Direct electromagnetic coupling for non‐invasive measurements of stability in simulated fracture healing

Abstract

Diagnostic monitoring and prediction of bone fracture healing is critical for the detection of delayed union or non‐union and provides the requisite information as to whether therapeutic intervention or timely revision are warranted. A promising approach to monitor fracture healing is to measure the mechanical load‐sharing between the healing callus and the implanted hardware used for internal fixation. The objectives of this study were to evaluate a non‐invasive measurement system in which an antenna electromagnetically couples with the implanted hardware to sense deflections of the hardware due to an applied load and to investigate the efficacy of the system to detect changes in mechanical load‐sharing in an ex vivo fracture healing model. The measurement system was applied to ovine metatarsal bones treated with osteotomies, resulting in four different levels of bone stability which simulated various degrees of fracture healing. Computational finite element simulations supplemented these ex vivo experiments to compare the osteotomy model of fracture healing to a more clinically applicable callus stiffening model of healing. In the ex vivo experiments, the electromagnetic coupling system detected significant differences between the four simulated degrees of healing with good repeatability. Computational simulations indicated that the experimental model of fracture healing provided a good surrogate for studying healing during the early time period as the callus stiffness is increasing as well as when diagnostic monitoring of the healing process is most critical. Based upon the data reported herein, the direct electromagnetic coupling method holds strong potential for clinical assessments and predictions of fracture healing. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res

Real-time monitoring of mechanical cues in the regenerative niche reveal dynamic strain magnitudes that enhance bone repair

“…Such an approach is pertinent to pediatric patients after procedures that would typically entail CT imaging, as radiation exposure should be curtailed to minimize risk of radiation-induced cancers ( 35 ). This idea has been explored of late in percutaneous devices to measure strain and tissue impedance ( 36 , 37 ), but emerging developments in passive and active devices could offer fully implantable, wireless embodiments ( 38 ). In addition, we obtained measurements in real-time while animals walked on a treadmill.…”

Diagnostic prediction of ovine fracture healing outcomes via a novel multi-location direct electromagnetic coupling antenna

“…To address these limitations, our research group has developed a diagnostic system capable of measuring temporal changes in the relative fracture callus stiffness for any fracture treated with standard off-the-shelf orthopaedic hardware stabilization devices, without the need to modify existing hardware design (50). This diagnostic relies upon fractures with orthopaedic implant fixation behaving as a composite structure, where stiffness of the healing fracture tissues and the implanted hardware both contribute to the stiffness of the composite structure.…”

Continuous Implant Load Monitoring to Assess Bone Healing Status—Evidence from Animal Testing

“…Kienast et al [ 9 ] reported further clinical data from the same system and categorized patients into different healing patterns similar to Burny et al [ 22 ]. New device proposals are constantly upcoming [ 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 ] underlining the importance of the topic.…”