Understanding Inaccuracy and Low Repeatability in Bone Torsional Mechanical Testing

Understanding Inaccuracy and Low Repeatability in Bone Torsional Mechanical Testing | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Understanding Inaccuracy and Low Repeatability in Bone Torsional Mechanical Testing Hexin Zhang, Mei Wang, Yu Deng, Terry Y.P. Yuen, Chin Fhong Soon, and 10 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8874800/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract This study aims to raise awareness about the widespread use of flawed torsion test setups for measuring the torsional mechanical properties of bones, prevalent in both past research and current practices. It addresses critical inaccuracies in bone torsion testing that impact the understanding of key properties such as torsional rigidity and shear modulus. The widely adopted machine-mounted angle transducer (MMAT) often leads to incorrect measurements by combining specimen, machine and parts’ rotations, introducing errors from slippage, mechanical tolerances and other resources. To correct this, a specimen-mounted angle transducer (SMAT) was developed using standard laboratory equipment, including linear variable differential transformers (LVDTs) and metal pins. The SMAT focuses solely on the central bone specimen's rotation, offering more precise measurements. Torsion tests were conducted on eight porcine femur samples, and finite-element twin (FE-twin) models were developed through 3D scanning of bone geometry. These models were calibrated using MMAT and SMAT data to evaluate differences in torsional rigidity and shear modulus. The results revealed significant discrepancies between MMAT-based data and literature values, while SMAT-based tests aligned more accurately with theoretical predictions and strain gauge measurements. Additionally, scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) analyses highlighted micro structural differences between fractured and unfractured bones. The findings underscore the importance of accurate torsion testing for clinical and research applications, offering improved methods for designing orthopaedic devices and assessing bone health. Biomedical Engineering Mechanical Engineering Bone Mechanical property Torsional rigidity Torsional stiffness Torsion test Finite Element-Twins Microstructure Full Text Additional Declarations The authors declare no competing interests. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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It addresses critical inaccuracies in bone torsion testing that impact the understanding of key properties such as torsional rigidity and shear modulus. The widely adopted machine-mounted angle transducer (MMAT) often leads to incorrect measurements by combining specimen, machine and parts\u0026rsquo; rotations, introducing errors from slippage, mechanical tolerances and other resources. To correct this, a specimen-mounted angle transducer (SMAT) was developed using standard laboratory equipment, including linear variable differential transformers (LVDTs) and metal pins. The SMAT focuses solely on the central bone specimen's rotation, offering more precise measurements. Torsion tests were conducted on eight porcine femur samples, and finite-element twin (FE-twin) models were developed through 3D scanning of bone geometry. These models were calibrated using MMAT and SMAT data to evaluate differences in torsional rigidity and shear modulus. The results revealed significant discrepancies between MMAT-based data and literature values, while SMAT-based tests aligned more accurately with theoretical predictions and strain gauge measurements. Additionally, scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) analyses highlighted micro structural differences between fractured and unfractured bones. 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