Transplantation of fresh-frozen menisci: an experimental study in dogs

Transplantation of 25 fresh-frozen medial menisci was studied in 15 adult dogs. Before implantation, the allografts were deep-frozen and stored at -70 degrees C for 6 weeks to 18 months. The animals were killed 2 to 8 months postoperatively, and their knees and transplants were examined macroscopically and histologically. Complete healing of the allografts was found in 19 knees, incomplete in 3, and healing by massive fibrovascular tissue in 3 knees. Some shrinkage of the transplants taken 2 to 4 months after the surgery was observed; however, the 6- and 8-month specimens appeared grossly normal. Histologically, all transplants displayed a characteristic decrease in the number of cells, but this was significantly less pronounced in the 6- and 8-month specimens. Some degenerative alterations were found in all transplanted knees, but was obviously less pronounced in areas covered by the allografts and in the 6- and 8-month specimens. It is concluded that the transplantation of the fresh-frozen menisci could be successful; although the transplants are subjected to a remodeling process, they appear to function normally and protect the articular cartilage. The technique of conservation by freezing at -70 degrees C offers the advantage of an effective meniscal banking.