The bony landmarks are the patella, the two condyles of the femur, the tibia, and the fibula (Fig. 543).

The patella is pointed below where the tendo patellae is attached, is slightly convex on its upper border, and its lateral edges are prominent, especially the outer. It usually has little tissue over it. With the limb extended and quadriceps relaxed the patella can be moved laterally. There is a hollow above the patella. When the muscle contracts this hollow is filled up by the rectus, and the muscular swells on each side produced by the vastus internus and externus are visible. When the quadriceps muscle is contracted the tense tendo patellae becomes evident, when relaxed the soft fatty pad beneath the tendon can be felt.

About midway between the patella and tubercle of the tibia on each side can be felt a groove which indicates the line of the joint and the location of the semilunar cartilages. On the outer side posteriorly opposite the level of the tibial tubercle can be felt the head of the fibula. Running upward from it is the tendon of the biceps. In front of the biceps can be seen and felt the ilio-tibial band. It is difficult to distinguish the joint-line on the sides, therefore it is better to locate it by recognizing the sulci anteriorly on each side of the tendo patellae; flexing the knee makes these depressions more distinct. The joint on the outer side is about 2 cm. (3/4 in.) above the head of the fibula.

Posteriorly, with the leg extended, the condyles of the femur can readily be outlined; the inner is the more prominent. The upper edge of their articular surfaces can be felt on firm pressure at the sides, and the inner leads to the adductor tubercle, into which the adductor magnus tendon is inserted - this tendon can likewise frequently be felt. The tubercle of the tibia can best be seen and felt when the tendo patellae is relaxed. It is about 4 cm. (1 1/2 in.) below the patella. Just above and to its outer side, about 4 cm. (1 1/2 in.) distant, is the external tuberosity of the tibia; into it is inserted the lower end of the iliotibial band. To the outer side at a little lower level can be seen and felt the head of the fibula. On the inner side is the flat rounded internal tuberosity of the tibia. Posteriorly is seen the fulness of the popliteal space; on its outer side the tendon of the biceps is readily felt and running with it is the external popliteal or fibular nerve; on the inner side the most prominent tendon is the semitendinosus with the semimembranosus beneath and the gracilis to the inner side.

Fig. 543.   Surface anatomy of the knee.

Fig. 543. - Surface anatomy of the knee.