Platelet-rich fibrin and cartilage granules facilitate cartilage repair Kuo T-F et al. CLINICS 2011;66(10):1835-1838 Figure 1 - Platelet-rich fibrin gel obtained from the middle layer of the blood sample after centrifugation. spin-echo sequence with the following parameters: TR = 1500 ms; TE = 12, 24, 36, 48 ms/30, 60, 90, and 120 ms; slice thickness = 1.5 mm; matrix size = 2566256; in-plane resolution = 0.4760.47 mm; and field of view = 120 mm. The region of interest was manually drawn on the first echo image (TE = 12 ms) to calculate the mean and standard deviation of the T2 relaxation rate of the defective cartilage. The femoral cartilage was covered by approximately 2 pixels, and the selected image was enlarged threefold to minimize partial volume effects. The T2 value for each rabbit in group A and group B was compared with that of the same rabbit’s normal cartilage on the contralateral side. For comparison under the same conditions, normalized T2 values were calculated using the values for defective cartilage divided by the values for the normal cartilage of the same animal. We used the Mann-Whitney test to compare the normalized T2 values between groups with p,0.05 indicating significance. After sacrificing the animal, all experimental limbs were dissected. The specimens were embedded in paraffin, sectioned, and processed for routine hematoxylin-eosin (HE) staining, which is recommended by the ICRS to assess the degree of cartilage regeneration.8 All histology specimens were evaluated by two indepen- dent and blinded observers who were experienced in skeletal histopathology. The observers reached a consensus for all samples. Sections of regenerated tissue were graded based on the ICRS Visual Histological Assessment Scale (distribution of cells, mineralization of cartilage, scores for surface and matrix, cell population viability, and subchon- dral bone abnormalities).9 The center of the original defect was used for interpretation following the recommendations of the ICRS.9 We used the Kruskal-Wallis test to compare the sums of the ICRS scores among the groups. A nonparametric Mann- Whitney U test was performed to compare the two groups Figure 2 - Bar graph illustrating the International Cartilage Repair Society (ICRS) scores. Significant differences in cell distribution and cartilage mineralization were detected between the experimental group and the control group. * Significant differences. 1836