A novel approach to observing articular cartilage deformation in vitro via magnetic resonance imaging.
The design of a pressure cell that compresses a cartilage specimen in one dimension within an imaging magnet is presented. One-dimensional projection images in a direction perpendicular to the articular surface of the cartilage specimen were used to generate a uniaxial confined deformation creep curve for normal and trypsin-degraded cartilage specimens during a continuous 0.690 MPa (100 psi) pressure application. The resulting curves are shown to fit a two time constant viscoelastic model well and also indicate that the elastic modulus of cartilage decreases and the deformation rate increases upon trypsin proteolysis. Furthermore, cartilage permeability is shown as a function of cartilage strain for both the normal and trypsin-degraded case. Several two-dimensional slice-selective images were collected both before and after 80 minutes of continuous compression. These images were used to evaluate the relative changes in the spin-lattice, T1, and spin-spin, T2, relaxation time constant maps for both normal and degraded cartilage specimens in response to compression. The results of this study demonstrate the utility of a novel, non-magnetic, cartilage compression device and also support the validity of a simple two-component rheological model of articular cartilage.
Kaufman
J H
JH
Department of Radiology, University of Pennsylvania School of Medicine, Philadelphia 19104, USA.
Regatte
R R
RR
Bolinger
L
L
Kneeland
J B
JB
Reddy
R
R
Leigh
J S
JS
D000818:Animals; D002358:Cartilage, Articular / Q000187:drug effects / Q000473:pathology* / Q000502:physiology; D002417:Cattle; D004548:Elasticity; D066298:In Vitro Techniques; D008279:Magnetic Resonance Imaging; D010539:Permeability; D011312:Pressure; D012212:Rheology; D013314:Stress, Mechanical; D014357:Trypsin / Q000494:pharmacology; D014783:Viscosity
D014357:Trypsin