Biological resurfacing of full-thickness defects in patellar articular cartilage of the rabbit

We compared the effects of continuous passive motion with those of intermittent active motion on the results of the resurfacing with autogenous periosteal grafts of full-thickness defects on the articular surface of rabbit patellae. of 45 rabbits with defects, 30 received grafts. Fifteen of these had continuous passive motion for two weeks and intermittent active motion for four weeks; the other 15 had intermittent active motion for six weeks. In 15 the defects were not grafted (confrol group) and they had intermittent active motion for six weeks. Ten more rabbits had a sham operation. Six weeks after surgery, the results were assessed by the gross appearance, histology, histochemistry, immunohistochemistry and elecfron microscopy. By all assessments the quality of neochondrogenesis produced by penosteal grafts was superior to that in ungrafted defects (p < 0.05) and the results in continuous passive motion freated animals were superior to those in intermittent active motion freated animals (p < 0.05). The periosteal grafts produced hyaline cartilage containing type II collagen but the organisation of its fibres was irregular. The articular cartilage of the patella is the thickest in the human body and the most frequent site of degeneration which may lead to osteoarthritis of the patellofemora