Multimodal Evaluation of the Spatiotemporal Variations of Periprosthetic Bone Properties

Abstract

Titanium implants are widely used clinically. However, surgical failures still occur because of a lack of implant stability. Periprosthetic biomechanical bone properties need to be characterized to better understand osseointegration phenomena and anticipate implant failures. The aim of this study was toinvestigate the spatio-temporal variations of i) the indentation modulus E* and ii) the wave velocity v of newly formed bone tissue. Eight coin-shaped Ti6Al4V implants were inserted into rabbit tibiae for 7 and 13 weeks. This in vivo model allowed to distinguish mature and newly formed bone and to work in a standardized configuration. Nanoindentation, histological analysis and micro-Brillouin scattering measurements were carried out to assess the indentation modulus E*, the BA/TA (bone area/total area) and the wave velocity v, respectively, at different locations relatively to the implant surface. This approach allowed to determine the relative variation of bone mass density at the microscopic scale. All measured parameters (E*, v, ? and BA/TA) are found to be higher in the vicinity of the implant and for higher healing duration, suggesting increased mineralization. The indentation modulus is 12.3 % (respectively 3.2 %) higher in the close than in the far groups and 14.4 % (respectively 2.8 %) higher in the lateral than in the central groups after 7 weeks (respectively 13 weeks) of healing, leading to similar evolution of the bone mass density. These results lead to a bone spreading pathway confirmed by histology consistent with contact osteogenesis phenomena.

Neutron microtomography to investigate the bone-implant interface—comparison with histological analysis

“…In addition to the possible technical improvements discussed above, this study is based on four bone-implant specimens coming from one single animal. Nonetheless, the coin-shaped implant model has been validated in former studies, revealing comparable bone content and BIC values as quantified by histological slices after 13 weeks of healing (Fraulob et al, 2020a;Le Cann et al, 2020;Mathieu et al, 2011;Vayron et al, 2014).…”

“…To further investigate local variations in the bone-implant interface formation, this reference coin-shaped implant model has been modified by our group to include a bone chamber which allow a clear distinction between mature and newly formed bone tissues. Adopting this implant model, it was possible to explore the spatiotemporal variations of the mechanical (Fraulob et al, 2020a;Mathieu et al, 2011;Vayron et al, 2011Vayron et al, , 2012Vayron et al, , 2014, structural (Le Cann et al, 2020) and compositional properties (Fraulob et al, 2020b) of bone.…”

Osteocyte pericellular and perilacunar matrices as markers of bone–implant mechanical integrity

“…While mechanical loading is known to be involved in the stress shielding mechanism (Sumner, 2015), bone resorption can also be associated with a mechanically-induced inflammatory response (Amirhosseini et al, 2017). The bone-implant system thus appears to promote the development of a complex mechanical environment in which specific tissue properties develop (Fraulob et al, 2020;Le Cann et al, 2020;Li et al, 2018). Whether or not these properties are suitable for ensuring the mechanical integrity of the bone-implant system is still an open question.…”