Investigation of the Biomechanical Properties of the Human Spinal Cord and Its Connective Tissue

Human cadaver spinal cord specimens with and without intact pia mater were subjected to axial deformation over various strain rates. For those specimens with the pia mater intact, the force response to an applied stretch ratio of 1.1 was independent of strain rate over 0.1 s^-1 to 10 s^-1. Plastic deformation of the specimens was noted when the stretch ratio exceeded 1.06. The neo-Hookean elastic modulus for specimens with intact pia mater was 1.40 MPa. In contrast, the neo-Hookean elastic modulus for specimens with the pia mater incised was 0.09 MPa. These results depict that during axial extension, the pia mater is the load bearing structure.

In addition to axial loading, spinal cord specimens with intact pia mater were subjected to subluxation in a custom designed apparatus. The neo-Hookean elastic modulus was determined to be 1.45 MPa in these studies. 35% occlusion of the vertebral canal by the simulated vertebral discs resulted in an axial stretch ratio of 1.025 and no evidence of plastic deformation. In contrast, 100% occlusion resulted in an axial stretch ratio of 1.2 and gross plastic deformation similar to that observed by MRI after acute spinal cord injury. These results suggest that the vertebral canal can be minimally occluded without significantly stretching the spinal cord in the axial direction.

A novel mechanism for the interaction between the dentate ligaments and pia mater depicted how motion of the dura mater results in deformation of the spinal cord. Individual axons were traced in fixed human spinal cord specimens using the fluorescent tracer Dil. Results from these studies depicted that axons undulate within the neural substance. A tortuosity coefficient was defined and determined for each axon. This inherent undulation of the axons suggests that the spinal cord can undergo deformation without significantly deforming individual axons.

Lastly, a mechanism of spinal cord injury was presented that is capable of predicting a variety of clinical syndromes ranging from transient neurapraxia to quadriplegia. This mechanism and the results described within this thesis can be utilized to refine current biofidelic models of the head-neck complex.

Year	Entry
1993	Saatman KE. An Isolated Single Myelinated Nerve Fiber Model for the Biomechanics of Axonal Injury [PhD thesis]. Philadelphia, PA: University of Pennsylvania; 1993.
1993	Galbraith JA, Thibault LE, Matteson DR. Mechanical and electrical responses of the squid giant axon to simple elongation. J Biomech Eng. February 1993;115(1):13-22.
1994	Bilston LE. The Biomechanics of the Spinal Cord During Traumatic Spinal Cord Injury [PhD thesis]. Philadelphia, PA: University of Pennsylvania; 1994.
1973	Barbenel JC, Evans JH, Finlay JB. Stress-strain-time relations for soft connective tissues. In: Kenedi RM, ed. Perspectives in Biomedical Engineering: Proceedings of a Symposium Organised in Association With the Biological Engineering Society and Held in the University of Strathclyde, Glasgow, June 1972. Baltimore, MD: University Park Press; 1973:165-172.
1995	Yoganandan N, Pintar FA, Maiman DJ, Cusick JF, Sances A Jr. Cervical spinal cord injury using biomechanical experimentation. In: 39th Annual Proceedings, Association for the Advancement of Automotive Medicine (AAAM). October 16-18, 1995; Chicago, IL.149-161.
1983	Sauren AAHJ, Rousseau EPM. A concise sensitivity analysis of the quasi-linear viscoelastic model proposed by Fung. J Biomech Eng. February 1983;105(1):92-95.
1973	Ewing CL, Thomas DJ. Torque versus angular displacement response of human head to -Gx impact acceleration. In: Proceedings of the 17th Stapp Car Crash Conference. November 17-19, 1973; Coronado, CA. Warrendale, PA: Society of Automotive Engineers:309-342. SAE 730976.
1971	Orne D, Liu YK. A mathematical model of spinal response to impact. J Biomech. 1971;4(1):49-71.
1991	Myers BS, McElhaney JH, Doherty BJ. The viscoelastic responses of the human cervical spine in torsion: experimental limitations of quasi-linear theory, and a method for reducing these effects. J Biomech. 1991;24(9):811-817.
1996	LaPlaca MC. Deformation Response and Cytosolic Calcium Increases in NTera2 Neurons Subjected to Traumatic Levels of Hydrodynamic Shear Stress [PhD thesis]. Philadelphia, PA: University of Pennsylvania; 1996.
1993	Fung YC. Biomechanics: Mechanical Properties of Living Tissues. 2nd ed. New York, NY: Springer-Verlag; 1993.
1967	Mertz HJ Jr, Patrick LM. Investigation of the kinematics and kinetics of whiplash. In: Proceedings of the 11th Stapp Car Crash Conference. October 10-11, 1967; Anaheim, CA. Warrendale, PA: Society of Automotive Engineers:267-317. SAE 670919.
1992	Margulies SS, Meaney DF, Bilston LB, Thibault LE, Campeau NG, Riederer SJ. In vivo motion of the human cervical spinal cord in extension and flexion. In: Proceedings of the 1992 International IRCOBI Conference on the Biomechanics of Impact. September 9-11, 1992; Verona, Italy.213-224.
1973	McElhaney JH, Melvin JW, Roberts VL, Portnoy HD. Dynamic characteristics of the tissues of the head. In: Kenedi RM, ed. Perspectives in Biomedical Engineering: Proceedings of a Symposium Organised in Association With the Biological Engineering Society and Held in the University of Strathclyde, Glasgow, June 1972. Baltimore, MD: University Park Press; 1973:215-222.
1972	Fung YC, Perrone N, Anliker M, eds. Biomechanics: Its Foundations and Objectives. Symposium on Biomechanics, its Foundations and Objectives; July 29-31, 1970. Englewood Cliff, NJ: Inc., Prentice-Hall International; 1972.
1988	Galbraith JA. The Effects of Mechanical Loading on the Electrophysiology of the Squid Giant Axon [PhD thesis]. Philadelphia, PA: University of Pennsylvania; 1988.
1983	Lanir Y. Constitutive equations for fibrous connective tissues. J Biomech. 1983;16(1):1-12.
1996	Bilston LE, Thibault LE. The mechanical properties of the human cervical spinal cord in vitro. Ann Biomed Eng. January–February 1996;24(1):67-74.
1984	Wismans J, Spenny CH. Head-neck response in frontal flexion. In: Proceedings of the 28th Stapp Car Crash Conference. November 6-7, 1984; Chicago, IL. Warrendale, PA: Society of Automotive Engineers:161-171. SAE 841666.
1987	Wismans J, Philippens M, van Oorschot E, Kallieris D, Mattern R. Comparison of human volunteer and cadaver head-neck response in frontal flexion. In: Proceedings of the 31st Stapp Car Crash Conference. November 9-11, 1987; New Orleans, LA. Warrendale, PA: Society of Automotive Engineers:1-13. SAE 872194.
1986	Wismans J, van Oorschot H, Woltring HJ. Omni-directional human head-neck response. In: Proceedings of the 30th Stapp Car Crash Conference. October 27-29, 1986; San Diego, CA. Warrendale, PA: Society of Automotive Engineers:313-331. SAE 861893.
1911	Allen AR. Surgery of experimental lesion of spinal cord equivalent to crush injury of fracture dislocation of spinal column: a preliminary report. JAMA. September 9, 1911;58(11):878-880.
1994	Cargill RS II. The Response of Neural-Like Cells to Mechanical Stimuli and Hypoxia [PhD thesis]. Philadelphia, PA: University of Pennsylvania; 1994.
1969	Frisén M, Mägi M, Sonnerup L, Viidik A. Rheological analysis of soft collagenous tissue, I: theoretical considerations. J Biomech. March 1969;2(1):13-20.
1996	Nightingale RW, McElhaney JH, Richardson WJ, Myers BS. Dynamic responses of the head and cervical spine to axial impact loading. J Biomech. March 1996;29(3):307-318.
1971	Mertz HJ, Patrick LM. Strength and response of the human neck. In: Proceedings of the 15th Stapp Car Crash Conference. November 17-19, 1971; Coronado, CA. Warrendale, PA: Society of Automotive Engineers:207-255. SAE 710855.
1988	Chang G-L, Hung T-K, Feng WW. An in-vivo measurement and analysis of viscoelastic properties of the spinal cord of cats. J Biomech Eng. May 1988;110(2):115-122.

Year

Entry

1993

Saatman KE. An Isolated Single Myelinated Nerve Fiber Model for the Biomechanics of Axonal Injury [PhD thesis]. Philadelphia, PA: University of Pennsylvania; 1993.

1993

Galbraith JA, Thibault LE, Matteson DR. Mechanical and electrical responses of the squid giant axon to simple elongation. J Biomech Eng. February 1993;115(1):13-22.

1994

Bilston LE. The Biomechanics of the Spinal Cord During Traumatic Spinal Cord Injury [PhD thesis]. Philadelphia, PA: University of Pennsylvania; 1994.

1973

Barbenel JC, Evans JH, Finlay JB. Stress-strain-time relations for soft connective tissues. In: Kenedi RM, ed. Perspectives in Biomedical Engineering: Proceedings of a Symposium Organised in Association With the Biological Engineering Society and Held in the University of Strathclyde, Glasgow, June 1972. Baltimore, MD: University Park Press; 1973:165-172.

1995

Yoganandan N, Pintar FA, Maiman DJ, Cusick JF, Sances A Jr. Cervical spinal cord injury using biomechanical experimentation. In: 39th Annual Proceedings, Association for the Advancement of Automotive Medicine (AAAM). October 16-18, 1995; Chicago, IL.149-161.

1983

Sauren AAHJ, Rousseau EPM. A concise sensitivity analysis of the quasi-linear viscoelastic model proposed by Fung. J Biomech Eng. February 1983;105(1):92-95.

1973

Ewing CL, Thomas DJ. Torque versus angular displacement response of human head to -Gx impact acceleration. In: Proceedings of the 17th Stapp Car Crash Conference. November 17-19, 1973; Coronado, CA. Warrendale, PA: Society of Automotive Engineers:309-342. SAE 730976.

1971

Orne D, Liu YK. A mathematical model of spinal response to impact. J Biomech. 1971;4(1):49-71.

1991

Myers BS, McElhaney JH, Doherty BJ. The viscoelastic responses of the human cervical spine in torsion: experimental limitations of quasi-linear theory, and a method for reducing these effects. J Biomech. 1991;24(9):811-817.

1996

LaPlaca MC. Deformation Response and Cytosolic Calcium Increases in NTera2 Neurons Subjected to Traumatic Levels of Hydrodynamic Shear Stress [PhD thesis]. Philadelphia, PA: University of Pennsylvania; 1996.

1993

Fung YC. Biomechanics: Mechanical Properties of Living Tissues. 2nd ed. New York, NY: Springer-Verlag; 1993.

1967

Mertz HJ Jr, Patrick LM. Investigation of the kinematics and kinetics of whiplash. In: Proceedings of the 11th Stapp Car Crash Conference. October 10-11, 1967; Anaheim, CA. Warrendale, PA: Society of Automotive Engineers:267-317. SAE 670919.

1992

Margulies SS, Meaney DF, Bilston LB, Thibault LE, Campeau NG, Riederer SJ. In vivo motion of the human cervical spinal cord in extension and flexion. In: Proceedings of the 1992 International IRCOBI Conference on the Biomechanics of Impact. September 9-11, 1992; Verona, Italy.213-224.

1973

McElhaney JH, Melvin JW, Roberts VL, Portnoy HD. Dynamic characteristics of the tissues of the head. In: Kenedi RM, ed. Perspectives in Biomedical Engineering: Proceedings of a Symposium Organised in Association With the Biological Engineering Society and Held in the University of Strathclyde, Glasgow, June 1972. Baltimore, MD: University Park Press; 1973:215-222.

1972

Fung YC, Perrone N, Anliker M, eds. Biomechanics: Its Foundations and Objectives. Symposium on Biomechanics, its Foundations and Objectives; July 29-31, 1970. Englewood Cliff, NJ: Inc., Prentice-Hall International; 1972.

1988

Galbraith JA. The Effects of Mechanical Loading on the Electrophysiology of the Squid Giant Axon [PhD thesis]. Philadelphia, PA: University of Pennsylvania; 1988.

1983

Lanir Y. Constitutive equations for fibrous connective tissues. J Biomech. 1983;16(1):1-12.

1996

Bilston LE, Thibault LE. The mechanical properties of the human cervical spinal cord in vitro. Ann Biomed Eng. January–February 1996;24(1):67-74.

1984

Wismans J, Spenny CH. Head-neck response in frontal flexion. In: Proceedings of the 28th Stapp Car Crash Conference. November 6-7, 1984; Chicago, IL. Warrendale, PA: Society of Automotive Engineers:161-171. SAE 841666.

1987

Wismans J, Philippens M, van Oorschot E, Kallieris D, Mattern R. Comparison of human volunteer and cadaver head-neck response in frontal flexion. In: Proceedings of the 31st Stapp Car Crash Conference. November 9-11, 1987; New Orleans, LA. Warrendale, PA: Society of Automotive Engineers:1-13. SAE 872194.

1986

Wismans J, van Oorschot H, Woltring HJ. Omni-directional human head-neck response. In: Proceedings of the 30th Stapp Car Crash Conference. October 27-29, 1986; San Diego, CA. Warrendale, PA: Society of Automotive Engineers:313-331. SAE 861893.

1911

Allen AR. Surgery of experimental lesion of spinal cord equivalent to crush injury of fracture dislocation of spinal column: a preliminary report. JAMA. September 9, 1911;58(11):878-880.

1994

Cargill RS II. The Response of Neural-Like Cells to Mechanical Stimuli and Hypoxia [PhD thesis]. Philadelphia, PA: University of Pennsylvania; 1994.

1969

Frisén M, Mägi M, Sonnerup L, Viidik A. Rheological analysis of soft collagenous tissue, I: theoretical considerations. J Biomech. March 1969;2(1):13-20.

1996

Nightingale RW, McElhaney JH, Richardson WJ, Myers BS. Dynamic responses of the head and cervical spine to axial impact loading. J Biomech. March 1996;29(3):307-318.

1971

Mertz HJ, Patrick LM. Strength and response of the human neck. In: Proceedings of the 15th Stapp Car Crash Conference. November 17-19, 1971; Coronado, CA. Warrendale, PA: Society of Automotive Engineers:207-255. SAE 710855.

1988

Chang G-L, Hung T-K, Feng WW. An in-vivo measurement and analysis of viscoelastic properties of the spinal cord of cats. J Biomech Eng. May 1988;110(2):115-122.

Year	Entry
2022	Rycman AL. Computational Modeling of the Cervical Spinal Cord: Integration Into a Human Body Model to Investigate Response to Impact [PhD thesis]. University of Waterloo; 2022.

Year

Entry

2022

Rycman AL. Computational Modeling of the Cervical Spinal Cord: Integration Into a Human Body Model to Investigate Response to Impact [PhD thesis]. University of Waterloo; 2022.