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Tensile Properties of the Human Muscular and Ligamentous Cervical Spine
Technical Paper
2000-01-SC07
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English
Abstract
Tensile neck injuries are amongst the most serious cervical
injuries. However, because neither reliable human cervical tensile
tolerance data nor tensile structural data are currently available,
the quantification of tensile injury risk is limited. The purpose
of this study is to provide previously unavailable kinetic and
tolerance data for the ligamentous cervical spine and determine the
effect of neck muscle on tensile load response and tolerance. Using
six male human cadaver specimens, isolated ligamentous cervical
spine tests (occiput - T1) were conducted to quantify the
significant differences in kinetics due to head end condition and
anteroposterior eccentricity of the tensile load. The spine was
then separated into motion segments for tension failure testing.
The upper cervical spine tolerance of 2400 ± 270 N (occiput- C2)
was found to be significantly greater (p< 0.01) than the lower
cervical spine tolerance of 1780 ± 230 N (C4-C5 and C6-C7
segments). Data from these experiments were used to develop and
validate a computational model of the ligamentous spine. The model
predicted the end condition and eccentricity responses for the
tensile force-displacement relationship. Cervical muscular geometry
data derived from cadaver dissection and MRI imaging were used to
incorporate a muscular response into the model. The cervical
musculature under maximal stimulation increased the tolerance of
the cervical spine from 1800 N to 4160 N. In addition, the cervical
musculature resulted in a shift in the site of injury from the
lower cervical spine to the upper cervical spine and offers an
explanation for the mechanism of upper cervical spine tension
injuries observed clinically. The results from this study predict a
range in tensile tolerance from 1.8 - 4.2 kN based on the varying
role of the cervical musculature.