## 3 Results  
Both groups showed a marked improvement of all clinical scores from baseline to the last follow-up. The IKDC subjective score improved significantly in the mosaicplasty group from the basal level of 38.1 \(\pm\) 11.8 to 75.3 \(\pm\) 21.8 (p \(<\) 0.0005) at the final follow-up. Similarly, in the MACT group there was a significant improvement from the basal level of \(37.6\pm 14.9\) to the final follow-up of \(81.8\pm 13.0\) (p \(<\) 0.0005). No significant differences in the IKDC subjective scores were found between mosaicplasty and MACT groups (Figure 1). The IKDC objective score in the mosaicplasty group improved from baseline, where no knees were evaluated as normal or nearly normal (13 C, 7 D), to 16 normal or nearly normal knees at 12 years of follow-up (7 A, 9 B, 3 C, 1 D). In the MACT group, this score improved from 7 normal or nearly normal knees at baseline (1 A, 6 B, 9 C, 7 D) to 23 at the final follow-up (16 A, 7 B). The IKDC objective score improvement was significantly higher in the MACT group compared with the mosaicplasty group at 12 years of follow-up (p = 0.029). The Tegner score in the mosaicplasty group showed a significant improvement from \(2.9\pm 1.4\) at the pre-operative evaluation to \(5.0\pm 2.4\) at the final follow-up (p = 0.043); however, the mean activity level remained lower vs. pre-injury (\(7.1\pm 2.0\), p = 0.081). Similarly, the Tegner score of the MACT group showed a statistically significant improvement (p = 0.001) from the pre-operative level (\(1.6\pm 1.5\)) to the final follow-up (\(5.3\pm 2.1\)), although also in this case without reaching the pre-injury level (\(7.0\pm 1.6\), p = 0.081). No significant differences were found in the Tegner scores between mosaicplasty and MACT at the final follow-up, with only eight patients for each group achieving the pre-injury activity level 12 years after surgery (Figure 2). Two patients of the mosaicplasty group failed (one with four plugs and one with three plugs) and were treated with MACT 2 years after the treatment, fixing a 10% reoperation rate. At the final mean follow-up of 12 years, three more patients in the mosaicplasty group (one patient with one plug, one with two plugs, and one with four plugs) were considered clinical failures, for an overall failure rate of 25%, significantly higher compared to the MACT group, where no surgical or clinical failures occurred (p = 0.016). The MRI findings of 30 knees (15 mosaicplasty and 15 MACT), analyzed with the MOCART 2.0 scoring system, showed a high rate of cartilage defect filling in both groups, and a complete integration into the adjacent cartilage in half of the patients in both groups. However, the surface of the repair tissue was damaged in the majority of cases. The structure of the repair tissue was homogeneous in most cases, and the signal intensity was normal (isointense) in half of the patients in both groups. At subchondral bone level, a bony defect or bony overgrowth was reported in the majority of patients, while an edema-like marrow signal was reported in almost half of the patients in both groups (Figures 3  
Figure 1: Comparison of the International Knee Documentation Committee (IKDC) subjective score achieved at a final follow-up of 12 years by both groups of patients. The values are expressed in median and 25 th and 75 th percentiles. No significant differences were found between the two groups. FU, follow-up. and 4). No significant differences were reported between the two groups in the overall MOCART 2.0 scores and in all the seven subscales (Table 2). Further analysis was performed to determine the parameters that influenced the clinical outcome at the final follow-up in the two treatment groups. Defect size was found to significantly influence the final IKDC scores between the two groups, with MACT producing significantly higher objective results (p = 0.031) and a tendency for higher subjective results compared to mosaicplasty (81.8 \(\pm\) 18.3 vs 58.8 \(\pm\) 25.0, p = 0.092) for lesions > 2 cm\({}^{2}\).