title: Photoshop-based image analysis of canine articular cartilage after subchondral damage.
abstract: BACKGROUND
  The validity of histopathological grading is a major problem in the assessment of articular cartilage. Calculating the cumulative strength of signal intensity of different stains gives information regarding the amount of proteoglycan, glycoproteins, etc. Using this system, we examined the medium-term effect of subchondral lesions on initially healthy articular cartilage.
  
  
  METHODS
  After cadaver studies, an animal model was created to produce pure subchondral damage without affecting the articular cartilage in 12 beagle dogs under MRI control. Quantification of the different stains was provided using a Photoshop-based image analysis (pixel analysis) with the histogram command 6 months after subchondral trauma.
  
  
  RESULTS
  FLASH 3D sequences revealed intact cartilage after impact in all cases. The best detection of subchondral fractures was achieved with fat-suppressed TIRM sequences. Semiquantitative image analysis showed changes in proteoglycan and glycoprotein quantities in 9 of 12 samples that had not shown any evidence of damage during the initial examination. Correlation analysis showed a loss of the physiological distribution of proteoglycans and glycoproteins in the different zones of articular cartilage.
  
  
  CONCLUSIONS
  Currently available software programs can be applied for comparative analysis of histologic stains of hyaline cartilage. After subchondral fractures, significant changes in the cartilage itself occur after 6 months.
authors.affiliation: Department of Orthopaedic Surgery, University Hospital Freiburg, Hugstetter Str. 55, 79106 Freiburg, Germany. lahm@ch11.ukl.uni-freiburg.de
authors.forename: A
authors.initials: A
authors.lastname: Lahm
authors.forename: M
authors.initials: M
authors.lastname: Uhl
authors.forename: H A
authors.initials: HA
authors.lastname: Lehr
authors.forename: C
authors.initials: C
authors.lastname: Ihling
authors.forename: P C
authors.initials: PC
authors.lastname: Kreuz
authors.forename: J
authors.initials: J
authors.lastname: Haberstroh
mesh_terms: D000818:Animals; D001842:Bone and Bones / Q000293:injuries* / Q000473:pathology*; D002358:Cartilage, Articular / Q000378:metabolism / Q000473:pathology*; D019902:Chondrocytes / Q000473:pathology; D002999:Clone Cells / Q000473:pathology; D004285:Dogs; D005260:Female; D006023:Glycoproteins / Q000378:metabolism; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D023421:Models, Animal; D011509:Proteoglycans / Q000378:metabolism; D012598:Sclerosis; D012984:Software; D013194:Staining and Labeling
chemical_list: D006023:Glycoproteins; D011509:Proteoglycans