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The knee has been subjected to more clinical investigation and scientific research than any other joint in the body.1 A reason for this may be the enormous number of patients with knee disorders—more than 2 million of annual visits to emergency departments in the United States are made because of knee trauma.2

The complex arthrokinematics of the knee allows for great stability combined with great mobility. This mechanical compromise enables the knee to withstand tremendous weight-bearing and load-transmission forces while promoting ambulatory freedom. The knee’s unique anatomy, combined with its exposed location between the two longest bones of the body, does, however, predispose it to various injuries, trauma, and other pathological conditions.

The knee is well demonstrated on the routine radiologic evaluation. Most fractures as well as nontraumatic disorders are adequately defined via conventional radiographs. Internal derangement of the joint and other soft tissue pathological conditions usually is demonstrated best with magnetic resonance imaging (MRI).

Review of Anatomy

Osseous Anatomy

The knee joint, or femorotibial joint, is formed by the articulation of the distal end of the femur to the proximal end of the tibia.3–10 Adaptive congruency of the articular surfaces is made possible by the interposed menisci. Associated with the knee joint are the patellofemoral joint, an articulation between the anterior aspect of the femur and the patella, and the tibiofibular joint, an articulation between the lateral aspect of the tibia and the fibular head (Figs. 13-1 and 13-2).

Figure 13-1

Knee, anterior aspect.

Figure 13-2

Coronal, T1-weighted MRI of the knee. (Image courtesy of by GE Healthcare.)

Distal Femur

The distal femur exhibits medial and lateral condyles, which are separated anteriorly by the patellar surface, also known as the trochlear groove or intercondylar sulcus. Posteriorly, the femoral condyles are divided by the deep intercondylar fossa. Medial and lateral epicondyles are prominences, proximal to the condyles, serving as sites of muscle or ligament attachment.


The patella is the large sesamoid bone embedded in the quadriceps tendon. Its smooth articular surface has multiple facets for efficient load-distribution mechanisms during its tracking actions on the trochlear groove. The outer anterior surface is convex and roughened. The broad superior surface is the base, and the pointed inferior surface is the apex of the patella.

Proximal Tibia

The proximal tibia exhibits medial and lateral condyles, which superiorly form the flared articular surface, the tibial plateau. Located between the condyles on the tibial plateau is the intercondylar eminence, or tibial spine, composed of ...

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