Predicting the Fracture Toughness of Human Cancellous Bone in Fractured Neck of Femur Patients Using Bone Volume and Micro-Architecture

George J Adams; Richard B Cook; Michael Gibson; Peter Zioupos

doi:10.3390/life14040467

Predicting the Fracture Toughness of Human Cancellous Bone in Fractured Neck of Femur Patients Using Bone Volume and Micro-Architecture

Life (Basel). 2024 Apr 3;14(4):467. doi: 10.3390/life14040467.

Authors

George J Adams¹, Richard B Cook², Michael Gibson¹, Peter Zioupos³

Affiliations

¹ Cranfield Forensic Institute, Cranfield University, Cranfield MK43 0AL, UK.
² nCATS, School of Engineering Science, University of Southampton, Southampton SO17 1BJ, UK.
³ Biomedical Engineering Research Group, School of Engineering, University of Hull, Kingston upon Hull HU6 7RX, UK.

Abstract

The current protocol used to determine if an individual is osteoporotic relies on assessment of the individual's bone mineral density (BMD), which allows clinicians to judge the condition of a patient with respect to their peers. This, in essence, evaluates a person's fracture risk, because BMD is a good surrogate measure for strength and stiffness. In recent studies, the authors were the first to produce fracture toughness (FT) data from osteoporotic (OP) and osteoarthritic (OA) patients, by using a testing technique which basically analyzes the prerequisite stress conditions for the onset of growth of a major crack through cancellous bone tissue. FT depends mainly on bone quantity (BV/TV, bone volume/tissue volume), but also on bone micro-architecture (mArch), the inner trabecular design of the bone. The working research hypothesis of the present study is that mArch offers added prediction power to BV/TV in determining FT parameters. Consequently, our aim was to investigate the use of predictive models for fracture toughness and also to investigate if there are any significant differences between the models produced from samples loaded across (A_C, transverse to) the main trabecular orientation and along (A_L, in parallel) the trabeculae. In multilinear regression analysis, we found that the strength of the relationships varied for a crack growing in these two orthogonal directions. Adding mArch variables in the Ac direction helped to increase the R² to 0.798. However, in the A_L direction, adding the mArch parameters did not add any predictive power to using BV/TV alone; BV/TV on its own could produce R² = 0.730. The present results also imply that the anisotropic layout of the trabeculae makes it more difficult for a major crack to grow transversely across them. Cancellous bone models and remodels itself in a certain way to resist fracture in a specific direction, and thus, we should be mindful that architectural quality as well as bone quantity are needed to understand the resistance to fracture.

Keywords: BV/TV; cancellous bone; crack growth; fracture toughness; micro-architecture; microCT; multi-regression predictions.

Grants and funding

The authors acknowledge the support provided by the UK Department of Transport under the BOSCOS (Bone Scanning for Occupant Safety) program and the Engineering and Physical Science Research Council (EPSRC under GR/N33225; GR/N33102; GR/M59167; and EP/K020196/1).