Millions of Americans have been given a new lease on life by trading in diseased, worn joints for new models.
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Hip and knee joints are wonders of engineering, allowing us to do the hippy, hippy shake, get down for the limbo rock or twist the night away. Thanks to them, we can bend, squat, pivot and stride with ease, until injury, disease or plain old wear and tear start to slow us down, eroding joints so they catch and stiffen to hinder our moves.
Hip and knee problems typically develop after loss of the protective cushioning and lubrication that allow bones to glide smoothly over each other where they intersect. When bone meets bone, the result is pain and increasing damage to the joint.
Modern medicine may still be a long way from creating bionic man, but it has given millions of men and women a new lease on life by allowing them to trade in diseased, worn joints for new models.
More than 150,000 Americans have hip replacement surgery each year. It used to be reserved primarily for adults over age 60, but younger adults with hip damage related to arthritis are increasingly candidates for surgery. The inclusion of younger patients is the result of a new generation of prostheses and evolving surgical techniques.
Hip replacement involves creating a new ball and socket. The end of the thigh bone is cut off and replaced with a prosthesis with a ball-shaped head. The socket is not removed but is smoothed and relined, often with a metal casing lined with ceramic or polyethylene. The metal head fits into the relined socket to form a smooth joint.
In the past hip replacements have lasted an average of 10 to 15 years. That’s why physicians urge patients to wait as long as possible for surgery as repeat surgeries have a higher risk of complication.
New Materials, Longer Life
A new generation of materials raises the hope that new hips will last 20 years and beyond in the future, especially if patients take care of them by not engaging in high-impact activities. Prostheses are commonly made of metal, but ceramic and plastic joints are also used, as well as combinations of these materials.
Joints are normally cemented in place. Once in place patients are able to begin putting weight on the hip shortly after surgery.
Some patients now receive cementless prostheses with a roughened surface that allows bone to grow into the new joint. Younger patients who might later put heavier wear on the hip are considered good candidates for this method. The drawback is that patients must spend a long time on crutches while the bone and implant grow together.
Hip failure is often a result of the wearing away of the polyethylene liner in the socket abraded by constant friction from the metal head. New, tougher plastics are being developed to address this problem.
Another innovative solution is the use of replaceable socket liners, enabling a physician to replace only the liner rather than the entire joint when wear becomes a problem.
With new materials now available, there is the hope that
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hip prostheses may last 20 years and longer.
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Increasingly hip replacement is being done using minimally invasive surgery. Instead of the 8- to 10-inch incision required in the traditional procedure the new surgery requires only several small incisions, called portals, that allow the surgeon to insert instruments and the new joint. Minimally invasive surgery uses the same prosthetic devices but allows patients to recover more rapidly because it involves less cutting of muscles and tendons. Many patients are able to return home the day after surgery.
Minimally invasive surgery involves less cutting of muscles and tendons, allowing for faster recovery.
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Minimally invasive surgery is now being developed for knee replacement surgery. Traditional knee replacement involves a large incision of 8 to 10 inches, flipping the knee cap back and cutting the quadriceps tendon. This isn’t necessary with the new technique which cuts less tissue and involves less tearing and stretching of tissues. Smaller, slimmer instruments have been designed to facilitate this minimally invasive approach.
Although ex-football star Joe Namath had knee replacement surgery at a relatively early age, the surgery has not been offered as widely as hip replacement. New, more reliable prosthetic devices and improved surgical techniques are making total knee replacement a viable option for more patients.
And the need is great. A British study estimated that 2 of every 100 persons over age 55 might benefit from knee replacement surgery.
Anyone contemplating hip or knee replacement needs to be aware of potential risks as well as benefits. The two most common post-surgical risks are the development of blood clots, which in rare cases can prove fatal, and infection around the implant site.
Infection is far less common now than in the past. It occurs in about 2 percent of all hip and knee replacements and can usually be treated with antibiotics.
Patients undergoing hip or knee replacement normally take anticoagulant medication for two weeks or more to prevent the development of blood clots. Clots occur in 32 of every 1000 patients and are fatal in 1 in every 1000 patients within three months of surgery.
Because of the risks associated with major surgery plus the fact that artificial joints wear out over time, surgeons encourage patients to wait as long as possible to have hips or knees replaced.
Physicians advise patients to consider replacement only after all other treatment options have been tried and failed. These include cutting back on high-impact activities, using drugs to manage pain and arthritis symptoms, strengthening muscles around the affected joint (this doesn’t cure underlying arthritis, but it may delay the need for surgery), and steroid injections into the joint. The longer surgery is delayed, the greater the chance that your new joint is the only one you’ll ever need.
The technology and surgical expertise surrounding total hip and knee replacement continues to evolve, giving those who suffer pain and loss of mobility because of joint damage a chance to be free of pain and become active and vigorous again. For those who truly need it, the surgery is a life-changing event.
REFERENCES:
“Advances Could Mean Longer-Lasting Artificial Hips,” Biotech Week, April 18, 2001.
“Arthritis–Hip Replacement,” Harvard Health Letter, February 2002.
James Douketis et al, “Short-Duration Prophylaxis Against Venous Thromboembolism After Total Hip or Knee Replacement,” Archives of Internal Medicine, July 8, 2002.
“Explore New Coatings that Repel Immune Attacks on Hip Replacements,” Advanced Coatings and Surface Technology,” January 2003.
“Hip Replacement Surgery Viable Option for Younger Patients, Thanks to New Prostheses,” Medical Devices and Surgical Technology Week, March 17, 2002.
Jeffrey Kirchner, “Venous Thromboembolism Following Hip Surgery,” American Family Physician, July 15, 2001.
Joseph Lentino, “Prosthetic Joint Infections,” Clinical Infectious Diseases, May 1, 2003.
“New Approach to Hip Replacement,” USA Today Magazine, February 2002.
“New Knee Replacement Surgery Improves Recovery Time, Doctor Says,” Medical Devices and Surgical Technology Week, April 6, 2001.
“Patients Suitable for Metal on Metal Hip Resurfacing Arthroplasty,” Pulse, May 5, 2003.
G. Brennan Polvoorde et al, “Total Hip Arthroplasty,” Physical Therapy, May 2001.
Alan Tennant et al, “Prevalence of Knee Problems in the Population Aged 55 Years and Over: Identifying the Need for Knee Arthroplasty,” British Medical Journal, May 20, 1995.
