# Biomechanical Comparisons between One- and Two-Compartment Devices for Reconstructing Vertebrae by Kyphoplasty

## TL;DR

This study compared two kyphoplasty devices for spinal reconstruction and found no significant difference in performance, but higher cement volume increased adjacent fractures.

## Contribution

The study provides biomechanical evidence that higher cement volume correlates with adjacent fractures in kyphoplasty.

## Key findings

- Both kyphoplasty devices similarly reconstructed vertebral height without significant difference.
- Higher cement volume was strongly correlated with increased risk of adjacent fractures.
- Adjacent fractures occurred during cyclic loading regardless of device type.

## Abstract

Background: This biomechanical in vitro study compared two kyphoplasty devices for the extent of height reconstruction, load-bearing capacity, cement volume, and adjacent fracture under cyclic loading. Methods: Multisegmental (T11–L3) specimens were mounted into a testing machine and subjected to compression, creating an incomplete burst fracture of L1. Kyphoplasty was performed using a one- or two-compartment device. Then, the testing machine was used for a cyclic loading test of load-bearing capacity to compare the two groups for the amount of applied load until failure and subsequent adjacent fracture. Results: Vertebral body height reconstruction was effective for both groups but not statistically significantly different. After cyclic loading, refracture of vertebrae that had undergone kyphoplasty was not observed in any specimen, but fractures were observed in adjacent vertebrae. The differences between the numbers of cycles and of loads were not statistically significant. An increase in cement volume was strongly correlated with increased risks of adjacent fractures. Conclusion: The two-compartment device was not substantially superior to the one-compartment device. The use of higher cement volume correlated with the occurrence of adjacent fractures.