Static and dynamic bending responses of the human cervical spine.
The quasi-static and dynamic bending responses of the human mid-lower cervical spine were determined using cadaver intervertebral joints fixed at the base to a six-axis load cell. Flexion bending moment was applied to the superior end of the specimen using an electrohydraulic piston. Each specimen was tested under three cycles of quasi-static load-unload and one high-speed dynamic load. A total of five specimens were included in this study. The maximum intervertebral rotation ranged from 11.0 to 15.4 deg for quasi-static tests and from 22.9 to 34.4 deg for dynamic tests. The resulting peak moments at the center of the intervertebral joint ranged from 3.8 to 6.9 Nm for quasi-static tests and from 14.0 to 31.8 Nm for dynamic tests. The quasi-static stiffness ranged from 0.80 to 1.35 Nm/deg with a mean of 1.03 Nm/deg (+/- 0.11 Nm/deg). The dynamic stiffness ranged from 1.08 to 2.00 Nm/deg with a mean of 1.50 Nm/deg (+/- 0.17 Nm/deg). The differences between the two stiffnesses were statistically significant (p < 0.01). Exponential functions were derived to describe the quasi-static and dynamic moment-rotation responses. These results provide input data for lumped-parameter models and validation data for finite element models to better investigate the biomechanics of the human cervical spine.
Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, USA.
L M
LM
Voo
F A
FA
Pintar
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N
Yoganandan
Y K
YK
Liu
D000368:Aged; D000369:Aged, 80 and over; D015982:Bias; D002102:Cadaver; D002574:Cervical Vertebrae / Q000502:physiology*; D019245:Compressive Strength; D004548:Elasticity; D020342:Finite Element Analysis; D006801:Humans; D008875:Middle Aged; D008954:Models, Biological; D016059:Range of Motion, Articular / Q000502:physiology*; D015203:Reproducibility of Results; D012399:Rotation; D016474:Weight-Bearing / Q000502:physiology