Orthopedic implants like hips and knee joints last about 10 years, after which patients must undergo surgery to have them replaced. With longer life spans, an aging population and the increasing demand for prosthetics, the hunt is on for more durable faux bones. Now, a new ceramic developed by material scientists in France promises to extend an implant's life span to 30 years. A research team based at the National Institute for Applied Sciences in Lyon has developed a process that combines alumina and zirconia, two ceramics commonly used to replace the ball part of the femur that sits in the hip socket. The new alumina-zirconia composites boast significantly greater resistance to crack propagation resulting from defects and scratches and can handle twice as much load as either of the two ceramics alone. Before you ring up your doctor, however, note that human tests won't start until late 2002.

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