Wireless sensor enables longitudinal monitoring of regenerative niche mechanics during rehabilitation that enhance bone repair

• Type of Material: Article
• Authors: Brett S Klosterhoff, Georgia Institute of Technology; Jarred Kaiser, Emory University; Bradley D Nelson, Michigan Technological University; Salil S Karipott, Michigan Technological University; Marissa A Ruehle, Georgia Institute of Technology; Scott J Hollister, Georgia Institute of Technology; Jeffrey A Weiss, University of Utah; Keat Ghee Ong, Michigan Technological University; Nick Willett, Emory University; Robert Guldberg, Emory University
• Language: English
• Date: 2020-06-01
• Publisher: ELSEVIER SCIENCE INC
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2020 Elsevier Inc. All rights reserved.
• License: Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1016/j.bone.2020.115311
• Title of Journal or Parent Work: BONE
• Volume: 135
• Start Page: 115311
• End Page: 115311
• Grant/Funding Information: This work was supported by a research partnership with Children’s Healthcare of Atlanta and grants from the National Institutes of Health (NIH R21 AR066322; NIH R01 AR069297) and the National Science Foundation (NSF CMMI-1400065). This work was also supported in part by VA (Merit) Grant RX001985 from the United States (U.S.) Department of Veterans Affairs Rehabilitation Research and Development Service. B.S.K. was supported by the Cell and Tissue Engineering NIH Biotechnology Training Grant (T32-GM008433) and the National Science Foundation Graduate Research Fellowship Program (DGE-1650044).
• Keywords: STABILITY; Bone defect fixation; Science & Technology; Mechanobiology; FIXATION; TOMOGRAPHY; Endocrinology & Metabolism; FRACTURE; SYSTEM; DELIVERY; STEM-CELL BEHAVIOR; Life Sciences & Biomedicine; TISSUES; Biomechanics; Implantable sensor; Regenerative rehabilitation; GROWTH

Abstract

Mechanical loads exerted on the skeleton during activities such as walking are important regulators of bone repair, but dynamic biomechanical signals are difficult to measure inside the body. The inability to measure the mechanical environment in injured tissues is a significant barrier to developing integrative regenerative and rehabilitative strategies that can accelerate recovery from fracture, segmental bone loss, and spinal fusion. Here we engineered an implantable strain sensor platform and longitudinally measured strain across a bone defect in real-time throughout rehabilitation. The results showed that load-sharing permitted by a load-sharing fixator initially delivered a two-fold increase in deformation magnitude, subsequently increased mineralized bridging by nearly three-fold, and increased bone formation by over 60%. These data implicate a critical role for early mechanical cues on the long term healing response as strain cycle magnitude at 1 week (before appreciable healing occurred) had a significant positive correlation with the long-term bone regeneration outcomes. Furthermore, we found that sensor readings correlated with the status of healing, suggesting a role for strain sensing as an X-ray-free healing assessment platform. Therefore, non-invasive strain measurements may possess diagnostic potential to evaluate bone repair and reduce clinical reliance on current radiation-emitting imaging methods. Together, this study demonstrates a promising framework to quantitatively develop and exploit mechanical rehabilitation strategies that enhance bone repair.