2015 ISAKOS Biennial Congress ePoster #406
Implantation of Autogenous Meniscal Fragments Wrapped With a Fascia Sheath Enhances Fibrocartilage Regeneration In Vivo in a Large Harvest Site Defect: An Experimental Study With Sheep
Yasuyuki Kawaguchi, MD, PhD, Ikoma, Nara JAPAN
Eiji Kondo, MD, PhD, Sapporo, Hokkaido JAPAN
Nobuto Kitamura, MD, PhD, Sapporo, Hokkaido JAPAN
Shunji Yunoki, PhD, Tokyo JAPAN
Masashi Kimura, MD, PhD, Gumma JAPAN
Yasuhito Tanaka, Prof., Kashihara, Nara JAPAN
Kazunori Yasuda, MD, PhD, Prof., Sapporo, Hokkaido JAPAN
Dpartment of Sports Medicine and Joint Surgery, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido, JAPAN
FDA Status Not Applicable
Summary: This study has clarified that implantation of autogenous meniscal fragments wrapped with a fascia sheath into the donor site defect significantly enhanced fibrocartilage regeneration in vivo in a large harvest site defect at 12 weeks after implantation in a sheep model.
Poor healing capacity of the meniscal tissue often dictates removal of the damaged tissue. However, the loss of meniscus results in secondary osteoarthritis. Recently, the authors reported that implantation of autogenous meniscal fragments wrapped with a fascia sheath into the meniscal defect significantly enhances fibrocartilage regeneration in the defect after implantation in the rabbit (AJSM 2010). In addition, we clarified that this phenomenon of the regeneration is achieved by synergic effects of the native meniscal matrix and the living chondrocyte implantation. These studies proposed a novel strategy for meniscal repair. However, we should know whether the meniscus regeneration can be induced in large animals by the autologous meniscal fragment implantation for the feasibility of human meniscus repair. We have hypothesized that this phenomenon of the regeneration would occur in the sheep model. The purpose of this study is to test this hypothesis.
Twenty Suffolk sheep were used. In each animal, an anterior 1-cm width of the right medial meniscus was resected. Then, the animals were divided into the following 2 groups. In Group I, the defect was covered with a fascia from the left thigh. In Group II, the resected meniscus fragmented into small pieces was grafted into the defect. Then the defect was covered with a fascia. In each group, each 5 sheep were used for morphological, histological, and biomechanical evaluations at 12 weeks after surgery. Tissue dimensions of the regenerated tissue were determined in both morphological and histological observations. Histological findings of the regenerated tissue observed with HE and Safranin-O staining were quantified with the scoring system. For biomechanical evaluations, the tibia-meniscus-tibia complex from each harvested knee was mounted on a tensile tester. Tensile tests were performed at a cross-head speed of 20 mm/min. We determined the structural properties of the regenerated portion under quasi-hoop stress, because all meniscus specimens failed at the regenerated portion. Statistical analyses were used unpaired t-test. The significance level was set at p=0.05.
In Group I, the defect was incompletely filled with thin fibrous tissues, while cartilage tissues rarely regenerated in the tissue. In Group II, all defects were completely filled with thick fibrocartilage tissues, which were richly stained with the Safranin-O staining. Both the gross and histological observation score of the cartilage regeneration of Group II was significantly greater than that of Group I. Concerning the width and the cross-sectional area of the regenerated tissue, Group II was significantly greater than Group I. In the biomechanical evaluation, the maximal load and the linear stiffness of the regenerated tissues were significantly greater in Group II than in Group I.
The morphological and histological results of this study demonstrated that implantation of autogenous meniscal fragments wrapped with a fascia sheath into the defect significantly enhanced fibrocartilage regeneration in a large harvest site defect at 12 weeks after implantation even in the sheep model. In the present study, we performed the uniaxial tensile test of the meniscal specimens in the circumferential direction. The reason is that the circumferential fibers are the most essential because they are dominant and bear the hoop stress generated by a compression force between the femoral and tibial joint surfaces. Therefore, our biomechanical findings suggest that the capacity for transmitting the tibiofemoral load of the regenerated tissue is better in Group II than in Group I. As for clinical relevance, the present study suggested that the proposed novel strategy has a high feasibility for human meniscus repair.