[Experiences with arthroscopic therapy of chondral and osteochondral defects of the knee joint with OATS (Osteochondral Autograft Transfer System)].

Between 1.6.1997 and 31.12.1998 an osteochondral transplantation with the OATS (Osteochondral Autograft Transfer System) was performed in 18 patients. Indication for OATS was in 9 cases a chondral defect in ACL deficient knees. 3 times we found a fresh chondral defect, in 6 cases we found cartilage damage on the medial femoral condyle at the main weight-bearing area (Outerbridge, type III-IV) in chronic ACL deficient knees. The defect-size in these 9 patients (7 male and 2 female) ranged between 12 mm and 23 mm in diameter and had an average-size of 15 mm. There have been 3 cases with osteochondrosis dissecans, 4 patients had a osteonecrosis at the medial femoral condyle. In the 18 cases an average of 1.8 grafts was needed; more than 3 grafts were used only in exceptional cases, because in such cases the stability between the grafts is reduced. The short outcome in the Lysholm-score showed mainly good results. The average score value during follow-up was 89.5 (range 78-92). This outcome makes hopeful for likewise middle-term-results. The OATS can be recommended for the treatment of chondral and osteochondral defects in the main-weight-bearing area of the knee as a safe procedure for transplantation of hyaline cartilage.