Effect of needle diameter, type and volume of contrast agent on intervertebral disc degeneration in rats with discography.

PURPOSE: Discography can increase disc degeneration, but the influence of different discography variables on the degeneration of discs has not been reported. The aim of this study was to investigate the effects of discography variables of needle diameter, type of contrast agent and volume of contrast agent on disc degeneration. METHODS: Three separate experiments examined needle diameter, and type and volume of contrast agent. Coccygeal discs (Co7-10) adult male rats were used. X-rays were used to detect the disc height degeneration index at 1, 2 and 4 weeks after the procedure. MRI was used to study the changes in the disc structure and the signal intensity of IVD 2 and 4 weeks after the procedure. Disc water content and histology were measured at 4 weeks after the procedure. RESULTS: A 21-g needle significantly increased disc degeneration when compared with the 30-g needle as detected by X-ray, MRI, disc water content and histology (P < 0.05). Two microlitres of iodine significantly decreased the disc MRI signal and water content at 4 weeks compared with the same volume of normal saline (P < 0.05). Three microlitres of iodine significantly increased disc degeneration when compared with 2 µl iodine, as detected by X-ray, MRI, disc water content and histology at 4 weeks (P < 0.05). CONCLUSION: To reduce disc degeneration after discography, it may be best to choose a smaller needle size, minimize the use of contrast agent and use non-ionic contrast agents with osmotic pressure similar to the intervertebral disc. These slides can be retrieved under Electronic Supplementary Material.