CompuMed Inc. shares rose 38% as the computer diagnostic company unveiled a prototype machine that can diagnose both osteoporosis and arthritis. Shares of the Manhattan Beach-based company rose 78 cents to close at $2.84 in Nasdaq small-cap trading. The machine, called the OsteoView 2000, is expected to be the first device that can diagnose both arthritis and the bone-thinning disease osteoporosis, the company said. CompuMed expects the machine to be available for sale in the U.S. next year, pending Food and Drug Administration approval. It announced the prototype at the American Society for Bone and Mineral Research meeting in Cincinnati. The company said it expects the machine to play a key role as new osteoporosis treatments come to market. Few treatments exist today for women with osteoporosis, aside from estrogen replacement therapies. The market is expected to explode to as much as $5 billion in annual sales by 2005, some analysts say.