The Adverse impact of bone cement injection to lower vertebral body on proximal disc in terms of polymerization temperature

Abstract

Introduction: Bone cement, particularly polymethyl methacrylate (PMMA), is commonly used in spinal procedures such as vertebroplasty, kyphoplasty and cement augmented screw to reduce probability of proximal junctional failure. While PMMA provides mechanical stabilization and pain relief, the exothermic polymerization reaction can lead to significant temperature increases, potentially affecting adjacent structures such as proximal disc. This study investigates the polymerization temperature of PMMA in relation to its effects on the proximal intervertebral disc, using both human and porcine cadaver specimens. Materials and Methods: The study involved four porcine cadavers and one human cadaver. The polymerization temperature was measured at various locations within the vertebral body and proximal disc(anterior, middle, posterior) using K-type thermocouples. Two porcine cadavers were experimented in air, the remaining two were tested in a water bath at 37°C reflecting body temperature, and one human cadaver was tested in air. A bi-pedicular approach was used for PMMA injection, and temperature measurements were taken at one-minute intervals for ten minutes post-injection. Results: In porcine cadavers, in the air, average peak temperature at the middle of the disc was 57.1°C and in warm bath, it was 48.2°C. In human cadavers, the average of peak temperature at the disc center measured 52.1°C. Near the PLL, the average peak temperature was 27.1°C and negative correlation was observed between distance from the cement and temperature. Discussion: This study demonstrates that the insertion of PMMA bone cement can raise the temperature of the adjacent intervertebral disc to a critical threshold of 50°C, with the effect depending on the distance from the cement. Temperatures near adjacent nerves did not exceed 50°C, suggesting minimal impact on nerves, though this may vary by proximity. Key limitations include the thermometer's margin of error (±1°C), differences between experimental and in vivo conditions such as body temperature (35–40°C) and blood flow (e.g., Batson's plexus), and the avascular nature of intervertebral discs. Individual variations in muscle and soft tissue distribution and differences in cement quantity and distribution between vertebrae also influence heat diffusion. Conclusions: The study concludes that clinicians should be aware of the exothermic reactions associated with PMMA injection, as they can significantly impact the temperature of adjacent structures, potentially leading to adverse effects such as proximal disc degeneration.