Durability of artificial implants for repair of osteochondral defects of the medial femoral condyle in rabbits.

Full-thickness osteochondral defects in the femoral condyles of 25 rabbits were repaired using artificial implants made of Teflon or Dacron. The 6 and 12 month results were compared with ungrafted defects (natural repair) and periosteal grafting. Throughout the observation period, all repair sites were three-fold more compliant than normal cartilage (P < 0.01). The adjacent cartilage was unaffected. Splits between the repair sites and the adjacent cartilage were common. At 6 months, the Dacron repairs had higher scores than natural repair (P < 0.05). Between 6 and 12 months, no significant change in appearance was noted for the artificial repairs. At 1 yr, the scores for natural and Dacron repairs were similarly high, but natural repair had more surface fibrillation (P < 0.05). Periosteal grafting had a lower score than Dacron repair (P < 0.01). Synovitis and artificial debris tended to decrease with time (n.s., P < 0.06). In the present model, Dacron repair of small cartilage defects at 1 yr showed better neocartilage quality than periosteal grafting. Dacron had earlier neocartilage formation than unrepaired defects, and showed no late deterioration, but normal cartilage mechanics and morphology were not attained.