Articular cartilage deformation under physiological cyclic loading--apparatus and measurement technique. 1997

M K Barker, and B B Seedhom
Rheumatology and Rehabilitation Research Unit, University of Leeds, U.K.

In locomotive activities, areas of cartilage in both the hip, and especially the knee, experience periods of complete unloading between loading cycles as contact is lost between opposing articulating surfaces. During these periods these cartilage sites experience load-free recovery. Therefore, it was decided to model as closely as possible the physiological situation described, in order to study the deformation response of articular cartilage to physiological cyclic loading. For this it was necessary to design an apparatus in order to overcome some of the difficulties experienced with servo-hydraulic materials testing apparatus when specifying a lower load limit of zero. Cyclic loading in the frequency range 0-2.5 Hz was controlled by a cam and follower assembly driven by a stepper motor. The ratio of loading to recovery duration per cycle could be adjusted using a two-plate cam design enabling cartilage loading to occur for a duration as short as 20 ms within a 1 Hz cycle. Interchangeable impervious, porous, hemispherical or plane-ended indenters could be used. Load amplitude was controlled by compression of a spring giving a wide range of contact stresses (0.04-7.0 MPa). Load rise times were controlled by the spring in conjunction with a dashpot, enabling critically damped loads to reach their maximum value within an interval as short as 15 ms. The measurement technique and subsequent analysis relied on simultaneous recording of indenter load and vertical displacement at a sampling frequency of 5 kHz.

UI MeSH Term Description Entries
D009983 Orthopedic Equipment Nonexpendable items used in the performance of orthopedic surgery and related therapy. They are differentiated from ORTHOTIC DEVICES, apparatus used to prevent or correct deformities in patients. Equipment, Orthopedic,Equipments, Orthopedic,Orthopedic Equipments
D009985 Orthopedics A specialty which utilizes medical, surgical, and physical methods to treat and correct deformities, diseases, and injuries to the skeletal system, its articulations, and associated structures.
D002358 Cartilage, Articular A protective layer of firm, flexible cartilage over the articulating ends of bones. It provides a smooth surface for joint movement, protecting the ends of long bones from wear at points of contact. Articular Cartilage,Articular Cartilages,Cartilages, Articular
D004867 Equipment Design Methods and patterns of fabricating machines and related hardware. Design, Equipment,Device Design,Medical Device Design,Design, Medical Device,Designs, Medical Device,Device Design, Medical,Device Designs, Medical,Medical Device Designs,Design, Device,Designs, Device,Designs, Equipment,Device Designs,Equipment Designs
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D001696 Biomechanical Phenomena The properties, processes, and behavior of biological systems under the action of mechanical forces. Biomechanics,Kinematics,Biomechanic Phenomena,Mechanobiological Phenomena,Biomechanic,Biomechanic Phenomenas,Phenomena, Biomechanic,Phenomena, Biomechanical,Phenomena, Mechanobiological,Phenomenas, Biomechanic
D016474 Weight-Bearing The physical state of supporting an applied load. This often refers to the weight-bearing bones or joints that support the body's weight, especially those in the spine, hip, knee, and foot. Load-Bearing,Axial Loading,Loadbearing,Weightbearing,Axial Loadings,Load Bearing,Weight Bearing

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