Matrix-Induced Autologous Chondrocyte Implantation (MACI): clinical results, mri findings and morphological analysis of implants

We prospectively evaluate clinical results and MRI findings on a series of 47 patients, with an average age of 31.7 years, treated by Matrix-induced Autologous Chondrocyte Implantation (MACI) for knee and ankle chondral defects. As isolated lesions, the joints affected were 37 knees and 5 ankle. As combined lesions, there were 4 knees and 1 kissing lesion in the ankle. The average size of the defects was 3.5 cm2. Clinical-functional evaluation was carried out according to ICRS, modified Cincinnati knee, Lysholm II and Tegner scales. The AOFAS score was used for the evaluation of the ankle. MRIs were taken before the operation as well as at 6, 12 and 24 months postoperatively. Among 10 second arthroscopic looks (4 knees, 6 ankles), two biopsies were carried out after 2 years, respectively from the medial femoral condyle and the patella. These specimens were evaluated by light microscopy, immunohistochemistry (type I and II collagen), SEM and TEM analysis. Follow-up averaged 25.6 months. At the latest follow up, knee scores improved after surgery. AOFAS did not improve in patient with kissing lesion. MRIs showed hyaline-like cartilage at the site of implantation in all treated joints with exception of the kissing lesion; four knees showed recurrence of subchondral bone edema one years after surgery. Histological analysis on the biopsies revealed good definition of the tidemark and presence of type II collagen. Clinical results and MRI findings support the efficacy of the MACI technique. Morphological findings are indicative for hyaline-like tissue formation in the implant site.