It is rarely relevant to knee problems and the information below will not be useful to most people with a knee injury. It is unusual for the blood supply of the knee to interfere with operations such as arthroscopy or ACL reconstruction but it can be more relevant in the case of a total knee replacement or high tibial osteotomy.
The arteries to the knee joint and surrounding structures are supplied by the femoral and popliteal arteries. The femoral artery enters the lower limb and then sends off the large profunda femoris branch which dives deep into the thigh. The femoral artery continues closer to the surface giving off branches to the quadriceps muscle. The profunda femoris also gives off muscular branches and contributes to the circulation around the knee joint.
The femoral artery moves from the front to the back of the thigh and then to the back of the knee where it becomes the popliteal artery. Before entering the adductor canal the femoral artery gives rise to the descending genicular artery which contributes to the anastomosis and blood supply around the knee.
The popliteal artery travels through the popliteal space and is separated from the intercondylar fossa (the valley between the femoral condyles at the back of the knee) by fat, the posterior oblique ligament and the popliteus fascia. The popliteal artery is the deepest of the vascular structures in the popliteal fossa lying deep to the popliteal vein and the tibial nerve. During its course through the popliteal fossa, it gives multiple branches that supply the knee joint and musculature. Opposite the lower border of the popliteus muscle the popliteal artery ends by dividing into the anterior tibial and posterior tibial artery.
The blood vessels around the knee form an extensive anastomosis linking the femoral artery above with the popliteal and tibial arteries below. During its course, the popliteal artery gives off the medial and lateral superior genicular artery, the middle genicular artery, the sural artery and the lateral inferior and medial inferior genicular arteries. All these vessels together supply the muscles, tendons, ligaments and bone of the knee joint as well as the synovial membrane lining the knee joint and capsular structures.
As we get older we deposit calcium in our arteries which makes them more rigid. This can be a problem when using a tourniquet during surgery. For this reason I typically do not use a tourniquet during total knee replacement surgery. This allows less blood loss and faster recovery from the surgery.