Biomaterial Database

A novel method for determining articular cartilage chondrocyte mechanics in vivo. 2011

Z Abusara, and R Seerattan, and A Leumann, and R Thompson, and W Herzog

Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, 2500 University Drive N.W. Alberta, Canada. zabusara@kin.ucalgary.ca

Work relating the mechanical states of articular cartilage chondrocytes to their biosynthetic responses is based on measurements in isolated cells or cells in explant samples removed from their natural in situ environment. Neither the mechanics nor the associated biological responses of chondrocytes have ever been studied in cartilage within a joint of a live animal, and no such measurements have ever been performed using physiologically relevant joint loading through muscular contractions. The purpose of this study was to design and apply a method to study the mechanics of chondrocytes in the exposed but fully intact knee of live animals, which was loaded near-physiologically through muscular contraction. In order to achieve this purpose, we developed an accurate and reliable method based on two-photon laser excitation microscopy. Near-physiological knee joint loading was achieved through controlled electrical activation of the knee extensor muscles that compress the articulating surfaces of the femur, tibia and patella. Accuracy of the system was assessed by inserting micro-beads of known dimensions into the articular cartilage of the mouse knee and comparing the measured volumes and diameters in the principal directions with known values of the beads. Accuracy was best in the plane perpendicular to the optical axis (average error = 1%) while it was slightly worse, but still excellent, along the optical axis (average error = 3%). Reliability of cell volume and shape measurements was 0.5% on average, and 2.9% in the worst-case-scenario. Pilot measurements of chondrocyte deformations upon sub-maximal muscular loading causing a mean articular contact pressure of 1.9 ± 0.2 MPa showed an "instantaneous" decrease in cell height (17 ± 4.5%) and loss of cell volume (22.3 ± 2.4%) that took minutes to recover upon deactivation of the knee extensor muscles.

UI	MeSH Term	Description	Entries
D007596	Joints	Also known as articulations, these are points of connection between the ends of certain separate bones, or where the borders of other bones are juxtaposed.	Joint
D007834	Lasers	An optical source that emits photons in a coherent beam. Light Amplification by Stimulated Emission of Radiation (LASER) is brought about using devices that transform light of varying frequencies into a single intense, nearly nondivergent beam of monochromatic radiation. Lasers operate in the infrared, visible, ultraviolet, or X-ray regions of the spectrum.	Masers,Continuous Wave Lasers,Pulsed Lasers,Q-Switched Lasers,Continuous Wave Laser,Laser,Laser, Continuous Wave,Laser, Pulsed,Laser, Q-Switched,Lasers, Continuous Wave,Lasers, Pulsed,Lasers, Q-Switched,Maser,Pulsed Laser,Q Switched Lasers,Q-Switched Laser
D008853	Microscopy	The use of instrumentation and techniques for visualizing material and details that cannot be seen by the unaided eye. It is usually done by enlarging images, transmitted by light or electron beams, with optical or magnetic lenses that magnify the entire image field. With scanning microscopy, images are generated by collecting output from the specimen in a point-by-point fashion, on a magnified scale, as it is scanned by a narrow beam of light or electrons, a laser, a conductive probe, or a topographical probe.	Compound Microscopy,Hand-Held Microscopy,Light Microscopy,Optical Microscopy,Simple Microscopy,Hand Held Microscopy,Microscopy, Compound,Microscopy, Hand-Held,Microscopy, Light,Microscopy, Optical,Microscopy, Simple
D009119	Muscle Contraction	A process leading to shortening and/or development of tension in muscle tissue. Muscle contraction occurs by a sliding filament mechanism whereby actin filaments slide inward among the myosin filaments.	Inotropism,Muscular Contraction,Contraction, Muscle,Contraction, Muscular,Contractions, Muscle,Contractions, Muscular,Inotropisms,Muscle Contractions,Muscular Contractions
D009132	Muscles	Contractile tissue that produces movement in animals.	Muscle Tissue,Muscle,Muscle Tissues,Tissue, Muscle,Tissues, Muscle
D010003	Osteoarthritis	A progressive, degenerative joint disease, the most common form of arthritis, especially in older persons. The disease is thought to result not from the aging process but from biochemical changes and biomechanical stresses affecting articular cartilage. In the foreign literature it is often called osteoarthrosis deformans.	Arthritis, Degenerative,Osteoarthrosis,Osteoarthrosis Deformans,Arthroses,Arthrosis,Arthritides, Degenerative,Degenerative Arthritides,Degenerative Arthritis,Osteoarthritides,Osteoarthroses
D011312	Pressure	A type of stress exerted uniformly in all directions. Its measure is the force exerted per unit area. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)	Pressures
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
D006614	Hindlimb	Either of two extremities of four-footed non-primate land animals. It usually consists of a FEMUR; TIBIA; and FIBULA; tarsals; METATARSALS; and TOES. (From Storer et al., General Zoology, 6th ed, p73)	Hindlimbs