The Influence of Kyphoplasty on the Progression of Intervertebral Disc Degeneration: a Retrospective Cohort Study

Abstract Background: The effect of kyphoplasty or rather Polymethylmethacrylate (PMMA) on adjacent intervertebral discs is still controversial. The evidence from experimental study to clinical study presents bipolar conclusions. Therefore, in this study, we aimed to investigate the influence of percutaneous kyphoplasty (PKP) on adjacent intervertebral discs degeneration (IDD).Methods: The adjacent intervertebral discs of vertebral treated by PKP procedure are classified as experimental group, and the adjacent intervertebral discs of non-traumatized vertebral are included in the control group. The intervertebral disc height are compared by using the Mann-Whitney U test. Modified Pfirrmann Scores (MPS) differences were compared by using simple regression analysis after eliminating the influence of time. The relationship between the quantity of intradiscal cement leakage and the progression rate of disc degeneration was assessed by using MPS differences and Z Klezl and S Patel (ZK and SP) classification with simple regression analysis. Results. 264 intervertebral discs of 66 people were finally selected for the study. The comparison of intervertebral disc height differences results with a p-value of > 0.05. Comparing with MPS differences between 2 groups, in terms of upper disc scores difference, the degree of degeneration (MPS differences) increases by 0.394 compared with the control group, regardless of lower disc scores difference, MPS differences increases by 0.333 compared with the control group. Comparing the ZK and SP grade and the MPS differences of upper / lower intervertebral disc, each increase of the grade will increase the MPS differences by 0.123 / 0.155 compared with the previous level. Conclusion: PKP procedure can accelerate adjacent IDD but would not cause disc height changes in the early stage. The quantity of cement leaking into the disc space is positively correlated with the rate of progression of disc degeneration.