| Hip replacement is a medical procedure in which the | | | | extract from Dr San Baw's paper, which he |
| hip joint is replaced by a synthetic implant. It is the | | | | presented at the British Orthopeadic Association's |
| most successful, cheapest and safest form of joint | | | | Conference in 1969, is published in Journal of Bone |
| replacement surgery. The earliest recorded attempts | | | | and Joint Surgery (British edition), February 1970. |
| at hip replacement, which were carried out in | | | | In the last decade, several evolutionary |
| Germany, used ivory to replace the femoral head. | | | | improvements have been made in the total hip |
| Use of artificial hips became more widespread in the | | | | replacement procedure and prosthesis. Many hip |
| 1930s; the artificial joints were made of steel or | | | | implants are made of a ceramic material rather than |
| chrome. They were considered to be better than | | | | polyethylene, which some research indicates |
| arthritis but had a number of drawbacks. The main | | | | dramatically reduces joint wear. Metal-on-metal |
| problem was that the articulating surfaces could not | | | | implants are also gaining popularity. Some implants are |
| be lubricated by the body, leading to wear and | | | | joined without cement; the prosthesis is given a |
| loosening and hence the need to replace the joint | | | | porous texture into which bone grows. This has been |
| again (known as revision operations). | | | | shown to reduce the need for revision of the |
| Attempts to use teflon produced joints that caused | | | | acetabular component. Surgeons still frequently use |
| osteolysis and wore out within two years. Another | | | | bone cement for the femoral component, however, |
| significant problem was infection. Before the advent | | | | which has proven very successful after 35 years of |
| of antibiotics, surgery on the joints carried a high risk | | | | clinical experience. |
| of infection. Even with antibiotic treatments, infection | | | | The latest developments are several competing |
| is still a cause for some revision operations. Such | | | | Minimally Invasive Surgery (MIS) approaches, which |
| infections are not necessarily caused at surgery; they | | | | may result in far less soft tissue damage and a |
| can also be the result of bacteria entering the | | | | quicker recovery. C.A.O.S (Computer assisted |
| bloodstream during dental treatment. | | | | orthopedic surgery) is also being marketed heavily by |
| The modern artificial joint owes much to the work of | | | | the implant manufacturers, though its value remains |
| John Charnley at the Manchester Royal Infirmary; his | | | | largely unproven.. Computer assisted surgery is said |
| work in the field of tribology resulted in a design that | | | | to better navigate prosthetic implantation. |
| completely replaced the other designs by the 1970s. | | | | An alternative to total hip replacement (THR) is hip |
| Charnley's design consisted of 3 parts - (1) a metal | | | | surface replacement (HSR), also referred to as hip |
| (originally Stainless Steel) femoral component, (2) an | | | | resurfacing. With both THR and HSR, a prosthetic |
| Ultra high molecular weight polyethylene acetabular | | | | socket is pressed into the pelvis. With THR, the end |
| component, both of which were fixed to the bone | | | | of the femur is amputated, a metal shank is inserted |
| using (3) special bone cement. The replacement joint, | | | | into the femur, and the shank holds a ball which |
| which was known as the Low Friction Arthroplasty, | | | | mates with the socket. With resurfacing, the end of |
| was lubricated with synovial fluid. | | | | the femur is not amputated; the outer surface of |
| The small femoral head (22.25mm) produced wear | | | | the femoral ball is replaced with a cylindrical metal cap. |
| issues which made it suitable only for sedentary | | | | Resurfacing eliminates the common THR problem of |
| patients, but - on the plus side - a huge reduction in | | | | the metal shaft loosening from the femur. |
| resulting friction led to excellent clinical results. For | | | | Resurfacing preserves bone stock if a revision is |
| over two decades, the Charnley Low Friction | | | | ever needed. A larger diameter ball and socket more |
| Arthroplasty design was the most used system in | | | | closely mimic the natural joint structure, reducing the |
| the world, far surpassing the other available options | | | | risk of dislocation and improving range of motion. |
| (like McKee and Ring). | | | | There has been no published clinical evidence to show |
| In 1960 a Burmese orthopaedic surgeon, Dr. San Baw | | | | that today's CoCr metal-on-metal articulating surfaces |
| (29 June 1922 - 7 December 1984), pioneered the | | | | have the osteolytic effect on bone that earlier |
| use of ivory hip prostheses to replace ununited | | | | polyethylene devices had. Ten year success rates of |
| fractures of the neck of femur ('hip bones'), when he | | | | hip resurfacing from studies in England report success |
| first used an ivory prosthesis to replace the fractured | | | | equal to or greater than standard total hip |
| hip bone of an 83 year old Burmese Buddhist nun, | | | | replacement, in age-matched patients. In the United |
| Daw Punya. This was done while Dr San Baw was | | | | States, the first modern resurfacing device received |
| the chief of orthopeadic surgery at Mandalay General | | | | FDA approval in May 2006, while some 90,000 |
| Hospital in Manadalay, Burma. Dr San Baw used over | | | | resurfacings have been performed world-wide. |
| 300 ivory hip replacements from the 1960s to 1980s. | | | | Patients need to be aware of all surgical options |
| He presented a paper entitled 'Ivory hip replacements | | | | before hip replacement surgery. Hip surgeons have |
| for ununited fractures of the neck of femur' at the | | | | different surgical techniques and surgical outcomes. |
| conference of the British Orthopeadic Association | | | | Currently, there are several different incisions used to |
| held in London in September 1969. An 88% success | | | | access your hip joint. The posterior approach (widely |
| rate was discerned in that Dr San Baw's patients | | | | used by the majority of orthopedic surgeons) |
| ranging from the ages of 24 to 87 were able to | | | | separates the gluteus maximus muscle in line with the |
| walk, squat, ride the bicycle and play football a few | | | | muscle fibers to access the hip joint. Other methods |
| weeks after their fractured hip bones were replaced | | | | access the hip from the lateral side of the hip joint. In |
| with ivory prostheses. Dr San Baw's use of ivory | | | | contrast to the posterior approach and lateral |
| was, at least in Burma during the 1960s, 1970s and | | | | approach, the anterior approach uses a natural |
| 1980s (before the illicit ivory trade became rampant | | | | interval between soft tissue to gain access to the hip |
| starting around the early 1990s) cheaper than metal. | | | | joint. Its main disadvantages are that it risks damage |
| Moreover, due to the physical, mechanical, chemical, | | | | to the lateral femoral cutaneous nerve, and it is not |
| and biological qualities of ivory, it was found that | | | | widely available to the public because fewer surgeons |
| there was a better 'biological bonding' of ivory with | | | | have been trained in this technique. |
| the human tissues nearby the ivory prostheses. An | | | | |