A new way to repair bad backs could offer relief to tens of thousands of people. Each year in the United States, some 75,000 people undergo surgery to relieve back pain. One common procedure fuses compressed vertebrae, limiting the movement that pinches surrounding nerves and causes discomfort. Such fusion now requires the surgeon to screw a hollow, porous cylinder into the space between compressed vertebrae. But this twisting action strips the bone of the tough coating that provides strength. Now Spinal Concepts-a four-year-old venture-backed company in Austin, Texas-has developed a less invasive fusion device. The recently patented "InFix" consists of two porous plates-shaped to model the natural curve of the spine-that are packed with bone taken from the patient's hip. The surgeon inserts the plates into the spine and spreads them apart, fusing the vertebrae. Clinical trials are under way, with commercial availability expected by 2002.