title: Immature porcine knee cartilage lesions show good healing with or without autologous chondrocyte transplantation.
abstract: OBJECTIVE
  The purpose of this study was to find out how deep chondral lesions heal in growing animals spontaneously and after autologous chondrocyte transplantation.
  
  
  METHODS
  A 6mm deep chondral lesion was created in the knee joints of 57 immature pigs and repaired with autologous chondrocyte transplantation covered with periosteum or muscle fascia, with periosteum only, or left untreated. After 3 and 12 months, the repair tissue was evaluated with International Cartilage Repair Society (ICRS) macroscopic grading, modified O'Driscoll histological scoring, and staining for collagen type II and hyaluronan, and with toluidine blue and safranin-O staining for glycosaminoglycans. The repair tissue structure was also examined with quantitative polarized light microscopy and indentation analysis of the cartilage stiffness.
  
  
  RESULTS
  The ICRS grading indicated nearly normal repair tissue in 65% (10/17) after the autologous chondrocyte transplantation and 86% (7/8) after no repair at 3 months. At 1 year, the repair tissue was nearly normal in all cases in the spontaneous repair group and in 38% (3/8) in the chondrocyte transplantation group. In most cases, the cartilage repair tissue stained intensely for glycosaminoglycans and collagen type II indicating repair tissue with true constituents of articular cartilage. There was a statistical difference in the total histological scores at 3 months (P=0.028) with the best repair in the spontaneous repair group. A marked subchondral bone reaction, staining with toluidine blue and collagen type II, was seen in 65% of all animals.
  
  
  CONCLUSIONS
  The spontaneous repair ability of full thickness cartilage defects of immature pigs is significant and periosteum or autologous chondrocytes do not bring any additional benefits to the repair.
authors.affiliation: Department of Orthopaedics, Helsinki University Hospital, Peijas Hospital, Vantaa, Finland. anna.vasara@fimnet.fi
authors.forename: A I
authors.initials: AI
authors.lastname: Vasara
authors.forename: M M
authors.initials: MM
authors.lastname: Hyttinen
authors.forename: O
authors.initials: O
authors.lastname: Pulliainen
authors.forename: M J
authors.initials: MJ
authors.lastname: Lammi
authors.forename: J S
authors.initials: JS
authors.lastname: Jurvelin
authors.forename: L
authors.initials: L
authors.lastname: Peterson
authors.forename: A
authors.initials: A
authors.lastname: Lindahl
authors.forename: H J
authors.initials: HJ
authors.lastname: Helminen
authors.forename: I
authors.initials: I
authors.lastname: Kiviranta
mesh_terms: D000818:Animals; D002358:Cartilage, Articular / Q000293:injuries / Q000601:surgery*; D019902:Chondrocytes / Q000637:transplantation*; D024043:Collagen Type II / Q000737:chemistry; D006025:Glycosaminoglycans / Q000737:chemistry; D006614:Hindlimb; D006820:Hyaluronic Acid / Q000737:chemistry; D007719:Knee Joint / Q000601:surgery*; D010521:Periosteum / Q000637:transplantation*; D013552:Swine; D014182:Transplantation, Autologous; D014945:Wound Healing
chemical_list: D024043:Collagen Type II; D006025:Glycosaminoglycans; D006820:Hyaluronic Acid