Introduction: (OCD) is characterized by bone necrosis and softening of the overlying cartilage, which may separate and displace. It is thought to be secondary to trauma, ischaemia or abnormal epiphyseal ossification. Management remains controversial during the early stages of the disease. Surgery for advanced chondral lesions with loose bodies however remains a challenge. Options that include periosteal graft and autologous chondrocyte transplantation have been used with variable degrees of success. This study investigates the efficacy of these techniques and the use of mesenchymal stem cells to treat advanced chondral lesions found in OCD in animal models.

Materials and Methods: A full thickness articular cartilage defect (6mm long, 3mm wide and 1mm deep) was created in the weight-bearing surface of medial femoral condyle in 22-week old NZW rabbits. A total of 90 knees were randomly divided into 3 groups as follows: 1) Transfer of cultured chondrocytes 2) Transfer of cultured periosteum-derived MSCs and 3) Repair by periosteal graft with their contralateral knees as control. The rabbits were allowed to move freely in their cages. The rabbits were sacrificed at 2, 6, 12, 24 and 36 weeks post-operatively. The healing of the defects was assessed by gross examination and histological grading and subjected biomechanical testing.

Results: Gross and histological examination at 36 weeks post operation (Wakitani et al grading), the mean score for Group 1 is 2.5, Group 2 is 2.3 and Group 3 is 4.5 with control group of 8.9 in terms of cell morphology, matrix staining, surface regularity, thickness of repaired cartilage and integration of cartilage to adjacent host. Biomechanically by indentation test, Group1 had value of 0.22 MPa, Group 2 0.20 MPa, Group 3 0.16 MPa and Control group of 0.12 MPa.

Conclusion: The findings suggested that cultured chondrocytes and mesenchymal stem cells had comparable enhancing effect of the repair of chondral defect in advanced OCD