Computer simulation of the distal aspect of the femur for assessment of donor core size and surface curvature for autologous osteochondral transplantation in the canine stifle joint.

Objective: To report topographic matching of selected donor sites and donor core sizes for congruous reconstruction of the weight-bearing aspect of the femoral condyles in dogs for autologous osteochondral transplantation (AOT) using computer simulation.

Study Design: Computer simulation.

Sample Population: Computed tomographic scans of the distal aspect of 1 femur from each of 6 mature dogs (>20 kg).

Methods: Three-dimensional surface models of the distal femora were constructed for virtual AOT. Different donor sites (n=15) within and outside the femoropatellar joint and 5 transplant sizes (diameters 3.5, 4.5, 6.0, 8.0, and 10.0 mm) were analyzed with respect to their topographic match with the articular surface of both femoral condyles.

Results: Transplants from the proximal abaxial aspect of the medial condyle and from the abaxial aspects of the medial and lateral trochlear ridges were the best topographic match. Mismatch increased linearly with increasing core diameter. Small core diameters (3.5 mm, 4.5 mm) from within the femoropatellar joint allowed restoration of surface contour at both femoral condyles similar to large core diameters (6 mm, 8 mm) from outside the femoropatellar joint.

Conclusions: Based on this computer simulation, large core diameters should only be harvested from convex donor sites outside the femoropatellar joint, whereas transplants from the concave, axial aspects of the trochlear ridges may result in similar topographic match provided they are of small diameter.

Clinical Relevance: The abaxial aspect of the medial trochlear ridge and the proximal aspect of the medial femoral condyle appear to be the preferred AOT donor sites.