The “30 year” total knee

Q: On TV, they talk of a knee replacement that has a life of 30 years… does yours last that long?

A: First, I must say that I DO use a fair amount of this technology in my practice for my total knees (you will find me on the Smith & Nephew website www.RediscoverYourGo.com), and it IS great technology. It is not available in the robotic partial knee replacement. While we hope that they will last longer, most of us feel that most total knee systems will reliably last 10-15yrs under standard use, despite the wear claims.

The “30 year knee” is part of the Smith & Nephew total knee replacement product line. The specific technology is tradenamed “Verilast”, which is the combination of a specialized ceramic-like metal and a high-density plastic. Wear-simulator studies have shown a compelling decrease in wear for these 2 surfaces in combination, which is why the FDA has approved the claim “30 year knee”.

However, I am hesitant to make a claim that any total knee replacement will last 30 years. This technology has not been implanted for long enough for us to know. Additionally, the wear that we are seeing in the simulator studies is controlled wear, and likely does not truly mimic what happens in the human body naturally. Finally, the “30 year” claim is for WEAR ONLY. A knee replacement can fail for a variety of reasons over time (fatigue of the metal, bone loss around the implant, failure of the cement interface, fracture, infection, etc.) that are not related to the materials’ wear characteristics.

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