title: Comparison of nonlinear mechanical properties of bovine articular cartilage and meniscus.
abstract: Nonlinear, linear and failure properties of articular cartilage and meniscus in opposing contact surfaces are poorly known in tension. Relationships between the tensile properties of articular cartilage and meniscus in contact with each other within knee joints are also not known. In the present study, rectangular samples were prepared from the superficial lateral femoral condyle cartilage and lateral meniscus of bovine knee joints. Tensile tests were carried out with a loading rate of 5mm/min until the tissue rupture. Nonlinear properties of the toe region, linear properties in larger strains, and failure properties of both tissues were analysed. The strain-dependent tensile modulus of the toe region, Young's modulus of the linear region, ultimate tensile stress and toughness were on average 98.2, 8.3, 4.0 and 1.9 times greater (p<0.05) for meniscus than for articular cartilage. In contrast, the toe region strain, yield strain and failure strain were on average 9.4, 3.1 and 2.3 times greater (p<0.05) for cartilage than for meniscus. There was a significant negative correlation between the strain-dependent tensile moduli of meniscus and articular cartilage samples within the same joints (r=-0.690, p=0.014). In conclusion, the meniscus possesses higher nonlinear and linear elastic stiffness and energy absorption capability before rupture than contacting articular cartilage, while cartilage has longer nonlinear region and can withstand greater strains before failure. These findings point out different load carrying demands that both articular cartilage and meniscus have to fulfil during normal physiological loading activities of knee joints.
authors.affiliation: Department of Applied Physics, University of Eastern Finland, P.O. Box 1627, FI-70211 Kuopio, Finland; Department of Clinical Neurophysiology, Kuopio University Hospital, P.O. Box 1777, FI-70211 Kuopio, Finland. Electronic address: elvis.danso@uef.fi.
authors.forename: E K
authors.initials: EK
authors.lastname: Danso
authors.affiliation: Department of Applied Physics, University of Eastern Finland, P.O. Box 1627, FI-70211 Kuopio, Finland.
authors.forename: J T J
authors.initials: JT
authors.lastname: Honkanen
authors.affiliation: Department of Medical Technology, Institute of Biomedicine, University of Oulu, P.O. Box 5000, FI-90014 Oulu, Finland; Department of Diagnostic Radiology, Oulu University Hospital, P.O. Box 5000, FI-90014 Oulu, Finland.
authors.forename: S
authors.initials: S
authors.lastname: Saarakkala
authors.affiliation: Department of Applied Physics, University of Eastern Finland, P.O. Box 1627, FI-70211 Kuopio, Finland. Electronic address: rami.korhonen@uef.fi.
authors.forename: R K
authors.initials: RK
authors.lastname: Korhonen
mesh_terms: D000465:Algorithms; D000818:Animals; D001696:Biomechanical Phenomena; D002358:Cartilage, Articular / Q000502:physiology*; D002417:Cattle; D003198:Computer Simulation; D007596:Joints / Q000502:physiology*; D008592:Menisci, Tibial / Q000502:physiology*; D011312:Pressure; D013314:Stress, Mechanical; D013718:Tensile Strength
keywords: Articular cartilage; Mechanical testing; Meniscus; Tensile properties