ed the surface of the bone. "This research is preliminary, and more tests are necessary to determine whether this product works safely over the long term, but the early data is very encouraging," said researcher Dr. Jeffrey Felt. Felt, whose work was funded by the U.S. Department of Education, presented his findings to a meeting of the American College of Rheumatology in Washington. His group injected the polyurethane into the sheep`s back leg joints, then killed the sheep and examined how it fared. "Encouraging signs of cartilage regeneration were detected at the tissue-polyurethane surface," they said. They did not see any signs of synovitis, a painful swelling of the joint.