What should the patient know?

Barry J. Waldman MD, Esther A. Schaftel CRNP  www.totaljointjoint.com

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.


  1. Dennis DA. Trends in total knee arthroplasty.Orthopedics. 2006 Sept;29 (9  Suppl): S13-6.2.
  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.
  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.
  4. 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