Anatomic and biomechanical properties of human lumbar dura mater.

Determinants of dural defects subsequent to deliberate or accidental dural puncture include the equipment, techniques, and the inherent anatomic and biomechanical properties of dura mater. These properties were studied in specimens of human and canine lumbar dura mater in an attempt to delineate the structure of the tissue and to characterize its behavior in biomechanical terms. Human dura had a longitudinal orientation on gross appearance, and was confirmed microscopically to be composed of longitudinal lamella of collagen and elastin fibers. Longitudinal tensile strength and stiffness were greater than transverse tensile strength and stiffness, which is consistent with the dura's apparent anatomic structure and functional requirements. Additional biomechanical testing of the dura demonstrated the property of relaxation which is a characteristic of a viscoelastic material. Significant differences were observed between human and canine dural properties, suggesting limited value of this animal model. Integration of these observed anatomic and biomechanical properties of the lumbar dura provides a greater understanding of dural puncture and may explain previous and often confusing clinical and experimental findings.