Purdue News

May 1993 Custom-fit hip, knee replacements made easy with new program WEST LAFAYETTE, IND.–Physicians may soon be able to custom design implants such as artificial hip or knee joints using a new computer program developed at Purdue University. The tailor-made implants could prove more durable and allow a wider range of motion for patients, says Chandrajit (chahn-DRAHjit) Bajaj (bah-JAHJ), professor of computer sciences who teamed up with an orthopedic surgeon, Dr. Robert Hagen, to develop the program. The research group at Purdue is one of several nationwide working to make custom-designed implants more widely available. Tailor-made implants currently are available at a handful of research institutions, including Cornell University and Johns Hopkins University, but are not available outside such centers. "This new technology, along with research already under way at a number of medical centers, indicates that the technology to design custom-made implants is ready to go forward," Bajaj says. "With this new program, physicians from any location can work side-by-side with specialists to design implants that suit a patient's medical and life-style needs." The Purdue program is the most sophisticated to date, providing more accurate computer modeling of curved surfaces and allowing a wider range of sculpting. The program is also the first to provide a multi-user and multi-workstation environment, allowing physicians and bone specialists to work simultaneously with technicians. Bajaj and Hagen are contacting implant manufacturers in Indiana and New Jersey to find ways to implement the new technology. Information on the program will be presented in August at the Association of Computing Machinery's Multimedia Conference to be held in Anaheim, Calif. The new program allows physicians to model the geometry and design replacements for a patient's joints using data obtained from magnetic resonance imaging scans. The program works with curved surfaces like those found in the body, making it easy to obtain precise measurements. Though the idea of making customized implants is not new, finding ways to create accurate computer reconstructions has proven to be quite difficult, says Bajaj, who specializes in modeling various shapes. "The geometry of the human body is very complicated, and can be especially tricky in areas such as the hip or knee joint," he says. "Furthermore, bone is made up of living tissue and can change in shape over time, causing problems such as bone spurs or bone retraction from the implant." The custom-designed implants may help reduce such risks by allowing doctors to computer-simulate use of the implant over time. "Some of these problems are caused by incorrect load transfer or extended wear on a specific region of the bone," Bajaj explains. "With the computer model, doctors and technicians can simulate tasks such as walking and lifting to see if there are any immediate problems with wear on a region." Contact Purdue News Service (765) 494-2096 or purduenews@purdue.edu To the Purdue News and Photos Page