BASIC ANATOMY OF THE KNEE
The knee consist of two main or weight bearing compartments and a third compartment that accommodates the extensor (Quadriceps) tendon mechanism, namely the patella (knee cap).
The weight bearing compartments are formed by the femoral condyles (Knuckle shaped end of the thigh bone) and the tibial plateau surfaces (The flat surfaces at the top of the shin bone). In the front and between the femoral condyles is the femoral trochlea. This is a groove for the patella to move in while flexing (bending) and extending (straightening) the knee. The lower leg consists of the Tibia (Shin bone) and the Fibula which is a thin bone for muscle and ligament attachment.
I the middle of the knee formed by a notch between the femoral condyles there is a space the accommodates the cruciate ligaments. These attach to a raised area in the middle of the tibial plateau in a patch called the tibial eminence. The one attaching to the front is called the Anterior Cruciate Ligament and the one attaching to the back is called the Posterior Cruciate Ligament. These ligaments prevent the tibia (shin bone ) from moving too far forward or backward respectively relative to the center of rotation of the knee joint.
Overlying the femoral condyles, the tibial plateaus, the femoral trochlea and the under surface of the patella, is articular cartilage, which is the main component of the joint.
Wedged between the round femoral condyles and the flat tibial plateaus are collagen structures known as the medial (inside aspect) and lateral (outside aspect) menisci. These structures are very important for the distribution of forces in the knee (like shock absorbers), maintenance of normal fluid flow in the knee and assist with nourishment of the cartilage as well as stability and proprioception for the knee joint.
Other structures of import are the medial/tibial and lateral/fibula collateral ligaments for side to side stability. The posterolateral and posteromedial corner ligamentous complexes aid in rotational stability. The medial and lateral patella-femoral ligaments that help stabilize the patella as it runs in the groove of the femoral trochlea. The patella tendon/ligament which connects the quadriceps muscle to the tibia, for extension of the knee.