Cartilage repair with autogenic perichondrium cell and polylactic acid grafts

The repair of articular cartilage injuries remains a challenge, with many o f the current therapeutic strategies based on the grafting or recruitment o f 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 co ndyle of 24 New Zealand White rabbits; the defect was obtained using an aut ogenic perichondrium cell polylactic acid composite graft with a contralate ral control in which the osteochondral defect remained empty. To elucidate the effect of host immune responses on the repair process after perichondri um cell transplantation, the results of the autogenic perichondrium cell po lylactic acid graft group were compared with those obtained in the authors' previous 1-year study of allogenic perichondrium cell polylactic acid comp osite grafts implanted in a similar model. One year after surgery, the repa ir site underwent gross inspection and histologic, histomorphometric, bioch emical, and biomechanical analyses. The autogenic perichondrium cell polyla ctic acid graft group (92%) and the control group in which the osteochondra l defect remained empty (88%) resulted in a high percentage of grossly acce ptable repairs. The autogenic grafts appeared to augment the intrinsic heal ing capacity of the animals (as compared with the animals in the No Implant Group), The autogenic perichondrium cell polylactic acid grafts improved t he histologic appearance and percentage of Type II collagen of the cartilag inous repair tissue. Compared with allogenic grafts, the autogenic grafts h ad better reconstitution of the subchondral bone, However, the results of t his experimental model suggest a suboptimal concentration of glycosaminogly cans 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 t hat can be applied in the clinical arena.