The Impact of Static Distraction for Disc Regeneration in a Rabbit Model—A Longitudinal MRI Study

Abstract

Low back pain is a disabling condition that imposes an enormous socioeconomic burden. Intervertebral disc (IVD) regeneration strategies are ideal goals aiming to provide a better solution. While regeneration occurs with tensile loading of degenerated IVDs, no long-term longitudinal data exists to show the sustained impact of tensile loading under physiological conditions. The aim of this study is to develop an MRI-compatible rabbit IVD distraction model to enable longitudinal monitoring of nutrient supply and regeneration process of degenerated discs. Rabbits were divided into two groups. (1) IVD stabbing, no treatment (2) IVD stabbing, distractor implant on 6 weeks post-stabbing, treated by 120 N tensile force. Under C-arm guidance, L4-5 IVD was stabbed by bone marrow aspirate needle to induce disc degeneration. At 6 weeks post stabbing, baseline IVD degeneration was verified by MRI. Under C-arm guidance, path was created by stainless steel k-wire on L4-5 vertebra and replaced by zirconia k-wire. Distractor was connected to k-wire and 120 N force was applied on rabbit spine. Rabbit disc health was evaluated by MRI at 7, 11- and 15-weeks post distractor implant. Rabbit was euthanized after the last MRI scan. From T2 STIR MRI, disc distraction can arrest the progression of disc degeneration in treated group but further deteriorate in control. Post-contrast MRI showed the improvement of nutrient flow in distracted disc. The development of MRI compatible distractor will allow a longitudinal study of the degenerated disc regeneration process under tensile distraction.