Knee joint

Knee joint Knee joint

The knee joint is a modified hinge joint between the femur, tibia, and patella. It is the largest synovial joint in the body and allows flexion and extension of the leg as well as some rotation in the flexed position.
The knee is the femur 、 Between tibia and patella , An improved Flexion joint ^[1]. It is the largest synovial joint in the body , Allow the legs to bend and stretch , And some rotation in the bending position .

Summary The main points of

• location: two condylar joints between femur and tibia; saddle joint between patella and femur
  Location ： The two condylar joints between the femur and tibia ; The saddle joint between the patella and femur
• blood supply: main supply are the genicular branches of the popliteal artery
  Blood supply ： The main blood supply is the knee branch of popliteal artery
• nerve supply: branches from the femoral, tibial, common peroneal, and obturator nerves
  Nerve distribution ： Femoral nerve 、 Tibial nerve 、 Branches of the common peroneal nerve and obturator nerve
• movement: flexion to 150°, extension to 5-10° hyperextension; rotation whilst in the flexed position to 10° actively and 60° passively
  motion ： Buckle to 150°, Stretch to 5-10° Hyperextension ; When in the bending position , Positive rotation to 10°, Negative rotation to 60°.

Gross anatomy Gross anatomy

Articulations The joints

There are two condylar joints between the femur and tibia (tibiofemoral). There are medial and lateral articular facets on the tibial plateau and medial and lateral femoral condyles on the distal femur with are convex and circular shaped.
Femur and tibia （ Tibia and femur ） There are two condylar joints between them . There are medial and lateral articular surfaces on the tibial plateau , The medial and lateral condyles of the distal femur are convex and round .

medially: between a narrow and curved femoral condyle, and an oval tibial articular surface with a long anteroposterior length laterally: between a wide and flat femoral condyle; and a circular tibial articular surface which overhangs the shaft posterolaterally the knee menisci are shaped accordingly Saddle joint between the patella and femoral condyles:
inside ： Between the narrow and curved femoral condyle and the long oval tibial articular surface ; outside ： Between the broad and flat femoral condyles ; And a round articular surface of the tibia , The articular surface protrudes posterolateral to the meniscus of the knee joint , Therefore, a saddle joint is formed between the patella and the femoral condyle ：

medial, lateral and odd facet on the posterior surface of the patella articulate with the medial and lateral condyles of the femur on flexion, more parts of the bony surface are exposed to articulation (four below, odd facet) and are more proximal on the patella with extension, the contact area lessens and moves distally
The medial side of the posterior surface of the patella 、 The lateral and odd articular surfaces are connected to the medial and lateral condyles of the femoral flexion , More bone surfaces are partially exposed to joints （ The next four , Odd articular surface ）, And more proximal to the patella , As you stretch , The contact area decreases and moves to the far side

Menisci Meniscus

• fibrocartilaginous, C-shaped in appearance and triangular in cross-section
• the medial meniscus is attached to the medial collateral ligament and the lateral meniscus is attached to the popliteus tendon
• attached to the femur and tibia via the coronary ligaments

Joint capsule Joint capsule

• knee capsule

  • on the femur

    • adheres below the epiphyseal line down to the articular margin except in two places

      • posteriorly attached to the intercondylar ridge at the lower limit of the popliteal surface
      • on the lateral condyle it encloses a pit and groove for the popliteus tendon
  • on the tibia

    • attached around the margins of the tibial plateau except in two places

      • posteriorly to the ridge between the two condyles at the lower end of the groove for the PCL
      • laterally the capsule is not attached to the tibia but is prolonged down over the popliteus tendon
  • two main gaps

    • one allowing the popliteus to enter
    • one communicating with suprapatellar bursa

Synovial membrane Synovium

• joint capsule is lined by synovial membrane, however, the attachment of the synovial membrane does not coincide with the capsular attachments because of the intra-articular structures
• the cruciate ligament and popliteus tendon are extrasynovial but intracapsular
• communicates with the suprapatellar bursa

Fat pads Fat pad

There are three anterior fat pads:

• infrapatellar fat pad (of Hoffa)
• posterior suprapatellar (prefemoral or supratrochlear) fat pad
• anterior suprapatellar (quadriceps) fat pad

Attachments The attachment

• intracapsular ligaments

  • anterior intermeniscal ligament

    • connect the anterior limbs of the two menisci
  • anterior (Humphrey) and posterior (Wrisberg) meniscofemoral ligaments:

    • the lateral meniscus is attached to the medial femoral condyle via the anterior and posterior meniscofemoral ligament of Humphrey and Wrisberg
  • cruciate ligaments: cross each other to form an "x" shape.

    • anterior cruciate ligament: from the anterior tibial plateau to the lateral femoral condyle
    • posterior cruciate ligament: from the posterior intercondylar area to the medial femoral condyle
• extracapsular ligaments

  • patellar retinacular ligaments: medial and lateral portions of the quadriceps tendon pass down on either side of the patella and are inserted into the upper extremity of the tibia on either side of the tuberosity, merging into the capsule
  • medial collateral ligament

    • from the medial epicondyle to the medial surface of the tibia, which it is separated from by the passage of the inferior medial genicular arteries
    • attached to the medial meniscus
    • flat band like approximately 12 cm long
    • has superficial and deep parts (thickening of the capsule)
  • lateral collateral ligament

    • from the lateral epicondyle to the fibular head
    • not attached to the lateral meniscus
    • thin cord like, approximately 5 cm long
    • separated from the tibia within the joint by the popliteus tendon and outside the joint by the inferior lateral genicular artery
  • oblique popliteal ligament

    • tendinous expansion of the semimembranosus muscle terminating on the popliteal surface of the femur
    • perforated by the middle genicular artery
  • arcuate popliteal ligament

    • thickened part of the joint capsule that arches over the popliteus tendon as it emerges from the joint capsule and attached to the styloid process of the fibular head
  • popliteofibular ligament

    • extends from the popliteus tendon near the myotendinous junction to the posterior aspect of the fibular styloid process, posteromedial to the biceps insertion
  • patella ligament

    • from the apex of the patella to the tibial tuberosity
• other

  • anterolateral ligament
  • posterolateral ligamentous complex
• tendons

  • popliteal tendon
• knee menisci
• knee capsule
• knee synovial membrane

Bursa Bursa Fabricius

• suprapatellar - superior extension of - the knee joint cavity
• prepatellar - communicates with the joint cavity, between the lower half of the patella and skin
• subcutaneous infrapatellar - between the patella ligament and skin
• deep infrapatellar - between the tibia and patella tendon
• posterior (between muscle and bone)

  • popliteal - communicates with the joint cavity, beneath the tendon of popliteus lying in the gutter between tibia and head of fibula
  • gastrocnemius

    • bursa beneath the medial head (and usually the lateral head) communicates with the joint cavity
  • semimembranosus - may communicate with the bursa beneath the medial head of the gastrocnemius

Relations contact

• knee bursae
• anterior knee fat pads

Blood supply Blood supply

The knee is supplied by anastomoses of:

• five genicular branches of the popliteal artery (main supply)

  • medial and lateral superior genicular arteries encircle the femoral condyle
  • medial and lateral inferior genicular arteries encircle the tibial condyle
  • middle genicular artery supplies the anterior and posterior cruciate ligaments
• descending branch of the lateral circumflex femoral artery
• descending genicular branch of the femoral artery
• circumflex fibular branches of the posterior tibial artery
• anterior and posterior recurrent branches of the anterior tibial artery

Innervation

Multiple articular branches are derived from several nerves (Hilton's law):

• branches of the femoral nerve to vastus medialis, and also intermedius and lateralis
• from the sciatic nerve by genicular branches of the tibial and common peroneal nerves
• from the obturator nerve by a branch from the posterior division

Movements

• flexion

  • semimembranosus, semitendinosus, biceps femoris, gracilis, sartorius
  • also gastrocnemius, plantaris and popliteus
• extension

  • quadriceps femoris, iliotibial tract
  • also gluteus maximus, tensor fascia latae
• internal rotation (when flexed)

  • semimembranosus, semitendinosus, gracilis, sartorius
• external rotation (when flexed)

  • biceps femoris
• unlocking

  • popliteus externally rotates femur on tibia, locked ligaments loosen, hamstrings can then flex free
• locking

  • as the knee moves into full extension, the anterior cruciate ligament becomes taut, with no further extension of the lateral condyle possible
  • passive rotation forwards of the lateral condyle around the radius of the taut anterior cruciate ligament
  • medial femoral condyle is then able to glide backwards into full extension
  • tightening of the oblique popliteal, lateral collateral and medial collateral ligaments
  • purely passive due to the skew pull of the obliquely set ligaments
  • Radiographic features
  • Plain radiograph
  • See knee radiograph (an approach)

Radiographic features

Plain radiograph

See knee radiograph (an approach)

Related pathology

• absent patella

• ACL ganglion cyst

• ACL mucoid degeneration

• anterior tibial translocation sign

• arcuate sign

• avulsion fractures of the knee

• bipartite patella

• chondromalacia patellae

• contrecoup injury of the knee

• jumper's knee

• meniscal cyst

• Osgood-Schlatter disease

• patella alta

• patella baja

• patellar instability

• patella fracture

• patellar sleeve fractures

• patellar tendon lateral femoral condyle friction syndrome

• patella tendon rupture

• patellar tooth sign

• pes anserinus bursitis

• reverse Segond fracture

• Segond fracture

• semimembranosus tendon avulsion fracture

• Sinding-Larsen-Johansson syndrome

• Stieda fracture (MCL avulsion fracture)

• tibial plateau fracture

• tibial pseudoarthrosis

• tibial tuberosity avulsion fracture

Cases and figures

References

1. Last's Anatomy. Churchill Livingstone. (2011) ISBN:0702033944. Read it at Google Books - Find it at Amazon

2. Butler P, Mitchell A, Healy JC. Applied Radiological Anatomy. Cambridge University Press. (2012) ISBN:0521766664. Read it at Google Books - Find it at Amazon

3. Moore KL, Agur AMR, Dalley AF. Clinically oriented anatomy. LWW. ISBN:1451119453. Read it at Google Books - Find it at Amazon

Reference material

[1]

Flexor amyl joint : HingeJoint  Flexor amyl joint   Like the hinge of a door , For example, the connection between humerus and ulna --Osmosis chinese