Knee Replacements for Women

Knee Replacements Designed Specifically for Women

knee rehab
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Orthopedic surgeons are constantly striving to improve the design of artificial joint replacements. Over the past 40 years, a variety of implant designs have been tested and been used in patients. Some of these designs have been improvements, and led to increased longevity of the total joint replacements. Other designs, on the other hand, have not fared so well, and have not offered improvement or have even been worse than their predecessor.

Knee replacement implants are designs use a metal shell that covers the ends of the thigh bone (the femur) and the top of the shin bone (the tibia) with a plastic insert placed between.  It is important that the metal shell closely replicates the normal anatomy of the knee joint.  Implants that are too thick or not properly sized to the patient can cause limitations in joint mobility and lead to stiffness after the knee replacement.

Gender Specific Implants

A gender-specific total knee replacement implant is a prosthesis that is specifically designed either for a male or a female. The size of the implant is slightly different to accommodate for the slightly different size of the bones between genders.  Most knee replacements marketed as gender specific are specially designed to fit a woman's knee joint anatomy.

Traditionally, implant designs have been made using "average" size data. This means that the designers of implants tried to find the "average" size at a joint, and then design implants that are both slightly larger and slightly smaller than the average.

  As one might expect, the average size of a woman's knee joint is different from the average size of a man's knee joint.

Gender-specific implants are designed in a similar way, except that the "average" is different for a man's bone and a woman's bone. The idea behind doing this is that by better replicating the normal anatomy, the joint replacement implants may allow for better function, as well as improved durability.

Are These Implants Better?

There is no data to suggest that creating a gender-specific implant design will help achieve the goals of better function or improved durability. Most orthopedic surgeons will tell you that implants already come in a variety of sizes that will accommodate almost any patient's anatomy.

It is clear that orthopedic implant companies are looking for ways to distinguish themselves. Sometimes solutions are created for problems that don't necessarily exist. Only time will tell if a gender-specific implant is actually a better, or worse, implant design. However, nothing suggests that it is an important determinant of a patient's satisfaction or outcome following joint replacement surgery.

Sources:

Barrett, WP, "The need for gender-specific prostheses in TKA" Orthopedics. 2006 Sep;29(9 Suppl):S53-5.

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