title: How do visual, spectroscopic and biomechanical changes of cartilage correlate in osteoarthritic knee joints?
abstract: BACKGROUND
  Characteristic changes in cartilage of human knee joints with different degrees of osteoarthritis (OA) have been investigated by visual, biophotonical and biomechanical examination. Knowledge about the cartilage composition and changes during the development of OA is important for diagnostic decisions and understanding the pathogenesis of OA.
  
  
  METHODS
  Thirty two patients with severe knee OA received endoprosthetic replacement. During surgical intervention cartilage specimen were harvested from defined surface areas of the joints. The degree of cartilage defects was classified visually (ICRS Grade: International Cartilage Repair Society), biophotonically (NIRS: near infrared spectroscopy) and biomechanically (Young's Modulus). To characterise links between the investigated parameters the Spearman's rank correlation coefficient was used.
  
  
  RESULTS
  Significant negative correlations were found between visual macroscopic degree of degeneration (ICRS Grade) and biophotonic characteristics (NIRS) (rho=-0.467) or cartilage stiffness (Young's Modulus) (rho=-0.501). Between NIRS and Young's Modulus significant positive correlation of rho=0.535 was detected.
  
  
  CONCLUSIONS
  Visual, biophotonic and biomechanical properties of cartilage reveal strong correlations in all degrees of cartilage defects in patients with severe OA. According to these results, we indicate that an objective, non-invasive and non-destructive measurement of cartilage properties during open and arthroscopic knee surgery is possible by NIRS and provide a novel tool to evaluate disease intervention and treatment.
authors.affiliation: Department of Traumatology and Orthopaedic Surgery, Friedrich Schiller University of Jena and Trauma Centre Halle (Saale), Germany. julia.pester@med.uni-jena.de
authors.forename: Julia K
authors.initials: JK
authors.lastname: Marticke
authors.forename: Anja
authors.initials: A
authors.lastname: Hösselbarth
authors.forename: Konrad L
authors.initials: KL
authors.lastname: Hoffmeier
authors.forename: Ivan
authors.initials: I
authors.lastname: Marintschev
authors.forename: Steffi
authors.initials: S
authors.lastname: Otto
authors.forename: Matthias
authors.initials: M
authors.lastname: Lange
authors.forename: Holger K W
authors.initials: HK
authors.lastname: Plettenberg
authors.forename: Gunter
authors.initials: G
authors.lastname: Spahn
authors.forename: Gunther O
authors.initials: GO
authors.lastname: Hofmann
mesh_terms: D000328:Adult; D000368:Aged; D002358:Cartilage, Articular / Q000473:pathology* / Q000503:physiopathology*; D055119:Elastic Modulus; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000473:pathology* / Q000503:physiopathology*; D013223:Statistics as Topic