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AAOS SAN FRANCISCO, March 7, 2008 - Some of the purported advantages of hip resurfacing over standard arthroplasty, though not all, seem to be real, researchers found in a randomized trial.

But other pluses in activity and function can probably be chalked up to patient selection bias and expectations, reported Martin Lavigne, M.D., of the University of Montreal, and colleagues, at the American Academy of Orthopaedic Surgeons meeting here.

In the randomized trial, patients who had hip resurfacing were significantly more likely to return to work and sports and had better step and hop test scores than standard arthroplasty patients did.

But functional scores and range of motion were no better than with hip replacement, the investigators found.

Hip resurfacing gained popularity with patients and some orthopedic surgeons on the basis of assumptions about better clinical function and ability to return to a high level of activity.

While retrospective cohort studies reinforced this perceived benefit, Dr. Lavigne said, "obviously there was a bias in the patient selection for hip resurfacing." Patients who sought hip resurfacing tended to be younger, more active, healthier, and expected a more active life after surgery, he said.

The newer procedure is still controversial among orthopedic surgeons despite rapid increases, commented Tom Schmalzried, M.D., of the Orthopaedic Hospital in Los Angeles, in a press conference where there was debate over the two approaches.

"The results of good, modern total hip replacement are really, really good," he said. "So for resurfacing to have a favorable risk-to-benefit ratio, you have to show you are getting something you don't get with total hip replacement."

For a more objective answer to this issue, Dr. Lavigne's group randomized 210 patients who were candidates for either procedure to undergo either uncemented 28-mm metal-on-metal total hip arthroplasty or hybrid metal-on-metal hip resurfacing.

All procedures were done by the same three surgeons with a posterior approach. Patients were informed which surgery they underwent only afterward.

Patients had a mean age around 50. Body mass index was higher in the total hip arthroplasty group.

Functional scores were slightly worse in the hip replacement group at six months (17 versus 11 on the WOMAC scale) but identical by two years (5 for both).

At six months after surgery, hopping on the affected leg was significantly easier for resurfacing group patients ("easy" or "very easy" 91.7% versus 78.9% and "difficult" or "impossible" 8.3% versus 21.1%, P=0.023).

Likewise, climbing stairs in a step test was easier at six months in the resurfacing group compared with the replacement group ("easy" or "very easy" 94.4% versus 76.3% and "difficult" or "impossible" 5.6% versus 23.7%, P=0.015).

Hip resurfacing group patients were also more likely to return to their prior work (96% versus 83%, P=0.02).

The young age of the patients made this an important outcome, Dr. Lavigne said.

Among the patients, 152 had data on activity level pre- and post-procedure.

Despite similar activity levels before surgery (P=0.22), more hip resurfacing than hip replacement patients returned to sports activities by one year after surgery (15% versus 7% high impact and 38% versus 28% moderate impact activity, P=0.022).

On a scale that included activities of daily living as well as sports, the difference tended to favor hip resurfacing but was not significant at one year (P=0.074).

"Both groups returned to a high level of activity," Dr. Lavigne said. "Hip resurfacing patients seem to be more active, but not as much as expected."

Type of surgery had no significant impact on what factors patients reported as limiting their return to sports activities, including implant protection, discomfort, fear of instability, and thigh pain.

Hip range of motion -- including total arc, arc of rotation, flexion-extension arc, and abduction-adduction arc -- was also similar for both groups among the 122 patients with data on this outcome (P>0.05).

Satisfaction with the procedure was uniformly high over time and across treatments.

While resurfacing is a more aggressive technique, Dr. Lavigne said, the rate of complications was similar between groups.

Long-term follow-up will be important to determine whether there are differences in need for revision between the procedures, he concluded.

Dr. Lavigne reported receiving research or institutional support from Zimmer, Stryker Howmedica, Biomet, DePuy, and Smith & Nephew and consulting for Zimmer.

Dr. Schmalzried reported receiving research or institutional support from Stryker, DePuy, Johnson & Johnson, Corin, and Wright Medical Technology; receiving miscellaneous funding from Stryker, DePuy, Johnson & Johnson, Corin, Wright Medical Technology, Zimmer, and Smith & Nephew; receiving royalties from Stryker, DePuy, Johnson & Johnson, Corin, and Wright Medical Technology; holding stock options in Stryker, DePuy, Johnson & Johnson, Corin, Wright Medical Technology, Zimmer, Biomet, Bristol-Myers Squib, and Pfizer; and being a consultant for Stryker.

Primary source: American Academy of Orthopaedic Surgeons meeting
Source reference:
Lavigne M, et al "Range of motion after hip resurfacing and THA: A single-blind randomized clinical study" AAOS meeting 2008; Abstract 058.

Additional source: American Academy of Orthopaedic Surgeons meeting
Source reference:
Lavigne M, et al "A randomized study comparing surface replacement arthroplasty to total hip arthroplasty" AAOS meeting 2008; Abstract 056.

Additional source: American Academy of Orthopaedic Surgeons meeting
Source reference:
Lavigne M, et al "Return to sports after hip resurfacing and total hip arthroplasty: A randomized clinical trial" AAOS meeting 2008; Abstract 053.

Ken Kuipers' hip pain started in 2006. At first, the 51-year-old Platte farmer tried to tough it out.

Even though a couple doctors recommended hip replacement, Kuipers wasn't ready to give in.

"I wanted to keep my own joint as long as possible," he says.

Doctors told him he could try cortisone injections, but Kuipers ruled that out because the shots were expensive and provided temporary relief. He needed to keep up with his animals and field work, so when the pain didn't ease up, Dr. Matthew McKenzie, orthopedic surgeon at the Orthopedic Institute, offered another option.

Kuipers was a perfect candidate for hip resurfacing, McKenzie says. People who are active, younger than 65 and have normal bone tissues have the best chance for success with the procedure, he says.

Doctors also consider the expected life span of the patient before deciding on the type of surgery performed. Hip replacements don't last forever.

"There is about a 20 percent failure rate in 25 years, depending on what study you're looking at," McKenzie says.

He has done the resurfacing procedure for about nine months, something that Orthopedic Institute added because patients were going out of town to have the surgery, he says.

A hip resurfacing procedure has the same goal as a standard total hip: Pain alleviation. Contrary to popular belief and Internet promises, the procedure is not less invasive or expensive nor does it mean a shorter recovery time.

With hip resurfacing, Kuipers faces six weeks of healing, the same time a total hip replacement would have taken. The newer surgery is not cheaper because new technology always costs more, McKenzie says.

The main reason to have a hip resurfacing is because it means less bone removal. "If it fails, you can revise it to a standard total hip," he says. "Anything to save bone is the right thing to do."

During a hip resurfacing procedure, the ball of the hip is machined down, a metal cap is fitted over it and a short anchoring spike is driven down the femur. The neck of the femur is preserved as well as much of the ball. The position of the implant and the patient's muscles hold the hip in place.

In a traditional hip replacement, the entire ball and joint is removed and replaced with an artificial joint, and a long rod is placed in the femur.

Kuipers' incision is 10 inches long, that compared with a hip replacement that is typically half that or less.

He was in the hospital for several days. He had the surgery on a Wednesday and went home Saturday. He had two physical therapy sessions on Thursday and Friday while in the hospital, says his wife, Donna. They taught him stretching and strengthening exercises to do at home.

He's using a walker right now.

"I'm just about ready to switch to a cane," he says.

The pain is better but different, he says. It's surgical pain from the muscles being cut. And he still needs pain pills to sleep.

At two weeks post-op, he had his first office visit where his staples were removed and his incision was looked over. Healing is progressing, and McKenzie gave permission to increase activity as tolerated.

"I was given the go ahead to get on a tractor," Kuipers says.That's exactly what he plans to do as soon as it dries out enough to get in the fields.

 

Vicky Marlow, Patient Advocate/Technical Contributor, asks "What is your opinion on cementless devices for resurfacing?"


Maybe they are good, but we do not know yet. Cement is a shock absorber between prosthesis and bone or between prosthesis/ bone+cement/ bone, so maybe a good thing, certainly taking in account that Chrome Cobalt has not the same elasticity as bone and is quite stiff!

So

Read More Doctors Opinions About Cementless Hip Resurfacing Here