September 2001

Painless Screws

By Technology Review

Ten percent of fractures require reconstructive surgery that uses titanium plates, screws or pins to realign bones. With these orthopedic implants comes the risk of infection and chronic pain. And once a fracture heals, a second surgery is required to remove the metal parts. However, MIT engineers have developed a synthetic bone implant that would fuse with natural bone in the body during healing. Coinventor Edward Ahn took a synthetic biocompatible material called hydroxyapatite in its powder form and synthesized crystals of the material less than 150 nanometers across. Packing these tiny crystals tightly together yielded a very dense material that is as strong as metal implants, stronger than other synthetic bone now available and 30 percent cheaper to make. Unlike metal implants, the new synthetic bone is defect free, poses little risk of infection and doesn't need to be removed. Ahn launched Angstrom Medica in Cambridge, MA, to commercialize the technology; he hopes to have its first orthopedic screws on the market in about a year.