Microdialysis Technique for Quantifying Drug Concentration in Human Intervertebral Discs

New diagnostic and treatment techniques for chronic lower back pain involve localized drug delivery into the lumbar intervertebral disc [1,2]. A better understanding of these new techniques could be gained by measuring drug concentration at specific intradiscal locations at different time points [1]. Currently, there are no established methods for quantifying real-time in situ drug concentrations in the human intervertebral disc; however, injection profiles have been successfully characterized in pig disc, human brain, adipose tissue, and blood using microdialysis [3,4,5]. This technique involves continuous sampling of interstitial fluid via semi-permeable membranes mounted on miniature, implantable catheters [6]. Given the success of microdialysis in characterizing the real-time composition of other poroelastic tissues, we hypothesize that this method will be similarly successful when applied to human lumbar disc.