Eduard, a rare Siberian crane, suffered from severe arthritis for five years. In the wild, Siberian cranes stand on soft, mushy marshland. In zoos, however, where the birds typically live on hard surfaces, arthritis is not uncommon. Since neither painkillers nor anti-inflammatory medication could ease Eduard's pain, surgeons recently implanted an artificial joint in his left ankle. The procedure, never tried on a bird, was performed by Avery Bennett, an assistant professor of wildlife and zoological medicine at the University of Florida, and Eugene O'Brien, a hand surgeon with the Hand Center in San Antonio, Texas. In a four-hour operation at the University of Florida Veterinary Medical Teaching Hospital, the surgeons replaced part of the ankle joint with a flexible plastic device about the size of a clothespin, normally used as an artificial joint in the big toes of humans. Eduard is now recovering nicely, say his keepers. While the bird's surgery may be used to help other arthritic cranes, younger, healthy captive birds need preventive care. The International Crane Foundation in Baraboo, Wisconsin, Eduard's home, plans to build shallow, soft wetland environments to better accommodate its 17 Siberian cranes.