Long-term results of deep defects in articular cartilage. A scanning electron microscope study

Core defects produced in the medial femoral condyle of the rabbit were studied by scanning electron microscopy and light microscopy over a period of 2 years. In some cases the defect was filled by hyaline articular cartilage with a fairly smooth surface, but in others the tissue was markedly fibrillated and resembled fibrous tissue and fibrocartilage. Appearances suggesting disintegration of the newly formed cartilage were seen in some cases. It would appear that a continuation of this process can lead to the exposure of subchondral bone. In one instance no repair tissue or new cartilage could be identified but the surrounding old cartilage had formed a shelf over the defect. The cartilage surrounding the defect was either normal or showed superficial fibrillation, and/or flow formation, and/or fissures.