Anatomical Variation of Human Bone Bioapatite Crystallography

Brittany Foley,Wolfgang W Schmahl,Martina Greiner,George Mcglynn

doi:10.3390/cryst10100859

Abstract

This systematic investigation of bioapatite, the mineral component of human bone, aims to characterize its crystallographic state, including lattice parameters and average crystallite size, and correlate these values with respect to anatomical position (bone function), physicality, and bone chemical composition. In sample sets of buried bone from three different human adult skeletons, anatomical variation of crystallographic parameters and correlation to chemical composition were indeed observed. In general, the observed bioapatite a unit-cell edge-length among all analyzed human bones in this study was larger by 0.1–0.2% compared to that of stoichiometric hydroxylapatite (HAp), and substantially larger than that of fluorapatite (FAp). Across all analyzed samples, the a (=b) lattice parameter (unit cell edge-length) varies more than does the c lattice parameter. Average crystallite size (average coherent diffracting domain size) in the c-direction was equal to approximately 25 nm, ranging among the analyzed 18 bone samples from about 20–32 nm, and varying more than crystallite size in the a,b-direction (~8–10 nm). Neither lattice parameters nor average bioapatite crystallite sizes appeared to be correlated with bone mechanical function. The relative chemical composition of the bone material, however, was shown to correlate with the a (=b) lattice parameter. To our knowledge, this research provides, for the first time, the systematic study of the crystallographic parameters of human bone bioapatite in the context of anatomical position, physical constitution, and bone chemical composition using X-ray powder diffraction (XRPD) and Fourier transform infrared spectroscopy (FTIR).

Highlights

Apatites have long been employed in biomedical innovations
We present results on the bioapatite crystallographic structural variations in buried human bones and consider their relation to the body’s physical constitution and the bones’
Anatomical variation of bioapatite unit cell dimensions was observed in all investigated sample sets

Summary

Introduction

Apatites have long been employed in biomedical innovations. The first documented use of an implanted calcium phosphate mineral dates back to almost 100 years ago, when Albee (1920) [1]successfully demonstrated the use of tricalcium phosphate as a stimulus to enhance bone growth and repair after fracture in rabbits. The first documented use of an implanted calcium phosphate mineral dates back to almost 100 years ago, when Albee (1920) [1]. Over the last decades, substituted hydroxylapatites have been synthesized and investigated for their suitability in biomedical applications, which range from bone tissue scaffolds to bioactive coatings for implants [4,5,6,7]. Learning more about human bone mineral structure should be considered a priority in biomaterials research; archaeologists and anthropologists can face difficulties identifying the ages of subjects post-mortem from skeletal remains for individuals ranging in age between the young adult and late adult age groups [8,9], in those remains which are archaeological [10]

Methods

Results

Conclusion