Transplantation of De Novo Scaffold-Free Cartilage Implants into Sheep Knee Chondral Defects

Abstract

Background New cell-based treatments for articular cartilage repair are needed. As the optimal scaffold for cartilage repair has yet to be developed, scaffold-free cartilage implants may remove the complications caused by suboptimal scaffolds. Hypothesis The implantation of a scaffold-free, autologous de novo cartilage implant into standardized full-thickness cartilage defects of femoral condyles in sheep leads to a qualitatively better regenerative tissue than does periosteal flap alone or no treatment. Study Design Controlled laboratory study. Methods Chondral defects 4 mm in diameter (1 per sheep) were created in the center of 1 medial femoral condyle of 48 sheep. Twelve defects were allowed to heal spontaneously, 16 defects were covered with periosteal flaps alone, and 20 defects were filled with autologous de novo cartilage graft and overlaid with a periosteal flap. Differences were assessed macroscopically using the International Cartilage Repair Society score and microscopically using the International Cartilage Repair Society histological score and Mankin score at 26 and 52 weeks. Results The results of the International Cartilage Repair Society Cartilage repair assessment showed that the transplant group was better than was the untreated control at both time periods but not significantly different than was the periosteal flap group. Implanted groups demonstrated a marked improvement in grade of defect filling, cartilage stability, cell distribution, and matrix assessments in each method of assessment. In the transplant group, 2 defects were filled with hyaline cartilage, 5 with mixed hyaline and fibrocartilage, and 2 with fibrocartilage alone. Conclusion Chondral defects treated with de novo cartilage transplantation show qualitatively better microscopic and macroscopic regeneration than do those treated with periosteal flaps alone. Clinical Relevance Results of the current study show that third-generation autologous chondrocyte transplantation is a promising development in the field of biologic cartilage regeneration. Future studies should compare this technique with the original Brittberg technique.