title: Digital volume correlation and micro-CT: An in-vitro technique for measuring full-field interface micromotion around polyethylene implants.
abstract: Micromotion around implants is commonly measured using displacement-sensor techniques. Due to the limitations of these techniques, an alternative approach (DVC-μCT) using digital volume correlation (DVC) and micro-CT (μCT) was developed in this study. The validation consisted of evaluating DVC-μCT based micromotion against known micromotions (40, 100 and 150 μm) in a simplified experiment. Subsequently, a more clinically realistic experiment in which a glenoid component was implanted into a porcine scapula was carried out and the DVC-μCT measurements during a single load cycle (duration 20 min due to scanning time) was correlated with the manual tracking of micromotion at 12 discrete points across the implant interface. In this same experiment the full-field DVC-μCT micromotion was compared to the full-field micromotion predicted by a parallel finite element analysis (FEA). It was found that DVC-μCT micromotion matched the known micromotion of the simplified experiment (average/peak error=1.4/1.7 μm, regression line slope=0.999) and correlated with the micromotion at the 12 points tracked manually during the realistic experiment (R(2)=0.96). The DVC-μCT full-field micromotion matched the pattern of the full-field FEA predicted micromotion. This study showed that the DVC-μCT technique provides sensible estimates of micromotion. The main advantages of this technique are that it does not damage important parts of the specimen to gain access to the bone-implant interface, and it provides a full-field evaluation of micromotion as opposed to the micromotion at just a few discrete points. In conclusion the DVC-μCT technique provides a useful tool for investigations of micromotion around plastic implants.
authors.affiliation: Biomechanics Group, Department of Mechanical Engineering, Imperial College London, London SW7 2AZ, UK.
authors.forename: Chamaiporn
authors.initials: C
authors.lastname: Sukjamsri
authors.affiliation: Biomechanics Group, Department of Mechanical Engineering, Imperial College London, London SW7 2AZ, UK.
authors.forename: Diogo M
authors.initials: DM
authors.lastname: Geraldes
authors.affiliation: Department of Orthopaedic Surgery, APHP, European Hospital Pompidou, Paris 75015, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Gregory
authors.affiliation: The Natural History Museum, London SW7 5BD, UK.
authors.forename: Farah
authors.initials: F
authors.lastname: Ahmed
authors.affiliation: LaVision UK Ltd., Oxon OX12 9FF, UK.
authors.forename: David
authors.initials: D
authors.lastname: Hollis
authors.affiliation: Mathys Ltd., Bettlach 2544, Switzerland.
authors.forename: Samuel
authors.initials: S
authors.lastname: Schenk
authors.affiliation: Biomechanics Group, Department of Mechanical Engineering, Imperial College London, London SW7 2AZ, UK; Department of Musculoskeletal Surgery, Imperial College London, School of Medicine, Charing Cross Hospital, London W6 8RF, UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: Amis
authors.affiliation: Department of Musculoskeletal Surgery, Imperial College London, School of Medicine, Charing Cross Hospital, London W6 8RF, UK.
authors.forename: Roger
authors.initials: R
authors.lastname: Emery
authors.affiliation: Biomechanics Group, Department of Mechanical Engineering, Imperial College London, London SW7 2AZ, UK. Electronic address: u.hansen@imperial.ac.uk.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Hansen
mesh_terms: D000818:Animals; D020342:Finite Element Analysis; D007595:Joint Prosthesis; D009038:Motion; D020959:Polyethylene / Q000737:chemistry*; D012540:Scapula / Q000000981:diagnostic imaging / Q000473:pathology; D013552:Swine; D055114:X-Ray Microtomography
chemical_list: D020959:Polyethylene
keywords: CT; Digital volume correlation; Implants; Micromotion; Osseointegration