Implant resonance and the mechanostat theory: Applications of therapeutic ultrasound for porous metallic scaffolds

June 04, 2021

Joseph Deering (1), Alexandre Presas (2), Bosco Yu (1), David Valentin (2), Christian Heiss (3,4), Wolfram A. Bosbach (3,4), Kathryn Grandfield (1,5)
Materials Science and Engineering: C, 125, June 2021. DOI: 10.1016/j.msec.2021.112070


Mechanostat theory; Osseointegration; Resonance; Osteogenesis; Porous implants; Implant design


The development of treatment strategies for improving secondary stability at the bone-implant interface is a challenge. Porous implants are one solution for improving long-term implant stability, but the osteoconduction process of implants into the bone can be slow. Strain-driven osteogenesis from the mechanostat theory offers insight into pathways for post-operative treatment but mechanisms to deliver strain to the bone-implant interface need refinement. In this work, the use of therapeutic ultrasound is simulated to induce resonance into a porous implant structure. Local strains through the scaffold are measured by varying systemic variables such as damping ratio, applied vibrational force, primary bone-implant stability, and input frequency. At the natural frequency of the system with applied forces of 0.5 N and a damping ratio of 0.5%, roughly half of the nodes in the simulated environment exceed the microstrain threshold of 1000 με required for new bone formation. A high degree of sensitivity was noted upon changing input frequency, with minor sensitivities arising from damping ratio and applied vibrational force. These findings suggest that the application of therapeutic resonance to improve osseointegration of the bone-implant interface may be viable for applications including dental implants or segmental bone defects.

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Author Affiliation

(1) Department of Materials Science and Engineering, McMaster University, Hamilton, ON, Canada.
(2) Center for Industrial Diagnostics and Fluid Dynamics (CDIF), Polytechnic University of Catalonia (UPC), Barcelona, Spain .
(3) Experimental Trauma Surgery, Justus-Liebig-University of Giessen, Germany.
(4) Department of Trauma, Hand, and Reconstructive Surgery, University Hospital of Giessen, Germany.
(5)School of Biomedical Engineering, McMaster University, Hamilton, ON, Canada.