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ELECTRONICS

Jared Diegmueller, a biomedical engineering doctoral student at Purdue, and associate professor Ozan Akkus discuss details of a prototype device that could help to prevent stress fractures.

Runners and other athletes who participate in repetitive high-impact activity often subject weight-bearing bones to a cumulative force measured in tons. If insufficient rest is provided in the athletes’ training regimen, the bones’ regenerative capability can be overwhelmed, causing tiny cracks to accumulate and lead to stress fractures. The condition is particularly common in track and field athletes and military recruits undergoing basic training. Researchers at Purdue University (West Lafayette, IN, USA) and the University of Toledo (Toledo, OH, USA) have developed a device that records acoustic emissions in the bone in order to detect the microscopic cracks. “The goal is to create a prototype that would alert the person when a stress fracture becomes imminent,” explains Ozan Akkus, a Purdue associate professor of biomedical engineering who heads the project. “The athlete could then stop rigorous physical activity long enough for the bone to heal.”

Seismologists use a similar technique for detecting earthquakes. “This is in principle similar to what happens during an earthquake, but on a microscopic scale and at a higher frequency,” Akkus notes. His research team is using earthquake models and pattern-recognition software to better understand the tiny cracks in the bones, which most frequently affect the tibia, fibula, and metatarsals.

To measure the acoustic emissions in bones, the researchers are using wireless flexible polymer-based sensors that could later be incorporated in athletic apparel such as running shoes and exercise tights to monitor areas susceptible to fractures. The sensors would send data to a receiver module and trigger an alarm once a certain threshold has been reached, alerting the athlete to stop training. The resulting data could then be downloaded to a PDA and analyzed by medical professionals to determine bone condition.

Akkus estimates that it will be two or three years before the system is commercially available. “The device could very well go into the mainstream. Anyone very active in the sports arena could use this,” he says. In the meantime, his research team will work on determining exactly when athletes pushing themselves to the limit should give their bones a rest. “You don’t want to give a professional athlete a premature warning,” Akkus remarks.