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Hip replacementImage:Hip replacement Image 3684-PH.jpg Hip replacement is the most successful, cheapest and safest form of joint replacementsurgery. The earliest recorded attempts at hip replacement (Gluck T, 1891), which were carried out in Germany, used ivory to replace the femoral head (the ball on top of the thighbone). Use of artificial hips became more widespread in the 1930s; the artificial jointswere made of steelor chrome. They were considered to be better than arthritisbut had a number of drawbacks. The main problem was that the articulating surfacescould not be lubricatedby the body, leading to wear and loosening and hence the need to replace the joint again (known as revision operations). Attempts to use teflonproduced joints that caused osteolysisand wore out within two years. Another significant problem was infection. Before the advent of antibiotics, surgery on the joints carried a high risk of infection. Even with antibiotic treatments, infection is still a cause for some revision operations. Such infections are not necessarily caused at surgery; they can also be the result of bacteriaentering the bloodstreamduring dental treatment. The modern artificial joint owes much to the work of John Charnleyat the Manchester Royal Infirmary; his work in the field of tribologyresulted in a design that completely replaced the other designs by the 1970s. Charnley's design consisted of 3 parts – (1) a metal (originally Stainless Steel) femoral component, (2) a Ultra high molecular weight polyethyleneacetabular component, both of which were fixed to the bone using (3) special bone cement. The replacement joint, which was known as the Low Friction Arthroplasty, was lubricated with synovial fluid. The small femoral head (22.25mm) produced wear issues which made it suitable only for sedentary patients, but - on the plus side - a huge reduction in resulting frictionled to excellent clinical results. For over two decades, the Charnley Low Friction Arthroplasty design was the most used system in the world, far surpassing the other available options (like McKee and Ring). In 1960 a Burmese orthopaedic surgeon, Dr. San Baw(29 June1922– 7 December1984), pioneered the use of ivoryhip prosthesesto replace ununited fractures of the neck of femur('hip bones'), when he first used an ivory prosthesis to replace the fractured hip bone of an 83 year old BurmeseBuddhistnun, Daw Punya. This was done while Dr San Baw was the chief of orthopeadic surgery at Mandalay General Hospital in Manadalay, Burma. Dr San Baw used over 300 ivory hip replacements from the 1960s to 1980s. He presented a paper entitled 'Ivory hip replacements for ununited fractures of the neck of femur' at the conference of the British Orthopeadic Associationheld in London in September 1969. An 88% success rate was discerned in that Dr San Baw's patients ranging from the ages of 24 to 87 were able to walk, squat, ride the bicycle and play football a few weeks after their fractured hip bones were replaced with ivory prostheses. Dr San Baw's use of ivory was, at least in Burma during the 1960s, 1970s and 1980s (before the illicit ivory trade became rampant starting around the early 1990s) cheaper than metal. Moreover, due to the physical, mechanical, chemical, and biological qualities of ivory, it was found that there was a better 'biological bonding' of ivory with the human tissues nearby the ivory prostheses. An extract from Dr San Baw's paper, which he presented at the British Orthopeadic Association's Conference in 1969, is published in Journal of Bone and Joint Surgery(British edition), February1970. In the last decade, several evolutionary improvements have been made in the total hip replacement procedure and prosthesis. Many hip implants are made of a ceramicmaterial rather than polyethylene, which some research indicates dramatically reduces joint wear. Metal-on-metal implants are also gaining popularity. Most implants are joined without cement; the prosthesis is given a porous texture into which bone grows. This has been shown to reduce the need for revision. The latest developments are several competing Minimally Invasive Surgery(MIS) approaches, which may result in far less soft tissue damage and a much quicker recovery. C.A.O.S(Computer assisted orthopedic surgery) is also very up and coming. Computer assisted surgery is used to better navigate prosthetic implantation. Another option for hip problems is resurfacing, where the end of the femur bone is capped with a metal ball and a metal socket is pressed into the pelvis. Resurfacing preserves bone stock if a revision is ever needed, and the large diameter ball and socket more closely mimic the natural joint structure. There has been no published clinical evidence to show that today?s CoCr metal-on-metal articulating surfaces have the osteolytic effect on bone that Teflon had. External links
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