| Objective: To observe the effects and feasibility of cryopreserved osteochondral allografts combined with IGF-â… and fibrin gel on repairing local osteochondral defect in rabbits'knee.Methods: Cartilage defects were created in 18 rabbits on the bilateral knee.The left side of knee was served as experimental group and the right side served as control group. Experimental group filled with cryopreserved osteochondral allografts combined with IGF-â… and fibrin gel, control group filled with cryopreserved osteochondral allografts only.The animals were sacrificed in the 6th and 12th week after operation respectively. The cartilage defect repair efficacy was evaluated by morphological and histological exam at the 6th and 12th week after operation.Results: 1. Gross findings of osteochondral grafts: Grafts had a similar color and local height to the surrounding normal articular cartilage in experimental group. The transplants were as firm as the surrounding cartilage , and the regenerated area showed smooth, consistent. None of the grafts collapsed ,slanted and get absorbed in this study were found.The cartilage reparation capacities of control group was inferior to experimental group,which cartilaginous surface was thin and atrophic in part regenerated area with a few damaged. The semi-quantitative histological scores were significantly higher in the experimental group than in the control group (p < 0.05). 2. Microscopic observation of cartilage after transplantation: Under the light microscope, all grafts covered the defect with a relatively smooth surface in experimental group. The thickness and appearance were comparable to normal cartilage.Many mature living chondrocytes were found in regenerated area which remained the shape of hyaline cartilage and produced plenty of cartilage matrix. Arrangement of cells was more regular than control group.There were no lymphocytes and plasmacytes infiltrative peripherally. Grafts in the control group connected with the margin of normal cartilage but with micro clefts, and cartilage matrix did not fused with surrounding cartilage as a whole.Under transmission electron microscope, the chondrocytes lied in lacunae clearly in a thin and flat shape in two groups. There were many elliptic processes on the cellular surface. Chromatin had a uniform distribution, and rough endoplasmic reticulum was dilated. Abundant mitochondrias were found in the chondrocytes. Findings were similar between the control group and the experimental group,but the latter behaved better than the former . 3. Amino acid analysis showed that collagen for reparing the cartilage defects were type-II and type-I composite in two groups,indicating a transformation from hyaline cartilage to fibrocartilage.The other hand, newly formed cartilage was more intense for type-II collagen in the matrix in the experimental group,which indicated that tissue element of repaired cartilage was better and less degeneration in the experimental group than that in the control group .(p<0.05)Conclusions: Cryopreserved osteochondral allografts combined with IGF-â… and fibrin gel can repair cartilage defects of knee joints, this solution has the advantage of firm fixation , high cartilage cells survival and good repairation, and may become the effective method for repair of osteochondral defects.
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