An Experimental Study On The Allograft Meniscus Revascularization In Rabbits

Objective To study the vascularization restoration process and further provide test reference to clinical rehabilitation after meniscus autograft, through establishing meniscus autograft and allograft models fromOryctolagus cuniculusand observing their revascularization. Methods 24 rabbits at mature bone age (weight,2.5-3.0 kg; male and female) were undergo operation, the medial meniscus was resected in left knee and then be sutured, the right knee were tansplanted allograft medial meniscus which preserved at deep freezing temperature with 3-layor seal, and sterilized through cobalt-60 radiation. In 4 weeks,8 weeks, and 12 weeks postoperatively,2 rabbits were randomly chosen for ink intra-abdominal aorta infusion at the knee and the grafted meniscus carved into wax slices to observe the vascular distribution. Meanwhile,6 rabbits were chosen to detect the meniscus vascular perfusion by laser Doppler flowmeter. Then the rabbits were sacrificed. The grafted meniscus and surrounding tissues were taken out, for which the general observation was recorded. The meniscus in knee joints were performed with histological examination (HE staining of meniscus tissues) and immunochemical detection (monoclonal antibody immunochemical staining of meniscus vascular endothelial growth factor). Results. The meniscus in joint was good in shape and well healed with surrounding joint capsule. No obvious damage of joint cartilage at tibia plateau was seen, due to the protection of grafted meniscus. The autograft and allograft meniscus were good in shape within the joint and well healed in joint capsule. No serious cartilage damage or osteophyte was observed medial tibia plateau and femoral condyle.. According to the ink perfusion, meniscus vessels were gradually established. In 4 weeks, vessel started to grow in the anterior and posterior parts. In 8 weeks, the vessels were further moved medially. In 12 weeks, there were abundant vessels at both anterior and posterior parts, while the meniscus body showed vessel growth mainly at adhesion margin with less than one third of meniscus transverse diameter; no significant vascular distribution was found at the free margin. Thus, very few vascularization of meniscus was found through ink perfusion. In 4 weeks,8 weeks, and 12 weeks, vascularization developed step by step at the adhesion margin of meniscus with almost no vessel growth or blood supply at the free margin. As shown in Doppler flowmeter, In 8 weeks, blood circulation reached the maximum at anterior and posterior parts In 12 weeks, blood circulation started to decrease. With respect to the histochemical examination of vascular endothelial growth factor, both groups reported maximum positive rate (n=6) in 4 weeks after surgery. In the 8weeks,6 species of autografts and allografts,2 species were negative and 1 specie of allograft was negative. In 12 weeks,2 out of 6 autografted species were slightly positive,2 of the allografted species were slightly positive, and the rest ones were negative. As for the HE staining, the vascular endothelial cells gradually increased.Conclusions In 12 weeks after meniscus allografting and autografting, vascular endothelial growth factor expression deregulated, the vascular circulation almost recovered, and the reconstruction of cell and fiber gradually started.