A prospective, randomized clinical study of osteochondral autologous transplantation versus microfracture for the treatment of osteochondritis dissecans in the knee joint in children.

PURPOSE: The aim of this study was to compare the outcomes of the arthroscopic mosaic-type osteochondral autologous transplantation (OAT) and microfracture (MF) procedures for the treatment of osteochondritis dissecans (OCD) defects of the femoral condyles of the knee joint in children under the age of 18 years.

TYPE OF STUDY: Prospective, randomized clinical study.

METHODS: Between 2001 and 2005, a total of 50 children with a mean age of 14.3 years (12 to 18) and with symptomatic lesions of the OCD in the femoral condyle of the knee were randomized to undergo either the OAT or the MF procedure. Only those children with grade 3 or 4 (OCD) in the medial or lateral femoral condyle (according to International Cartilage Repair Society, ICRS) were included in the study. Forty-seven patients (94%) were available for follow-up. There were 25 patients in the OAT group and 22 patients in the MF group. The mean duration of symptoms was 23.54+/-4.24 months and the mean follow-up was 4.2 years (range from 3 to 6 y), and none of the children had prior surgical interventions to the affected knee. Children were evaluated using ICRS score, x-rays, magnetic resonance imaging, and second-look arthroscopies.

RESULTS: After 1 year, both groups had significant clinical improvement (P<0.05) and the ICRS functional and objective assessment showed that 23 of 25 (92%) patients had excellent or good results after OAT compared with 19 of 22 (86%) after MF (NS), but 19 of 23 (83%) after OAT and only 12 of 19 (63%) after MF procedure maintained excellent or good results after 4.2 years (range from 3 to 6 y). The MF group showed significant deterioration over the 4.2 years follow-up (P<0.05), but still had significant clinical improvement compared with pretreatment evaluation (P=0.004). There were 9 of 22 (41%) failures in the MF group, and none in the OAT group. Magnetic resonance imaging evaluation according to the ICRS evaluation system showed excellent or good repairs in 19 of 21 patients (91%) after OAT compared with 10 of 18 (56%) after MF.

CONCLUSIONS: At an average of 4.2 years follow-up, our prospective, randomized, clinical study in children under the age of 18 years has shown significant superiority of the mosaic-type OAT over MF for the treatment of osteochondritis dissecans defects in the knee. However, our study has shown that both MF and OAT give encouraging clinical results for children under the age of 18 years.

LEVEL OF EVIDENCE: Level 1: randomized controlled trial, significant difference.