Paper #128 An optimal donor site for the weight bearing area of the femoral condyle in an autologous osteochondral transplantation

Abstract

Localized articular cartilaginous lesions present a challenging clinical problem. To relieve pain and resume joint function, the articular cartilage should be repaired with hyaline cartilage of good congruity. Autologous osteochondral transplantation, which is one of the useful techniques to repair cartilaginous lesion, has several advantages including the initial stabilization of the osteochondral graft followed by a bony union at the subchondral area and the elimination of the risk of disease transmission. However, there are few reports regarding the selection of the donor site in autologous osteochondral transplantation. Therefore, we have measured the cartilage thickness and the surface curvature of the femoral condyle taken from cadavers and attempted to determine the optimal location of the donor site for the chondral lesion in the weight bearing area of both medial and lateral femoral condyles. Eight cadarveric femoral condyles were sectioned sagittally. To analyze the thickness and surface curvature of the cartilage, photographs of the sliced condyles were taken. The film was digitized and a morphological analysis was performed using an NIH image program. As a unit of analysis, the cartilage layer of the sliced condyle was divided into 1-cm-long compartment on both sides of the sulcus terminalis. The thickness was measured at the center of each compartment and the curvature of the surface of each compartment was calculated as the reciprocal of the curvature radius. The curvature radius of the cartilage surface was measured as the radius of a circle passing three points that divided each compartment equally. Thereafter, because chondral lesion is predominantly observed in the weight bearing area of the medial and lateral femoral condyles located 2 to 3cm posterior to the sulcus terminalis, the cartilage in this area was assumed as a recipient site. To determine the optimal donor site of this presumptive chondral lesion, we compared the thickness and curvature of the recipient sites with those of each compartment. The differences in thickness and curvature between each compartment and the recipient sites were calculated and mapped schematically on the femoral condyle. The average thickness of the cartilage was 1.69 mm (range, 0.22 to 3.65 mm), with the maximum curvature 27.2 m-1 and the minimum −20.0 m-1. When the recipient site was assumed to be the weight bearing area of the medial and lateral condyles, the most compatible donor site in terms of the cartilage thickness and curvature was located anterior to the sulcus terminalis in the middle portion of the lateral condyle with a thickness difference of less than 0.07 mm and a curvature difference less than 2.22 m-1. The anterior portion of the lateral femoral condyle can be an optimal donor site for the chondral lesion in the weight bearing area of both medial and lateral femoral condyles.