Current Trends in Knee
Arthroplasty: What should the patient know?
Barry J. Waldman MD, Esther A. Schaftel CRNP
www.totaljointjoint.com
(Thank You to Dr. Waldman for submitting this
article to Hip Resurfacing News)
An Arthritis Epidemic
Unfortunately, there is an epidemic of knee arthritis in
the United States. The American Academy of Orthopaedic Surgeons, estimates that
between 2006 and 2030, the number of knee implants performed in the United
States will increase from 300,000 a year to nearly 3.5 million. Even more
concerning, the average age of knee implant patients gets younger each year1.
It is not unusual for patients as young as 40 to experience severe knee
arthritis and require knee implant surgery. Women account for about 60% of
patients who need a knee implant - a proportion that has remained steady for the
past few decades.3
Because the market for knee implants is growing so rapidly,
there is intense competition between manufactures of implants for future
business. Orthopaedic implant manufactures are working hard to convince
surgeons and consumers that their knee products are superior to their
competitor’s products. Because knee implants are very similar to one another,
manufacturers have begun to market directly to consumers to increase their brand
recognition and steer patients to their implants.
Implant Manufacturers
The four major manufactures are Zimmer, Stryker, DePuy (a
division of Johnson and Johnson) and Biomet. All have very similar implants
that work extremely well if they are implanted correctly. This has forced many
of them to differentiate themselves using some unproved claims. Recently,
Zimmer has been marketing a “gender-specific knee”, targeted at women. It
claims that it has designed "a total knee system with the women in mind".3
In response, Stryker has asserted that their "design closely matches the anatomy
of a female knee"3 and Biomet Inc. states the differences between
sexes are not enough to warrant a difference in designs.3
DePuy has advocated a rotating platform knee that “bends
and rotates.” to better match natural anatomy. While, these designs may have
some benefit, there is no long-term data proving that they are any better than
any other modern design. Differences in patient anatomy have long been
recognized and incorporated into knee designs. These differences have far more
to do with the patients overall size, not their gender or race.
Additionally, these newer implants may have some
detrimental effect that isn’t obvious today, but will become apparent some time
in the future. Because knee replacements are so durable and work so well for
most people, it will take many decades to sort out the effect of new designs.
To further confuse patients, hospital and doctors have begun to advertise
directly through local media and the internet. Many claims made are not
reviewed by other doctors and may be somewhat exaggerated.
Surgeon and hospital advertising often focuses on
“minimally invasive” procedures. While a smaller incision can be beneficial,
there is no agreement amongst surgeons as to the best methods to use. Some of
these techniques have a higher complication rate and may cause more problems
then they help.4
Advice to Patients
With the barrage of questionable information contained in
advertising and on the internet, what can a patient do to obtain the best
possible knee? Multiple studies have shown that the overall success in knee
replacement can be traced to the surgeon and the team that cares for the patient
during and after surgery. Surgeons and centers that do large numbers of
implants have more success, on the average, than surgeons who do this type of
surgery less often. When considering a doctor, it’s important to ask how many
operations of this type they do each year and what their personal outcomes are.
The hospital they use should have a dedicated joint center and do a large number
of joint replacements each year. It is also important to find a physician that
responds in a timely manner to phone calls and patient requests.
Almost all of the knee implants available today are the
result of years of research and should offer excellent functional performance
and longevity.1 Patients should be able to reap the benefits of any
TKA with the right surgeon with the right supportive team. Try to view all the
advertising and hype with skepticism and you won’t be fooled by unsubstantiated
claims. It is far more important for patients to find a doctor that they feel
comfortable with and that they can discuss their concerns with, rather than
worry about the implant used.
References
- Dennis DA. Trends in total knee
arthroplasty.Orthopedics. 2006 Sept;29 (9 Suppl): S13-6. 2.
- Barrett WP. The need for gender-specific prosthesis in
TKA: does size make a difference? Orthopedics. 2006 Sept; 29 (9 Suppl):
S53-5.3.
- Ptacek G. Gender-specific knee implants. Orthopedic
Technology Review. 2006 May-June.4. Booth RE. The gender-specific (female)
knee. Orthopedics. 2006 Sept;29 (9 Suppl): S768.
Waldman BJ, Jackson G, Schaftel EA.
Complications of Quad Sparing Total Knee Arthroplasty, Annual Meeting, American
Academy of Orthopaedic Surgeons, Feb. 2007, San Diego CA