The Mechanical Properties of the Spinal Cord: A Systematic Review

Abstract

BACKGROUND CONTENT: Spinal cord compression is a source of pathology routinely seen in clinical practice. However, there remain unanswered questions surrounding both the understanding of pathogenesis and the best method of treatment. This arises from limited real-life testing of the mechanical properties of the spinal cord, either through cadaveric human specimens or animal testing, both of which suffer from methodological, as well as ethical, issues. PURPOSE: To conduct a review of the literature on the mechanical properties of the spinal cord. STUDY DESIGN/SETTING: A systematic review of the literature on the mechanical properties of the spinal cord is undertaken. PATIENT SAMPLE: All literature reporting the testing of the mechanical properties of the spinal cord. OUTCOME MEASURES: Reported physiological mechanical properties of the spinal cord. METHODS: The methodological quality of the studies has been assessed within the ARRIVE guidelines using the CAMARADES framework and SYRCLE's risk of bias tool. This paper details the methodologies and results of the reported testing. RESULTS: We show that (1) the research quality of previous work does not follow published guidelines on animal treatment or risk of bias, (2) no standard protocol has been employed for sample preparation or mechanical testing, (3) this leads to a wide distribution of results for the tested mechanical properties, not applicable to the living human or animal, and (4) animal testing is not a good proxy for human application. CONCLUSIONS: The findings summarize the sum of current knowledge inherent to the mechanical properties of the spinal cord and may contribute to the development of a physical model which is applicable to the living human for analysis and testing in a controlled and repeatable fashion. Such a model would be the basis for further clinical research to improve outcomes from spinal cord compression.