Hip replacement is a medical procedure that replaces the hip joint with a synthetic one. This is the best, most cost-effective and safest type of joint replacement surgery. In Germany, the first known attempts at hip replacement were made using ivory as the femoral head.
Artificial hips were popularized in the 1930s. The artificial joints were made from steel or chrome. Although they were better than arthritis, there were a few drawbacks. The problem was that the articulating surfaces couldn’t be lubricated properly by the body. This led to wear and loosening, and the need for a new joint (also known as revision operations).
Teflon was used to create osteolysis-producing joints. They lasted for two years. Infection was another problem. Surgery on the joints was a risky business before antibiotics were invented. Some revisions may still be necessary, even with the use of antibiotics. These infections do not always occur during surgery. They can also happen when bacteria enters the bloodstream from dental treatment.
John Charnley, Manchester Royal Infirmary’s tribologist, was responsible for the creation of the modern artificial joint. His work completely overtook the previous designs in the 1970s. Charnley’s design was composed of three parts: (1) a metal (originally Stainless Steel), femoral component and (2) an Ultra-high molecular weight polyethylene acetabular part. Both were attached to the bone with (3) special bone cement. The synovial fluid was used to lubricate the replacement joint, also known as Low Friction Arthroplasty.
Although the 22.25mm femoral head was a problem, it made it suitable for patients who are not sedentary. However, the significant reduction in friction allowed for excellent clinical results. The Charnley Low Friction Arthroplasty design has been the most popular in the world for over 20 years, surpassing all other options like McKee and Ring.
1960 saw Dr. San Baw, a Burmese orthopaedic doctor, pioneer the use of ivory hip prostheses. He used them to replace fractures in the neck of the femur (or ‘hip bones’) and was the first to use an ivory prosthesis to fix the broken hip bone of Daw Punya, an 83-year-old Burmese Buddhist nun. This was done during Dr San Baw’s tenure as chief of orthopeadic surgeon at Mandalay General Hospital, Manadalay in Burma. From the 1960s through 1980s, Dr San Baw used more than 300 ivory hip replacements.
At the September 1969 conference of British Orthopedic Association, London, he presented a paper entitled “Ivory hip replacements in ununited fractures in the neck of the femur”. A 88% success rate was observed in the fact that patients from Dr San Baw’s age range of 24 to 87 were able, within a few weeks, to walk, squat and ride a bicycle, as well as play football, after their broken hip bones were replaced by ivory prostheses. In Burma, Dr. San Baw used ivory in the 1960s, 1970s, and 1980s. This was before the rise of the illegal ivory trade. Due to the biological, physical, chemical and mechanical qualities of ivory, it was discovered that ivory bonds better with human tissues than metal. A portion of Dr San Baw’s paper, presented at the British Orthopeadic Association’s Conference in 1969, has been published in Journal of Bone and Joint Surgery, British edition, February 1970.
The total hip replacement procedure has seen many improvements over the past decade. Research shows that hip implants made from ceramic materials are significantly less likely to wear than those made of polyethylene. Popularity is also growing for metal-on-metal implant. Implants can be joined without the use of cement. The prosthesis is made porous so that bone can grow. This reduces the need to revise the acetabular portion. After 35 years of clinical experience, surgeons still use bone cement to fix the femoral part.
There are many competing Minimally Invasive Surgery methods (MIS) that have been developed recently. These may cause less tissue damage and a faster recovery. Implant manufacturers are also heavily marketing C.A.O.S. (Computer-Assisted Orthopedic Surgery), although its value is still largely unknown.
Hip surface replacement (HSR) is an alternative to total hip replacement (THR), also known as hip resurfacing. A prosthetic socket is pressed into your pelvis with both HSR and THR. THR involves the amputation of the femur. A metal shank is then inserted into the bone. The shank holds the ball that will fit in the socket. Resurfacing does not require the removal of the end of a femur; instead, the cap is made of a cylindrical metal. Resurfacing eliminates the THR problem of the metal shaft slipping from the femur. If a revision is ever required, the bone stock can be preserved by resurfacing. The socket and ball are larger in diameter, which more closely mimics the natural joint structure. This reduces the chance of dislocation and improves range of motion. No clinical evidence has been published to prove that CoCr metal on-metal articulating surface have the same osteolytic effect as earlier polyethylene devices. Studies in England have shown that hip resurfacing has a ten-year success rate. This is based on age-matched patients. The FDA approved the first modern resurfacing device in the United States in May 2006. There have been approximately 90,000 resurfacings performed around the world.
Before undergoing hip replacement surgery, patients need to be informed about all options. There are many surgical options for hip surgeons. There are many incisions that can be used to access the hip joint. The posterior approach, which is widely used by most orthopedic surgeons, separates the gluteus maximus muscles from the muscle fibers in order to access the hip joint. Others access the hip via the lateral side. Contrary to the lateral and posterior approaches, the anterior approach makes use of a natural gap between the soft tissues to access the hip joint. The main drawbacks of this approach are the risk of injury to the lateral foemoral cutaneous nerve and the limited availability to the general public.