Biomechanical adaptation of the cervical dura mater: a matched comparison of fresh and embalmed specimens.

BACKGROUND

This study aimed to quantify the biomechanical strain of the human cervical spinal dura mater in physiological positions and to directly evaluate the altering effects of formaldehyde embalming.

MATERIALS AND

METHODS

A matched comparative design was employed in eighteen fresh human cadavers. The posterior surface length of the C1-C7 dura mater segment was measured using digital calipers in four standardized headneck positions (neutral, flexion, extension, right rotation). Measurements were first performed in the fresh state, and then repeated on the same specimens following formalin embalming. Strain was calculated relative to the neutral position. Statistical analysis included repeated-measures ANOVA and paired t-tests.

RESULTS

In the fresh state, neck flexion induced significant tensile strain (7.51%), while extension induced compressive strain (-6.28%); right rotation produced minimal strain (-1.87%). Embalming significantly reduced the neutral length of the dura mater and substantially amplified the strain magnitude in both flexion (12.74%, p < 0.001) and extension (-9.55%, p < 0.001), corresponding to relative increases of 69.8% and 53.9%, respectively. A significant interaction was found between specimen state (fresh/embalmed) and neck position (p < 0.001), indicating that the embalming effect was position-dependent.

CONCLUSIONS

This study provides the direct and quantitative evidence that formaldehyde embalming fundamentally alters the biomechanical properties of the human cervical spinal dura mater, leading to a stiffer tissue response with exaggerated strain under load. These findings highlight the native viscoelasticity of fresh tissue and caution against the uncritical extrapolation of biomechanical data from embalmed specimens to living humans. The results establish a critical reference for interpreting existing literature and for selecting appropriate specimen models in future spinal biomechanical research.