New Tool for Measuring Human Bone Hailed as Medical Breakthrough
By GEORGE FOULSHAM
Hansma, a professor of physics who has spent much of the past 20 years developing Atomic Force Microscopes, has focused on biophysical research and the study of human bones. His renowned bone tissue research has led him to what he believes will be a significant step in the study of biomaterials: development of a new medical diagnostic tool –– the Reference Point Indentation (RPI) instrument.
Hansma is a co-author of a new study published in the Journal of Bone and Mineral Research. In the study, “Microindentation for in vivo Measurement of Bone Tissue Mechanical Properties in Humans,” Hansma and his co-authors say they have validated the RPI as a new tool for measuring the strength and quality of bones by using live human test subjects.
“This is a revolutionary breakthrough,” Hansma said of the RPI.
The study documents the first clinical trials of the RPI, which uses a mechanically driven test probe enclosed in a microscopically small cylinder about the size of a hypodermic needle. The test probe is driven like a tiny piston into the bone of the test subject for about 10 seconds, creating microscopic indentations. The indentations are repeated and the microfractures are measured to determine the bone’s strength and quality.
What’s been missing is a way to measure bone quality. Using the RPI, a doctor would be able to determine bone quality by studying the microfractures created in the bones of tested patients. “There’s been no way to measure this until now,” Hansma said. “This is just a local measurement of how easily the bone is fractured. Since there was no way to measure this, there was no way to develop therapies. But with the RPI, we can measure how easily a bone could be fractured.”
All clinical trials have taken place in Barcelona, Spain, under the supervision of Hansma and Dr. Adolfo Diez-Perez, a physician at Hospital del Mar in Barcelona and the study’s first author. Hospital patients –– victims of hip fractures and other ailments –– were injected with a local anesthetic in their tibias. The leg bone was then tested using the RPI instrument. The RPI’s probe creates microfractures in the tibia, measuring the force that’s being applied and the distance that the probe goes into the bone.
The Food and Drug Administration (FDA) has not approved the RPI for tests in the United States. What would it take to get FDA approval? “Several million dollars for clinical studies in the U.S.,” Hansma said.
A new Santa Barbara company, Active Life Scientific, is currently selling the instruments to researchers for laboratory studies and hopes to raise the funds necessary to fund clinical studies and receive FDA approval. For now, the company is focusing on preclinical and clinical research applications. It hopes to eventually develop diagnostic tools, making this new technology available to people who want to know about their risk of bone fracture and how to reduce it.
Hansma’s next project will be a collaboration with Chancellor Henry T. Yang, who’s also a professor of engineering, and Srinivasan Chandrasekar, a professor of industrial and materials engineering at Purdue University.