Both total hip replacement and hip resurfacing procedures continue to spark a lively, ongoing discussion among orthopaedic surgeons. Total hip replacement is a proven, effective technique that results in excellent pain relief and function in most patients for many years. Hip resurfacing, on the other hand, has had its ups and downs—with implants that were introduced in the early 1990s, then withdrawn from the market, and reintroduced under special circumstances more than a decade later.
“Hip resurfacing is not new to orthopaedics. It has been around for more than 10 years now,” said William Maloney, MD, who moderated a media briefing on the issue during the 2008 AAOS Annual Meeting. “But direct-to-consumer advertising is driving patients to ask for the procedure without really understanding what is involved or even if they are suitable candidates.”
According to panelist Paul F. Lachiewicz, MD, new technologies in total hip replacement make this procedure ideal for most patients with osteoarthritis and other conditions. Improved bearing surfaces and new ingrowth surfaces are significantly reducing previous concerns about wear and loosening.
New, highly cross-linked polyethylenes are showing 40 percent to 70 percent less wear, even in patients younger than age 40. Modern, uncemented stemmed femoral components are showing survival rates of 40 percent to 100 percent at 10 to 18 years. Additionally, hip replacement procedures are effective for just about all patients, regardless of age, diagnosis, body mass index, or anatomic hip shape.
Paul E. Beaulé, MD, FRCSC, on the other hand, noted that new technologies in hip resurfacing are making this option more appealing to many patients. Compared to the all-cemented, large head components of the early 1990s, newer metal-on-metal hip resurfacing designs are showing a 60-fold reduction in volumetric wear. “Less wear debris production means better long-term fixation,” he said, although the degree of metal ion release remains a concern.
“Resurfacing the hip is like crowning a tooth,” he said. “It can serve as an initial step, preserving bone in the event that a total hip replacement is needed later.” That’s a concept that appeals to many patients. But, as Dr. Beaulé noted, “New technology is not the answer to everything.”
Learning how to resurface, rather than replace, a hip is challenging. The inability to insert screws can make initial implant stability difficult. Different femoral component designs influence the amount of cement fixation, which could affect longevity. Finally, surgical technique and the surgeon’s learning curve are keys for successful outcomes.
Robert T. Trousdale, MD, agreed, and offered some solutions to the problems. Patient selection and surgical technique are keys to reducing the incidence of femoral neck fracture. He also advised against using hip resurfacing in patients with poor hip mechanics and those who might have metal sensitivity issues, such as young women and patients with kidney problems or metal hypersensitivity.
According to Thomas P. Schmalzried, MD, changing demographics are making patient selection an issue. Active “baby boomers,” whom he called “millennium” patients, are more concerned with function and lifestyle issues and want to continue their activities without limits or restrictions even after a hip replacement or resurfacing procedures. “And we’ve found that early intervention is better than waiting,” he said.
“Results of a good total hip replacement are really good,” said Dr. Schmalzried. “Resurfacing isn’t necessarily better. The average demographics for patients who have hip replacement are very different than for patients who have hip resurfacing. It’s not the technology, it’s the patient.”
“Total hip and knee replacements together are Medicare’s biggest expense,” said Dr. Maloney. “At the end of the day, we are all paying for these procedures. Our biggest priorities are to continue offering the best benefits and outcomes to all our patients, no matter what procedure they undergo.”