Regeneration of defects in articular cartilage with callus and cortical bone grafts. An experimental study

Cartilage regeneration was studied in an experiment in rats. A standardised full-thickness articular cartilage defect was created and autogenous 12-day-old callus or cortical bone graft was transplanted into it, or the defect was left empty. The follow up periods were three, six, 12, and 24 weeks, and each subgroup consisted of five animals. A total of 60 animals were operated on. From six weeks onwards hyaline-like cartilaginous tissue had started to develop at the edges of the defect in all three groups. In the middle section of the hole, however, the picture was different; at 24 weeks none of the specimens in the defect group, two of the five in the callus graft group, and all five in the bone graft group had developed full-thickness, hyaline-like cartilaginous regeneration. The hyaline-like cartilaginous tissue in the medical segment was hypocellular when analysed by histomorphometry. On scanning electron microscopy the surface of the reparative tissue looked fibrillated in all specimens from the three groups.