Testing the impact of discoplasty on the biomechanics of the intervertebral disc with simulated degeneration: An in vitro study

Experimental workflow of the study. The arrow represents the applied load and the resulting moment M.

The intervertebral discs are soft tissues of the spine that are between vertebrae.  In the healthy condition they allow smooth motion.  In case of degeneration, the patient experiences severe pain and motion is hindered. Percutaneous Cement Discoplasty is a surgical technique that has recently been developed to relieve pain in highly degenerated intervertebral discs in patients that cannot undergo major surgery. Little is currently known about the biomechanical effects of discoplasty.

This study aimed at investigating the effects of discoplasty surgery and measuring its impact over the specimen geometry and mechanical behaviour. Tests were performed on porcine specimens in three conditions for each specimen: with intact disc, after simulating disc degeneration, and after discoplasty. An optical system (3D Digital Image Correlation, DIC) was used to measure the surface displacements and strains.

The posterior disc height, range of motion (ROM), and stiffness were measured at the peak load. The specimens were scanned with medical imaging (Computed Tomography, CT) to confirm that the cement distribution was acceptable. Discoplasty recovered the height loss caused by disc degeneration with respect to the intact condition, but it did not impact significantly either the ROM or the stiffness. The strains over the disc surface increased after nucleotomy, while discoplasty concentrated the strains on the endplates.

In conclusion, this preliminary study has shown that discoplasty has the potential of restoring the intervertebral height, opening the neuroforamen as clinically observed, without compromising the spine mobility. This study confirms that this in vitro approach can be used to further investigate discoplasty.

Chloé Techens, Marco Palanca, Peter Endre Éltes, Áron Lazáry, Luca Cristofolini, Testing the impact of discoplasty on the biomechanics of the intervertebral disc with simulated degeneration: An in vitro study, Medical Engineering & Physics,
Volume 84, (2020), Pages 51-59, ISSN 1350-4533.
https://doi.org/10.1016/j.medengphy.2020.07.024