puncture of the skin, rather than by using an open approach where inner organs or tissue are exposed (typically with the use of a scalpel). ... Kyphoplasty is a medical procedure where the original height and angle of kyphosis of a fractured vertebra (of certain types) are restored, followed by its stabilization using injected bone filler material. ...

Osseointegration

Osseointegration is the pattern of growth exhibited by bone tissue during assimilation of surgically-implanted devices, prostheses or bone grafts to be used as either replacement parts (e.g., hip) or as anchors (e.g., endosseous dental implants). A United States Army soldier plays table football with two prosthetic arms Jon Comer, professional skateboarder with a prosthetic leg. ... A bone graft is a surgical procedure where bone is taken from a donor site and placed elsewhere within the patient. ... This article does not cite any references or sources. ... X-Ray picture of two rectangular dental implants inserted into the jaw. ...

References

Notes

^ Brighton and Hunt (1997), p. 248: The extravascular blood cells are identified as erythrocytes, platelets and neutrophils.
^ Brighton and Hunt (1991), p. 837: The cells within the clot are identified.
^ Brighton and Hunt (1997)
^ Ham and Harris
^ Brighton and Hunt (1997), p. 248: Two light micrographs showing the cells of the woven bone and hyaline cartilage.
^ Brighton and Hunt (1986), p. 704: Two light micrographs of a typical fracture callus: one showing the tissues and the other showing the cells.
^ Brighton and Hunt (1986); Brighton and Hunt (1997); Ham and Harris
^ Ham and Harris

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