Choosing a Knee Implant / Prosthesis

One of the most important things you will want to discuss with your chosen knee surgeon is the type of knee replacement prosthesis he or she will be implanting. There is most certainly no single  “best prosthesis” on the market.

Many manufacturers – including the ones listed on this site – create and sell many different knee implant models and components. As will be discussed below, the choice of prosthesis may not be left entirely to you, the patient, it is still very important to understand which prosthesis your surgeon recommends and why. You will then have an opportunity to do some of your own research or seek out additional opinions as to that particular implant.

Materials

Three different bone surfaces may be replaced in a knee replacement surgery. These include the bottom surface of the femur (thighbone), the top surface of the tibia (shinbone), and the back surface of the patella (kneecap). Implant components are designed so that metal will always articulate against plastic, creating a smooth movement.

The femoral component is metal, made of titanium- or cobalt/chromium-based alloys (metal). The tibial component is a flat metal platform with a polyethylene (plastic) cushion. The patellar component, if used, is a dome-shaped piece of polyethylene that duplicates the shape of the kneecap. All together, the components weigh between 9-10½ ozs depending on the size selected. More about knee implant materials >>

Discussing Implants with Surgeon

In your search for information about your knee replacement surgery, you may learn about different implants on the market. Though knee replacement prostheses are many, basically they are of the same general design. with real differences between them being in certain design concepts.  Each surgeon has particular manufacturers and prostheses with which they are more experienced and comfortable. This is generally a good thing – you want your surgeon to know the implant like the back of his hand.

Never the less, you should discuss with your surgeon that the implant he or she is recommending not just his or her favorite device but the proper implant for your circumstances.

If you have questions about a specific implant, ask your surgeon to compare it to the implant he or she usually uses.

What criteria are considered when making the prosthesis determination?

Your surgeon will consider your age, weight, lifestyle and severity of joint degeneration as well as your gender and/or your stature and the surgeon’s own experience before making a recommendation or choice as to which prosthesis might be the right one for you.

When matching an implant to your specific circumstances, the doctor will be looking at necessary and possible range-of-motion with the implant, stability of the implant and wear-resistance of the materials in light of your physical and lifestyle activity considerations.

What questions should be raised with the surgeon about the prosthesis prior to even scheduling your surgery?

A few of our suggestions:

  • Do you use the newest implant or the most tested and popular implant? (You want an implant with a successful track record over a reasonable time period.)
  • Do you use different implants depending on each patient, or are you most comfortable with using one type for every patient?
  • How long have you been using the implant recommended for me?
  • Why is this implant the appropriate one for my circumstances?

The ideal knee replacement will permit normal activities, normal motion, and generally last the patient’s lifetime.

image credit: Conformis

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