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Down to the bone

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12:34pm, August 28, 2002
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From Boston, Mass., at a meeting of the American Chemical Society

A new technique for anchoring artificial joints into bones could improve the outcome of surgeries while making the procedures easier and faster.

In about half of the 500,000 knee and hip replacements performed in the United States each year, surgeons secure the implant in bone with a polymer-based cement, says Jeremy Gilbert of Syracuse University in New York. Each surgeon makes this cement in the operating room by combining a liquid and a powder into a mixture that immediately starts to harden. The physician injects the mixture into a cavity that's been drilled into a bone and lets it firm up to the right doughy consistency before fitting an implant into the cavity.

This method requires a surgeon to time these steps perfectly. That can be tricky because the cement's hardening depends on the operating room's temperature, says Gilbert. What's more, the initial powder-liquid combination leaves pores in the resulting cement that weaken it.

Gilbert has created cement that starts with two liquids made from the same chemical components as the standard cement, rather than a liquid and a powder. The liquids can be injected from separate chambers of a device that resembles a caulking gun, he says. The fluids combine on contact–without mixing–forming a doughy material, says Gilbert. The technique also eliminates some of those cement-weakening pores, he claims.

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