Spinal dura mater: biophysical characteristics relevant to medical device development

Abstract

Understanding the relevant biophysical properties of the spinal dura mater is essential to the design of medical devices that will directly interact with this membrane or influence the contents of the intradural space. We searched the literature and reviewed the pertinent characteristics for the design, construction, testing, and imaging of novel devices intended to perforate, integrate, adhere or reside within or outside of the spinal dura mater. The spinal dura mater is a thin tubular membrane composed of collagen and elastin fibres that varies in circumference along its length. Its mechanical properties have been well-described, with the longitudinal tensile strength exceeding the transverse strength. Data on the bioelectric, biomagnetic, optical and thermal characteristics of the spinal dura are limited and sometimes taken to be similar to those of water. While various modalities are available to visualise the spinal dura, magnetic resonance remains the best modality to segment its structure. The reaction of the spinal dura to imposition of a foreign body or other manipulations of it may compromise its biomechanical and immune-protective benefits. Therefore, dural sealants and replacements are of particular clinical, research and commercial interest. In conclusion, existing devices that are in clinical use for spinal cord stimulation, intrathecal access or intradural implantation largely adhere to traditional designs and their attendant limitations. However, if future devices are built with an understanding of the dura’s properties incorporated more fully into the designs, there is potential for improved performance.

Keywords:

• Dura mater
• spine surgery
• electric stimulation
• prostheses and implants
• biophysical characteristics

Acknowledgements

The authors thank University of Iowa colleague Shawn Roach for assistance with preparation of the figures.

Disclosure statement

Drs. Gillies, Reddy, and Howard may receive patent royalties from the commercial license of the I-Patch intradural stimulator’s intellectual properties negotiated by their respective institutions. Drs. Gillies and Howard hold equity in the licensee and serve on its Board of Directors, respectively. Research reported in this publication was supported, in part, by the National Institutes of Health’s National Center for Advancing Translational Sciences [Grant Number TL1TR001423]. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.