Correlative Multiscale Imaging and Quantification of Bone Ingrowth in Porous Ti Implants

Access to files

•   FULL-TEXT.PDF (pdf)

Abstract

Additive manufactured porous titanium scaffolds have been extensively investigated for orthopaedic applications. The quantification of tissue response to the biomaterial implants is primarily achieved by analysing a two-dimensional (2D) stained histological section. More recently, three-dimensional X-ray micro-computed tomography (μCT) has become increasingly applied. Although histology is the gold standard, μCT allows non- destructive quantification of 3D tissue structures with minimal sample preparation and high contrast. A methodology to correlate information from both histology and μCT of a single sample might provide greater insights than either examining the results separately. However, this task is challenging because histology and μCT provide different types of information (stained tissue morphology vs. greyscale dependent on the X-ray absorption of material) and dimensionality (2D vs 3D). A semi-automated methodology was developed to directly quantify tissue formation and efficacy within an additive manufactured titanium implant using histology and μCT. This methodology was then extended to correlatively integrate nano-scale elemental information from nano- secondary ion mass spectroscopy (NanoSIMS). The correlative information was applied to investigate the impact of silver release on bone formation within a nano-silver coated additive manufactured implant. The correlative imaging methodology allowed for the quantification of the significant volumetric shrinkage (~15%) that occurs on histology slice preparation. It also demonstrated the importance of the location of the histological sectioning of the tissue and implant, revealing that up to 30% differences in bone ingrowth can be found along the entire length of the porous implant due to preferential bone ingrowth from the periphery to the centre. The quality and quantity of newly formed bone were found to be comparable between the uncoated and nano-silver coated Ti-implants, suggesting that the layer of silver nanoparticles on the Ti-implant does not negatively impact bone formation. Further, the newly formed bone at 2 weeks had a trabecula morphology with bone at the interface of Ti-implant as well as at a distant. This indicates that both contact (bone apposition on implant) and distance (bone ingrowth from host bone) osteogenesis were present in both types of implants. Finally, nanoscale elemental mapping showed silver was present primarily in the osseous tissue and was co-localised to sulphur suggesting that silver sulphide may have formed.

Keyword(s)

Bone Ingrowth; Correlative Imaging; Porous Ti; Quantification

Bibliographic metadata

Institutional metadata

Record metadata