title: Molecular NMR T2 values can predict cartilage stress-relaxation parameters.
abstract: Articular cartilage lines synovial joints and functions as a low-friction deformable tissue to enable smooth and stable joint articulation. The objective of this study was to determine the relationships between cartilage stress-relaxation properties and the collagen and GAG NMR transverse relaxation times (T(2)) toward understanding mechanisms of cartilage viscoelasticity. Stress-relaxation tests were performed on both cultured and enzymatically digested bovine cartilage, followed by measurements of both the collagen and GAG T(2) using the Call-Purcell-Meiboom-Gill pulse sequence. The peak and equilibrium stresses were correlated with the GAG T(2), and the stress-relaxation time constant was correlated with the collagen T(2). Multiple linear regression models were successful in using the specific T(2) values to predict the stress-relaxation properties. As a model of osteoarthritis, enzymatic digestion with collagenase and testicular hyaluronidase had weak effects on T(2) values. These data present a complex picture of cartilage mechanical behavior, with cartilage stiffness associated with the GAG T(2) values and the stress-relaxation time constant associated with the collagen T(2).
authors.affiliation: UCSD and VA Medical Research Foundation, La Jolla, CA 92093-9111K, USA. rjune@ucsd.edu
authors.forename: Ronald K
authors.initials: RK
authors.lastname: June
authors.forename: David P
authors.initials: DP
authors.lastname: Fyhrie
mesh_terms: D000818:Animals; D002358:Cartilage, Articular / Q000737:chemistry* / Q000502:physiology; D002417:Cattle; D003094:Collagen / Q000737:chemistry*; D004548:Elasticity; D006025:Glycosaminoglycans / Q000737:chemistry*; D016014:Linear Models; D019906:Nuclear Magnetic Resonance, Biomolecular; D013314:Stress, Mechanical; D013997:Time Factors
chemical_list: D006025:Glycosaminoglycans; D003094:Collagen