title: Indentation testing of human cartilage: sensitivity to articular surface degeneration.
abstract: OBJECTIVE
  To determine, for clinical indentation testing of human articular cartilage, the effects of aging and degeneration on indentation stiffness and traditional indices of cartilage degeneration; the relationship between indentation stiffness and indices of degeneration; and the sensitivity and specificity of indentation stiffness to cartilage degeneration.
  
  
  METHODS
  Osteochondral cores from femoral condyles of cadaveric human donors were harvested. Samples were distributed into experimental groups based on donor age (young [20-39 years], middle [40-59 years], and old [>/=60 years]), and a macroscopic articular surface appearance that was either normal or mildly degenerate, without deep erosion. Samples were analyzed for indentation stiffness, cartilage thickness, India ink staining (quantitated as the reflected light score), and Mankin-Shapiro histopathology score.
  
  
  RESULTS
  Indentation stiffness, India ink staining, and the histopathology score each varied markedly between normal-sample and degenerate-sample groups but varied relatively little between normal samples obtained from different age groups. A decrease in indentation stiffness (softening) correlated with a decrease in the reflectance score and an increase in the overall histopathology score, especially the surface irregularity component of the histopathology score. Receiver operating characteristic analysis suggested that the indentation testing could accurately detect cartilage degeneration as indicated by macroscopic appearance, India ink staining, and histopathology score.
  
  
  CONCLUSIONS
  The indentation stiffness of the normal to mildly degenerate samples tested in this study was sensitive to mild degeneration at the articular surface and was insensitive to changes associated with normal aging or to slight variations in cartilage thickness. This suggests that indentation testing may be a useful clinical tool for the evaluation of early-stage degenerative changes in articular cartilage.
authors.affiliation: University of California-San Diego, La Jolla, California 92093-0412, USA.
authors.forename: Won C
authors.initials: WC
authors.lastname: Bae
authors.forename: Michele M
authors.initials: MM
authors.lastname: Temple
authors.forename: David
authors.initials: D
authors.lastname: Amiel
authors.forename: Richard D
authors.initials: RD
authors.lastname: Coutts
authors.forename: Gabriele G
authors.initials: GG
authors.lastname: Niederauer
authors.forename: Robert L
authors.initials: RL
authors.lastname: Sah
mesh_terms: D000328:Adult; D000375:Aging / Q000473:pathology*; D002102:Cadaver; D002244:Carbon; D002356:Cartilage / Q000473:pathology*; D004548:Elasticity; D005260:Female; D005269:Femur; D006801:Humans; D066298:In Vitro Techniques; D007719:Knee Joint / Q000473:pathology; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity
chemical_list: C028433:chinese ink; D002244:Carbon