Quantification of bone microarchitecture damage in human femoral press-fit implantation using HR-pQCT and digital volume correlation

Sophie Rapagna, Sanaz Berahmani, Caroline E Wyers, Joop P W van den Bergh, Karen J Reynolds, Gianluca Tozzi, Dennis Janssen, Egon Perilli

Research output: Contribution to conferencePaper

Abstract

INTRODUCTION: During prostheses press-fit implantation, high compressive and shear stresses at the implant-bone interface are generated.Permanent bone damage occurs[1], but the extent remains unknown.The aim of this study isto quantify, using high-resolution peripheral quantitative computed tomography (HR-pQCT) and Digital Volume Correlation (DVC), permanent bone changes and deformation due to press-fit femoral knee implantation.METHODS: Pre-implantation scan: Six human cadaveric distal femora (85±3 years) were resected and scanned with HR-pQCT (XtremeCT II, Scanco) at 60.7μm/voxel, isotropic.Implant fitting: An experienced surgeon fitted the femurs with a cementless cruciate retaining femoral knee implant Sigma® (DePuy Synthes, UK)with porous surface coating (Porocoat). Post-implantation scan: Implants were then carefully removed and femurs rescanned with HR-pQCT. Image Registration:3D image-registration of pre- and post-implantation cross-section images was performed (DataViewer, Skyscan-Bruker). Image Analysis: For each femur, volumes of interest(VOI) were selected (CT-Analyzer, Skyscan-Bruker) in the posterior-medial and posterior-lateral condyles and anterior flange; VOIs included 10 mm of depth in the coronal plane atthe bone-implant surface. The bone volume fraction (BV/TV) for the VOIs in pre- and post-implantation images and their ratio (BV/TVpost/BV/TVpre) was calculated, slice by slice, at increasing depth. Digital Volume Correlation:DVC direct correlation (DaVis, LaVision) [2](3-step multipass, final subvolumes 20 voxels, 1.2 mm)was applied on the same VOIs pre- and post-implantation, to assess trabecular bone displacements and plastically accumulated strains. RESULTS AND DISCUSSION: The “BV/TVpost/BV/TVpre ratio vs. depth” graphs (Fig. 1a) showed,consistently among the six femurs, three characteristic points, differing significantly in BV/TVpost/BV/TVpre ratios and depth among them(p<0.05, Friedman and Wilcoxon signed rank tests), indicating: bone removal (A, ratio<100%),compaction (B, ratio>100%) and correspondence between pre- and post-implantation (C, ratio=100%)(Fig.1a, b). Correspondingly, trabecular bone displacement computed by DVC for the 6 femurs, suggested bone compaction up to 2.3±0.5mm in depth(Fig.1c), with peak third principal strains of -150,500±39,500με(mean absolute error: 1,000-2,000με, SD: 200-500με; Fig.1d), well above the yield strain of bone (7,000-10,000με). CONCLUSIONS: Combining high-resolution 3D-imaging and DVC enables to quantify permanent bone damage occurring after press-fit knee implantation. The apparent damage occurs up to 2 mm in depth, first with bone removal, followed by compaction and by no changes (correspondence). This data can be used to inform surgeons and manufacturers, advancing implant development.
Original languageEnglish
Number of pages1
Publication statusPublished - 2018
EventAustralian & New Zealand Orthopaedic Research Society (ANZORS) 24th Annual Scientific Meeting - Perth, Australia
Duration: 5 Oct 20187 Oct 2018
http://www.anzors.org.au/annual-conference-2018.html

Conference

ConferenceAustralian & New Zealand Orthopaedic Research Society (ANZORS) 24th Annual Scientific Meeting
CountryAustralia
CityPerth
Period5/10/187/10/18
Internet address

Keywords

  • bone
  • microarchitecture
  • press-fit implantation

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    Rapagna, S., Berahmani, S., Wyers, C. E., van den Bergh, J. P. W., Reynolds, K. J., Tozzi, G., Janssen, D., & Perilli, E. (2018). Quantification of bone microarchitecture damage in human femoral press-fit implantation using HR-pQCT and digital volume correlation. Paper presented at Australian & New Zealand Orthopaedic Research Society (ANZORS) 24th Annual Scientific Meeting, Perth, Australia. http://www.anzors.org.au/pdfs/2018-ANZORS-proceedings.pdf