Cartilage Repair by Joint Distraction and Motion Using an External Fixator for Massive Cartilage Defect

The objective of the present study was to investigate our novel methods for the repair of massive cartilage defects by joint distraction and motion using an external fixator. In this study, we used a rabbit model of massive articular cartilage defect in order to evaluate the effectiveness of using joint distraction and motion with a ring-type external fixator. This external fixator has a hinged joint with a center of rotation along the femoral transepicondylar axis, which allows the knee joint to freely flex and extend. Mesenchymal cells from bone marrow, induced by spongialization, were differentiated into mature chondrocytes and formed hyaline-like cartilage as a result of joint distraction and movement. The transplantation of autologous cells expanded from bone-marrow-derived mesenchymal cells, concentrated autologous bone marrow aspirate, and concentrated autologous peripheral blood cells were all effective in promoting cartilage repair. The quality of the cartilage after long-term joint distraction for 6 months was inferior to that after 12 weeks. In general, weight bearing on the regenerated cartilage promoted cartilage repair, although this effect differed based on when gradual weight bearing was begun. Specifically, gradual weight bearing beginning at 9 weeks produced superior results to that beginning at 6 weeks. Our methods provide an optimal environment for cartilage regeneration.