Computerized matching of autologous femoral grafts for the treatment of medial talar osteochondral defects

Background. Cored autologous graft from the distal ipsilateral femur has been used to fill osteochondral defects in the talus. There are no studies that compare the articular morphology of potential donor sites on the distal femur with recipient sites on the talus. Methods: Using coronal MRI of the talus and distal femur of five matched cadaver, computer reconstructions of the articular surfaces were prepared. From these, six 10-mm in diameter donor sites from the nonweightbearing surfaces of the medial and lateral aspects of the femoral condyles were matched to three recipient sites on the anterior, middle, and posterior aspects of the corresponding medial talus using customized computer software that minimized differences between the articular surfaces of the graft and the talus. After matching the femoral to the talar graft, the average and maximal distances between the surfaces (surface contour) and the average and maximal distances of the offset at the outer 1 mm of the graft periphery (step-off) were determined. Results: For all graft combinations, the average step-off was 0.24 +/- 0.03 mm and the maximum 0.60 mm. The average surface contour was 0.32 +/- 0.04 mm and the maximum was 1.16 mm. In all cases, the best donor site was from the superolateral femur for any medial talar lesion. Conclusion: In this study of grafts from the femoral condyles, the superolateral femur was the optimal location for an osteochondral graft for any medial talar lesion.