Cartilage repair with autogenic perichondrium cell and polylactic acid grafts

The repair of articular cartilage injuries remains a challenge, with many of the current therapeutic strategies based on the grafting or recruitment of chondrogenic tissues or cells. This 1-year study compared the repair of a 3.7-mm diameter by 3-mm deep osteochondral defect in the medial femoral condyle of 24 New Zealand White rabbits; the defect was obtained using an autogenic perichondrium cell polylactic acid composite graft with a contralateral control in which the osteochondral defect remained empty. To elucidate the effect of host immune responses on the repair process after perichondrium cell transplantation, the results of the autogenic perichondrium cell polylactic acid graft group were compared with those obtained in the authors' previous 1-year study of allogenic perichondrium cell polylactic acid composite grafts implanted in a similar model. One year after surgery, the repair site underwent gross inspection and histologic, histomorphometric, biochemical, and biomechanical analyses. The autogenic perichondrium cell polylactic acid graft group (92%) and the control group in which the osteochondral defect remained empty (88%) resulted in a high percentage of grossly acceptable repairs. The autogenic grafts appeared to augment the intrinsic healing capacity of the animals (as compared with the animals in the No Implant Group). The autogenic perichondrium cell polylactic and grafts improved the histologic appearance and percentage of Type II collagen of the cartilaginous repair tissue. Compared with allogenic grafts, the autogenic grafts had better reconstitution of the subchondral bone. However, the results of this experimental model suggest a suboptimal concentration of glycosaminoglycans in the neocartilage matrix, a depressed surface of the repair tissue, a histologic appearance that was not equivalent to that of normal articular cartilage, and reduced biomechanical properties for the repair tissue. The future application of growth factors to this model may yield a treatment that can be applied in the clinical arena.