Medical Device Daily National Editor
PALM DESERT, California — So how does an orthopedic surgeon, one of the prime end-users of the products that come from the materials and processes being discussed at a conference at the posh Marriott Desert Springs Resort here this week, view the state of his industry?
Stuart Goodman, MD, PhD, professor of orthopedic surgery at Stanford University (Stanford, California) and a busy surgeon who specializes in hip and knee replacements, was a keynote speaker Sunday as the Materials and Processes for Medical Devices Conference sponsored by ASM International (Materials Park, Ohio) got under way.
His view of the materials and processes that go into the hip and knee prostheses that he implants on almost a daily basis, can be synthesized rather simply: Much has been done in the way of developing new materials used in such products, but not so much that anyone doing research in that area should be content to rest on his or her laurels.
In other words, just as in every other sector of medical device development, there’s ample room for improvement, particularly in areas involving device wear and the avoidance of debris that can turn a good implant sour in a hurry.
The unanswered question — perhaps unanswerable, at least at this point — is how can any given joint replacement “last a lifetime and yield normal function?” That’s the challenge, passed on by surgeons from their patients on to the developers and designers of both the materials and processes that go into such implants.
Goodman operates — pun unintended — within one of the best-known materials and processes sub-sectors. Driven by what he characterized as the “epidemic” of arthritis in both the U.S. and worldwide — an epidemic that he said knows no boundaries as to sex or age — the statistics for total joint replacement (TJR) are pretty amazing.
Saying that TJR now “is being done routinely in most every hospital in the U.S. and world,” the professor/surgeon said that, for example, in 2003 some 220,000 first-procedure total hip replacements (THR) were done in the U.S., along with 36,000 revision procedures.
Total knee replacements (TKRs) are even more pervasive, with some 418,000 first procedures in the same year.
“Patients usually have a very good understanding of the procedure and their expectations,” Goodman said. “They’ve been on the Internet and talked to friends and acquaintances, learning all they can about the procedure they’re going to undergo.”
And what do those patients want as an outcome?
“They want a replacement joint that works like normal,” he said.
“Can we as surgeons — and as device developers and manufacturers — deliver?” Not completely, he said, answering his own question.
The reason those patients’ aspirations and expectations can be only partially met, Goodman said, relates to a variety of societal, patient, surgical and design/materials issues.
A sub-set of societal issues involves what might better be termed political or “policy” questions such as “What does it cost?” and “Who pays for it?”
Goodman said, “New technology is the largest driver of healthcare inflation; we spend a lot of money per patient —most of it private, not public funds.”
Add to that a growing elderly population, with the percentage of those in the U.S. over the age of 65 hovering now between 12% and 13% and expected to balloon to almost 20% of the total by 2030.
And that elderly population “doesn’t sit around in a rocking chair anymore,” Goodman said. “They’re much more active at an older age than our parents were.
“They want to do more,” and often require joint-replacement procedures in order to be able to do so.
As for surgical issues, Goodman cited minimally-invasive surgery as the “latest craze,” adding that he has something of a “Where’s the beef?” concern about MIS outcomes. His additional query is: “Where are the studies?”
He said there has been a shortage thus far of detailed studies as to the effectiveness of minimally invasive approaches to THP or TKR.
Goodman cited advances in surgical navigation as contributing to more accurate placement of hip or knee prostheses. The latest wrinkle is image-free navigation, with intra-operative localization of specific anatomical “landmarks” helping guide surgeons as they make bone cuts.
However, he noted that in alignment studies involving experienced surgeons on cadavers, he sees “an amazingly wide spectrum of results.”
Insofar as materials are concerned, he said, “We’ve come a long way in regard to hip replacement materials since Sir John Charnley pioneered THP with the Charnley prosthesis.”
Now one of the highly discussed points of reference in the sector is “gender knees,” with several companies producing redesigned products to better accommodate the differences in male/female structure.
“And some of the hottest stuff going on now,” he said, “is bearing surfaces. “With younger and younger patients —the average age now for TJR patients is about 60, while 20 years ago it was about 70 — the traditional metal-on-metal prosthesis is generating too much wear.”
The leader in the clubhouse in the materials “race” is highly cross-linked, ultra-high molecular weight polyurethane, which Goodman said is very biocompatible, has high wear characteristics and offers greater stability because larger femoral heads are possible.
Hailing any effort that improves wear properties, he noted that re-do THRs and TKRs are “much harder to do than first procedures,” and that as both surgeons and device developers, “we do need to take every opportunity to minimize both wear and wear debris.”
Responding to a question from the audience as to the likely “winner” among the various materials/processes development efforts currently under way — not necessarily including what he characterized as “our hope [of] being able to reconstruct biologically — Goodman said, “For my money, now and in the foreseeable future, metal on plastic probably is the gold standard.”
The MPMD conference concludes today.