title: Stress distribution and consolidation in cartilage constituents is influenced by cyclic loading and osteoarthritic degeneration.
abstract: The understanding of load support mechanisms in cartilage has evolved with computational models that better mimic the tissue ultrastructure. Fibril-reinforced poroelastic models can reproduce cartilage behaviour in a variety of test conditions and can be used to model tissue anisotropy as well as assess stress and pressure partitioning to the tissue constituents. The goal of this study was to examine the stress distribution in the fibrillar and non-fibrillar solid phase and pressure in the fluid phase of cartilage in axisymmetric models of a healthy and osteoarthritic hip joint. Material properties, based on values from the literature, were assigned to the fibrillar and poroelastic components of cartilage and cancellous and subchondral compact bone regions. A cyclic load representing walking was applied for 25 cycles. Contact stresses in the fibrillar and non-fibrillar solid phase supported less than 1% of the contact force and increased only minimally with load cycles. Simulated proteoglycan depletion increased stresses in the radial and tangential collagen fibrils, whereas fibrillation of the tangential fibrils resulted in increased compressive stress in the non-fibrillar component and tensile stress in the radial fibrils. However neither had an effect on fluid pressure. Subchondral sclerosis was found to have the largest effect, resulting in increased fluid pressure, non-fibrillar compressive stress, tangential fibril stress and greater cartilage consolidation. Subchondral bone stiffening may play an important role in the degenerative cascade and may adversely affect tissue repair and regeneration treatments.
authors.affiliation: Department of Mechanical and Aerospace Engineering, Carleton University, 3135 Mackenzie, 1125 Colonel By Drive, Ottawa, ON, Canada K1S 5B6. Electronic address: andrew.speirs@carleton.ca.
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Speirs
authors.affiliation: Division of Orthopaedic Surgery, Ottawa Hospital, Ottawa, Canada.
authors.forename: Paul E
authors.initials: PE
authors.lastname: Beaulé
authors.affiliation: Institute for Biomechanics, ETH Zurich, Zurich, Switzerland.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Ferguson
authors.affiliation: Department of Mechanical and Aerospace Engineering, Carleton University, 3135 Mackenzie, 1125 Colonel By Drive, Ottawa, ON, Canada K1S 5B6.
authors.forename: Hanspeter
authors.initials: H
authors.lastname: Frei
mesh_terms: D016880:Anisotropy; D002356:Cartilage / Q000503:physiopathology; D002358:Cartilage, Articular / Q000502:physiology*; D003094:Collagen / Q000737:chemistry; D004548:Elasticity; D005109:Extracellular Matrix; D005270:Femur Head / Q000502:physiology*; D020342:Finite Element Analysis; D006621:Hip Joint / Q000503:physiopathology*; D006801:Humans; D008953:Models, Anatomic; D010003:Osteoarthritis / Q000503:physiopathology*; D016062:Porosity; D011312:Pressure; D011509:Proteoglycans / Q000737:chemistry; D013314:Stress, Mechanical; D014057:Tomography, X-Ray Computed
chemical_list: D011509:Proteoglycans; D003094:Collagen
keywords: Bone; Cartilage; Finite element analysis; Hip joint; Osteoarthritis