title: Strain-rate sensitivity of the lateral collateral ligament of the knee.
abstract: The material properties of ligaments are not well characterized at rates of deformation that occur during high-speed injuries. The aim of this study was to measure the material properties of lateral collateral ligament of the porcine stifle joint in a uniaxial tension model through strain rates in the range from 0.01 to 100/s. Failure strain, tensile modulus and failure stress were calculated. Across the range of strain rates, tensile modulus increased from 288 to 905 MPa and failure stress increased from 39.9 to 77.3 MPa. The strain-rate sensitivity of the material properties decreased as deformation rates increased, and reached a limit at approximately 1/s, beyond which there was no further significant change. In addition, time resolved microfocus small angle X-ray scattering was used to measure the effective fibril modulus (stress/fibril strain) and fibril to tissue strain ratio. The nanoscale data suggest that the contribution of the collagen fibrils towards the observed tissue-level deformation of ligaments diminishes as the loading rate increases. These findings help to predict the patterns of limb injuries that occur at different speeds and improve computational models used to assess and develop mitigation technology.
authors.affiliation: The Academic Department of Military Surgery and Trauma, The Royal Centre for Defence Medicine, Birmingham B15 2SQ, UK; Department of Bioengineering, Imperial College London, London SW7 2AZ, UK.
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Bonner
authors.affiliation: Department of Bioengineering, Imperial College London, London SW7 2AZ, UK.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Newell
authors.affiliation: Department of Bioengineering, Imperial College London, London SW7 2AZ, UK.
authors.forename: Angelo
authors.initials: A
authors.lastname: Karunaratne
authors.affiliation: Department of Civil and Environmental Engineering, Imperial College London, London SW7 2AZ, UK.
authors.forename: Andy D
authors.initials: AD
authors.lastname: Pullen
authors.affiliation: Department of Mechanical Engineering, Imperial College London, London SW7 2AZ, UK; Department of Musculoskeletal Surgery, Imperial College London, London W6 8RF, UK.
authors.forename: Andrew A
authors.initials: AA
authors.lastname: Amis
authors.affiliation: Department of Bioengineering, Imperial College London, London SW7 2AZ, UK.
authors.forename: Anthony
authors.initials: A
authors.lastname: M J Bull
authors.affiliation: Department of Bioengineering, Imperial College London, London SW7 2AZ, UK. Electronic address: s.masouros04@imperial.ac.uk.
authors.forename: Spyros D
authors.initials: SD
authors.lastname: Masouros
mesh_terms: D000818:Animals; D005260:Female; D006801:Humans; D007717:Knee; D017844:Lateral Ligament, Ankle; D008422:Materials Testing; D008954:Models, Biological; D013314:Stress, Mechanical; D013552:Swine
keywords: Injury; Ligament; Modulus; Strain rate; Stress