Hip Resurfacing, Knee Replacement Surgery

by Food and Drug Administration (FDA)

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Hip Resurfacing

An alternative to total hip replacement is an operation called hip resurfacing. Unlike the prostheses used in total hip replacement, which are made to replace the femoral head, resurfacing prosthesis designs allow the head to be preserved and reshaped. The resurfaced bone is then capped with a metal prosthesis. Like total hip replacement, the socket is fitted with a prosthesis.

In the United States, hip resurfacing is being conducted only in FDA-approved clinical studies. It is necessary for each manufacturer of a hip resurfacing device to collect clinical data on its resurfacing design. The data collected in these studies will be used to demonstrate whether each hip resurfacing design is safe and effective for market approval in the United States. Presently, no manufacturer has obtained FDA approval to market its hip resurfacing design.

Not everyone is a candidate for resurfacing; the femoral head may be too damaged to hold the resurfacing component. "Good bone stock is required," says Michael Mont, M.D., director of the Center for Joint Preservation and Reconstruction at Sinai Hospital in Baltimore.

James Puglisi considers himself fortunate to have good bone stock. Puglisi was 47 when he began limping because of a burning, aching pain in his hip that spread through his leg and into his knee and ankle. For this marathon runner and cyclist, just walking and standing became painful, and sometimes the pain was so intense that it would wake him up during the night.

Puglisi was diagnosed with osteoarthritis, brought on by an abnormally formed hip joint. He was advised by his orthopedic surgeon to wait as long as possible before getting a total hip replacement because it might wear out with his active lifestyle and require one or more revisions.

Revision surgery, which replaces both artificial parts and damaged bone, is more difficult than first-time surgery, says NIAMS. The outcome is generally not as good because bone is not as strong as when first operated on and the supporting ligaments may be damaged.

"But the pain was getting to the point where I needed to do something," says Puglisi.

Puglisi flew from his home in Amherst, N.Y., to Baltimore to take part in a study on hip resurfacing. Mont performed Puglisi's resurfacing operation in March 2003 and Puglisi returned home after a four-day stay at Sinai Hospital. Gradually putting more weight on his new hip, Puglisi was able to be full weight-bearing (walking without a cane or crutches) after three months. Now pain-free, the 50-year-old is back to cycling 200 miles a week and anticipates running again soon. "I'm so happy with the results," he says. "I had forgotten what it was like to have a pain-free life, and now I have it back. It feels as normal as my other hip."

Puglisi notes that different surgeons may have different recommendations. Another surgeon who saw Puglisi's X-rays told him he shouldn't run again. "But Dr. Mont was OK with it as long as I waited at least six months after surgery," says Puglisi. "He just told me I couldn't bungee jump or parachute!"

Mont advises the six-month waiting period to give a patient time to build strong muscles. He also says he doesn't "totally condone heavy sporting activities" after resurfacing. "You do it at your own risk," he says, adding that if the resurfaced hip ever fails, it can be converted to a total hip replacement.

Current hip resurfacing technology is too new to know how long the resurfaced hip will last. Puglisi has volunteered to return to Sinai Hospital for an annual checkup for the next 10 years to help clinical investigators gather long-term data on resurfaced hips.

Knee Replacement Surgery

The largest joint in the body, the knee joint is formed where the lower part of the thighbone (femur) joins the upper part of the shinbone (tibia) and the kneecap (patella). Shock-absorbing cartilage covers the surfaces where these three bones touch.

In a standard total knee replacement, the damaged areas of the thighbone, shinbone and kneecap are removed and replaced with prostheses. The ends of the remaining bones are smoothed and reshaped to accommodate the prostheses. Pieces of the artificial knee are typically held in place with bone cement.

A knee replacement usually involves three to four days in the hospital. The recovery period depends on a patient's general health, age, and other factors, but many people can resume their normal activities four to eight weeks after surgery.

"While a knee replacement can dramatically improve the quality of life for a person with debilitating knee pain, it is major surgery," says Gerard Engh, M.D., director of knee research at Anderson Orthopaedic Research Institute in Alexandria, Va. "We usually recommend total knee replacements and partial knee replacements after other less invasive treatments have been attempted."

But most who opt for knee joint replacement are generally happy with the results. Ninety percent of those who have total knee replacement report fast pain relief, improved mobility, and better quality of life, according to a panel of independent experts. The panel was convened at a conference in December 2003 sponsored by the National Institutes of Health (NIH) and cosponsored by the FDA and other federal organizations.

The panel concluded that, overall, total knee replacement surgery is a safe, very successful, and relatively low-risk treatment for decreasing pain and increasing mobility in people who are not helped by nonsurgical treatments. Follow-up studies showed that revision surgery was needed in 10 percent of knee replacements after 10 years, and in 20 percent after 20 years, according to the panel.

About the Author

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