Barry J.
Waldman, MD and Esther A. Schaftel, CRNP
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 1. 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): S768.5. 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