Hip replacement

Hip replacement is the most successful, cheapest and safest form of replacement surgery. The first artificial hips were inserted in the 1930s, made of steel or chrome. They were better than arthritis but had a number of drawbacks. The main problem was that the articulating surfaces could not be lubricated by the body, leading to wear and loosening and hence the need to replace the joint again (known as revision operations). Attempts to use teflon produced joints that caused osteolysis and wore out within two years.

Related Topics:
Replacement surgery - 1930s - Steel - Chrome - Arthritis - Surface - Lubricated - Teflon - Osteolysis

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The modern artificial joint owes much to the work of John Charnley at the Manchester Royal Infirmary; his work in the field of tribology resulted 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 plastic polyethylene acetabular 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 friction led 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).

Related Topics:
John Charnley - Manchester Royal Infirmary - Tribology - 1970s - Polyethylene - Synovial fluid - Friction

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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 ceramic material 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.

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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.

Related Topics:
Minimally Invasive Surgery - C.A.O.S

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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 not been published any clinical evidence to show that today?s CoCr metal-on-metal articulating surfaces have the osteolytic effect on bone that Teflon had.

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