EFFECT OF CULTURED AUTOLOGOUS CHONDROCYTES ON REPAIR OF CHONDRAL DEFECTS IN A CANINE MODEL

Articular cartilage has a limited capacity for repair, In recent clini cal and animal experiments, investigators have attempted to elicit the repair of defects of articular cartilage by injecting cultured autolo gous chondrocytes under a periosteal flap (a layer of periosteum). The objective of the present study was to determine the effect of culture d autologous chondrocytes on healing in an adult canine model with use of histomorphometric methods to assess the degree of repair, A total of forty-four four-millimeter-diameter circular defects were created d own to the zone of calcified cartilage in the articular cartilage of t he trochlear groove of the distal part of the femur in fourteen dogs, The morphology and characteristics of the original defects were define d in an additional six freshly created defects in three other dogs, So me residual noncalcified articular cartilage, occupying approximately 2 per cent of the total cross-sectional area of the defect, was someti mes left in the defect, The procedure sometimes damaged the calcified cartilage, resulting in occasional microfractures or larger fractures, thinning of the zone of calcified cartilage, or, rarely, small locali zed penetrations into subchondral bone, The forty-four defects were di vided into three treatment groups, In one group, cultured autologous c hondrocytes were implanted under a periosteal flap. In the second grou p, the defect was covered with a periosteal flap but no autologous cho ndrocytes were implanted, In the third group (the control group), the defects were left empty, The defects were analyzed after twelve or eig hteen months of healing. Histomorphometric measurements were made of t he percentage of the total area of the defect that became filled with repair tissue, the types of tissue that filled the defect, and the int egration of the repair tissue with the adjacent cartilage at the sides of the defects and with the calcified cartilage at the base of the de fect, In histological sections made through the center of the defects in the three groups, the area of the defect that filled with new repai r tissue ranged from a mean total value of 36 to 76 per cent, with 10 to 23 per cent of the total area consisting of hyaline cartilage, Inte gration of the repair tissue with the adjacent cartilage at the edges of the defect ranged from 16 to 32 per cent in the three groups. Bondi ng between the repair tissue and the calcified cartilage at the base o f the defect ranged from 41 to 89 per cent, With the numbers available , we could detect no significant difference among the three groups wit h regard to any of the parameters used to assess the quality of the re pair, In the two groups in which a periosteal flap was sutured to the articular cartilage surrounding the defect, the articular cartilage sh owed degenerative changes that appeared to be related to that suturing , CLINICAL RELEVANCE: The technique of injecting cultured autologous c hondrocytes under a periosteal nap recently was introduced to treat de fects in the articular cartilage of humans. The long-term efficacy of this treatment is unknown. An animal model was developed to evaluate t he procedure and its effectiveness.