Dr. Kraay notes that in some ways this is the continuation of a process that began soon after the introduction of the first total knee prosthesis. “When I started doing knee replacement surgery, there were four different sizes of implants compared to the eight to 10 from each company that we have now,” he said. “We have a lot more ability to accommodate differences in anatomy than we used to, and GSK adds to that ability.”
In a similar vein, Dr. Sporer sees the release of the GSK more evolutionary than revolutionary. “By no means do I think that the older generation of implants was detrimental to women. As time goes on, the natural response of most of us in medicine is trying to fine tune things and optimize treatments to the individual patient.”
Surgeon Determines Outcome
All three experts agree that it is important that patients and physicians do not focus on the kind of prosthesis used in the procedure. Other aspects, especially the skill of the surgeon, have more impact on outcomes. As Dr. Kraay notes: “It is the magician, not the wand, that performs the magic.”
Dr. Boettner agrees. “Outcome is determined by the experience of the surgeon as well as their training and the number of cases they do,” he says. “There are a lot of very good implant surgeons who never have used a gender-specific implant and still have better outcomes than the one who does 20 GSKs a year.”
Another area of expert agreement is that the GSK is still a very new and untested technology. Randomized studies are currently ongoing, although any definitive results are still years away.
Gender-Specific Hip on the Way
Zimmer is also preparing to introduce a gender-specific hip (GSH) implant, the Zimmer M/L Taper Hip Prosthesis with Kinectiv Technology. A woman has smaller bones and shorter hips. In some cases, the stem of the implant may be too long, causing the hip to push out and the leg to be slightly longer than normal. The stress can cause the new hip to fail or can lead to significant pain and disability, requiring a revision.
The GSH is a system of modular stem and neck components designed to help the surgeon restore the hip joint center intraoperatively by addressing leg length, offset, and version independently. The many neck options available are said by the company to target a broad range of patient anatomies.
