And Now, Robodoc!

MEDICAL ROBOTS HAVE BEEN USED TO LOCATE hard-to-find tumors and guide a surgeon's scalpel but have never actually performed surgery on people -- at least not in the U.S. Now that line has been crossed. At Sacramento's Sutter General Hospital, a 90-kg (200 lbs.) machine called Robodoc has operated on its first human patient: a 64-year-old man with a bad hip.

The robot played a key role in a total-hip replacement, one of 500,000 such operations performed each year. The trick in these procedures is to cut a snug hole into which the artificial hip snaps. The standard method is to jam a tool into the thighbone with a hand-held mallet. Robodoc, using the high-speed drill at the end of its mechanical arm, can ream a cavity that is 20 times as precise.

Robosurgery doesn't have to stop at the hip. In Europe, where officials are less squeamish about such things, robots have assisted in operations on the brain, the prostate and the inner ear.