The effect of porosity and mechanical property of a synthetic polymer scaffold on repair of osteochondral defects.

We have made three types of poly (DL-lactide-co-glycolide) (PLG) scaffolds (porosity: scaffold I 80 +/- 0.9%, II 85 +/- 0.8%, III 92 +/- 0.7%; compression module determined with 10% strain: scaffold I 0.26 MPa, II 0.091 MPa, III 0.0047 MPa). Osteochondral defects made in the femoral condyle of rabbits were treated with these scaffolds and the possibilities of cartilage repair were investigated histologically. At post-operative weeks 6 and 12, histological scores in the groups of scaffolds II and III were significantly higher than the score in the group of scaffold I. Scaffolds II and III, which have higher porosity than scaffold I, allow better migration of bone marrow cells and better replacement of the scaffold with bone and cartilage than scaffold I. This study suggests that higher porosity allowing bone marrow cells to migrate to the scaffold is important in repairing osteochondral defects.