Imperial College London

DrUlrichHansen

Faculty of EngineeringDepartment of Mechanical Engineering

Senior Lecturer
 
 
 
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Contact

 

+44 (0)20 7594 7061u.hansen

 
 
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Location

 

714City and Guilds BuildingSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

94 results found

Junaid S, Gregory T, Fetherston S, Emery R, Amis AA, Hansen Uet al., 2018, Cadaveric study validating in vitro monitoring techniques to measure the failure mechanism of glenoid implants against clinical CT., J Orthop Res

Definite glenoid implant loosening is identifiable on radiographs, however, identifying early loosening still eludes clinicians. Methods to monitor glenoid loosening in vitro have not been validated to clinical imaging. This study investigates the correlation between in vitro measures and CT images. Ten cadaveric scapulae were implanted with a pegged glenoid implant and fatigue tested to failure. Each scapulae were cyclically loaded superiorly and CT scanned every 20,000 cycles until failure to monitor progressive radiolucent lines. Superior and inferior rim displacements were also measured. A finite element (FE) model of one scapula was used to analyze the interfacial stresses at the implant/cement and cement/bone interfaces. All ten implants failed inferiorly at the implant-cement interface, two also failed at the cement-bone interface inferiorly, and three showed superior failure. Failure occurred at of 80,966 ± 53,729 (mean ± SD) cycles. CT scans confirmed failure of the fixation, and in most cases, was observed either before or with visual failure. Significant correlations were found between inferior rim displacement, vertical head displacement and failure of the glenoid implant. The FE model showed peak tensile stresses inferiorly and high compressive stresses superiorly, corroborating experimental findings. In vitro monitoring methods correlated to failure progression in clinical CT images possibly indicating its capacity to detect loosening earlier for earlier clinical intervention if needed. Its use in detecting failure non-destructively for implant development and testing is also valuable. The study highlights failure at the implant-cement interface and early signs of failure are identifiable in CT images. © 2018 The Authors. Journal of Orthopaedic Research® Published by Wiley Periodicals, Inc. on behalf of the Orthopaedic Research Society. J Orthop Res 9999:XX-XX, 2018.

JOURNAL ARTICLE

Ridzwan MIZ, Sukjamsri C, Pal B, van Arkel RJ, Bell A, Khanna M, Baskaradas A, Abel R, Boughton O, Cobb J, Hansen UNet al., 2018, Femoral fracture type can be predicted from femoral structure: A finite element study validated by digital volume correlation experiments, JOURNAL OF ORTHOPAEDIC RESEARCH, Vol: 36, Pages: 993-1001, ISSN: 0736-0266

JOURNAL ARTICLE

Arnold M, Zhao S, Ma S, Giuliani F, Hansen U, Cobb JP, Abel RL, Boughton Oet al., 2017, Microindentation - a tool for measuring cortical bone stiffness? A systematic review., Bone Joint Res, Vol: 6, Pages: 542-549, ISSN: 2046-3758

OBJECTIVES: Microindentation has the potential to measure the stiffness of an individual patient's bone. Bone stiffness plays a crucial role in the press-fit stability of orthopaedic implants. Arming surgeons with accurate bone stiffness information may reduce surgical complications including periprosthetic fractures. The question addressed with this systematic review is whether microindentation can accurately measure cortical bone stiffness. METHODS: A systematic review of all English language articles using a keyword search was undertaken using Medline, Embase, PubMed, Scopus and Cochrane databases. Studies that only used nanoindentation, cancellous bone or animal tissue were excluded. RESULTS: A total of 1094 abstracts were retrieved and 32 papers were included in the analysis, 20 of which used reference point indentation, and 12 of which used traditional depth-sensing indentation. There are several factors that must be considered when using microindentation, such as tip size, depth and method of analysis. Only two studies validated microindentation against traditional mechanical testing techniques. Both studies used reference point indentation (RPI), with one showing that RPI parameters correlate well with mechanical testing, but the other suggested that they do not. CONCLUSION: Microindentation has been used in various studies to assess bone stiffness, but only two studies with conflicting results compared microindentation with traditional mechanical testing techniques. Further research, including more studies comparing microindentation with other mechanical testing methods, is needed before microindentation can be used reliably to calculate cortical bone stiffness.Cite this article: M. Arnold, S. Zhao, S. Ma, F. Giuliani, U. Hansen, J. P. Cobb, R. L. Abel, O. Boughton. Microindentation - a tool for measuring cortical bone stiffness? A systematic review. Bone Joint Res 2017;6:542-549. DOI: 10.1302/2046-3758.69.BJR-2016-0317.R2.

JOURNAL ARTICLE

Boughton OR, Zhao S, Arnold M, Ma S, Cobb JP, Giuliani F, Hansen U, Abel RLet al., 2017, Measuring bone stiffness using microindentation, British Orthopaedic Research Society (BORS) 2016 Conference, Publisher: British Editorial Society of Bone and Joint Surgery, Pages: 31-31, ISSN: 2049-4416

CONFERENCE PAPER

Geraldes DM, Hansen U, Amis AA, 2017, Parametric Analysis of Glenoid Implant Design and Fixation Type, JOURNAL OF ORTHOPAEDIC RESEARCH, Vol: 35, Pages: 775-784, ISSN: 0736-0266

JOURNAL ARTICLE

Geraldes DM, Hansen U, Jeffers J, Amis AAet al., 2017, Stability of small pegs for cementless implant fixation, JOURNAL OF ORTHOPAEDIC RESEARCH, Vol: 35, Pages: 2765-2772, ISSN: 0736-0266

JOURNAL ARTICLE

Jin A, Cobb J, Hansen U, Bhattacharya R, Reinhard C, Vo N, Atwood R, Li J, Karunaratne A, Wiles C, Abel Ret al., 2017, The effect of long-term bisphosphonate therapy on trabecular bone strength and microcrack density, BONE & JOINT RESEARCH, Vol: 6, Pages: 602-609, ISSN: 2046-3758

JOURNAL ARTICLE

Junaid S, Sanghavi S, Anglin C, Bull A, Emery R, Amis AA, Hansen Uet al., 2017, Treatment of the Fixation Surface Improves Glenoid Prosthesis Longevity in vitro, JOURNAL OF BIOMECHANICS, Vol: 61, Pages: 81-87, ISSN: 0021-9290

JOURNAL ARTICLE

Ma S, Goh EL, Jin A, Bhattacharya R, Boughton OR, Patel B, Karunaratne A, Vo NT, Atwood R, Cobb JP, Hansen U, Abel RLet al., 2017, Long-term effects of bisphosphonate therapy: perforations, microcracks and mechanical properties, SCIENTIFIC REPORTS, Vol: 7, ISSN: 2045-2322

JOURNAL ARTICLE

Chong DYR, Hansen UN, Amis AA, 2016, CEMENTLESS MIS MINI-KEEL PROSTHESIS REDUCES INTERFACE MICROMOTION VERSUS STANDARD STEMMED TIBIAL COMPONENTS, JOURNAL OF MECHANICS IN MEDICINE AND BIOLOGY, Vol: 16, ISSN: 0219-5194

JOURNAL ARTICLE

Geraldes D, Hansen U, Jeffers J, Amis Aet al., 2016, Interference fit optimisation for small press-fitted pegs, International Society for Technology in Arthroplasty 2015, Publisher: BRITISH EDITORIAL SOCIETY OF BONE & JOINT SURGERY, Pages: 150-150, ISSN: 2049-4416

CONFERENCE PAPER

Ma S, Boughton O, Karunaratne A, Jin A, Cobb J, Hansen U, Abel Ret al., 2016, Synchrotron Imaging Assessment of Bone Quality, CLINICAL REVIEWS IN BONE AND MINERAL METABOLISM, Vol: 14, Pages: 150-160, ISSN: 1534-8644

JOURNAL ARTICLE

Ma S, Goh EL, Patel B, Jin A, Boughton O, Cobb J, Hansen U, Abel RLet al., 2016, Are the cracks starting to appear in bisphosphonate therapy?, British Orthopaedic Research Society (BORS) 2016 Conference, Publisher: British Editorial Society of Bone and Joint Surgery, Pages: 53-53, ISSN: 2049-4416

CONFERENCE PAPER

Tempelaere C, Pierrart J, Lefèvre-Colau M-M, Vuillemin V, Cuénod C-A, Hansen U, Mir O, Skalli W, Gregory Tet al., 2016, Dynamic Three-Dimensional Shoulder Mri during Active Motion for Investigation of Rotator Cuff Diseases, PLOS ONE, Vol: 11, Pages: e0158563-e0158563

JOURNAL ARTICLE

Geraldes D, Hansen U, Amis A, 2015, Parametric analysis of glenoid implant design, European Society of Biomechanics 2015

CONFERENCE PAPER

Geraldes D, Hansen U, Amis A, 2015, Parametric analysis of glenoid implant design, International Society of Biomechanics 2015

CONFERENCE PAPER

Simpson RL, Nazhat SN, Blaker JJ, Bismarck A, Hill R, Boccaccini AR, Hansen UN, Amis AAet al., 2015, A comparative study of the effects of different bioactive fillers in PLGA matrix composites and their suitability as bone substitute materials: A thermo-mechanical and in vitro investigation., Journal of the Mechanical Behavior of Biomedical Materials, Vol: 50, Pages: 277-289, ISSN: 1751-6161

Bone substitute composite materials with poly(L-lactide-co-glycolide) (PLGA) matrices and four different bioactive fillers: CaCO3, hydroxyapatite (HA), 45S5 Bioglass(®) (45S5 BG), and ICIE4 bioactive glass (a lower sodium glass than 45S5 BG) were produced via melt blending, extrusion and moulding. The viscoelastic, mechanical and thermal properties, and the molecular weight of the matrix were measured. Thermogravimetric analysis evaluated the effect of filler composition on the thermal degradation of the matrix. Bioactive glasses caused premature degradation of the matrix during processing, whereas CaCO3 or HA did not. All composites, except those with 45S5 BG, had similar mechanical strength and were stiffer than PLGA alone in compression, whilst all had a lower tensile strength. Dynamic mechanical analysis demonstrated an increased storage modulus (E') in the composites (other than the 45S5 BG filled PLGA). The effect of water uptake and early degradation was investigated by short-term in vitro aging in simulated body fluid, which indicated enhanced water uptake over the neat polymer; bioactive glass had the greatest water uptake, causing matrix plasticization. These results enable a direct comparison between bioactive filler type in poly(α-hydroxyester) composites, and have implications when selecting a composite material for eventual application in bone substitution.

JOURNAL ARTICLE

Sukjamsri C, Geraldes DM, Gregory T, Ahmed F, Hollis D, Schenk S, Amis A, Emery R, Hansen Uet al., 2015, Digital volume correlation and micro-CT: An in-vitro technique for measuring full-field interface micromotion around polyethylene implants, JOURNAL OF BIOMECHANICS, Vol: 48, Pages: 3447-3454, ISSN: 0021-9290

JOURNAL ARTICLE

Tuncer M, Patel R, Cobb JP, Hansen UN, Amis AAet al., 2015, Variable bone mineral density reductions post-unicompartmental knee arthroplasty, KNEE SURGERY SPORTS TRAUMATOLOGY ARTHROSCOPY, Vol: 23, Pages: 2230-2236, ISSN: 0942-2056

JOURNAL ARTICLE

Geraldes D, Hansen U, Amis A, 2014, A framework for parametric analysis of glenoid implant design, MECBioengineering 2014

CONFERENCE PAPER

Geraldes D, Hansen U, Jeffers J, Amis Aet al., 2014, A framework for parametric analysis of glenoid implant design, International Society for Technology in Arthroplasty 2014

CONFERENCE PAPER

Gregory T, Hansen U, Khanna M, Mutchler C, Urien S, Amis AA, Augereau B, Emery Ret al., 2014, A CT scan protocol for the detection of radiographic loosening of the glenoid component after total shoulder arthroplasty, ACTA ORTHOPAEDICA, Vol: 85, Pages: 91-96, ISSN: 1745-3674

JOURNAL ARTICLE

Tuncer M, Hansen UN, Amis AA, 2014, Prediction of structural failure of tibial bone models under physiological loads: Effect of CT density-modulus relationships, MEDICAL ENGINEERING & PHYSICS, Vol: 36, Pages: 991-997, ISSN: 1350-4533

JOURNAL ARTICLE

Geraldes D, Sukjamsri C, Gregory T, Ahmed F, Hollis D, Hansen Uet al., 2013, A study of micromotion in cementless arthroplasty using digital volume correlation technique, Tomography for Scientific Advancement Symposium 2013

CONFERENCE PAPER

Gregory TM, Sankey A, Augereau B, Vandenbussche E, Amis A, Emery R, Hansen Uet al., 2013, Accuracy of Glenoid Component Placement in Total Shoulder Arthroplasty and Its Effect on Clinical and Radiological Outcome in a Retrospective, Longitudinal, Monocentric Open Study, PLOS ONE, Vol: 8, ISSN: 1932-6203

JOURNAL ARTICLE

Tuncer M, Cobb JP, Hansen UN, Amis AAet al., 2013, Validation of multiple subject-specific finite element models of unicompartmental knee replacement, MEDICAL ENGINEERING & PHYSICS, Vol: 35, Pages: 1457-1464, ISSN: 1350-4533

JOURNAL ARTICLE

Gregory T, Hansen U, Emery R, Amis AA, Mutchler C, Taillieu F, Augereau Bet al., 2012, Total shoulder arthroplasty does not correct the orientation of the eroded glenoid, ACTA ORTHOPAEDICA, Vol: 83, Pages: 529-535, ISSN: 1745-3674

JOURNAL ARTICLE

Chong DYR, Hansen UN, Amis AA, 2011, THE INFLUENCE OF TIBIAL PROSTHESIS DESIGN FEATURES ON STRESSES RELATED TO ASEPTIC LOOSENING AND STRESS SHIELDING, JOURNAL OF MECHANICS IN MEDICINE AND BIOLOGY, Vol: 11, Pages: 55-72, ISSN: 0219-5194

JOURNAL ARTICLE

Chong DYR, Hansen UN, van der Venne R, Verdonschot N, Amis AAet al., 2011, The influence of tibial component fixation techniques on resorption of supporting bone stock after total knee replacement, JOURNAL OF BIOMECHANICS, Vol: 44, Pages: 948-954, ISSN: 0021-9290

JOURNAL ARTICLE

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