The arterial supply of the femoral condyles.

The most frequent site for aseptic bone necrosis and osteochondrosis dissec ans in the human knee joint is the medial femoral condyle. The aim of this study is to analyze the three-dimensional vascularization of the human knee joint and to find out if there are any differences in the blood supply of the medial and lateral femoral condyles which may explain the preponderance of aseptic bone necrosis in the medial side. Material and Methods: The fem oral arteries of 14 unfixed lower extremities have been injected with epoxy resin. After documentation of the extraosseous course of the blood vessels the bone was macerated with 10% formic acid. The insertions of tendons and ligaments were investigated by light microscopy and immunohistochemistry. Results: The arterial supply of the lateral femoral condyle originates from the upper lateral geniculate artery, the terminal ends of which penetrate the bone from lateral. Branches of the middle geniculate artery reach the b one from the medial wall of the intertubercular notch. The subchondral bone of the medial femoral condyle draws its blood supply mainly from the desce nding geniculate artery. Branches of the middle geniculate artery penetrate the medial femoral condyle only in the posterior part of the intercondylar fossa. These posterior vessels do not contribute to the supply of the subc hondral bone. In the anterior part of the medial wall of the intercondylar fossa there is the wide femoral insertion of the posterior cruciate ligamen t. Injection techniques and immunohistochemical investigations show that th e fibrocartilage of the chondral apophyseal insertion of the posterior cruc iate ligament is avascular and acts as banier which impedes blood vessels t o penetrate the bony surface in this region. The subchondral bone adjacent to the femoral insertion of the posterior cruciate ligament receives its bl ood supply from vessels that penetrate the bone at the medial wall of the m edial femoral condyle. The blood vessels which supply the lateral parts of the medial condyle have the longest intraosseous course. The density of ves sels within this region is largely reduced. Conclusions: The region adjacen t to the femoral insertion of the posterior cruciate ligament is the most f requent site for osteochondrosis dissecans in the knee joint. Our results s how that the arterial supply of the subchondral bone may be considered as a cofactor for the etiology of osteochondrosis dissecans.