Topographic analysis of the capitellum and distal femoral condyle: finding the best match for treating osteochondral defects of the humeral capitellum.

Purpose: The purpose of this study was to determine the donor zone of most congruent topographic match by comparing 4 donor sites from the femur with 4 potential recipient sites of osteochondritis dissecans at the capitellum.

Methods: Computed tomography was performed on 5 right elbows and 6 right medial and 6 right lateral distal femoral hemicondyles, which included the femoral notch. Three-dimensional computed tomography models were created and exported into point-cloud models. A local coordinate map of the distal humerus and distal femoral articular surfaces was created. The capitellum was compared with the medial and lateral distal femoral condyles, with 2 donor zones in each condyle (medial trochlea and medial intercondylar notch or lateral trochlea and lateral intercondylar notch). In each capitellum 4 combinations of 10-mm defects were simulated (central and lateral, 30° and 45° anterior to shaft of humerus), resulting in 480 capitellum-femur comparative combinations being tested. The capitellum surfaces were virtually placed on a point on the femoral articular surface in 3-dimensional space. The least distances (i.e., the shortest distance from the point in question to the corresponding point in space) between the point clouds on the distal humerus and distal femoral articular surfaces were calculated.

Results: There was a less than 0.1-mm difference in the topographic articular surface match among the 4 commonly used donor sites of the distal femur and 4 recipient sites of the capitellum. However, the best match for any given 10-mm capitellar defect (central 30°, central 45°, lateral 30°, and lateral 45°) was the same such that the lateral trochlea on the femur always yielded the best fit compared with the 3 other graft locations (P < .005).

Conclusions: Our results indicate that there is a less than 0.1-mm difference in the topographic articular surface match among the 4 commonly used donor sites of the distal femur and the capitellum. The findings suggest that all 4 donor sites provide close articular matching for the capitellum articular surface, with the lateral trochlea articular surface providing the best match.

Clinical Relevance: These data suggest that a single donor plug may be obtained from multiple sites in the knee and placed into capitellar lesions with an excellent topographic articular surface match. The findings of our study will be useful to surgeons when managing capitellar osteochondritis dissecans lesions.