Chapter 20: The Knee and Related Structures

William E. Prentice

OBJECTIVES

When you finish this chapter you should be able to

• Recognize the normal structural and functional knee anatomy.

• Demonstrate the various ligamentous and meniscal stability tests discussed in this chapter.

• Explain how knee injuries can be prevented.

• Compare and contrast male/female differences relative to anterior cruciate ligament (ACL) injuries.

• Discuss etiological factors, symptoms and signs, and management procedures for the injuries to the ligaments and menisci.

• Identify the various etiological factors, symptoms and signs, and management procedures for injuries that occur in the patellofemoral joint and in the extensor mechanism.

• Design appropriate rehabilitation protocols for the injured knee.

Because so many activities place extreme stress on the knee, it is one of the most traumatized joints in the physically active population. The knee is commonly considered a hinge joint because its two principal movements are flexion and extension. However, because rotation of the tibia is an essential component of knee movement, the knee is not a true hinge joint. The stability of the knee joint depends primarily on the ligaments, the joint capsule, and the muscles that surround the joint. The knee is designed primarily to provide stability in weight bearing and mobility in locomotion; however, it is especially unstable laterally and medially.

ANATOMY OF THE KNEE

Bones

The knee joint complex consists of the femur, the tibia, the fibula, and the patella (Figure 20–1). The distal end of the femur expands and forms the convex lateral and medial condyles, which are designed to articulate with the tibia and the patella. The articular surface of the medial condyle is longer from front to back than is the surface of the lateral condyle. Anteriorly, the two condyles form a hollowed femoral groove, or trochlea, to receive the patella. The proximal end of the tibia, the tibial plateau, articulates with the condyles of the femur. On this flat tibial plateau are two shallow concavities that articulate with their respective femoral condyles and are divided by the popliteal notch. Separating these concavities, or articular facets, is a roughened area where the cruciate ligaments attach and from which a process commonly known as the tibial spine arises.²

Patella The patella is the largest sesamoid bone in the human body. It is located in the tendon of the quadriceps femoris muscle and is divided into three medial facets and a lateral facet that articulate with the femur (Figure 20–1). The lateral aspect of the patella is wider than the medial aspect. The patella articulates between the concavity ...