Material properties of human vertebral trabecular bone under compression can be predicted based on quantitative computed tomography

Dominic Gehweiler,Martin Schulze,Oliver Riesenbeck,Marius Schultz,Michael J. Raschke,Dirk Wähnert

doi:10.1186/s12891-021-04571-4

Abstract

BackgroundThe prediction of the stability of bones is becoming increasingly important. Especially osteoporotic vertebral body fractures are a growing problem and an increasing burden on the health system. Therefore, the aim of this study was to provide the best possible description of the relationship between the material properties of human vertebral trabecular bone measured under the most physiological conditions possible and the bone mineral density (BMD) determined by clinical quantitative computed tomography (QCT).MethodsForty eight cylindric cancellous bone samples with a diameter of 7.2 mm obtained from 13 human fresh-frozen lumbar vertebrae from 5 donors (3 men, 2 women) have been used for this study. After the specimens were temporarily reinserted into the vertebral body, the QCT was performed. For mechanical testing, the samples were embedded in a load-free manner using polymethylmetacrylate (PMMA). The surrounding test chamber was filled with phosphate buffered saline (PBS) and heated to 37 °C during the test. After 10 preconditioning load cycles, destructive testing was performed under axial compression. After determining the fracture site, BMD has been evaluated in this region only. Regression analyses have been performed.ResultsFracture site had an average length of 2.4 (±1.4) mm and a position of 43.9 (±10.9) percent of the measurement length from the cranial end. No fracture reached the embedding. The average BMD at the fracture site was 80.2 (±28.7 | min. 14.5 | max. 137.8) mgCaHA/ml.In summary the results of the regression analyses showed for all three parameters a very good quality of fit by a power regression.ConclusionThe results of this study show that QCT-based bone density measurements have a good predictive power for the material properties of the vertebral cancellous bone measured under near to physiological conditions. The mechanical bone properties of vertebral cancellous bone could be modelled with high accuracy in the investigated bone density range.

Highlights

The prediction of the stability of bones is becoming increasingly important
The results of this study show that quantitative computed tomography (QCT)-based bone density measurements have a good predictive power for the material properties of the vertebral cancellous bone measured under near to physiological conditions
The mechanical bone properties of vertebral cancellous bone could be modelled with high accuracy in the investigated bone density range

Summary

Introduction

Osteoporotic vertebral body fractures are a growing problem and an increasing burden on the health system. The prediction of the mechanical integrity of bones is becoming increasingly important. In an ageing society, osteoporotic vertebral body fractures are a growing problem and an increasing burden on the health system [1, 2]. A valid clinical method for predicting fracture probabilities and bone strength could help to address this problem and allow the development of an appropriate strategy to prevent osteoporotic fractures or implant failure. Biomechanical material properties are indispensable for making predictions about the mechanical integrity of the vertebral bone. They can be measured in vitro, but not non-invasively in vivo

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