Dance Anatomy & Kinesiology

The Knee and Patellofemoral Joints 239

Joint Structure and Movements of the Knee

The knee is very complex in its structure and func-
tion and is thought to have evolved from three sepa-
rate joints. Although there is only one joint cavity,
the following three articulations are present.

1. Between the medial condyle of the femur and
   the slightly concave medial plateau of the tibia


2. Between the lateral condyle of the femur and
   the slightly concave lateral plateau of the tibia


3. Between the backside of the kneecap and the
   underlying surface on the anterior femur, the
   femoral groove

The first two articulations between the femoral
condyles and tibia compose the tibiofemoral joint,
or what is commonly referred to as the knee joint. As
with other synovial joints, the articular surfaces are
covered by articular cartilage that reduces friction and
aids with the distribution and absorption of forces.
The third articulation is named the patellofemoral
joint and will be discussed in a later section of this
chapter.

Knee Joint Classification

and Associated Movements

The tibiofemoral joint is a modified hinge joint, and

its primary joint motions are flexion (or bending)

of the knee and extension (or straightening) of the

knee (see figure 5.2). In addition, its motion also

incorporates slight internal and external rotation,

and hence it is termed a “modified” hinge joint.

Knee Joint Capsule and Ligaments

The knee joint is surrounded by an extensive and

irregular joint capsule lined with the largest synovial

membrane found in the body (Hamill and Knutzen,

1995). In 20% to 60% of people, this membrane

contains a permanent fold, termed a plica (L. a fold),

that sometimes becomes inflamed. The stability

offered by this joint capsule is reinforced by numer-

ous strong ligaments. More than at any other joint in

the body, the ligaments are essential to stabilize and

guide the relative movements of the bones coming

together to form the joint (Magee, 1997). However,

these ligaments are arranged such that ligamentous

stability is not constant (Kreighbaum and Barthels,

FIGURE 5.1 Bones and bony landmarks of the knee region (right knee). (A) Anterior view, (B) posterior view.

Intercondylar

eminence

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