Allogeneic deep frozen meniscal graft for repair of osteochondral defects in the knee joint.

Osteochondral defects in the knee joints of five patients caused by trauma or osteochondritis dissecans were repaired using deep-frozen allogeneic meniscal grafts. Three patients were male and two were female, with a mean age of 26.4 years. The mean follow-up period was 31 months. Postoperative magnetic resonance imaging (MRI) at all periods clearly showed a smooth and congruous articular surface, although the signal intensity of the grafted meniscus was not the same as that of the articular cartilage. Second-look arthroscopy performed approximately 1 year after surgery demonstrated that the grafted meniscus was well bonded to the grafted site, not sunken; there was no gap between the grafted meniscus and the surrounding articular cartilage, indicating that the grafted meniscus functions as a part of the articular surface. Histologic examination revealed that host cells had infiltrated into the meniscus and that cells surrounded by thin collagen fibrils were morphologically similar to fibrochondrocytes. Thus, the acellular grafted meniscus regenerated as meniscal tissue and formed an articular surface, although hyalinization did not occur. Our results suggest that deep-frozen allogeneic meniscal grafting is a useful method to repair osteochondral defects in the knee joint.