Effect of load on the repair of osteochondral defects using a porous polymer scaffold

The aim of the present study was to evaluate if a porous polymer scaffold, currently used for partial meniscal replacement in clinical practice, could initiate regeneration and repair of osteochondral defects, and if regeneration and repair were related to mechanical stimulation. Two equally sized osteochondral defects were created bilaterally in each trochlear groove of 16 adult female New Zealand White rabbits. The defects were filled with polycaprolactone-polyurethane scaffolds of either 3 or 4 mm in height. Regeneration and repair of the defects were evaluated after 8 (n = 8) and 14 weeks (n = 8). After 8 weeks of implantation, both the 3- and 4-mm scaffolds were flush with the native cartilage. The amount of cartilaginous tissue was similar in both scaffold types. Pores located in the more central zones of the scaffolds contained less cartilaginous tissue when compared with pores located in the more superficial zones. After 14 weeks, significantly more cartilaginous tissue was present in 4 mm scaffolds when compared with the 3-mm scaffolds (p = 0.03). In the 4-mm scaffolds, progression of cartilaginous tissue from the surface of the scaffold toward the center was observed over time, whereas in the 3-mm scaffold, the percentage of cartilaginous tissue in the central zones was not different from the situation after 8 weeks. Osteochondral defects might be treated using porous polymer scaffolds currently used for partial meniscus replacement, although several limitations need yet to be overcome. The results suggest that mechanical forces may not have to be applied over long periods of time to accelerate tissue formation and increase cartilage repair longevity.