Knee Joint: Difference between revisions

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

Revision as of 19:50, 1 August 2021

This article is a stub.

{{{{{quality}}}}}

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.

Structures Involved in Support and Stability

Structures Involved in Knee Extension

Structures Involved in Knee Flexion

Bursa and Cystic Structures

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.

References

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

@@ Line 9: / Line 9: @@
 |ligaments=
 |muscles=
-|innervation=Branches from the femoral, tibial, common peroneal, and obturator nerves
+|innervation=Popliteal nerve, tibial nerve
 |vasculature=Genicular branches of the popliteal artery
 |rom=Mainly sagittal plane: 3° of hyperextension to 155° of flexion
@@ Line 18: / Line 18: @@
 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.
-==Movement==
+This article discusses knee joint anatomy. For a discussion on biomechanics of the knee see [[Knee Biomechanics]].
-'''Tibiofemoral Joint Movement'''
-*'''Sagittal plane''' motion dominates along with quadriceps muscle group action.
-**The typical range of motion is from 3° of hyperextension to 155° of flexion. In cultures where squatting is common flexion can reach beyond 155°.
-*'''Rotation''' is restricted by the interlocking of the femoral and tibial condyles. This is because the medial femoral condyle is longer than the lateral condyle; and also because there is tightening of the collateral ligaments, ACL, and posterior capsule.
-**Rotation is maximum at 30-40° of flexion where external tibial rotation is approximately 18° and internal tibial rotation is approximately 25°. Rotation is constant up to approximately 120° of flexion and then reduces up to full flexion due to soft tissue tightening.
-*'''Frontal plane''' (abduction/varus and adduction/valgus).
-**At full extension there is almost no frontal plane motion. Passive frontal plane motion increases with knee flexion up to 30°, but only up to a few degrees. With flexion past 30° there is reduced frontal plane motion due to soft tissue limitation.
-*For normal activities of daily living a range of motion of 117° of flexion is required. However squatting and kneeling require higher ranges of motion. During gait, the range of flexion needed increases from 0-6° with slow walking up to 18-30° with running.
-*There is sliding throughout the range of motion. Medially there is sliding with a close to constant contact point on the tibia. Laterally there is rolling and sliding as the contact point on the tibia moves posteriorly.
-'''Patellofemoral Joint Movement'''
-* Surface motion occurs primarily in the sagittal plane with respect to axes fixed in the femur.
+== Bones and Articulations ==
+The knee joint contains four bones: the femur, tibia, patella, and fibula.
-== Stability ==
+It has three compartments: the medial tibiofemoral, lateral tibiofemoral, and patellofemoral compartments. The three compartments all share a common synovial cavity.
-* '''Anterior Cruciate Ligament'''
+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.
-** predominant restraint to anterior tibial displacement. Resists 75% of anterior force at full extension and addition 10% up to 90° of knee flexion.
-* '''Posterior Cruciate Ligament'''
-** Primary restraint to posterior tibial translation. Resists 85-100% of posterior force at both 30° and 90° of knee flexion. Secondary stabiliser for rotation at high flexion angles.
-* '''Lateral Collateral Ligament'''
-** Primary restraint to varus angulation. Resists 55% of applied load at full extension
-* '''Medial Collateral Ligament'''
-** Superficial portion is primary restraint to valgus angulation. Resists 50% of applied valgus load. Capsule, ACL, and PCL share remaining valgus load.
-** MCL along with ACL also resists rotation at 20-40°of knee flexion.
-** Limits AP displacement of medial femoral condyle and provides medial pivot action in function.
-* Knee opens with varus moments with opening of the lateral knee more so than on the medial side. The MCL is paradoxically weaker than the LCL, but the ITB helps to dynamically stabilises the lateral side.
-* Muscle contraction and co-contraction of quadriceps and hamstrings contribute to knee stability by increasing the stiffness.
-* Scree-home mechanism of the tibiofemoral joint in extension adds stability in full extension. The tibia rotates externally and the contact point shifts anteriorly which acts as a brake to further extension and provides a stable knee posiion.
-== Patella Function ==
+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.
-* Lengthens the lever arm of the quadriceps muscle force about the centre of rotation of the knee, increasing the mechanics and efficiency of the quadriceps.
+== Structures Involved in Support and Stability ==
-* Quadriceps muscle force increases with knee flexion to counterbalance flexion moment, starting from minimal quadriceps action with standing. The torque around the patellofemoral joint is increased with flexion.
-* Quadriceps and ligament forces aren't parallel, which produces a laterally directed force on the patella, putting it at risk of laterally subluxing.
+== Structures Involved in Knee Extension ==
-** This is prevented by the slope and height of the patella groove on the lateral side, while the medial groove is shallow.
-** At flexion beyond approximately 90° the patella sinks into the intercondylar notch which has high slopes laterally and medially.
+== Structures Involved in Knee Flexion ==
-* With knee extension, the lower aspect of the patella sits against the femur. With flexion to 90° the contact between the patella and femur moves cranially and increases in area With a tight ITB, the patellofemoral joint force can shift laterally.
+== Bursa and Cystic Structures ==
+== 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==