Biomechanical characteristics of cement/gelatin mixture for prevention of cement leakage in vertebral augmentation.

PURPOSE

This study evaluated whether or not the addition of gelatin micro-particles into the polymethyl methacrylate (PMMA) could reduce cement infiltration in cancellous bone of vertebra.

METHODS

Gelatin micro-particles were prepared in various sizes and mixed with PMMA in different densities. Dynamic viscosity of the mixture was measured by a rotational rheometer. Fresh bovine vertebral bodies were sectioned into cylindrical samples. Permeability of the mixture through the samples was tested on a mechanical test machine, and calculated using Darcy's law. The PMMA/gelatin mixture also underwent compressive and bending tests, and their structures were examined by scanning electron microscopy.

RESULTS

The cement/gelatin mixture increased the viscosity. Significant reduction of cement permeability in cancellous bone was determined after the addition of the micro-particles. Micro-particles of 2 % in density and 125-250 μm in size decreased the permeability by 1/3 without any significant change of the cement viscosity. The biomechanical strength was unchanged in compression but decreased by up to 20 % in bending.

CONCLUSIONS

Gelatin micro-particles significantly increased the cement viscosity, reduced the permeability in cancellous bone of vertebra, decreased the flexural strength, but did not affect the compressive strength. Although it suggested a manageable approach in vertebral augmentation, the outcome should be further verified on a cadaveric model or an animal model before the mixture could be used safely and effectively in the clinical treatment.