A prospective randomized clinical study of mosaic osteochondral autologous transplantation versus microfracture for the treatment of osteochondral defects in the knee joint in young athletes.

PURPOSE: The purpose of this study was to compare the outcomes of mosaic-type osteochondral autologous transplantation (OAT) and microfracture (MF) procedures for the treatment of the articular cartilage defects of the knee joint in young active athletes. TYPE OF STUDY: Prospective randomized clinical study. METHODS: Between 1998 and 2002, a total of 60 athletes with a mean age of 24.3 years (range, 15 to 40 years) and with a symptomatic lesion of the articular cartilage in the knee were randomized to undergo either an OAT or an MF procedure. Only those athletes playing in competitive sports at regional or national levels were included in the study. Fifty-seven athletes (95%) were available for a follow-up. There were 28 athletes in the OAT group and 29 athletes in the MF group. The mean duration of symptoms was 21.32 +/- 5.57 months and the mean follow-up was 37.1 months (range, 36 to 38 months), and none of the athletes had prior surgical interventions to the affected knee. Patients were evaluated using modified Hospital for Special Surgery (HSS) and International Cartilage Repair Society (ICRS) scores, radiograph, magnetic resonance imaging (MRI), and clinical assessment. An independent observer performed a follow-up examination after 6, 12, 24, and 36 months. At 12.4 months postoperatively, arthroscopy with biopsy for histologic evaluation was carried out. A radiologist and a pathologist, both of whom were blinded to each patient's treatment, did the radiologic and histologic evaluations. RESULTS: After 37.1 months, both groups had significant clinical improvement (P < .05). According to the modified HSS and ICRS scores, functional and objective assessment showed that 96% had excellent or good results after OAT compared with 52% for the MF procedure (P < .001). At 12, 24, and 36 months after surgery, the HSS and ICRS showed statistically significantly better results in the OAT group (P = .03; P = .006; P = .006). Younger athletes did better in both groups. No serious complications were reported. There was 1 failure in the OAT group and 9 in the MF group. The ICRS Cartilage Repair Assessment for macroscopic evaluation during arthroscopy at 12.4 months showed excellent or good repairs in 84% after OAT and in 57% after MF. Biopsy specimens were obtained from 58% of the patients and histologic evaluation of repair showed better scores (according to ICRS) for the OAT group (P < .05). MRI evaluation showed excellent or good repairs in 94% after OAT compared with 49% after MF. Twenty-six (93%) OAT patients and 15 (52%) MF patients returned to sports activities at the preinjury level at an average of 6.5 months (range, 4 to 8 months). Others showed a decline in sports activity level. CONCLUSIONS: At an average of 37.1 months (range, 36 to 38 months) follow-up, our prospective, randomized, clinical study in young active athletes under the age of 40 has shown significant superiority of OAT over MF for the repair of articular cartilage defects in the knee. We found that only 52% of MF athletes could return to sports at the preinjury level. Limitations of our study included a small number of athletes and a relatively short (3-year) follow-up. A long-term follow-up is needed to assess the durability of articular cartilage repair using these methods in young active athletes. LEVEL OF EVIDENCE: Level I, Therapeutic study, randomized controlled trial, significant difference (a).