Functional Anatomy of the Knee: Difference between revisions
No edit summary |
No edit summary |
||
(18 intermediate revisions by 3 users not shown) | |||
Line 7: | Line 7: | ||
</div> | </div> | ||
== Introduction == | == Introduction == | ||
The knee joint is | The knee joint is the largest joint in the human body. It consists of bones, cartilage, ligaments, tendons, and other tissues. The ligaments provide stability during loading while the muscles around the knee have a secondary role in stabilising this joint. If these structures are compromised, there may be instability of the knee joint. This article will discuss the anatomy of the knee joint in detail and provide some examples of knee joint pathology. | ||
== | == Key Terms == | ||
[[Cardinal Planes and Axes of Movement|Axes]]: lines around which an object rotates. The rotation axis is a line that passes through the centre of mass. There are three axes of rotation: ''sagittal'' passing from posterior to anterior, ''frontal'' passing from left to right, and ''vertical'' passing from inferior to superior. The rotation axes of the foot joints are perpendicular to the cardinal planes. Therefore, motion at these joints results in rotations within three planes. Example: supination involves inversion, internal rotation, and plantarflexion. | [[Cardinal Planes and Axes of Movement|Axes]]: lines around which an object rotates. The rotation axis is a line that passes through the centre of mass. There are three axes of rotation: ''sagittal'' passing from posterior to anterior, ''frontal'' passing from left to right, and ''vertical'' passing from inferior to superior. The rotation axes of the foot joints are perpendicular to the cardinal planes. Therefore, motion at these joints results in rotations within three planes. Example: supination involves inversion, internal rotation, and plantarflexion. | ||
[[Bursitis|Bursae]]: reduces friction between the moving parts of the body joints. It is a fluid-filled sac. There are four types of bursae: adventitious, subcutaneous, [[Synovial Fluid Analysis|synovial]], and sub-muscular. | [[Bursitis|Bursae]]: reduces friction between the moving parts of the body joints. It is a fluid-filled sac. There are four types of bursae: adventitious, subcutaneous, [[Synovial Fluid Analysis|synovial]], and sub-muscular. | ||
[[Capsular Constraint Mechanism|Capsule]]: one of the characteristics of the synovial joints. It is a fibrous connective tissue which forms a band that seals the joint space, provides passive and active stability and may even form articular surfaces for the joint. The capsular pattern is "the proportional motion restriction in range of motion during passive exercises due to tightness of the joint capsule."<ref>Lim W. Clinical Application and Limitations of the Capsular Pattern. Phys. Ther. Korea 2021; 28(1): 13-17</ref> | [[Capsular Constraint Mechanism|Capsule]]: one of the characteristics of the synovial joints. It is a fibrous connective tissue which forms a band that seals the joint space, provides passive and active stability and may even form articular surfaces for the joint. The capsular pattern is "the proportional motion restriction in range of motion during passive exercises due to tightness of the joint capsule."<ref>Lim W. Clinical Application and Limitations of the Capsular Pattern. Phys. Ther. Korea 2021; 28(1): 13-17</ref> | ||
Closed pack position: the position with the most congruency of the joint surfaces. In this position, joint stability increases. The closed pack position for interphalangeal joints is | Closed pack position: the position with the most congruency of the joint surfaces. In this position, joint stability increases. The closed pack position for interphalangeal joints is full extension. | ||
Degrees of freedom: the direction of joint movement or rotation; there is a maximum of six, including three translations and three rotations. | Degrees of freedom: the direction of joint movement or rotation; there is a maximum of six degrees of freedom, including three translations and three rotations. | ||
[[Ligament]]: fibrous connective tissue that holds the bones together. | [[Ligament]]: fibrous connective tissue that holds the bones together. | ||
Line 27: | Line 27: | ||
== Knee Structure == | == Knee Structure == | ||
The knee joint includes four bones: the distal end of the [[femur]], the proximal end of the [[tibia]], the [[patella]] and the proximal part of the [[fibula]]. | The knee joint includes four bones: the distal end of the [[femur]], the proximal end of the [[tibia]], the [[patella]] and the proximal part of the [[fibula]]. The fibula is indirectly involved in the knee joint. | ||
* | * There are prominent lateral and medial condyles at the distal end of the '''femur'''. An epicondyle projects from each condyle. These are the attachment sites for the collateral ligaments. The intercondylar notch separates the lateral and medial condyles.<ref>Neumann DA, Kinesiology of the musculoskeletal system: Foundations for rehabilitation. 2nd ed. St. Louis, MO: Mosby Elsevier, 2010. p520-71.</ref> | ||
* The proximal end of the '''tibia''' terminates in a broad, flat region called the tibial plateau. The intercondylar eminence runs down the plateau's midline, separating the tibia's medial and lateral condyles. The two condyles form a flat, broad surface | * The proximal end of the '''tibia''' terminates in a broad, flat region called the tibial plateau. The intercondylar eminence runs down the plateau's midline, separating the tibia's medial and lateral condyles. The two condyles form a flat, broad surface, which articulates with the medial and lateral condyles of the femur.<ref>Neumann DA, Knee. In: Neumann DA, editor. Kinesiology of the musculoskeletal system: Foundations for rehabilitation. 2nd ed. St. Louis, MO: Mosby Elsevier, 2010. p520-71.</ref> | ||
* The '''patella''' articulates with the femur to form the patellofemoral joint. It functions as a fulcrum to increase the extension power of the quadriceps and serves as a stabilising structure that reduces frictional forces | * The '''patella''' articulates with the femur to form the patellofemoral joint. It functions as a fulcrum to increase the extension power of the quadriceps and serves as a stabilising structure that reduces frictional forces on the femoral condyles. | ||
* | * The proximal part of the '''fibula''' has an enlarged pointed head and small neck. | ||
=== Bones and | === Bones, Articulations and Kinematics of the Knee === | ||
Knee range of motion decreases as we age. This is part of the normal ageing process, and is related to the increasing rigidity of connective tissue that occurs with age. Age-related reductions in knee range of motion are observed from the second and third decades. Other factors that may cause variability in knee range of motion between individuals include mechanical stresses imposed on the body through vocational, recreational and daily activities. For example, the population of Calcutta have been found to have high knee flexion ranges - up to 160 degrees - this range of motion has been associated with the practice of squatting. In addition, researchers found that increased body mass affects knee flexion range of motion in obese women in South America.<ref>Rohatgi R, Bhatnagar A, Gupta N, Jain M. [https://www.ipinnovative.com/journal-article-file/17843 The study of variation of range of motion of knee joint with body mass index in normal, overweight and obese young adults.] Panacea J Med Sci 2022;12(3):657-661.</ref> | |||
{| class="wikitable" | {| class="wikitable" | ||
|+ | |+ | ||
!'''Bones''' | !'''Bones''' | ||
!'''Articulations''' | !'''Articulations''' | ||
!''' | !'''Characteristics''' | ||
!'''Key palpation''' | !'''Key palpation points''' | ||
|- | |- | ||
|Tibia | |Tibia | ||
Femur | Femur | ||
|Tibiofemoral joint | |Tibiofemoral joint | ||
|Joint articulation occurs between the medial and lateral femoral and tibial condyles. The tibiofemoral joint has two crescent-shaped fibrocartilaginous structures, | |Joint articulation occurs between the medial and lateral femoral and tibial condyles. The tibiofemoral joint has two crescent-shaped fibrocartilaginous structures, the lateral and medial meniscus. The menisci are attached to the tibial plateau by the coronary ligaments. Both menisci are concave superiorly to accommodate the surfaces of the femoral condyles. Their role is to increase the contact area between the tibial and femoral articular surfaces, thus increasing the stability of the joint. | ||
|To palpate the '''femoral condyle,''' flex the knee and locate the knee joint line by | |To palpate the '''femoral condyle,''' flex the knee and locate the knee joint line by grasping and rotating the tibia. The rotation movement of the tibia helps to mark the joint line. Return the lower leg to full extension and keep your fingers on the joint line. The medial condyle can be palpated above the medial side of the joint line, and the lateral condyle is above the lateral side of the joint line. The medial epicondyle is the most medial part of the medial condyle, while the lateral epicondyle is on the lateral condyle. | ||
To palpate the '''tibial tuberosity''' start | To palpate the '''tibial tuberosity''', start by locating the patella. Move your finger down, past the apex of the patella, and keep moving until you feel a bump on the anterior part of the tibia. This is the tibial tuberosity. | ||
|- | |- | ||
|Femur | |Femur | ||
Line 57: | Line 58: | ||
|Tibia | |Tibia | ||
Fibula | Fibula | ||
|Superior ( | |Superior (proximal) tibiofibular joint (STFJ) | ||
|STFJ comprises the tibial facet on the posterolateral aspect of the tibial condyle and the fibular facet on the medial upper surfaces of the head of the fibula. | |The STFJ comprises the tibial facet on the posterolateral aspect of the tibial condyle and the fibular facet on the medial upper surfaces of the head of the fibula. | ||
|To palpate the '''fibula''', | |To palpate the '''fibula''', position the patient supine and find the tibial tuberosity. Because the head of the fibula is in line with the tibial tuberosity, move your finger in a lateral direction until you reach a bony landmark - this is located more posterior than anterior. To verify the location of the head of the fibula, place your finger on this landmark and ask the patient to evert the foot. Your finger should move up and down as the patient activates the fibularis longus, which has its proximal attachment on the head of the fibula. | ||
|} | |} | ||
Line 66: | Line 67: | ||
|+ | |+ | ||
!'''Joint''' | !'''Joint''' | ||
!'''Type of | !'''Type of joint''' | ||
!'''Plane of | !'''Plane of movement''' | ||
!'''Motion''' | !'''Motion''' | ||
!'''Kinematics''' | !'''Kinematics''' | ||
Line 78: | Line 79: | ||
Transverse | Transverse | ||
|Flexion and | |Flexion and extension; | ||
internal and external rotation of the tibia in relation to the femur when the knee is flexed. | |||
|Normal range of motion: | |Normal ''active'' range of motion: | ||
Extension: 0 | Extension: 0 degrees | ||
Flexion: 140 degrees | Flexion: 140 degrees | ||
Internal and | Internal and external rotation of the tibia in relation to the femur is possible only when the knee is flexed | ||
|Full extension | |Full extension | ||
|25 degrees of flexion | |25 degrees of flexion | ||
|- | |- | ||
|[[Patellofemoral Joint]] (PFJ) | |[[Patellofemoral Joint]] (PFJ) | ||
|Saddle | |Saddle | ||
| | | | ||
|Superior/inferior glide | |Superior/inferior glide; | ||
medial and lateral glide; | |||
medial and lateral tilt; | |||
medial and lateral rotation | |||
|At full knee extension patella | |At full knee extension, the patella rests on the suprapatellar fat pad. | ||
At 20-30 degrees of knee flexion, the patella moves inferiorly, lying in the shallow part of the intercondylar groove. The patella contacts the femur with its inferior pole. | At 20-30 degrees of knee flexion, the patella moves inferiorly, lying in the shallow part of the intercondylar groove. The patella contacts the femur with its inferior pole. | ||
At 60-90 degrees of knee flexion, the patella has | At 60-90 degrees of knee flexion, the patella has maximum contact with the intercondylar groove (1/3 of the posterior surface area of the patella). | ||
At 135 degrees of knee flexion, the patella contacts the femur with its superior pole and rests below the intercondylar groove. | At 135 degrees of knee flexion, the patella contacts the femur with its superior pole and rests below the intercondylar groove. | ||
|Full extension with | |Full extension with medial rotation of the femoral condyle | ||
|Flexion | |Flexion | ||
|- | |- | ||
|Superior | |Superior Tibiofibular Joint (STFJ) | ||
|Plane synovial joint | |Plane synovial joint | ||
|A small range of gliding movements following the | |A small range of gliding movements following movement at the talocrural joint | ||
|Tibia and fibula move anterior/posterior, superior/inferior, and | |Tibia and fibula move anterior/posterior, superior/inferior, and rotate in relationship to each other | ||
|The proximal tibiofibular joint always moves | |The proximal tibiofibular joint always moves with the distal tibiofibular joint. Movement occurs during knee flexion and tibial internal and external rotation. | ||
Ankle dorsiflexion produces a few degrees of superior and posterior translation at the fibular head. | |||
Ankle plantarflexion results in a few degrees of inferior and anterior translation of the fibular head. | |||
|Maximum ankle dorsiflexion | |Maximum ankle dorsiflexion | ||
|Ankle plantarflexion | |Ankle plantarflexion | ||
Line 121: | Line 124: | ||
There are four bursae located in the knee joint: | There are four bursae located in the knee joint: | ||
* Suprapatellar bursa between | * Suprapatellar bursa between quadriceps femoris and the femur | ||
* Prepatellar bursa between the apex of the patella and the skin | * Prepatellar bursa between the apex of the patella and the skin | ||
* Deep and superficial infrapatellar bursa | * Deep and superficial infrapatellar bursa - the deep bursa is located between the tibia and the patellar ligament, and the superficial infrapatellar bursa is located between the patellar ligament and the skin | ||
* Semimembranosus bursa between | * Semimembranosus bursa between semimembranosus and the medial head of gastrocnemius | ||
=== Knee Joint Capsule === | === Knee Joint Capsule === | ||
The knee joint capsule connects the margins of the femoral and tibial articular surfaces. The anterior portion of the capsule attaches to the borders of the patella. The lateroposterior portion of the capsule gives passage to the tendon of the popliteus muscle. | The knee joint capsule connects the margins of the femoral and tibial articular surfaces. The anterior portion of the capsule attaches to the borders of the patella. The lateroposterior portion of the capsule gives passage to the tendon of the popliteus muscle. | ||
Like other joints in the body, the knee joint | Like other joints in the body, the knee joint has a specific capsular pattern. A combination of pain, with or without limitation, points toward a joint problem. The knee joint capsular pattern is characterised by an extension limitation and a greater flexion limitation.<ref>de Coninck S. What is a capsular pattern? Available from https://cyriax.eu/orthopaedic-medicine-knowledge-bank/definitions-in-orthopaedic-medicine/what-is-a-capsular-pattern/ [last access 25.04.2023]</ref> | ||
== Ligaments of the Knee == | == Ligaments of the Knee == | ||
Line 136: | Line 139: | ||
The ''intracapsular'' ligaments are located inside the joint capsule and include: | The ''intracapsular'' ligaments are located inside the joint capsule and include: | ||
* | * Anterior cruciate ligament (ACL) | ||
* | * Posterior cruciate ligament (PCL) | ||
* Coronary ligaments | * Coronary ligaments | ||
* | * Anterior ligament of the fibular head | ||
* | * Posterior ligament of the fibular head | ||
The ''extracapsular'' ligaments are located outside the joint capsule.They include the following: | The ''extracapsular'' ligaments are located outside the joint capsule. They include the following: | ||
* | * Patellar ligament (or patellar tendon) as it connects one bone to another | ||
* Lateral collateral ligament (LCL) | * Lateral collateral ligament (LCL) | ||
* Medial collateral ligament (MCL) | * Medial collateral ligament (MCL) | ||
Line 154: | Line 157: | ||
{| class="wikitable" | {| class="wikitable" | ||
|+ | |+ | ||
!'''Key | !'''Key ligaments''' | ||
!'''Origin''' | !'''Origin''' | ||
!'''Insertion''' | !'''Insertion''' | ||
!'''Action/ | !'''Action/role''' | ||
!'''Key | !'''Key palpation points''' | ||
|- | |- | ||
|[[Anterior Cruciate Ligament (ACL)| | |[[Anterior Cruciate Ligament (ACL)|Anterior cruciate ligament]] (ACL) | ||
|Posteromedial aspect of the lateral femoral condyle | |Posteromedial aspect of the lateral femoral condyle | ||
|Intercondylar tibial spine | |Intercondylar tibial spine | ||
|Resists anterior tibial translation and internal tibial rotation relative to the femur | |Resists anterior tibial translation and internal tibial rotation relative to the femur | ||
|To palpate the '''femoral condyle | |You cannot specifically palpate the ACL, but you can palpate structures around it to check for associated injury or swelling. To palpate the '''femoral condyle''', flex the knee and locate the knee joint line by grasping and rotating the tibia. The rotation movement of the tibia helps to mark the joint line. Return the lower leg to full extension and keep the fingers on the joint line. The '''lateral condyle''' is located above the lateral side of the joint line. | ||
|- | |- | ||
|[[Posterior Cruciate Ligament| | |[[Posterior Cruciate Ligament|Posterior cruciate ligament]] (PCL) | ||
|Anterolateral aspect of the medial femoral condyle | |Anterolateral aspect of the medial femoral condyle | ||
|Posterior aspect of the tibial plateau | |Posterior aspect of the tibial plateau | ||
|Resists posterior tibial translation relative to the femur | |Resists posterior tibial translation relative to the femur | ||
|The '''medial femoral condyle''' can be palpated above the medial side of the joint line. | |You cannot specifically palpate the PCL, but you can palpate structures around it to check for associated injury or swelling. The '''medial femoral condyle''' can be palpated above the medial side of the joint line. | ||
|- | |- | ||
|[[Coronary Ligaments of the Knee|Coronary ligaments]] (Meniscotibial ligaments): | |[[Coronary Ligaments of the Knee|Coronary ligaments]] (Meniscotibial ligaments): | ||
Line 186: | Line 189: | ||
|Front of the lateral condyle of the tibia | |Front of the lateral condyle of the tibia | ||
|Provides stabilisation to the tibiofibular joint | |Provides stabilisation to the tibiofibular joint | ||
|The '''head of the fibula''' is in | |The '''head of the fibula''' is in line with the tibial tuberosity. From the tibial tuberosity, move your finger in a lateral direction until you reach a bony landmark located more posterior than anterior. To verify the location of the head of the fibula, place your finger on this landmark and ask the patient to evert the foot. Your finger should move up and down as the patient activates the fibularis longus, which has its proximal attachment on the head of the fibula. | ||
|- | |- | ||
|Posterior ligament of the fibular head | |Posterior ligament of the fibular head | ||
Line 206: | Line 209: | ||
|[[Medial Collateral Ligament of the Knee|Medial collateral ligament]] (MCL) | |[[Medial Collateral Ligament of the Knee|Medial collateral ligament]] (MCL) | ||
|Medial epicondyle of the femur | |Medial epicondyle of the femur | ||
|Medial aspect of the tibia | |Medial aspect of the tibia and medial meniscus | ||
|Provides resistance to valgus stresses or forces directed from the lateral side of the knee and | |||
|Provides resistance to valgus stresses or forces directed from the lateral side of the knee | |||
resists rotational forces on the knee. | resists rotational forces on the knee. | ||
|To palpate the '''medial collateral ligament''' of the knee, | |To palpate the '''medial collateral ligament''' of the knee, palpate the femoral and tibial condyles with the knee flexed to identify the joint line. Return the lower leg to knee extension. Identify the medial condyle of the femur proximal to the joint line and the condyle of the tibia below the joint line. Partially flex the knee to move away the pes anserinus (see below). Place your fingers in the middle of the joint line and glide them in an anterior-posterior direction to palpate the rubbery structure of the MCL. | ||
|- | |- | ||
|[[Lateral Collateral Ligament of the knee|Lateral collateral ligament]] (LCL) | |[[Lateral Collateral Ligament of the knee|Lateral collateral ligament]] (LCL) | ||
|Lateral epicondyle of the femur | |Lateral epicondyle of the femur | ||
|Fibular head | |Fibular head | ||
|Resists varus stresses or forces directed from the medial side of the knee | |Resists varus stresses or forces directed from the medial side of the knee and | ||
resists rotational forces on the knee. | resists rotational forces on the knee. | ||
| | |To palpate the '''lateral collateral ligament''' of the knee, identify the joint line between the tibia and the femur. The lateral femoral condyle is proximal to the joint line. With your patient in knee flexion, place your fingers in the middle of the joint line and glide your fingers in an anterior-posterior direction. The rubbery band under your fingers is the LCL. | ||
|- | |- | ||
|Oblique popliteal ligaments | |Oblique popliteal ligaments | ||
| | |There is inconsistent information in the literature about these ligaments:<ref>LaPrade RF, Morgan PM, Wentorf FA, Johansen S, Engebretsen L. The anatomy of the posterior aspect of the knee. An anatomic study. J Bone Joint Surg Am. 2007 Apr;89(4):758-64. </ref><ref name=":0">Hedderwick, M. The Anatomy of the Oblique Popliteal Ligament (Thesis, Master of Science). University of Otago, 2012. Available from https://ourarchive.otago.ac.nz/handle/10523/2359 [last access 28.04.2023]</ref><ref name=":1">Wu XD, Yu JH, Zou T, Wang W, LaPrade RF, Huang W, Sun SQ. [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5311875/pdf/srep42698.pdf Anatomical Characteristics and Biomechanical Properties of the Oblique Popliteal Ligament.] Sci Rep. 2017 Feb 16;7:42698. </ref> | ||
''Primary origin:'' | ''Primary origin:'' | ||
Line 236: | Line 237: | ||
Posteromedial part of the capsule | Posteromedial part of the capsule | ||
|Fabella (if present) | |[[Fabella syndrome|Fabella]] (if present) | ||
Tendon of the lateral head of the gastrocnemius at the lateral femoral condyle | Tendon of the lateral head of the gastrocnemius at the lateral femoral condyle | ||
Knee joint capsule at the medial border of the lateral femoral condyle<ref name=":0" /><ref name=":1" /> | Knee joint capsule at the medial border of the lateral femoral condyle<ref name=":0" /><ref name=":1" /> | ||
|Prevents knee hyperextension | |Prevents knee hyperextension; | ||
Prevents excessive external rotation | Prevents excessive external rotation. | ||
| | | | ||
|} | |} | ||
== Knee Passive Range of Motion == | == Knee Passive Range of Motion == | ||
Knee passive range of motion | Knee passive range of motion refers to how far the knee can be moved by an external force (e.g. another person) when the leg muscles are relaxed. | ||
* | * To assess passive knee flexion: | ||
** The patient is in | ** The patient is in supine lying. | ||
** Flex the patient’s leg to 90° at the hip and maintain this position by holding the distal femur with one hand. | ** Flex the patient’s leg to 90° at the hip and maintain this position by holding the distal femur with one hand. | ||
** With | ** With your other hand holding onto the distal tibia, bring the knee into maximum flexion. | ||
** | ** There is typically a [[End-Feel|soft end feel]] (from the soft tissue structures of the calf/posterior thigh), so range of motion varies depending on the size of the patient's leg. The normal range for ''passive'' knee flexion is up to 150<sup>o</sup>. | ||
* | * To assess passive knee extension: | ||
** The patient | ** The patient is in supine lying. | ||
** One | ** One of your hands holds the patient's distal femur. | ||
** | ** Your second hand holds onto the medial side of the patient's distal tibia - this allows for the “screw-home” mechanism at terminal knee extension. | ||
** | ** Bring the knee into passive extension. | ||
* | ** The normal range for passive knee extension is up to 10<sup>o</sup> hyperextension. | ||
** | * To assess passive external and internal rotation of the knee: | ||
** Fixate the knee | ** Position the patient in a supine position with their knee in 30-90 degrees of passive flexion. | ||
** | ** Fixate the knee in this position with one hand. | ||
** With your other hand, hold the patient's foot and position it in dorsiflexion. | |||
** Move the tibia into internal rotation and external rotation. | ** Move the tibia into internal rotation and external rotation. | ||
** | ** Rotatory motion of the knee joint decreases with increased knee extension range of motion:<ref>Zarins B, Rowe CR, Harris BA, Watkins MP. Rotational motion of the knee. Am J Sports Med. 1983 May-Jun;11(3):152-6.</ref> | ||
** | *** At 30-90 degrees of passive flexion, there will typically be approximately 45 degrees of external rotation. | ||
*** At 5 degrees of passive flexion, there will typically be approximately 23 degrees of external and 10 degrees of internal rotation. | |||
== Muscles of the Knee == | == Muscles of the Knee == | ||
The knee muscles are located in the three compartments of the thigh and the posterior compartment of the leg. ''Pes anserinus'' is a point of insertion for the tendons of the semitendinosus, gracilis and sartorius muscles at the medial knee. The ''pes anserine bursa'' is located between the pes anserine tendons and the semimembranosus tendon. It can become inflamed, which results in pain on the inside of the knee.<ref name=":2" /> | |||
The following sections only include muscles that are relevant to the knee joint. Other muscles in these compartments that do not act on the knee are not included (e.g. soleus in the posterior compartment of the leg). | |||
=== Anterior Compartment of the Thigh === | === Anterior Compartment of the Thigh === | ||
The muscles located in | The majority of the muscles located in the anterior compartment of the thigh are knee extensors (i.e. quadriceps femoris), except for sartorius which is a knee flexor. | ||
{| class="wikitable" | {| class="wikitable" | ||
|+ | |+ | ||
Line 296: | Line 300: | ||
RF: anterior inferior iliac spine and the ilium of the pelvis | RF: anterior inferior iliac spine and the ilium of the pelvis | ||
|[[Patella]] via the quadriceps femoris tendon | |[[Patella]] via the quadriceps femoris tendon | ||
| | |[[Femoral Nerve|Femoral nerve]] | ||
|VL: extends the knee joint and maintains thigh and patella position while walking and running | |||
|VL: extends | |||
VIM: extends the knee joint and stabilises the patella | VIM: extends the knee joint and stabilises the patella | ||
VM: extends the knee joint and contributes to correct tracking | VM: extends the knee joint and contributes to correct patella tracking | ||
RF: extends the knee and flexes the hip | RF: extends the knee and flexes the hip | ||
Line 319: | Line 319: | ||
=== Medial Compartment of the Thigh === | === Medial Compartment of the Thigh === | ||
The | The medial compartment of the thigh contains the hip adductors. The only muscle in this compartment that acts on both the hip and the knee is gracilis. | ||
{| class="wikitable" | {| class="wikitable" | ||
|+ | |+ | ||
Line 329: | Line 329: | ||
|- | |- | ||
|[[Gracilis]] | |[[Gracilis]] | ||
|Inferior rami of the pubis and the body of the pubis | |Inferior rami of the pubis and the body of the pubis | ||
|The medial surface of the tibial shaft | |The medial surface of the tibial shaft | ||
|[[Obturator Nerve|Obturator nerve (L2-L4)]] | |[[Obturator Nerve|Obturator nerve (L2-L4)]] | ||
Line 336: | Line 336: | ||
=== Posterior Compartment of the Thigh === | === Posterior Compartment of the Thigh === | ||
The hamstrings are | The hamstrings are located in the posterior compartment of the thigh. Their role is to extend the hip and flex the knee. The hamstrings consists of four muscles: biceps femoris, semitendinosus and semimembranosus. | ||
{| class="wikitable" | {| class="wikitable" | ||
|+ | |+ | ||
Line 349: | Line 349: | ||
''Short head'': the linea aspera on the posterior surface of the femur. | ''Short head'': the linea aspera on the posterior surface of the femur. | ||
|Head of the fibula | |Head of the fibula | ||
|''Long head'': | |''Long head'': the tibial part of the sciatic nerve. | ||
''Short head'': the common fibular part of the sciatic nerve | ''Short head'': the common fibular part of the sciatic nerve. | ||
|Main action: knee flexion. In addition: the muscle extends the thigh at the hip and laterally rotates at the hip and knee | |Main action: knee flexion. In addition: the muscle extends the thigh at the hip and laterally rotates at the hip and knee. | ||
|- | |- | ||
|[[Semitendinosus]] | |[[Semitendinosus]] | ||
|Ischial tuberosity of the pelvis | |Ischial tuberosity of the pelvis. | ||
|Medial surface of the tibia | |Medial surface of the tibia | ||
|Tibial part of the [[Sciatic Nerve|sciatic nerve]] | |Tibial part of the [[Sciatic Nerve|sciatic nerve]] | ||
Line 376: | Line 376: | ||
=== Posterior Compartment of the Leg === | === Posterior Compartment of the Leg === | ||
The posterior compartment of the leg is divided into superficial and deep. The superficial compartment contains gastrocnemius and plantaris. Popliteus is | The posterior compartment of the leg is divided into superficial and deep compartments. The superficial compartment contains gastrocnemius and plantaris. Popliteus is located in the deep compartment of the leg. | ||
{| class="wikitable" | {| class="wikitable" | ||
|+ | |+ | ||
Line 389: | Line 389: | ||
''Medial head'': medial femoral condyle. | ''Medial head'': medial femoral condyle. | ||
| | |Distally, gastrocnemius and soleus form the Achilles (calcaneal) tendon, which inserts into the calcaneus | ||
|[[Tibial Nerve|Tibial nerve]] | |[[Tibial Nerve|Tibial nerve]] | ||
|Ankle plantarflexion Knee flexion | |Ankle plantarflexion | ||
Knee flexion | |||
|- | |- | ||
|[[Plantaris]] | |[[Plantaris]] | ||
Line 407: | Line 408: | ||
== Innervation of the Knee == | == Innervation of the Knee == | ||
The knee joint | The knee joint is innervated by the femoral nerve, the tibial and common fibular nerves, and the posterior division of the obturator nerve. The femoral nerve innervates the anterior compartment of the thigh, the sciatic nerve innervates the posterior compartment, the obturator nerve innervates the medial compartment of the thigh, and the tibial nerve innervates the posterior compartment of the leg. | ||
{| class="wikitable" | {| class="wikitable" | ||
|+ | |+ | ||
Line 421: | Line 422: | ||
The posterior (deep) femoral nerve, which becomes the saphenous nerve | The posterior (deep) femoral nerve, which becomes the saphenous nerve | ||
|Sartorius, quadriceps femoris, pectineus, iliacus | |Sartorius, quadriceps femoris, pectineus, iliacus | ||
|The saphenous nerve is the cutaneous branch of the femoral nerve providing sensory innervation along the anteromedial and posteromedial aspects of the leg into the medial foot | |The saphenous nerve is the cutaneous branch of the femoral nerve providing sensory innervation along the anteromedial and posteromedial aspects of the leg into the medial foot | ||
|- | |- | ||
|Obturator nerve | |Obturator nerve <ref>Chang MC, Choi KT, Cho HK, Man Kim Y, Kim TU. [https://apm.amegroups.com/article/view/61978/html#:~:text=Patients%20with%20obturator%20nerve%20injury,injuries%20(1%2D5). Obturator nerve injury diagnosed by nerve conduction: a case report]. Ann Palliat Med. 2021 Jun;10(6):7069-7072. </ref> | ||
|Lumbar plexus on the posterior abdominal wall (L2-L4) | |Lumbar plexus on the posterior abdominal wall (L2-L4) | ||
|Anterior and posterior branch | |Anterior and posterior branch | ||
Line 437: | Line 438: | ||
|No direct sensory functions. | |No direct sensory functions. | ||
But it indirectly provides sensory feedback to the skin of the lateral leg, heel, and both the dorsal and plantar surfaces of the foot via its terminal branches | |||
|- | |- | ||
|Tibial nerve | |Tibial nerve | ||
Line 454: | Line 455: | ||
== Vascular Supply of the Knee == | == Vascular Supply of the Knee == | ||
The descending branch of the lateral femoral circumflex artery, the popliteal artery, and the anterior tibial artery | The descending branch of the lateral femoral circumflex artery, the popliteal artery, and the anterior tibial artery are the main arteries supplying the knee joint region.<ref name=":3">Hirtler L, Lübbers A, Rath C. [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6637446/pdf/JOA-235-289.pdf Vascular coverage of the anterior knee region - an anatomical study.] J Anat. 2019 Aug;235(2):289-298. </ref><ref>Qazi E, Wilting J, Patel NR, Alenezi AO, Kennedy SA, Tan KT, Jaberi A, Mafeld S. [https://journals.sagepub.com/doi/pdf/10.1177/08465371211003860 Arteries of the lower limb—Embryology, variations, and clinical significance.] Canadian Association of Radiologists Journal. 2022 Feb;73(1):259-70.</ref> | ||
{| class="wikitable" | {| class="wikitable" | ||
|+ | |+ | ||
Line 495: | Line 496: | ||
|Inferior lateral (ILGA) and medial (IMGA) genicular arteries | |Inferior lateral (ILGA) and medial (IMGA) genicular arteries | ||
| | | | ||
ILGA: | ILGA: | ||
Line 513: | Line 512: | ||
== Clinical Relevance == | == Clinical Relevance == | ||
# The | # The collateral ligaments of the knee are commonly injured. These injuries often occur when the foot is planted and a force is applied to the side of the knee. You can learn more about this condition [https://members.physio-pedia.com/learn/introduction-to-the-knee-promopage/ here]. | ||
# | # Anterior cruciate ligament (ACL) injury can occur when the knee joint is hyperextended or when a force is applied to the back of a partly flexed knee. For more information on ACL rehabilitation, please see this [https://members.physio-pedia.com/learn/acl-rehabilitation-programme-promopage/ programme]. | ||
# | # Prepatellar bursitis (also known as housemaid’s knee) involves the prepatellar bursa.<ref>Rishor-Olney CR, Pozun A. Prepatellar Bursitis. [Updated 2022 Sep 6]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from https://www.ncbi.nlm.nih.gov/books/NBK557508/ [last access 25.04.2023]</ref> Signs of prepatella bursitis include inflammation and anterior knee swelling. | ||
# The menisci are | # The menisci are also commonly injured.<ref name=":2">Xuan D. Exploring anatomy of the knee. Plus Course 2023</ref> | ||
# A “high-riding” patella ([[patella alta]]) has been associated with patellofemoral pain, patellar instability, patellofemoral cartilage lesions, and patellofemoral osteoarthritis. <ref>Wheatley MGA, Rainbow MJ, Clouthier AL. [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7251040/pdf/12178_2020_Article_9626.pdf Patellofemoral Mechanics: a Review of Pathomechanics and Research Approaches.] Curr Rev Musculoskelet Med. 2020 Jun;13(3):326-337. </ref> | # A “high-riding” patella ([[patella alta]]) has been associated with patellofemoral pain, patellar instability, patellofemoral cartilage lesions, and patellofemoral osteoarthritis.<ref>Wheatley MGA, Rainbow MJ, Clouthier AL. [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7251040/pdf/12178_2020_Article_9626.pdf Patellofemoral Mechanics: a Review of Pathomechanics and Research Approaches.] Curr Rev Musculoskelet Med. 2020 Jun;13(3):326-337. </ref> | ||
# Patella | # Patella baja (or patella infera) refers to an atypically "low-lying patella that remains distal in relation to the femoral trochlea", which affects patellofemoral tracking.<ref>Perelli S, Ibañez M, Morales-Marin C, Acuña-Avila G, Espinoza-von Bischhoffshausen R, Masferrer-Pino A, Monllau JC. [https://www.arthroscopytechniques.org/article/S2212-6287(19)30187-2/fulltext Patellar Tendon Lengthening: Rescue Procedure for Patella Baja.] Arthroscopy Techniques 2020, 9(1):pages e1-e8.</ref> | ||
# Tibial torsion | # Tibial torsion that continues into adulthood is associated with patellofemoral pathology.<ref>Snow M. [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7930175/pdf/12178_2020_Article_9688.pdf Tibial Torsion and Patellofemoral Pain and Instability in the Adult Population: Current Concept Review.] Curr Rev Musculoskelet Med. 2021 Feb;14(1):67-75. </ref> For a comprehensive discussion of patellofemoral pathology, please see this [https://members.physio-pedia.com/patellofemoral-joint-programme-course/ programme]. | ||
== Resources == | == Resources == | ||
Line 530: | Line 529: | ||
[[Category:Course Pages]] | [[Category:Course Pages]] | ||
[[Category:Knee - Anatomy]] | [[Category:Knee - Anatomy]] | ||
[[Category:Plus Content]] |
Latest revision as of 11:28, 3 June 2023
Original Editor - Ewa Jaraczewska
Top Contributors - Ewa Jaraczewska, Jess Bell and Tony Lowe
Introduction[edit | edit source]
The knee joint is the largest joint in the human body. It consists of bones, cartilage, ligaments, tendons, and other tissues. The ligaments provide stability during loading while the muscles around the knee have a secondary role in stabilising this joint. If these structures are compromised, there may be instability of the knee joint. This article will discuss the anatomy of the knee joint in detail and provide some examples of knee joint pathology.
Key Terms[edit | edit source]
Axes: lines around which an object rotates. The rotation axis is a line that passes through the centre of mass. There are three axes of rotation: sagittal passing from posterior to anterior, frontal passing from left to right, and vertical passing from inferior to superior. The rotation axes of the foot joints are perpendicular to the cardinal planes. Therefore, motion at these joints results in rotations within three planes. Example: supination involves inversion, internal rotation, and plantarflexion.
Bursae: reduces friction between the moving parts of the body joints. It is a fluid-filled sac. There are four types of bursae: adventitious, subcutaneous, synovial, and sub-muscular.
Capsule: one of the characteristics of the synovial joints. It is a fibrous connective tissue which forms a band that seals the joint space, provides passive and active stability and may even form articular surfaces for the joint. The capsular pattern is "the proportional motion restriction in range of motion during passive exercises due to tightness of the joint capsule."[1]
Closed pack position: the position with the most congruency of the joint surfaces. In this position, joint stability increases. The closed pack position for interphalangeal joints is full extension.
Degrees of freedom: the direction of joint movement or rotation; there is a maximum of six degrees of freedom, including three translations and three rotations.
Ligament: fibrous connective tissue that holds the bones together.
Open (loose) pack position: position with the least amount of joint congruency where joint stability is reduced.
Planes of movement: describe how the body moves. Up and down movements (flexion/extension) occur in the sagittal plane. Sideway movements (abduction/adduction) occur in the frontal plane. Movements in the transverse plane are rotational (internal and external rotation).
Knee Structure[edit | edit source]
The knee joint includes four bones: the distal end of the femur, the proximal end of the tibia, the patella and the proximal part of the fibula. The fibula is indirectly involved in the knee joint.
- There are prominent lateral and medial condyles at the distal end of the femur. An epicondyle projects from each condyle. These are the attachment sites for the collateral ligaments. The intercondylar notch separates the lateral and medial condyles.[2]
- The proximal end of the tibia terminates in a broad, flat region called the tibial plateau. The intercondylar eminence runs down the plateau's midline, separating the tibia's medial and lateral condyles. The two condyles form a flat, broad surface, which articulates with the medial and lateral condyles of the femur.[3]
- The patella articulates with the femur to form the patellofemoral joint. It functions as a fulcrum to increase the extension power of the quadriceps and serves as a stabilising structure that reduces frictional forces on the femoral condyles.
- The proximal part of the fibula has an enlarged pointed head and small neck.
Bones, Articulations and Kinematics of the Knee[edit | edit source]
Knee range of motion decreases as we age. This is part of the normal ageing process, and is related to the increasing rigidity of connective tissue that occurs with age. Age-related reductions in knee range of motion are observed from the second and third decades. Other factors that may cause variability in knee range of motion between individuals include mechanical stresses imposed on the body through vocational, recreational and daily activities. For example, the population of Calcutta have been found to have high knee flexion ranges - up to 160 degrees - this range of motion has been associated with the practice of squatting. In addition, researchers found that increased body mass affects knee flexion range of motion in obese women in South America.[4]
Bones | Articulations | Characteristics | Key palpation points |
---|---|---|---|
Tibia
Femur |
Tibiofemoral joint | Joint articulation occurs between the medial and lateral femoral and tibial condyles. The tibiofemoral joint has two crescent-shaped fibrocartilaginous structures, the lateral and medial meniscus. The menisci are attached to the tibial plateau by the coronary ligaments. Both menisci are concave superiorly to accommodate the surfaces of the femoral condyles. Their role is to increase the contact area between the tibial and femoral articular surfaces, thus increasing the stability of the joint. | To palpate the femoral condyle, flex the knee and locate the knee joint line by grasping and rotating the tibia. The rotation movement of the tibia helps to mark the joint line. Return the lower leg to full extension and keep your fingers on the joint line. The medial condyle can be palpated above the medial side of the joint line, and the lateral condyle is above the lateral side of the joint line. The medial epicondyle is the most medial part of the medial condyle, while the lateral epicondyle is on the lateral condyle.
To palpate the tibial tuberosity, start by locating the patella. Move your finger down, past the apex of the patella, and keep moving until you feel a bump on the anterior part of the tibia. This is the tibial tuberosity. |
Femur
Patella |
Patellofemoral joint | Joint articulation is located between the anterior aspect of the distal femur and the posterior surface of the patella. | |
Tibia
Fibula |
Superior (proximal) tibiofibular joint (STFJ) | The STFJ comprises the tibial facet on the posterolateral aspect of the tibial condyle and the fibular facet on the medial upper surfaces of the head of the fibula. | To palpate the fibula, position the patient supine and find the tibial tuberosity. Because the head of the fibula is in line with the tibial tuberosity, move your finger in a lateral direction until you reach a bony landmark - this is located more posterior than anterior. To verify the location of the head of the fibula, place your finger on this landmark and ask the patient to evert the foot. Your finger should move up and down as the patient activates the fibularis longus, which has its proximal attachment on the head of the fibula. |
Knee Kinematics[edit | edit source]
Joint | Type of joint | Plane of movement | Motion | Kinematics | Closed pack position | Open pack position |
---|---|---|---|---|---|---|
Tibiofemoral Joint (TFJ) | Modified hinge | Saggital
Transverse |
Flexion and extension;
internal and external rotation of the tibia in relation to the femur when the knee is flexed. |
Normal active range of motion:
Extension: 0 degrees Flexion: 140 degrees Internal and external rotation of the tibia in relation to the femur is possible only when the knee is flexed |
Full extension | 25 degrees of flexion |
Patellofemoral Joint (PFJ) | Saddle | Superior/inferior glide;
medial and lateral glide; medial and lateral tilt; medial and lateral rotation |
At full knee extension, the patella rests on the suprapatellar fat pad.
At 20-30 degrees of knee flexion, the patella moves inferiorly, lying in the shallow part of the intercondylar groove. The patella contacts the femur with its inferior pole. At 60-90 degrees of knee flexion, the patella has maximum contact with the intercondylar groove (1/3 of the posterior surface area of the patella). At 135 degrees of knee flexion, the patella contacts the femur with its superior pole and rests below the intercondylar groove. |
Full extension with medial rotation of the femoral condyle | Flexion | |
Superior Tibiofibular Joint (STFJ) | Plane synovial joint | A small range of gliding movements following movement at the talocrural joint | Tibia and fibula move anterior/posterior, superior/inferior, and rotate in relationship to each other | The proximal tibiofibular joint always moves with the distal tibiofibular joint. Movement occurs during knee flexion and tibial internal and external rotation.
Ankle dorsiflexion produces a few degrees of superior and posterior translation at the fibular head. Ankle plantarflexion results in a few degrees of inferior and anterior translation of the fibular head. |
Maximum ankle dorsiflexion | Ankle plantarflexion |
Knee Bursae[edit | edit source]
There are four bursae located in the knee joint:
- Suprapatellar bursa between quadriceps femoris and the femur
- Prepatellar bursa between the apex of the patella and the skin
- Deep and superficial infrapatellar bursa - the deep bursa is located between the tibia and the patellar ligament, and the superficial infrapatellar bursa is located between the patellar ligament and the skin
- Semimembranosus bursa between semimembranosus and the medial head of gastrocnemius
Knee Joint Capsule[edit | edit source]
The knee joint capsule connects the margins of the femoral and tibial articular surfaces. The anterior portion of the capsule attaches to the borders of the patella. The lateroposterior portion of the capsule gives passage to the tendon of the popliteus muscle.
Like other joints in the body, the knee joint has a specific capsular pattern. A combination of pain, with or without limitation, points toward a joint problem. The knee joint capsular pattern is characterised by an extension limitation and a greater flexion limitation.[5]
Ligaments of the Knee[edit | edit source]
The knee joint has two types of ligaments based on location: extracapsular and intracapsular.
The intracapsular ligaments are located inside the joint capsule and include:
- Anterior cruciate ligament (ACL)
- Posterior cruciate ligament (PCL)
- Coronary ligaments
- Anterior ligament of the fibular head
- Posterior ligament of the fibular head
The extracapsular ligaments are located outside the joint capsule. They include the following:
- Patellar ligament (or patellar tendon) as it connects one bone to another
- Lateral collateral ligament (LCL)
- Medial collateral ligament (MCL)
- Arcuate popliteal ligaments
- Oblique popliteal ligaments
Intracapsular ligaments[edit | edit source]
Key ligaments | Origin | Insertion | Action/role | Key palpation points |
---|---|---|---|---|
Anterior cruciate ligament (ACL) | Posteromedial aspect of the lateral femoral condyle | Intercondylar tibial spine | Resists anterior tibial translation and internal tibial rotation relative to the femur | You cannot specifically palpate the ACL, but you can palpate structures around it to check for associated injury or swelling. To palpate the femoral condyle, flex the knee and locate the knee joint line by grasping and rotating the tibia. The rotation movement of the tibia helps to mark the joint line. Return the lower leg to full extension and keep the fingers on the joint line. The lateral condyle is located above the lateral side of the joint line. |
Posterior cruciate ligament (PCL) | Anterolateral aspect of the medial femoral condyle | Posterior aspect of the tibial plateau | Resists posterior tibial translation relative to the femur | You cannot specifically palpate the PCL, but you can palpate structures around it to check for associated injury or swelling. The medial femoral condyle can be palpated above the medial side of the joint line. |
Coronary ligaments (Meniscotibial ligaments):
Medial coronary ligament Lateral coronary ligament |
Inferior edges of the menisci | Tibial plateau | Stabilise the menisci | |
Anterior ligament of the fibular head | Front of the head of the fibula | Front of the lateral condyle of the tibia | Provides stabilisation to the tibiofibular joint | The head of the fibula is in line with the tibial tuberosity. From the tibial tuberosity, move your finger in a lateral direction until you reach a bony landmark located more posterior than anterior. To verify the location of the head of the fibula, place your finger on this landmark and ask the patient to evert the foot. Your finger should move up and down as the patient activates the fibularis longus, which has its proximal attachment on the head of the fibula. |
Posterior ligament of the fibular head | Back of the head of the fibula | Back of the lateral condyle of the tibia | Provides stabilisation to the tibiofibular joint |
Extracapsular ligaments[edit | edit source]
Key Ligaments | Origin | Insertion | Action/Role | Key Palpation |
---|---|---|---|---|
Medial collateral ligament (MCL) | Medial epicondyle of the femur | Medial aspect of the tibia and medial meniscus | Provides resistance to valgus stresses or forces directed from the lateral side of the knee and
resists rotational forces on the knee. |
To palpate the medial collateral ligament of the knee, palpate the femoral and tibial condyles with the knee flexed to identify the joint line. Return the lower leg to knee extension. Identify the medial condyle of the femur proximal to the joint line and the condyle of the tibia below the joint line. Partially flex the knee to move away the pes anserinus (see below). Place your fingers in the middle of the joint line and glide them in an anterior-posterior direction to palpate the rubbery structure of the MCL. |
Lateral collateral ligament (LCL) | Lateral epicondyle of the femur | Fibular head | Resists varus stresses or forces directed from the medial side of the knee and
resists rotational forces on the knee. |
To palpate the lateral collateral ligament of the knee, identify the joint line between the tibia and the femur. The lateral femoral condyle is proximal to the joint line. With your patient in knee flexion, place your fingers in the middle of the joint line and glide your fingers in an anterior-posterior direction. The rubbery band under your fingers is the LCL. |
Oblique popliteal ligaments | There is inconsistent information in the literature about these ligaments:[6][7][8]
Primary origin: Lateral expansion of the semimembranosus tendon Capsular arm of the posterior oblique ligament The posterior surface of the posteromedial tibial plateau Blending with fibres from the semimembranosus tendon Secondary medial origin: Posteromedial part of the capsule |
Fabella (if present)
Tendon of the lateral head of the gastrocnemius at the lateral femoral condyle Knee joint capsule at the medial border of the lateral femoral condyle[7][8] |
Prevents knee hyperextension;
Prevents excessive external rotation. |
Knee Passive Range of Motion[edit | edit source]
Knee passive range of motion refers to how far the knee can be moved by an external force (e.g. another person) when the leg muscles are relaxed.
- To assess passive knee flexion:
- The patient is in supine lying.
- Flex the patient’s leg to 90° at the hip and maintain this position by holding the distal femur with one hand.
- With your other hand holding onto the distal tibia, bring the knee into maximum flexion.
- There is typically a soft end feel (from the soft tissue structures of the calf/posterior thigh), so range of motion varies depending on the size of the patient's leg. The normal range for passive knee flexion is up to 150o.
- To assess passive knee extension:
- The patient is in supine lying.
- One of your hands holds the patient's distal femur.
- Your second hand holds onto the medial side of the patient's distal tibia - this allows for the “screw-home” mechanism at terminal knee extension.
- Bring the knee into passive extension.
- The normal range for passive knee extension is up to 10o hyperextension.
- To assess passive external and internal rotation of the knee:
- Position the patient in a supine position with their knee in 30-90 degrees of passive flexion.
- Fixate the knee in this position with one hand.
- With your other hand, hold the patient's foot and position it in dorsiflexion.
- Move the tibia into internal rotation and external rotation.
- Rotatory motion of the knee joint decreases with increased knee extension range of motion:[9]
- At 30-90 degrees of passive flexion, there will typically be approximately 45 degrees of external rotation.
- At 5 degrees of passive flexion, there will typically be approximately 23 degrees of external and 10 degrees of internal rotation.
Muscles of the Knee[edit | edit source]
The knee muscles are located in the three compartments of the thigh and the posterior compartment of the leg. Pes anserinus is a point of insertion for the tendons of the semitendinosus, gracilis and sartorius muscles at the medial knee. The pes anserine bursa is located between the pes anserine tendons and the semimembranosus tendon. It can become inflamed, which results in pain on the inside of the knee.[10]
The following sections only include muscles that are relevant to the knee joint. Other muscles in these compartments that do not act on the knee are not included (e.g. soleus in the posterior compartment of the leg).
Anterior Compartment of the Thigh[edit | edit source]
The majority of the muscles located in the anterior compartment of the thigh are knee extensors (i.e. quadriceps femoris), except for sartorius which is a knee flexor.
Muscle | Origin | Insertion | Innervation | Action |
---|---|---|---|---|
Quadriceps femoris:
Vastus lateralis(VL) Vastus intermedius (VIM) Vastus medialis (VM) Rectus femoris (RF) |
VL: greater trochanter and the lateral lip of linea aspera of the femur
VIM: the anterior and lateral surfaces of the femoral shaft VM: intertrochanteric line and medial lip of the linea aspera of the femur RF: anterior inferior iliac spine and the ilium of the pelvis |
Patella via the quadriceps femoris tendon | Femoral nerve | VL: extends the knee joint and maintains thigh and patella position while walking and running
VIM: extends the knee joint and stabilises the patella VM: extends the knee joint and contributes to correct patella tracking RF: extends the knee and flexes the hip |
Sartorius | Anterior superior iliac spine (ASIS) | Proximal end of the tibia below medial condyle (via pes anserinus) | Femoral nerve (L2-L3) | Hip flexion, abduction, and external rotation
Knee flexion and internal rotation |
Medial Compartment of the Thigh[edit | edit source]
The medial compartment of the thigh contains the hip adductors. The only muscle in this compartment that acts on both the hip and the knee is gracilis.
Muscle | Origin | Insertion | Innervation | Action |
---|---|---|---|---|
Gracilis | Inferior rami of the pubis and the body of the pubis | The medial surface of the tibial shaft | Obturator nerve (L2-L4) | Assists with hip adduction, knee flexion, and knee internal rotation |
Posterior Compartment of the Thigh[edit | edit source]
The hamstrings are located in the posterior compartment of the thigh. Their role is to extend the hip and flex the knee. The hamstrings consists of four muscles: biceps femoris, semitendinosus and semimembranosus.
Muscle | Origin | Insertion | Innervation | Action |
---|---|---|---|---|
Biceps femoris | Long head: the ischial tuberosity of the pelvis.
Short head: the linea aspera on the posterior surface of the femur. |
Head of the fibula | Long head: the tibial part of the sciatic nerve.
Short head: the common fibular part of the sciatic nerve. |
Main action: knee flexion. In addition: the muscle extends the thigh at the hip and laterally rotates at the hip and knee. |
Semitendinosus | Ischial tuberosity of the pelvis. | Medial surface of the tibia | Tibial part of the sciatic nerve | Knee flexion
Hip extension Hip and knee medial rotation |
Semimembranosus | Ischial tuberosity, superior to the semitendinosus and biceps femoris. | Medial tibial condyle | Tibial part of the sciatic nerve | Knee flexion
Hip extension Hip and knee medial rotation |
Posterior Compartment of the Leg[edit | edit source]
The posterior compartment of the leg is divided into superficial and deep compartments. The superficial compartment contains gastrocnemius and plantaris. Popliteus is located in the deep compartment of the leg.
Muscle | Origin | Insertion | Innervation | Action |
---|---|---|---|---|
Gastrocnemius | Lateral head: lateral femoral condyle.
Medial head: medial femoral condyle. |
Distally, gastrocnemius and soleus form the Achilles (calcaneal) tendon, which inserts into the calcaneus | Tibial nerve | Ankle plantarflexion
Knee flexion |
Plantaris | Lateral supracondylar line of the femur. | Calcaneus | Tibial nerve | Contributes to ankle plantarflexion and knee flexion |
Popliteus | Lateral condyle of the femur and the lateral meniscus of the knee joint. | Proximal tibia, immediately above the origin of the soleus muscle | Tibial nerve | Lateral rotation of the femur relative to the tibia to unlock the knee and allow for knee flexion |
Innervation of the Knee[edit | edit source]
The knee joint is innervated by the femoral nerve, the tibial and common fibular nerves, and the posterior division of the obturator nerve. The femoral nerve innervates the anterior compartment of the thigh, the sciatic nerve innervates the posterior compartment, the obturator nerve innervates the medial compartment of the thigh, and the tibial nerve innervates the posterior compartment of the leg.
Nerve | Origin | Branches | Motor Fibres | Sensory Fibres |
---|---|---|---|---|
Femoral nerve | Lumbar plexus L2-L4 | The anterior (superficial) femoral nerve
The posterior (deep) femoral nerve, which becomes the saphenous nerve |
Sartorius, quadriceps femoris, pectineus, iliacus | The saphenous nerve is the cutaneous branch of the femoral nerve providing sensory innervation along the anteromedial and posteromedial aspects of the leg into the medial foot |
Obturator nerve [11] | Lumbar plexus on the posterior abdominal wall (L2-L4) | Anterior and posterior branch | Anterior branch: Adductor longus, gracilis, and adductor brevis. Some motor fibres to the pectineus muscle
Posterior branch: obturator externus, adductor brevis, part of the adductor magnus muscle |
Skin on the medial thigh |
Sciatic nerve | Nerve roots L4-S3 | Two individual nerves are bundled together in the same connective tissue sheath – the tibial and common fibular nerves. These usually separate at the apex of the popliteal fossa | Biceps femoris, semimembranosus and semitendinosus | No direct sensory functions.
But it indirectly provides sensory feedback to the skin of the lateral leg, heel, and both the dorsal and plantar surfaces of the foot via its terminal branches |
Tibial nerve | Nerve roots L4-S3 | Lateral and medial motor branches
Sural nerve Medial calcaneal branches Medial plantar nerve Lateral plantar nerve |
Gastrocnemius, soleus, plantaris, popliteus, tibialis posterior, flexor digitorum longus and flexor hallucis longus | Innervates the skin of the posterolateral leg, lateral foot and the sole of the foot |
Vascular Supply of the Knee[edit | edit source]
The descending branch of the lateral femoral circumflex artery, the popliteal artery, and the anterior tibial artery are the main arteries supplying the knee joint region.[12][13]
Artery | Origin | Branches | Supply[12] |
---|---|---|---|
Femoral artery | External iliac artery | Descending genicular artery:
Saphenous branch Muscular branch Osteoarticular branch Superior lateral (SLGA) and medial (SMGA) genicular arteries |
Anterior compartment of the thigh
SLGA: Lateral femoral condyle The lateral head of the gastrocnemius muscle The vastus lateralis muscle The biceps femoris muscle SMGA: Cruciate ligaments and synovial tissue Sole nutrition to the medial femoral condyle |
Popliteal artery | Femoral artery | Inferior lateral (ILGA) and medial (IMGA) genicular arteries |
ILGA: The skin around the biceps femoris and the lateral border of the quadriceps tendon IMGA: Cutaneous branches to the lateral border of the sartorius muscle and at the medial border of the quadriceps tendon |
Tibial artery | Popliteal artery | Anterior (ATRA) and posterior (PTRA) recurrent arteries | Superior tibiofibular joint |
Clinical Relevance[edit | edit source]
- The collateral ligaments of the knee are commonly injured. These injuries often occur when the foot is planted and a force is applied to the side of the knee. You can learn more about this condition here.
- Anterior cruciate ligament (ACL) injury can occur when the knee joint is hyperextended or when a force is applied to the back of a partly flexed knee. For more information on ACL rehabilitation, please see this programme.
- Prepatellar bursitis (also known as housemaid’s knee) involves the prepatellar bursa.[14] Signs of prepatella bursitis include inflammation and anterior knee swelling.
- The menisci are also commonly injured.[10]
- A “high-riding” patella (patella alta) has been associated with patellofemoral pain, patellar instability, patellofemoral cartilage lesions, and patellofemoral osteoarthritis.[15]
- Patella baja (or patella infera) refers to an atypically "low-lying patella that remains distal in relation to the femoral trochlea", which affects patellofemoral tracking.[16]
- Tibial torsion that continues into adulthood is associated with patellofemoral pathology.[17] For a comprehensive discussion of patellofemoral pathology, please see this programme.
Resources[edit | edit source]
- Qazi E, Wilting J, Patel NR, Alenezi AO, Kennedy SA, Tan KT, Jaberi A, Mafeld S. Arteries of the lower limb—Embryology, variations, and clinical significance. Canadian Association of Radiologists Journal. 2022 Feb;73(1):259-70.
- Dasari SP, Kerzner B, Fortier LM, Gursoy S, Chahla J. Key Surgically Relevant Anatomy of the Medial and Lateral Aspects of the Knee. Operative Techniques in Sports Medicine. 2022 Mar 15:150908.
References[edit | edit source]
- ↑ Lim W. Clinical Application and Limitations of the Capsular Pattern. Phys. Ther. Korea 2021; 28(1): 13-17
- ↑ Neumann DA, Kinesiology of the musculoskeletal system: Foundations for rehabilitation. 2nd ed. St. Louis, MO: Mosby Elsevier, 2010. p520-71.
- ↑ Neumann DA, Knee. In: Neumann DA, editor. Kinesiology of the musculoskeletal system: Foundations for rehabilitation. 2nd ed. St. Louis, MO: Mosby Elsevier, 2010. p520-71.
- ↑ Rohatgi R, Bhatnagar A, Gupta N, Jain M. The study of variation of range of motion of knee joint with body mass index in normal, overweight and obese young adults. Panacea J Med Sci 2022;12(3):657-661.
- ↑ de Coninck S. What is a capsular pattern? Available from https://cyriax.eu/orthopaedic-medicine-knowledge-bank/definitions-in-orthopaedic-medicine/what-is-a-capsular-pattern/ [last access 25.04.2023]
- ↑ LaPrade RF, Morgan PM, Wentorf FA, Johansen S, Engebretsen L. The anatomy of the posterior aspect of the knee. An anatomic study. J Bone Joint Surg Am. 2007 Apr;89(4):758-64.
- ↑ 7.0 7.1 Hedderwick, M. The Anatomy of the Oblique Popliteal Ligament (Thesis, Master of Science). University of Otago, 2012. Available from https://ourarchive.otago.ac.nz/handle/10523/2359 [last access 28.04.2023]
- ↑ 8.0 8.1 Wu XD, Yu JH, Zou T, Wang W, LaPrade RF, Huang W, Sun SQ. Anatomical Characteristics and Biomechanical Properties of the Oblique Popliteal Ligament. Sci Rep. 2017 Feb 16;7:42698.
- ↑ Zarins B, Rowe CR, Harris BA, Watkins MP. Rotational motion of the knee. Am J Sports Med. 1983 May-Jun;11(3):152-6.
- ↑ 10.0 10.1 Xuan D. Exploring anatomy of the knee. Plus Course 2023
- ↑ Chang MC, Choi KT, Cho HK, Man Kim Y, Kim TU. Obturator nerve injury diagnosed by nerve conduction: a case report. Ann Palliat Med. 2021 Jun;10(6):7069-7072.
- ↑ 12.0 12.1 Hirtler L, Lübbers A, Rath C. Vascular coverage of the anterior knee region - an anatomical study. J Anat. 2019 Aug;235(2):289-298.
- ↑ Qazi E, Wilting J, Patel NR, Alenezi AO, Kennedy SA, Tan KT, Jaberi A, Mafeld S. Arteries of the lower limb—Embryology, variations, and clinical significance. Canadian Association of Radiologists Journal. 2022 Feb;73(1):259-70.
- ↑ Rishor-Olney CR, Pozun A. Prepatellar Bursitis. [Updated 2022 Sep 6]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from https://www.ncbi.nlm.nih.gov/books/NBK557508/ [last access 25.04.2023]
- ↑ Wheatley MGA, Rainbow MJ, Clouthier AL. Patellofemoral Mechanics: a Review of Pathomechanics and Research Approaches. Curr Rev Musculoskelet Med. 2020 Jun;13(3):326-337.
- ↑ Perelli S, Ibañez M, Morales-Marin C, Acuña-Avila G, Espinoza-von Bischhoffshausen R, Masferrer-Pino A, Monllau JC. Patellar Tendon Lengthening: Rescue Procedure for Patella Baja. Arthroscopy Techniques 2020, 9(1):pages e1-e8.
- ↑ Snow M. Tibial Torsion and Patellofemoral Pain and Instability in the Adult Population: Current Concept Review. Curr Rev Musculoskelet Med. 2021 Feb;14(1):67-75.