How young can a patient be for a hip replacement?
Total hip replacement has proven to be a very rewarding and successful procedure for many patients with hip disease. Recently, an increasing number of younger, more active patients are undergoing hip replacement. Because of the long life expectancy and high level of activity of young patients, it has become critical to minimize wear and maximize the "life" of the hip replacement.
Who is considered a young patient?
In regards to total hip replacement, young patients are loosely defined as patients under the age of 50, patients with life expectancy of greater than twenty years and people with a family history of longevity or living to an old age.
As medical science and technology improves the life expectancies of patients will also improve. As of 1995, the life expectancy of males is 72.5 years and 79.3 for females. By 2050 the life expectancy of Americans will be as high as 86.4 years for men and 92.3 years for women. Men that reach the age of 50 years today are expected to live to the age of 76.8 on average, while women who reach the age of 50 years are expected to live to the age of 81.6 years.
Thus, it quite apparent that increased durability of hip replacements is critical for the future.
Why would a young person need a hip replacement?
There are many disorders or diseases of the hip that can be treated by a total hip replacement. Young people commonly undergo hip replacement for a number of conditions including avascular necrosis (AVN) or osteonecrosis, congenital hip dysplasia (CHD) and early arthritis as a result of a previous trauma. Additional conditions that may be treated by a total hip replacement include hip disease as a result of osteoarthritis, rheumatoid arthritis, juvenile rheumatoid arthritis, sickle cell disease, slipped capital epiphysis or Legg-Calve-Perthes. Often young patients may have had previous hip surgeries for these disorders.
When should a young person have a hip replacement?
A hip replacement should be performed after conservative methods have failed and if a patient's quality of life and ability to perform activities of daily living is significantly affected. Many different non-operative modalities should be tried first. These include anti-inflammatory medications, physical therapy, weight loss and walking assistance devices.
Are there alternative operations for the young patient?
There are operative alternatives to hip replacement in patients with certain causes of hip disease. Children with CHD may undergo either pelvic or femoral osteotomies ("cutting the bone") to reconstruct alignment of the hip joint. Femoral osteotomies are usually done in children before the age of four and pelvic osteotomies are usually performed after the age of four.
Patients with AVN may undergo either core decompression, bone grafting or osteotomy depending on the severity of the osteonecrosis. Core decompression involves drilling holes in the femoral neck in order to get it to heal faster. Osteotomies are performed to realign the femoral head and take the stress off the involved area. Bone grafting is performed to improve the blood supply to the femoral head.
What are the results of hip replacement in the young patient?
In the past, total hip replacements have been performed with cement. Results of these procedures have had relatively good outcomes. Success rates are very promising in the short term. In one study 90% of hips implanted were still functioning at 15 years of follow-up. However, at twenty to twenty five years of follow-up, successful results have dropped to 70 to 75%.
In recent years, cementless hip replacements have become standard at the Rothman Institute. A study following cementless hip replacements found a 90% success rate in patients younger than 45 years old at a average follow-up of five years. The good thing about cementless hip replacement is that, once the bone heals onto the prosthesis, there is little chance of the prosthesis ever developing loosening.
Studies at the Rothman Institute have proven that a well- performed hip replacement is very successful with high patient satisfaction. After 10 years, approximately 95% of artificial hips implanted at the Rothman Institute are still in place. This success is now being applied to younger patients.
What is the problem of hip replacement in the young patient?
Young patients are generally more active and have higher physical demands than older, less active patients. An artificial hip is a ball and socket joint. Traditionally, the socket has been made out of a plastic called polyethylene and the ball is made out of metal. The increased activity of a younger patient leads to increased wear of the socket of the artificial hip.
What are solutions to the problem of polyethylene wear?
Because of the high wear rates found in young patients undergoing traditional hip replacements with metal on polyethylene, new surfaces that decrease friction between the ball and socket have been sought. Current options include ceramic heads on polyethylene liners, ceramic heads on ceramic liners, metal heads on metal liners and highly cross-linked polyethylene liners.
Highly polished ceramic heads are now being used instead of the traditional metal head in young patients. Ceramic against plastic has a coefficient of friction one tenth that of metal against plastic. Data suggests that ceramic on plastic has a wear rate twenty times lower than that of metal on plastic. One concern about ceramic heads is that they have been known to break or fracture in the past. Newer ceramics and production protocols have significantly lowered this possibility.
Ceramic-on- ceramic bearings are also being evaluated by the Rothman Institute. This combination places two extremely smooth surfaces in contact with one another, and this can result in significantly less wear and wear debris. In addition, ceramic is biologically inert and its wear debris may be less harmful than wear debris from other surfaces. Highly polished metal -on -metal surfaces are also available. This combination has been used in the past and has shown promising results. Metal is harder than plastic. The hard surface of metal theoretically leads to less wear. Currently studies are underway to evaluate its efficacy.
Finally, modifications on the traditional polyethylene, highly cross-linked polyethylene have been developed in order to decrease the amount of wear in hip replacements. In laboratory tests, highly cross-linked polyethylene has been shown to have significantly less wear than traditional polyethylene. Advocates of highly cross-linked polyethylene feel that this technique is a less drastic departure from the traditional hip replacement. No clinical data exists at this time to prove that one option is better than another. You should consult with your surgeon who will help you make a decision. |
