Osteochondral grafts in growing rabbits

Summary In 60-day (group A) and 90-day (group B) old rabbits a standardized osteochondral graft was taken from the distal articular surface of the femur and replanted immediately. Five animals in each group were observed at 9 different times between 3 days and 6 months. On histological and autoradiographic (³⁵S-sulphate) examination the following were found: In group A there was no ³⁵S uptake in the deep layers of the articular cartilage between 3 days and 1 week; in most cases there was normal articular cartilage in the transplants at 2 weeks to 6 months. In group B later changes (3 weeks—6 months), affecting the greater part of the articular cartilage, were observed. These changes appeared to be irreversible and were found in about 1/3 of the cases. The other 2/3 showed completely normal articular cartilage.Fluorescence-microscopic (after tetracycline administration), microradiographic and microangiographic (Indian ink) studies revealed the following: Revascularization of the subchondral bone took place after 3–5 days. The ossification process in the subchondral area was restored within 5–7 days. The osseous part of the transplants healed by primary bone union within 1–2 weeks. The revascularization took place more rapidly in group A.At the longest observation times (8 weeks and 6 months) in both groups slight flattening of the transplant area was seen, probably as a result of slightly retarded growth of the bone within the transplant.Supported by grants from the Swedish Medical Research Council, Project No. 17 X-138-08 A.