Mechanical Loads and Site-Dependent Changes in Crystal Structure and Molecular Dynamics in Native Bone

X-ray diffraction and Raman studies of human femur in knee compartment under osteoarthritis conditions are performed. The measurements have demonstrated the systematic site-dependent changes in crystal cell parameters and molecular dynamics in calcium hydroxyapatite in subchondral bone. To investigate the origin of the changes and to link them with the mechanical loads in the skeleton, relationships between the site-dependent changes in crystal cell volume and Raman shifts of the symmetric P–O stretching of PO₄³⁻ ions are examined. Small but distinct displacements of the v₁PO₄³⁻ band in the Raman spectra of subchondral bone on the proximal side are detected and assigned with the expansion of crystal cell and the peculiarities of biomechanics in knee joint. Combination of X-ray diffraction and Raman probing of mechanical loads in subchondral bone is discussed.