EVALUATION OF BONE CEMENT INFILTRATION WITHIN VERTEBRA USING MORPHOLOGICAL PARAMETERS

Abstract

To reduce vertebral fractures, emerging techniques such as vertebroplasty need to be improved by studying cement infiltration and leakage within bone. Thus we investigated samples extracted from lumbar spines using μCT to evaluate morphological parameters (trabecular thickness and separation, structural index). The specific finding is that relevant shifts of the trabecular thickness and separation Gaussian medians associated to sharpened distributions are related to donors’ age. These morphological parameters, correlated to common fluid laws, enable the prediction of bone cement flow within vertebrae and provide new ways for designing biomaterials and estimate key vertebroplasty parameters regarding time, pressure and injection site.

Osteoporosis, a pathological bone decay leading to fractures, is an economical burden on society. A prevalent fracture site is the spine. To avoid vertebral fractures, emerging techniques such as vertebroplasty are used. Nevertheless, the lack of knowledge relating to cement infiltration, distribution and leakage within vertebrae during cement injection interferes with an appropriate medical practice. This study, by assessing morphological parameters, aims at a better understanding of these processes.

The investigation includes size-controlled cylindrical samples (diameter of 18mm and height of 18mm), extracted from five lumbar spines (L1 to L5) of four female donors aged from forty-nine to eighty years old, analysed using micro-Computed Tomography technique (with a voxel size of 18μm*18μm*36μm) and three-dimensional computed reconstructions.

Then morphological parameters such as porosity, trabecular thickness, trabecular separation, tissue surface and structural index were extracted from the reconstructed volume using dedicated software.

The general findings are significant decreases in bone mass and mineral density while porosity increased and bone anisotropy remains unchanged. The specific finding is that relevant shifts of the trabecular thickness and separation Gaussian medians associated to sharpened distributions are related to donors’ age

Previously determined morphological parameters correlated to common fluid laws (Stokes, Reynolds) enable the prediction of bone cement flow, infiltration and leakage during vertebroplasty and thus provide new ways for designing and evaluating biomaterials and estimating key vertebroplasty parameters regarding time, pressure and injection site.

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