Engineers and neurosurgeons at the University of Pittsburgh have unveiled the world”s first self-powered spinal implant that can transmit healing data from within the body without the need for batteries or electronic components. This innovative project, funded by a $352,213 NIH R21 grant, aims to enhance spinal fusion surgery through real-time monitoring of recovery progress.
The initiative, titled “Wireless Metamaterial Interbody Cage for Real-Time Assessment of Lumbar Spinal Fusion In Vivo,” seeks to improve the safety of spinal fusion recovery by enabling physicians to monitor patients remotely and address complications proactively. Each year, approximately a million Americans undergo spinal fusion surgery, a procedure that involves fusing two vertebrae together using a metal cage and bone graft, secured with screws and brackets. Traditionally, recovery is assessed through X-rays and by observing patient symptoms.
“Currently, after we implant the hardware, we rely on X-rays and the symptoms reported by the patient for monitoring,” stated Nitin Agarwal, co-principal investigator and associate professor in the Department of Neurological Surgery. “This necessitates in-person visits, exposing patients to radiation.” Continuous monitoring of the healing process has proven challenging, leading Agarwal to describe the existing healthcare experience as disconnected.
While there are wireless devices available for implantation, their reliance on batteries and electronic components restricts their lifespan. Amir Alavi, the principal investigator and associate professor in civil and environmental engineering, drew from his experience as a PhD student developing sensors for bridge infrastructure, which generated their own power. He recognized that a similar approach could be applied to spinal implants. “No batteries, no antennas, no electronics in vivo, no worries!” Alavi exclaimed.
Utilizing metamaterials—engineered composites that combine conductive and non-conductive layers—Alavi”s team is creating implants that harvest energy and transmit signals when pressure is applied. In 2023, the researchers began incorporating this technology into spinal fusion cages. Their findings, published in Materials Today, highlight implants that stabilize the spine while also monitoring recovery.
As the spine heals, the implant”s signals will change. “When the spine is healing, the bone carries more load, and the implant”s self-generated signal naturally decreases,” Alavi explained. “Immediately after surgery, the signal is stronger due to the increased pressure from the vertebral endplates on the cage.”
The implant”s signals are captured by an electrode on the patient”s back, transmitting data to the cloud for real-time analysis by doctors, which could facilitate early intervention in case of complications. The team is also leveraging generative AI to tailor the design of the cage to each patient”s unique anatomy. “We can scan the patient”s spine and design the cage for a perfect fit,” Alavi noted. These metamaterial cages are not only customizable but also self-sustaining in terms of power generation.
Having conducted in vitro tests to confirm the concept”s viability, the research team is preparing to move to the next phase, which involves in vivo trials on animals, supported by NIH funding. “If successful,” Agarwal remarked, “the subsequent step would be human trials.” He emphasized the importance of integrating clinical and laboratory expertise to enhance the translation of scientific advancements into practical patient care, ultimately aiming to improve safety and outcomes while fostering a more connected healthcare experience.
