title: Quasi-linear viscoelastic properties of the human medial patello-femoral ligament.
abstract: The evaluation of viscoelastic properties of human medial patello-femoral ligament is fundamental to understand its physiological function and contribution as stabilizer for the selection of the methods of repair and reconstruction and for the development of scaffolds with adequate mechanical properties. In this work, 12 human specimens were tested to evaluate the time- and history-dependent non linear viscoelastic properties of human medial patello-femoral ligament using the quasi-linear viscoelastic (QLV) theory formulated by Fung et al. (1972) and modified by Abramowitch and Woo (2004). The five constant of the QLV theory, used to describe the instantaneous elastic response and the reduced relaxation function on stress relaxation experiments, were successfully evaluated. It was found that the constant A was 1.21±0.96MPa and the dimensionless constant B was 26.03±4.16. The magnitude of viscous response, the constant C, was 0.11±0.02 and the initial and late relaxation time constants τ1 and τ2 were 6.32±1.76s and 903.47±504.73s respectively. The total stress relaxation was 32.7±4.7%. To validate our results, the obtained constants were used to evaluate peak stresses from a cyclic stress relaxation test on three different specimens. The theoretically predicted values fit the experimental ones demonstrating that the QLV theory could be used to evaluate the viscoelastic properties of the human medial patello-femoral ligament.
authors.affiliation: Istituto di Ricerca Traslazionale per l'Apparato Locomotore - Nicola Cerulli - LPMRI, via A. Einstein 12, 52100 Arezzo, Italy; Research Center "E. Piaggio", University of Pisa, Largo Lucio Lazzarino 1, 56126 Pisa, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Criscenti
authors.affiliation: Research Center "E. Piaggio", University of Pisa, Largo Lucio Lazzarino 1, 56126 Pisa, Italy. Electronic address: carmelo.demaria@centropiaggio.unipi.it.
authors.forename: C
authors.initials: C
authors.lastname: De Maria
authors.affiliation: Istituto di Ricerca Traslazionale per l'Apparato Locomotore - Nicola Cerulli - LPMRI, via A. Einstein 12, 52100 Arezzo, Italy; Department of Orthopedic surgery, University of Perugia, via S. Andrea delle Fratte 1, 06134 Perugia, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Sebastiani
authors.affiliation: Istituto di Ricerca Traslazionale per l'Apparato Locomotore - Nicola Cerulli - LPMRI, via A. Einstein 12, 52100 Arezzo, Italy; Department of Orthopedic surgery, University of Perugia, via S. Andrea delle Fratte 1, 06134 Perugia, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Tei
authors.affiliation: Istituto di Ricerca Traslazionale per l'Apparato Locomotore - Nicola Cerulli - LPMRI, via A. Einstein 12, 52100 Arezzo, Italy; Department of Orthopedic surgery, University of Perugia, via S. Andrea delle Fratte 1, 06134 Perugia, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Placella
authors.affiliation: Istituto di Ricerca Traslazionale per l'Apparato Locomotore - Nicola Cerulli - LPMRI, via A. Einstein 12, 52100 Arezzo, Italy; Department of Orthopedic surgery, University of Perugia, via S. Andrea delle Fratte 1, 06134 Perugia, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Speziali
authors.affiliation: Research Center "E. Piaggio", University of Pisa, Largo Lucio Lazzarino 1, 56126 Pisa, Italy; Department of Ingegneria dell'Informazione, University of Pisa, via G. Caruso 16, 56126 Pisa, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Vozzi
authors.affiliation: Istituto di Ricerca Traslazionale per l'Apparato Locomotore - Nicola Cerulli - LPMRI, via A. Einstein 12, 52100 Arezzo, Italy; Department of Orthopedic surgery, University of Perugia, via S. Andrea delle Fratte 1, 06134 Perugia, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Cerulli
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D004548:Elasticity; D005260:Female; D006801:Humans; D008297:Male; D017847:Patellar Ligament / Q000502:physiology*; D014783:Viscosity
keywords: Ligament biomechanics; Ligament mechanical properties; Medial patello-femoral ligament (MPFL); QLV theory; Quasi-linear viscoelastic theory; Tissue Engineering