In this year of Hillary and Sarah, it is interesting that gender issues in medicine are becoming important... and profitable.
In 2006, Zimmer, Inc. received clearance from the United States Food and Drug Administration to market an artificial knee that is gender-specific. This is based on studies that have focused on the anatomical differences between men and women. Specifically, men have been found to have an increase in the contact area where the knee cap meets the rest of the knee joint compared to women. And women appear to have a more narrow space when one looks at the inner and outer aspect of the knee.
Osteoarthritis of the knee is a major cause of chronic pain and disability, and the concern up to this point is that perhaps the orthopedic profession and its suppliers of artificial knees are doing a disservice to some patients by not taking into account the differences between a male knee and a female knee. All of us know patients who have chronic pain even after a knee replacement. How much of this is due to a lack of the appropriate new knee?
Traditional femur implants are wider and may overhang the bone, which theoretically could rub against other tissue and cause chronic knee pain. The new gender-specific knee (GSK) was developed after careful analysis of the knee anatomy of 800 women. Not only were women's knees more narrow compared to men, but because women's hips are wider relative to their height, the legs are set at a different angle compared to men.
Obviously, the orthopedic surgeon wants to provide a new knee which reproduces the natural anatomy to the greatest extent possible. The more normal the anatomy, the less chronic pain occurring.
However, not all female knees are created different from the male counterpart. There will obviously be cases where a woman will do better with a "male" artificial knee. And it should be remembered that there are many factors thta can cause chronic pain after a knee replacement, including weight of the patient and patient activity patterns. As in all aspects of patient care, the patient must be treated as an individual.
Nevertheless, many surgeons see utility in the GSK concept, allowing the orthopedist to select the type of artificial knee that best fits the patient, as opposed to having to shape the leg bones to allow for the appropriate placement of the new knee.
Sort of like buying shoes of the right size.
Coming soon is a gender-specific hip. This is based on the observation that women have smaller bones and shorter hips compared to men. In fact, I have seen cases where the stem of the implant is too long, causing the hip to push outward, and the leg to be slightly longer than normal. The resultant stress can cause the new hip to fail, accompanied by significant pain and disability. Suddenly a new hip is required to replace the new hip.
Joint replacement surgery has been one of the great advances in the treatment of arthritis over the past century. It is a procedure that has allowed many to live without the pain and disability they would otherwise have suffered. The introduction of gender-specific artificial joints is an attempt to fine-tune things. It will be interesting to see whether outcomes are improved, and whether theory translates into worthwhile practice.
Published On: October 06, 2008