The knee joint is the largest joint in the human body, its structure is the most complicated and it is the most commonly injured joint. This is the reason why orthopaedists have such frequent visitors and why there is a need for either conservative of surgical treatment.
Joints are convex bodies, motions are run by soft tissue, active and passive stabilizers. It is comprised of the lower part of the thighbone (femur), upper part of the shin bone (tibia) and a calf bone (fibula) next to it. On the front, there is the knee cap (patella).
Motions are enabled by passive and active knee stabilizers. Passive stabilizers are ligaments, the most important ones are: anterior and posterior cruciate ligament and internal and external collateral ligament. Joint capsule is important as well. Passive stabilizers of the knee cap are patellar ligament, and medial and lateral retinaculum. The menisci are anatomic half-moon shaped structures which compensate for the incongruency of the joints and are very important passive stabilizers.
Active stabilizers of the knee are muscles. The most important is the strong quadriceps muscle on the front, muscles group on the back and aductors group on the interior side.
Knee joint is highly mobile; there is flexion, extension, both external and internal rotation, which is the reason of recurrent injuries.