Abstracts Category : Other

Correlative Multiscale Imaging and Quantification of BoneIngrowth in Porous Ti Implants

by Hua Geng

Additive manufactured porous titanium scaffoldshave been extensively investigated for orthopaedic applications.The quantification of tissue response to the biomaterial implantsis primarily achieved by analysing a two-dimensional (2D) stainedhistological section. More recently, three-dimensional X-raymicro-computed tomography (CT) has become increasingly applied.Although histology is the gold standard, CT allows non-destructive quantification of 3D tissue structures with minimalsample preparation and high contrast. A methodology to correlateinformation from both histology and CT of a single sample mightprovide greater insights than either examining the resultsseparately. However, this task is challenging because histology andCT provide different types of information (stained tissuemorphology vs. greyscale dependent on the X-ray absorption ofmaterial) and dimensionality (2D vs 3D). A semi-automatedmethodology was developed to directly quantify tissue formation andefficacy within an additive manufactured titanium implant usinghistology and CT. This methodology was then extended tocorrelatively integrate nano-scale elemental information from nano-secondary ion mass spectroscopy (NanoSIMS). The correlativeinformation was applied to investigate the impact of silver releaseon bone formation within a nano-silver coated additive manufacturedimplant. The correlative imaging methodology allowed for thequantification of the significant volumetric shrinkage (~15%) thatoccurs on histology slice preparation. It also demonstrated theimportance of the location of the histological sectioning of thetissue and implant, revealing that up to 30% differences in boneingrowth can be found along the entire length of the porous implantdue to preferential bone ingrowth from the periphery to the centre.The quality and quantity of newly formed bone were found to becomparable between the uncoated and nano-silver coated Ti-implants,suggesting that the layer of silver nanoparticles on the Ti-implantdoes not negatively impact bone formation. Further, the newlyformed bone at 2 weeks had a trabecula morphology with bone at theinterface of Ti-implant as well as at a distant. This indicatesthat both contact (bone apposition on implant) and distance (boneingrowth from host bone) osteogenesis were present in both types ofimplants. Finally, nanoscale elemental mapping showed silver waspresent primarily in the osseous tissue and was co-localised tosulphur suggesting that silver sulphide may haveformed.Advisors/Committee Members: CARTMELL, SARAH SH, POOLOGASUNDARAMPILLA, GOWSIHAN G, Cartmell, Sarah, Lee, Peter, Poologasundarampilla, Gowsihan.