Knee Joint

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Knee Joint
Primary Type	Saddle joint between patella and femur"Saddle joint between patella and femur" is not in the list (Synovial Joint, Cartilaginous Joint, Fibrous Joint, Compound Joint) of allowed values for the "Has joint type" property.
Secondary Type
Bones	Tibia, femur, patella (tibiofemoral and patellofemoral joints)"Patella (tibiofemoral and patellofemoral joints)" is not in the list (Vertebra, Sacrum, Coccyx, Scapula, Clavicle, Humerus, Radius, Ulna, Scaphoid, Lunate, ...) of allowed values for the "Has joint bones" property.
Ligaments
Muscles
Innervation	Popliteal nerve, tibial nerve
Vasculature	Genicular branches of the popliteal artery
ROM	Mainly sagittal plane: 3° of hyperextension to 155° of flexion
Volume
Conditions

The knee is a two joint structure composed of the tibiofemoral joint and the patellofemoral joint and is the largest joint in the body. It sits between the body's two longest lever arms namely the tibia and the femur which lends it to injury.

This article discusses knee joint anatomy. For a discussion on biomechanics of the knee see Knee Biomechanics.

Bones and Articulations

The knee joint contains four bones: the femur, tibia, patella, and fibula.

It has three compartments: the medial tibiofemoral, lateral tibiofemoral, and patellofemoral compartments. The three compartments all share a common synovial cavity.

The knee has three articulations: medial and lateral tibiofemoral and patellofemoral joints. The tibiofemoral articulations connect the distal femur to the tibia. The distal femur broadens to form the medial and lateral femoral condyles. The tibia is relatively flat, but the sloped menisci permit a tight articulation with the convexity of the femoral condyles. The femoral condyles are separated by an intercondylar fossa, also known as the femoral groove, or femoral trochlea. The joint lines are formed by the femoral condyles and tibial plateaus.

The patella is sesamoid shaped and is embedded within the quadriceps tendon that articulates with the trochlear grove of the femur. It increases the mechanical advantage of the quadriceps. The fibula head is located within the knee capsule but isn't normally involved as a weight-bearing surface.

Neurovascular Structures

There is a neurovascular bundles that contains the popliteal artery, popliteal nerve, and tibial nerve (continuation of sciatic nerve). It travels directly posterior to the knee joint. Injury to the vasculature can occur in severe trauma such as in tibiofemoral dislocation.

The peroneal nerve is found laterally and is a division of the sciatic nerve. It starts its course between the medial border of the biceps femoris muscle and lateral head of gastrocnemius. It then passes laterally around the biceps femoris muscle, and dives between the peroneus longus and fibular head called the peroneal tunnel. Finally it splits into three branches: the deep peroneal, superficial peroneal, and recurrent peroneal nerves. The peroneal nerve is susceptible to trauma due to its superficial location and course through narrow spaces.

See Also

Knee Biomechanics

References

• Basic biomechanics of the musculoskeletal system - Nordin 4th edition 2012.