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Knee joint and ligaments

Other Terms: Ligaments of the knee joint, Articulatio genus, Articulation du genou


The relationships between the femur and the tibia provide no interlocking joint mechanisms or stability between these neighboring bones and from this perspective the knee joint is completely unstable. That is, there are no deep-seated sockets or hinge-like grooves that limit and stabilize the movements of articulating bones. Instead, the knuckle-like ends of the femur sit on the flat plateau-like surface of the tibia. The strength of the knee joint is dependent on strong ligaments and surrounding muscles. Although its primary motions are of a hinge nature, it is a complex joint with subtle rotational and sliding movements also.


Two condylar joints and a saddle joint

Articular surfaces

Femoral condyles with the proximal surfaces of the tibia (condylar joints) and the posterior patellar surface with the patellar groove of the femur (saddle joint)

Close-packed position

Full extension


The major stabilizers of the joint are four strong ligaments. Two collateral ligaments support the joint on either side, while two cruciate ligaments criss-cross in the middle of the joint. The tibial or medial collateral ligament is a strong, flat band that stretches from the femoral epicondyle to the tibial condyle. Posteriorly it firmly attaches to the joint capsule and the medial meniscus, while anteriorly bursae separate it from these structures. The fibular or lateral collateral ligament is a strong cord that runs from the lateral femoral epicondyle to the head of the fibula. Unlike the tibial collateral ligament it does not attach to the lateral meniscus or joint capsule. The cruciate ligaments stabilize the knee from excessive anterior-posterior and rotational movements. The anterior cruciate ligament ascends posterolaterally from the medial aspect of the intercondylar area to the medial aspect of the lateral condyle of the femur. The shorter posterior cruciate ligament ascends from the posterior intercondylar area to the medial femoral condyle. Both cruciate ligaments have fibers that blend with the lateral meniscus. In addition to these ligamentous structures, two semilunar menisci project into the capsule between the femoral condyles and the articular plateaus of the tibia. The large, extensive articular capsule connects the femur, patella, and tibia. In numerous places the capsule projects between surrounding muscles and tendons in the form of a bursal sac to protect the tendons and muscles from excessive friction. For example, the suprapatellar bursa is a continuation of the joint capsule that is interposed between the quadriceps tendon (the tendon of the muscles of the anterior thigh) and the anterior surface of the femur.


Articulatio genus


Articulation du genou


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