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Osteogenesis imperfecta (OI and sometimes known as Brittle Bone Disease) is a genetic bone disorder. People with OI are born without the proper protein (collagen), or the ability to make it, usually because of a deficiency of Type-I collagen. People with OI either have less collagen than normal or the quality is poorer than normal. As collagen is an important protein in bone structure, this impairment causes those with the condition to have weak or fragile bones.
As a genetic disorder, OI is an autosomal dominant defect. Most people with OI receive it from a parent but it can also be an individual (de novo or "sporadic") mutation.
There are eight different types of OI, Type I being the most common, though the symptoms range from person to person.
Collagen is of normal quality but is produced in insufficient quantities:
IA and IB are defined to be distinguished by the absence/presence of dentinogenesis imperfecta (characterized by opalescent teeth; absent in IA, present in IB). Save for the increased risk of fatal bone fractures, life expectancy is normal.
Collagen is not of a sufficient quality or quantity
Type II can be further subclassified into groups A, B, C, which are distinguished by radiographic evaluation of the long bones and ribs. Type IIA demonstrates broad and short long bones with broad and beaded ribs. Type IIB demonstrates broad and short long bones with thin ribs that have little or no beading. Type IIC demonstrates thin and longer long bones with thin and beaded ribs.
Collagen quantity is sufficient but is not of a high enough quality
Type III is distinguished among the other classifications as being the "Progressive Deforming" type, wherein a neonate presents with mild symptoms at birth and develops the aforementioned symptoms throughout life. Lifespan may be normal, albeit with severe physical handicapping.
Collagen quantity is sufficient but is not of a high enough quality
Similar to Type I, Type IV can be further subclassified into types IVA and IVB characterized by absence (IVA) or presence (IVB) of dentinogenesis imperfecta.
Same clinical features as Type IV. Distinguished histologically by "mesh-like" bone appearance. Further characterized by the "V Triad" consisting of a) radio-opaque band adjacent to growth plates, b) hypertrophic calluses at fracture sites, and c) calcification of the radio-ulnar interosseous membrane.
OI Type V leads to calcification of the membrane between the two forearm bones, making it difficult to turn the wrist. Another symptom is abnormally large amounts of repair tissue (hyperplasic callus) at the site of fractures. At the present time, the cause for Type V is unknown, though doctors have determined that it is inherited.
X-Ray OI Type V in Adult X-Ray OI Type V Kid
More on Type V Research More on OI Study
Same clinical features as Type IV. Distinguished histologically by "fish-scale" bone appearance.
At present there is no cure for OI. Treatments are aimed at increasing overall bone strength to prevent fracture and maintain mobility.
There have been many clinical trials done with the drug, Fosamax, a drug used to treat women experiencing brittleness of bones due to osteoporosis. More success was seen in the pill form versus the IV form, but success was still seen. The FDA will not approve Fosamax as a treatment for OI because long term effects of the drug have not been studied, although it is often used in Preteens, instead of Pamidrinate.
Physiotherapy used to strengthen muscles and improve motility in a gentle manner, while minimizing the risk of fracture. This often involves hydrotherapy and the use of support cushions to improve posture. Individuals are encouraged to change positions regularly throughout the day in order to balance the muscles which are being used and the bones which are under pressure.
Children often develop a fear of trying new ways of moving due to movement being associated with pain. This can make physiotherapy difficult to administer to young children.
With adaptive equipment such as crutches, splints, grabbing arms, and/or modifications to the home many individuals with OI can obtain a significant degree of autonomy.
Bisphosphonates (BPs), particularly those containing nitrogen, are being increasingly administered to increase bone mass and reduce the incidence of fracture. BPs can be dosed orally (e.g. alendronate) or by intravenous injection/infusion (e.g. pamidronate, zoledronic acid).
BP therapy is being used increasingly for the treatment of OI. It has proven efficiency in reducing fracture rates in children, however only a trend towards decreased fracture was seen in a small randomized study in adults. While decreasing fracture rates, there is some concern that prolonged BP treatment may delay the healing of OI fractures, although this has not been conclusively demonstrated.
Pamidronate is used in both USA and Canada. Some hospitals, such as most Shriners, provide it to children. Also, some children are under a study of pamidrinate. Marketed under the brand name Aredia®, Pamidronate is usually administered as an intravenous infusion, lasting about three hours. The therapy is repeated every three to six months, and lasts for the life of the patient. Common side effects include bone pain, low calcium levels, nausea, and dizziness. According to recent results, extended periods of pamidrinate, (i.e.;6 years) can actually weaken bones, so patients are recommended to get bone densities every 6 moths-1 year, to monitor bone strength.
Metal rods can be surgically inserted in the long bones to improve strength, a procedure developed by Harold A. Sofield, MD, at Shriners Hospitals for Children in Chicago. During the late 1940’s, Sofield, Chief of Staff at Shriners Hospitals in Chicago, worked there with large numbers of children with OI and experimented with various methods to strengthen the bones in these children. In 1959, with Edward A. Millar, MD, Sofield wrote a seminal article describing a solution that seemed radical at the time: the placement of stainless steel rods into the intramedullary canals of the long bones to stabilize and strengthen them. His treatment proved extremely useful in the rehabilitation and prevention of fractures; it was adopted throughout the world and still forms the basis for orthopedic treatment of OI,
Spinal fusion can also be performed to correct scoliosis, although the inherent bone fragility makes this operation more complex in OI patients. Surgery for basilar impressions can be carried out if pressure being exerted on the spinal cord and brain stem is causing neurological problems.
History and alternative names
The condition, or types of it, have had various other names over the years and in different nations. Among some of the most common alternatives are Ekman-Lobstein syndrome, Vrolik syndrome, and the colloquial glass-bone disease. The name "Osteogenesis Imperfecta" dates to at least 1895 and has been the usual medical term in the twentieth century to present. The current four type system began with Sillence in 1979. An older system deemed less severe types "Osteogenesis Imperfecta Tarda" while more severe forms were deemed "Osteogenesis Imperfecta Congenita." As this did not differentiate well, and all forms are congenital, this has since fallen out of favour.
The condition has been found in an Ancient Egyptian mummy from 1000 BC. The Norse king Ivar the Boneless may have had this condition as well. The earliest studies of it began in 1788 with the Swede Olof Jakob Ekman. He described the condition in his doctoral thesis and mentioned cases of it going back to 1678. In 1831, Edmund Axmann described it in himself and two brothers. Johann Friedrich Georg Christian Martin Lobstein dealt with it in adults in 1833. Willem Vrolik did work on the condition in the 1850s. The idea that the adult and newborn forms were the same came in 1897 with Martin Benno Schmidt.
Variability of frequency in groups
Frequency is approximately the same across groups, but for unknown reasons the Shona and Ndebele of Zimbabwe seem to have a higher proportion of Type III to Type I than other groups.. However, a similar pattern was found in segments of the Nigerian and South African population. In these varied cases the total number of OIs of all four types was roughly the same as any other ethnicity.
Noted people with osteogenesis imperfecta
Historical figures whose OI status is disputed
Portrayal in popular culture
Figures in film and television depicted as being afflicted with osteogenesis imperfecta include:
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Osteogenesis_imperfecta". A list of authors is available in Wikipedia.|