Osseosurface electronics promise individualised orthopaedic care

Developed by a team at the University of Arizona, the osseosurface electronic devices are described in a paper published in Nature Communications.

"As a surgeon, I am most excited about using measurements collected with osseosurface electronics to someday provide my patients with individualised orthopaedic care – with the goal of accelerating rehabilitation and maximising function after traumatic injuries," said study co-senior author Dr. David Margolis, an assistant professor of orthopaedic surgery in the UArizona College of Medicine – Tucson and orthopaedic surgeon at Banner – University Medical Center Tucson.

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Although not yet tested or approved for use in humans, the osseosurface electronic devices could eventually be used not only to monitor health, but to improve it, said study co-senior author Philipp Gutruf, an assistant professor of biomedical engineering and Craig M. Berge faculty fellow in the College of Engineering.

"Being able to monitor the health of the musculoskeletal system is super important," said Gutruf, who is also a member of the university's BIO5 Institute. "With this interface, you basically have a computer on the bone. This technology platform allows us to create investigative tools for scientists to discover how the musculoskeletal system works and to use the information gathered to benefit recovery and therapy."

Because muscles are so close to bones and move so frequently, it is important that the device be thin enough to avoid irritating surrounding tissue or becoming dislodged, Gutruf said.

"The device's thin structure, roughly as thick as a sheet of paper, means it can conform to the curvature of the bone, forming a tight interface," said Alex Burton, a doctoral student in biomedical engineering and co-first author of the study. "They also do not need a battery. This is possible using a power casting and...near-field communication."

Outer layers of bones shed and renew, so a traditional adhesive would fall off after just a few months. To address this challenge, study co-author and BIO5 Institute member John Szivek – a professor of orthopaedic surgery and biomedical engineering – developed an adhesive that contains calcium particles with an atomic structure similar to bone cells, which is used as to secure osseosurface electronics to the bone.

"The bone basically thinks the device is part of it, and grows to the sensor itself," Gutruf said. "This allows it to form a permanent bond to the bone and take measurements over long periods of time."