Nanomechanical Characterization of Bone Quality Depending on Tissue Age via Bimodal Atomic Force Microscopy

Abstract

Characterization of bone quality during the healing process is crucial for successful implantation procedures and patient comfort. In this study, a bone implant specimen that underwent a 4-week healing period was investigated. Bimodal atomic force microscopy (AFM) was employed to simultaneously obtain the morphology and elastic modulus maps of the newly formed and pre-existing bone regions within the sample. Results indicate that the new bone matrix possessed lower mineralization levels and presented larger, uneven mineral grains, exhibiting the attributes of a woven bone. On the other hand, the old bone matrix exhibited a more uniform and mineralized structure, which is characteristic of lamellar bones. The new bone had a lower overall elastic modulus than the old bone. Bimodal AFM further confirmed that the new bone displayed three regions comprising unmineralized, partially mineralized, and fully matured sections, which indicate a turbulent change in its composition. Meanwhile, the old bone exhibited two sections comprising partially mineralized and matured bone parts, which denote the final phase of mineralization. This study provides valuable insights into the morphological and nanomechanical differences between the old and new bone matrixes and presents a novel approach to investigate bone quality at different phases of the bone-healing process.