The knee





The knee complex is the joint system that connects the thigh to the leg. It consists of femoral tibial joint and the patellafemoral articulation. The femoral tibial joint is considered a hinge joint, however it includes a small but significant arthrokinematic rotary component that enhances function. The joint surfaces are incongruent. Ligaments, cartilage, an extensive capsule provides needed stability.









The medial and lateral menisci are cartilaginous pads that increase joint congruency and provide some shock absorption.

The transverse ligament of the knee helps bind the menisci to each other.

The posterior meniscofemoral ligaments helps to stabilize the lateral meniscus.

The anterior cruciate ligament starts anterior on the tibia, runs posterior, and attaches on the external femoral condyle (APEX). It prevents excessive anterior displacement of the femur on the tibia.


The posterior cruciate ligament starts posterior on the tibia, runs anterior, and attaches on the internal femoral condyle (PAIN). It prevents excessive posterior displacement of the femur on the tibia.









Given the amount of soft tissue surrounding and supporting the knee joint, there exists several bursae to relieve friction and relieve pressure. In fact, there are at least 12 bursae associated with the knee including the: Suprapatellar bursa, Prepatellar bursa, Deep infrapatellar bursa, Superficial infrapatellar bursa, Lateral collateral ligament-biceps femoris bursa, Medial gastrocnemius bursa, Anserine bursa, Semimembranosus bursa, Medial collateral ligament bursa, Tibiofibular joint bursa, Head of the fibula bursa, and Posterior cruciate ligament bursa.

The infrapatellar fat pad of the knee is an intracapsular, extrasynovial adipose tissue that is situated below the patella, behind the patellar tendon. It is highly vascularized and richly innervated (predominantly by the posterior tibial nerve) and, therefore, impingement of the pad is a potential source of nociception (pain) in the anterior knee.


The infrapatellar fat pad helps to stabilize the patella and the patellar ligament and prevents pinching of the synovial membrane.


The patellofemoral ligaments provides lateral and medial stability of the patella. In some cases of patellar instability, the lateral patellofemoral ligament may be cut to prevent lateral displacement of the patella


The patellar retinaculum is an important stabilizer of the patella and resists lateral and medial patellar displacement.





The collateral ligaments





The collateral ligaments provides lateral and important medial/lateral support to the knee joint.