The effect of platelet rich plasma combined with microfractures on treatment of chondral defects: an experimental study in a sheep model

Objective
To evaluate the effect of autologous platelet rich plasma (PRP) combined with microfractures on the treatment of chondral defects. The hypothesis of the study was that PRP can enhance cartilage repair after microfractures.

Methods
A chronic full-thickness chondral lesion of the medial femoral condyle was performed in 15 sheep. Animals were divided into three groups, according to treatment: group 1: microfractures; group 2: microfractures+PRP and fibrin glue gel; group 3: microfractures+liquid-PRP injection. Animals were sacrificed at 6 months after treatment. Macroscopic appearance was evaluated according to International Cartilage Repair Society (ICRS) score; cartilage stiffness was analyzed with an electromechanical indenter (Artscan 200); histological appearance was scored according to a modified O’Driscoll score. Comparison between groups for each outcome was performed with Kruskal–Wallis test, and Tukey’s test for pairwise comparisons.

Results
Macroscopic ICRS score of group 2 was significantly better than those of the other groups, and score of group 1 was significantly lower than those of the other groups. Scores of group 1 and 3 were significantly lower than that of normal cartilage. Mean cartilage stiffness of groups 1 and 3 was significantly lower than that of normal cartilage. Histological total scores of group 2 and 3 were significantly better than that of group 1.

Conclusions
PRP showed a positive effect on cartilage repair and restoration after microfractures. The procedure was more effective when PRP was used as a gel in comparison with liquid intra-articular injection. Histological analysis revealed that none of experimental treatments produced hyaline cartilage.