This research was supported by funding from the Eunice Kennedy Shriver National Institute of Child Health and Human Development of the National Institutes of Health under Award Number R15HD093024 and R01HD104910A and NSF CAREER Award Number 1752513.

Biomechanical Analysis of Peripheral Nerves Using DLT-Calibrated Stereo-Imaging

<ol>
	<li>Bueno, F. R., Shah, S. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Implications+of+tensile+loading+for+the+tissue+engineering+of+nerves.">Implications of tensile loading for the tissue engineering of nerves.</a> Tissue Engineering Part B: Reviews. 14 (3), 219-233 (2008).</li><li>Grewal, R., Xu, J., Sotereanos, D. G., Woo, S. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biomechanical+properties+of+peripheral+nerves.">Biomechanical properties of peripheral nerves.</a> Hand Clinics. 12 (2), 195-204 (1996).</li><li>Papagiannis, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biomechanical+behavior+and+viscoelastic+properties+of+peripheral+nerves+subjected+to+tensile+stress:+common+injuries+and+current+repair+techniques.">Biomechanical behavior and viscoelastic properties of peripheral nerves subjected to tensile stress: common injuries and current repair techniques.</a> Critical Reviews in Physical and Rehabilitation Medicine. 32 (3), 155-168 (2020).</li><li>Castaldo, J., Ochoa, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanical+injury+of+peripheral+nerves.+Fine+structure+and+dysfunction.">Mechanical injury of peripheral nerves. Fine structure and dysfunction.</a> Clinics in Plastic Surgery. 11 (1), 9-16 (1984).</li><li>Singh, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Extent+of+impaired+axoplasmic+transport+and+neurofilament+compaction+in+traumatically+injured+axon+at+various+strains+and+strain+rates.">Extent of impaired axoplasmic transport and neurofilament compaction in traumatically injured axon at various strains and strain rates.</a> Brain Injury. 31 (10), 1387-1395 (2017).</li><li>Singh, A., Kallakuri, S., Chen, C., Cavanaugh, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Structural+and+functional+changes+in+nerve+roots+due+to+tension+at+various+strains+and+strain+rates:+an+in-vivo+study.">Structural and functional changes in nerve roots due to tension at various strains and strain rates: an in-vivo study.</a> Journal of Neurotrauma. 26 (4), 627-640 (2009).</li><li>Singh, A., Lu, Y., Chen, C., Kallakuri, S., Cavanaugh, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+new+model+of+traumatic+axonal+injury+to+determine+the+effects+of+strain+and+displacement+rates.">A new model of traumatic axonal injury to determine the effects of strain and displacement rates.</a> Stapp Car Crash Journal. 50, 601 (2006).</li><li>Singh, A., Lu, Y., Chen, C., Cavanaugh, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanical+properties+of+spinal+nerve+roots+subjected+to+tension+at+different+strain+rates.">Mechanical properties of spinal nerve roots subjected to tension at different strain rates.</a> Journal of Biomechanics. 39 (9), 1669-1676 (2006).</li><li>Singh, A., Shaji, S., Delivoria-Papadopoulos, M., Balasubramanian, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biomechanical+responses+of+neonatal+brachial+plexus+to+mechanical+stretch.">Biomechanical responses of neonatal brachial plexus to mechanical stretch.</a> Journal of Brachial Plexus and Peripheral Nerve Injury. 13 (01), e8-e14 (2018).</li><li>Zapa&#322;owicz, K., Radek, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanical+properties+of+the+human+brachial+plexus.">Mechanical properties of the human brachial plexus.</a> Neurologia I Neurochirurgia Polska. 34, 89-93 (2000).</li><li>Zapa&#322;owicz, K., Radek, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Annales Academiae Medicae Stetinensis. 51 (2), 11-14 (2005).</li><li>Zapa&#322;owicz, K., Radek, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+distribution+of+brachial+plexus+lesions+after+experimental+traction:+a+cadaveric+study.">The distribution of brachial plexus lesions after experimental traction: a cadaveric study.</a> Journal of Neurosurgery: Spine. 29 (6), 704-710 (2018).</li><li>Kawai, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stretching+of+the+brachial+plexus+in+rabbits.">Stretching of the brachial plexus in rabbits.</a> Acta Orthopaedica Scandinavica. 60 (6), 635-638 (1989).</li><li>Marani, E., Van Leeuwen, J., Spoor, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+tensile+testing+machine+applied+in+the+study+of+human+nerve+rupture:+a+preliminary+study.">The tensile testing machine applied in the study of human nerve rupture: a preliminary study.</a> Clinical Neurology and Neurosurgery. 95, 33-35 (1993).</li><li>Lee, S. K., Wolfe, S. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Peripheral+nerve+injury+and+repair.">Peripheral nerve injury and repair.</a> JAAOS-Journal of the American Academy of Orthopaedic Surgeons. 8 (4), 243-252 (2000).</li><li>Rickett, T., Connell, S., Bastijanic, J., Hegde, S., Shi, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functional+and+mechanical+evaluation+of+nerve+stretch+injury.">Functional and mechanical evaluation of nerve stretch injury.</a> Journal of Medical Systems. 35, 787-793 (2011).</li><li>Topp, K. S., Boyd, B. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Structure+and+biomechanics+of+peripheral+nerves:+nerve+responses+to+physical+stresses+and+implications+for+physical+therapist+practice.">Structure and biomechanics of peripheral nerves: nerve responses to physical stresses and implications for physical therapist practice.</a> Physical Therapy. 86 (1), 92-109 (2006).</li><li>Lu, Y., Chen, C., Kallakuri, S., Patwardhan, A., Cavanaugh, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+an+in+vivo+method+to+investigate+biomechanical+and+neurophysiological+properties+of+spine+facet+joint+capsules.">Development of an in vivo method to investigate biomechanical and neurophysiological properties of spine facet joint capsules.</a> European Spine Journal. 14 (6), 565-572 (2005).</li><li>Kallakuri, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tensile+stretching+of+cervical+facet+joint+capsule+and+related+axonal+changes.">Tensile stretching of cervical facet joint capsule and related axonal changes.</a> European Spine Journal. 17 (4), 556-563 (2008).</li><li>Abdel-Aziz, Y. I., Karara, H. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct+linear+transformation+from+comparator+coordinates+into+object+space+coordinates+in+close-range+photogrammetry.">Direct linear transformation from comparator coordinates into object space coordinates in close-range photogrammetry.</a> Photogrammetric Engineering &amp; Remote Sensing. 81 (2), 103-107 (2015).</li><li>Pourcelot, P., Audigi&#233;, F., Degueurce, C., Geiger, D., Denoix, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+method+to+synchronise+cameras+using+the+direct+linear+transformation+technique.">A method to synchronise cameras using the direct linear transformation technique.</a> Journal of Biomechanics. 33 (12), 1751-1754 (2000).</li><li>Hedrick, T. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Software+techniques+for+two-+and+three-dimensional+kinematic+measurements+of+biological+and+biomimetic+systems.">Software techniques for two- and three-dimensional kinematic measurements of biological and biomimetic systems.</a> Bioinspiration &amp; Biomimetics. 3 (3), 034001 (2008).</li><li>Chen, L., Armstrong, C. W., Raftopoulos, D. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+investigation+on+the+accuracy+of+three-dimensional+space+reconstruction+using+the+direct+linear+transformation+technique.">An investigation on the accuracy of three-dimensional space reconstruction using the direct linear transformation technique.</a> Journal of Biomechanics. 27 (4), 493-500 (1994).</li><li>Singh, A., Magee, R., Balasubramanian, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Methods+for+in+vivo+biomechanical+testing+on+brachial+plexus+in+neonatal+piglets.">Methods for in vivo biomechanical testing on brachial plexus in neonatal piglets.</a> Journal of Visualized Experiments. (154), e59860 (2019).</li><li>Black, J., Ellis, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multi+camera+image+tracking.">Multi camera image tracking.</a> Image and Vision Computing. 24 (11), 1256-1267 (2006).</li><li>Cardenas-Garcia, J. F., Yao, H. G., Zheng, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=3D+reconstruction+of+objects+using+stereo+imaging.">3D reconstruction of objects using stereo imaging.</a> Optics and Lasers in Engineering. 22 (3), 193-213 (1995).</li><li>Mahan, M. A., Yeoh, S., Monson, K., Light, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+stretch+injury+to+peripheral+nerves:+biomechanical+results.">Rapid stretch injury to peripheral nerves: biomechanical results.</a> Neurosurgery. 85 (1), E137-E144 (2019).</li><li>Rydevik, B. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+in+vitro+mechanical+and+histological+study+of+acute+stretching+on+rabbit+tibial+nerve.">An in vitro mechanical and histological study of acute stretching on rabbit tibial nerve.</a> Journal of Orthopaedic Research. 8 (5), 694-701 (1990).</li><li>Mahan, M. A., Warner, W. S., Yeoh, S., Light, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid-stretch+injury+to+peripheral+nerves:+implications+from+an+animal+model.">Rapid-stretch injury to peripheral nerves: implications from an animal model.</a> Journal of Neurosurgery. 133 (5), 1537-1547 (2019).</li><li>Singh, A., Ferry, D., Balasubramanian, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Efficacy+of+clinical+simulation+based+training+in+biomedical+engineering+education.">Efficacy of clinical simulation based training in biomedical engineering education.</a> Journal of Biomechanical Engineering. 141 (12), 121011-121017 (2019).</li></ol>

The authors have no conflicts of interest to disclose.

Studies reporting biomechanical properties of peripheral nerves (PNs) because of stretch injury vary, and that variation can be attributed to testing methodologies such as testing equipment and elongation analysis5,6,7,8,9,10,11,12,<sup class="xr...

Peripheral nerves (PNs) undergo stretch during development, growth, normal joint movement, injury, and surgery1. PNs display viscoelastic properties to protect the nerve during regular movements2,3 and maintain the structural health of its nerve fibers2. Because PN response to mechanical stretch has been shown to depend on the type of nerve fiber damage4, injuries to adjacent connective tissues2,4, and testing approaches (i.e., loading rate or direction)5,6,7,8,9,10,11,12,13,14, it is essential to distinguish the biomechanical responses of PNs during normal range of motion versus non-physiological range at both slow- and rapid-stretch rates. This can further the understanding of the PN injury mechanism in response to stretch and aid in timely and optimized intervention1,4,15,16. There has been a growing trend in physical therapy to evaluate and intervene based on the relationship between nerve physiology and biomechanics17. By understanding the differences in PN biomechanics at various applied loads, physical therapists can be better prepared to modify current interventions17.
Available biomechanical data of PNs in response to stretch remains variable and can be attributed to testing equipment and procedures and differences in elongation data analysis5,6,7,8,9,10,11,12,13,14,16. Furthermore, measuring three-dimensional (3D) in-situ nerve displacement remains poorly described in the currently available literature. Previous studies have used stereo-imaging techniques to maximize the accuracy of 3D reconstruction of tissue displacement of facet joint capsules18,19. The direct linear transformation (DLT) technique enables the conversion of two or more two-dimensional (2D) views to 3D real-world coordinates (i.e., in mm)20,21,22. DLT provides a high-accuracy calibration method for stereo-imaging camera systems because it enables precise reconstruction of 3D positions, accounting for lens distortion, camera parameters, and image coordinates, and permits flexibility in stereo-imaging camera setup20,21,22. Studies using DLT-calibrated stereo-imaging camera systems are typically used to study locomotion and gait analysis22,23. This protocol aims to offer a detailed methodology to determine the in-situ strain of PNs at varying degrees of stretch using a DLT-calibrated stereo-imaging camera system and an open-source tracking software22.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Clear Acrylic Plexiglass Square Sheet</td>
			<td>W W Grainger Inc</td>
			<td>BULKPSACR9</td>
			<td>Construct three-dimensional control volume</td>
		</tr>
		<tr>
			<td>Stereo-imaging camera system - ZED Mini Stereo Camera</td>
			<td>StereoLabs Inc.</td>
			<td>N/A</td>
			<td>N/A</td>
		</tr>
		<tr>
			<td>Imaging Software - ZED SDK</td>
			<td>StereoLabs Inc.</td>
			<td>N/A</td>
			<td>N/A</td>
		</tr>
		<tr>
			<td>Maintence Software - CUDA 12</td>
			<td>StereoLabs Inc.</td>
			<td>N/A</td>
			<td>Download to run ZED SDK&#160;</td>
		</tr>
		<tr>
			<td>Camera stand - Cast Iron Triangular Support Stand with Rod</td>
			<td>Telrose VWR Choice</td>
			<td>76293-346</td>
			<td>N/A</td>
		</tr>
		<tr>
			<td>MicroSribe G2 Digitizer with Immersion Foot Pedal</td>
			<td>SUMMIT Technology Group</td>
			<td>N/A</td>
			<td>N/A</td>
		</tr>
		<tr>
			<td>Proramming Software - MATLAB&#160;</td>
			<td>Mathworks</td>
			<td>N/A</td>
			<td>version 2019A or newer</td>
		</tr>
		<tr>
			<td>DLTcal5.m</td>
			<td>Hedrick lab</td>
			<td>N/A</td>
			<td>Open Source</td>
		</tr>
		<tr>
			<td>DLTdv7.m</td>
			<td>Hedrick lab</td>
			<td>N/A</td>
			<td>Open Source</td>
		</tr>
	</tbody>
</table>

direct linear transformation for the measurement of in-situ peripheral nerve strain during stretching

Peripheral nerves undergo physiological and non-physiological stretch during development, normal joint movement, injury, and more recently while undergoing surgical repair. Understanding the biomechanical response of peripheral nerves to stretch is critical to the understanding of their response to different loading conditions and thus, to optimizing treatment strategies and surgical interventions. This protocol describes in detail the calibration process of the stereo-imaging camera system via direct linear transformation and the tracking of the three-dimensional in-situ tissue displacement of peripheral nerves during stretch, obtained from three-dimensional coordinates of the video files captured by the calibrated stereo-imaging camera system.
From the obtained three-dimensional coordinates, the nerve length, change in the nerve length, and percent strain with respect to time can be calculated for a stretched peripheral nerve. Using a stereo-imaging camera system provides a non-invasive method for capturing three-dimensional displacements of peripheral nerves when stretched. Direct linear transformation enables three-dimensional reconstructions of peripheral nerve length during stretch to measure strain. Currently, no methodology exists to study the in-situ strain of stretched peripheral nerves using a stereo-imaging camera system calibrated via direct linear transformation. Capturing the in-situ strain of peripheral nerves when stretched can not only aid clinicians in understanding underlying injury mechanisms of nerve damage when overstretched but also help optimize treatment strategies that rely on stretch-induced interventions. The methodology described in the paper has the potential to enhance our understanding of peripheral nerve biomechanics in response to stretch to improve patient outcomes in the field of nerve injury management and rehabilitation.

Stereo-Imaging System DLT Calibration to Capture 3D In Situ Displacements of Stretched Peripheral Nerves

Direct Linear Transformation for the Measurement of In-Situ Peripheral Nerve Strain During Stretching

Using the described methodology, various output files are obtained. The DLTdv7.m *_xyzpts.csv (Supplemental File 12) contains the (x, y, z) coordinates in millimeters of each tracked point at each time frame that is further used to calculate the length, change in length, and strain of the stretched PN. Representative length-time, change in length-time, and strain-time plots of a stretched PN are shown in Figure 10. The stretched PN had an insertion marker, four markers along...

Read this Scientific Article Protocol about Direct Linear Transformation for the Measurement of In-Situ Peripheral Nerve Strain During Stretching at JoVE.com

This protocol implements a stereo-imaging camera system calibrated using direct linear transformation to capture three-dimensional in-situ displacements of stretched peripheral nerves. By capturing these displacements, strain induced at varying degrees of stretch can be determined informing the stretch injury thresholds that can advance the science of stretch-dependent nerve repair.

Peripheral nerves undergo physiological and non-physiological stretch during development, normal joint movement, injury, and more recently while ...

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276 Views.  Drexel University. This protocol implements a stereo-imaging camera system calibrated using direct linear transformation to capture three-dimensional in-situ displacements of stretched peripheral nerves. By capturing these displacements, strain induced at varying degrees of stretch can be determined informing the stretch injury thresholds that can advance the science of stretch-dependent nerve repair. 