How Impedance Spectroscopy Improves the Fracture Repair Process
What’s going on with a fracture as it moves through the healing process? A team of California researchers set out to bring some clarity to this question.
Their work, “New opportunities for fracture healing detection: Impedance spectroscopy measurements correlate to tissue composition in fractures,” appears in the December 30, 2018 edition of the Journal of Orthopaedic Research.
Monica Lin, a Ph.D. student in the University of California, Berkeley-University of California San Francisco Graduate Program in Bioengineering, first author on the study, told OTW, “A vast proportion of the population is affected by orthopaedic injuries, yet this field lags behind many other medical areas in terms of quantitative assessment techniques.”
“Physician examinations involving patient questionnaires and qualitative inspection still remain the most common form of assessing the state of fracture healing. While X-rays are typically used during follow-up visits, they rely on mineralization of bone tissue, and are thus only useful at the final stages of healing.”
“Determining how well a fracture is healing is crucial to making correct clinical decisions for patients, yet there are currently no standardized methods of assessing fracture union. Our study demonstrates the potential of impedance spectroscopy to provide additional quantitative information that can better inform physicians about the state of healing in their patients’ fractures.”
“We saw an opportunity to use impedance spectroscopy, a technique that has been used to study different types of tissues, to provide quantitative and more continuous information about the state of a fracture as it progresses through the entire healing process.”
“Smart implant technology in the field of orthopaedics has been mainly limited to mechanical measurements, while our study closely evaluates the potential of impedance spectroscopy to track the different electrical properties of the various tissue types present in fracture healing.”
“While previous studies have shown promise in using impedance spectroscopy to differentiate between fracture and control groups, to our knowledge, we are the first to correlate impedance measurements with histological characterization. In addition, in order to evaluate the translation of this technology to a clinical setting, we conducted an experiment to understand how a metal implant would affect our electrical measurements.”
“In an ex vivo mouse study with samples collected at three time points over healing time, we found that impedance correlates to tissue compositions of heterogeneous calluses. Impedance magnitude (reflects conductivity of tissue) and phase (reflects how resistive or capacitive a measurement is) both show clear trends with the percent of cartilage and trabecular bone within fracture calluses. This demonstrates the power of this technique to predict fracture tissue composition, which has the potential to enable early detection of bone healing and fracture nonunion.”
“We demonstrated the feasibility of impedance spectroscopy for detecting fracture callus composition, laying the groundwork for additional studies that measure in vivo changes in mice and larger animal models that will enable us to fully understand the sensitivity of this technique. Ultimately, for patients undergoing surgical intervention to stabilize their fractures, instrumented implants can provide a quantitative measure of healing during follow-up visits.”
