Background:

Different surgical approaches have been proposed for the treatment of chondral lesions. However surgical management of osteochondral defects of the knee joint involving subchondral bone are still under debate.

Aims: Histologically evaluate, at various intervals of time, osteochondral autografts transplanted in 10 adult goats. Methods: A full-thickness chondral defect of 1 cm in diameter was created on weight bearing surface of medial femoral condyle of goats. Multiple osteochondral grafts were harvested from the lateral trochlea using commercial arthroscopic tools (OATS); plugs were then inserted into prepared recipient site or the medial condyle without using a þxation device. The animals were killed at 3, 6, 9 and 12 months after surgery. Histologic examination using H and E staining was performed. The specimens were observed with light microscopy and polarized light microscopy. Results: At macroscopic evaluation, chondral lesions were completely reþlled by chondral tissue; the edges of the graft did not show complete incorporation with the host articular cartilage. Histology at 3 months showed the four layers of the articular cartilage in the middle of the implant; peripherically, we observed clusters of cells with many hypertrophic chondrocytes. Fibrocartilagineous tissue was present between the transplanted cartilage and the surrounding tissue. A well appearing tidemark was observed at all the follow-up. We also observed a change of staining of the intercellular matrix in the periphery. The donor sites were covered by þbrocartilagineous tissue. Conclusions: Multiple osteochondral autografts allow good clinical and functional results in chondral lesion treatment, but, at the second-look arthroscopy we always observed a þbrous layer between the implant and the host cartilage. The results of our experimental study shows that, at 12 months, the graft is viable, but there is a þbrocartilagineous layer between graft and the surrounding cartilage.