Femur
The femur is the longest and strongest bone in the body. The shaft of the femur is nearly cylindrical, fairly uniform in calibre and the shaft has a bow with the apex anteriorily progressing from proximal to distal.
The distal aspect of the femur broadens into the medial and lateral condyles with all but the sides of these condyles being articular and involved in the knee joint. The inferior, posterior oblong portions of the condyles articulate smoothly with the tibial plateau, whereas the central anterior surface between the condyles articulates with the facets of the patella. The inferior, oblong surfaces of the condyles are separated by the intercondylar fossa which houses the cruciate ligaments.
In shape and dimensions the femoral condyles are asymmetric; the larger medial condyle has a more symmetrical curvature. The lateral condyle viewed from the side has a sharply increasing radius of curvature posteriorily. The lateral condyle is slightly shorter than the medial. The long axis of the lateral condyle is slightly longer and is placed more sagittal than the long axis of the medial condyle. The lateral condyle is slightly wider than the medial condyle at the centre of the intercondylar notch. Anteriorily the condyles are separated by a groove, the femoral trochlea. The sulcus represents the deepest point in the trochlea relative the mid plane between the condyles, the sulcus lies slightly laterally. The lateral condyle has a greater posterior excursion than the medial. The contact surface of the patella is derived mostly from the lateral condyle. The anterior extensions of both condyles form a fossa for the patella to sit in extension. The lateral extension is the greatest.
The intercondylar notch separates the two condyles distally and posteriorily. The lateral wall of the notch has a flat impression where the proximal origin of the anterior cruciate ligament (ACL) arises. On the medial wall of the notch is a larger site where the posterior cruciate ligament (PCL) originates.
The lateral condyle has a short groove just proximal to the articular margin, in which lies the tendinous origin of the popliteus muscle. The groove separates the lateral epicondyle from the joint line. The lateral epicondyle is a small but distinct prominence which attaches the lateral (fibula) collateral ligament (LCL). On the medial condyle the prominent adductor tubercle is the insertion of the site of the adductor magnus. The medial epicondyle lies anterior and distal to the adductor tubercle and is C shaped with a central depression or sulcus. The epicondylar axis passes through the centre of the sulcus of the medial epicondyle and the prominence of the lateral epicondyle. This line serves as an important reference line in total knee replacements. The medial epicondyle is more prominent and provides attachment for the medial (tibial) collateral ligament (MCL)
