title: In vivo monitoring of bone architecture and remodeling after implant insertion: The different responses of cortical and trabecular bone.
abstract: The mechanical integrity of the bone-implant system is maintained by the process of bone remodeling. Specifically, the interplay between bone resorption and bone formation is of paramount importance to fully understand the net changes in bone structure occurring in the peri-implant bone, which are eventually responsible for the mechanical stability of the bone-implant system. Using time-lapsed in vivo micro-computed tomography combined with new composite material implants, we were able to characterize the spatio-temporal changes of bone architecture and bone remodeling following implantation in living mice. After insertion, implant stability was attained by a quick and substantial thickening of the cortical shell which counteracted the observed loss of trabecular bone, probably due to the disruption of the trabecular network. Within the trabecular compartment, the rate of bone formation close to the implant was transiently higher than far from the implant mainly due to an increased mineral apposition rate which indicated a higher osteoblastic activity. Conversely, in cortical bone, the higher rate of bone formation close to the implant compared to far away was mostly related to the recruitment of new osteoblasts as indicated by a prevailing mineralizing surface. The behavior of bone resorption also showed dissimilarities between trabecular and cortical bone. In the former, the rate of bone resorption was higher in the peri-implant region and remained elevated during the entire monitoring period. In the latter, bone resorption rate had a bigger value away from the implant and decreased with time. Our approach may help to tune the development of smart implants that can attain a better long-term stability by a local and targeted manipulation of the remodeling process within the cortical and the trabecular compartments and, particularly, in bone of poor health.
authors: Institute for Biomechanics, ETH Zurich, Zurich, Switzerland.
authors: Zihui
authors: Z
authors: Li
authors: Institute for Biomechanics, ETH Zurich, Zurich, Switzerland.
authors: Gisela
authors: G
authors: Kuhn
authors: Institute for Biomechanics, ETH Zurich, Zurich, Switzerland.
authors: Marcella
authors: M
authors: von Salis-Soglio
authors: Composite Metal Technologies, Hampshire, United Kingdom.
authors: Stephen J
authors: SJ
authors: Cooke
authors: pfm medical titanium gmbh, Nuremberg, Germany.
authors: Michael
authors: M
authors: Schirmer
authors: Institute for Biomechanics, ETH Zurich, Zurich, Switzerland.
authors: Ralph
authors: R
authors: Müller
authors: Institute for Biomechanics, ETH Zurich, Zurich, Switzerland; Department of Aerospace and Mechanical Engineering, University of Liege, Liege, Belgium. Electronic address: druffoni@ulg.ac.be.
authors: Davide
authors: D
authors: Ruffoni
mesh_terms: D000818:Animals; D016477:Artifacts; D015519:Bone Density; D016723:Bone Remodeling / Q000502:physiology*; D001862:Bone Resorption; D001842:Bone and Bones / Q000000981:diagnostic imaging / Q000502:physiology*; D005260:Female; D008670:Metals / Q000737:chemistry; D051379:Mice; D008810:Mice, Inbred C57BL; D016348:Osseointegration / Q000502:physiology; D010006:Osteoblasts / Q000378:metabolism; D010010:Osteoclasts / Q000378:metabolism; D010012:Osteogenesis / Q000502:physiology*; D010024:Osteoporosis; D019736:Prostheses and Implants; D019919:Prosthesis Implantation; D015203:Reproducibility of Results; D055114:X-Ray Microtomography
chemical_list: D008670:Metals
keywords: Bone remodeling; Implant anchorage; Implant osseointegration; In vivo micro-computed tomography; Metal artifacts