Allotransplantation of cryopreserved menisci in monkey: histological change.

The purpose of this study was to carry out a histological evaluation of cryopreserved menisci used as allografts in monkeys. Menisci were evaluated histologically at one, three, six and at twelve months after transplantation. In the deep layer of the allografts, the number of cells and the amount of the extracellular matrix had decreased at three to six months after transplantation. After twelve months, the evaluation revealed that both the cell counts and the extracellular matrix had increased returning to nearly normal levels. However, the colour of the matrix stained with Masson's trichrome had changed to red. This change may correspond with the occurrence that of young newly-formed collagen. Since the articular cartilage showed minimal degenerative change, it is concluded that meniscal transplantation is useful and should be considered for meniscal injuries.