1. A number of vascular foramina in the distal end of the femur have been classified according to their anatomical location as supracondylar, condylar, and intercondylar groups. Each group forms a perforated area on the bone.

2. In the intercondylar incisura, between the two upper attachments of the cruciate ligaments, is the intercondylar perforated area. The authors have named this the "area cribrosa vasorum intercondyloidae femoris". Centrally located are a group of foramina usually situated in a cylindrical depression, 3 to 8 millimeters in diameter. In roentgenograms of the dried femora, one sees this fovea as an area of decreased density.

3. The vascular supply to the distal end of the femur has been described on the basis of anatomical dissections. Osteal branches of the genicular arteries and veins can be demonstrated entering all of these foramina.

4. Distribution of these vessels within the bone was studied after injection of an opaque mixture of mercury and turpentine. Roentgenograms showed the distribution pattern of numerous small arteries within the bone.

5. Clinically this generous vascular supply explains the lack of ischaemic necrosis after fractures of the lower end of the femur.