Posterior cruciate ligament

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Posterior cruciate ligament
Diagram of the knee
Details
Fromantero-lateral aspect of medial femoral condyle
Toposterolateral aspect of proximal tibia
Identifiers
Latinligamentum cruciatum posterius genus
MeSHD016119
TA98A03.6.08.008
TA21891
FMA44617
Anatomical terminology

The posterior cruciate ligament (PCL) is a

posterior intercondylar area of the tibia to the medial condyle of the femur
. This configuration allows the PCL to resist forces pushing the tibia posteriorly relative to the femur.

The PCL and ACL are intracapsular ligaments because they lie deep within the knee joint. They are both isolated from the fluid-filled synovial cavity, with the synovial membrane wrapped around them. The PCL gets its name by attaching to the posterior portion of the tibia.[1]

The PCL, ACL, MCL, and LCL are the four main ligaments of the knee in primates.

Structure

The PCL is located within the

femoral condyle and the roof of the intercondyle notch[2] then stretches, at a posterior and lateral angle, toward the posterior of the tibia just below its articular surface.[3][4][5][6]

In this medial view of the extended knee, the lateral femoral condyle has been removed to reveal the structure of the PCL. Because the posteromedial bundle is stretched and the anterolateral bundle relaxed during extension, excessive extension in the form of hyperextension causes tensile stress, shown in red, on the posteromedial bundle of the PCL that leads to PCL injury.

Function

Although each PCL is a unified unit, they are described as separate anterolateral and posteromedial sections based on where each section's attachment site and function.

knee extension and the posteromedial bundle stretches in extension rather than flexion.[4][9]

The function of the PCL is to prevent the femur from sliding off the anterior edge of the tibia and to prevent the tibia from displacing posterior to the femur. The posterior cruciate ligament is located within the knee.

Ligaments are sturdy bands of tissues that connect bones. Similar to the anterior cruciate ligament, the PCL connects the femur to the tibia.[citation needed
]

Clinical significance

Main article: Posterior cruciate ligament injury

Common causes of injuries are direct blows to the flexed knee, such as the knee hitting the dashboard in a car accident or falling hard on the knee, both instances displacing the tibia posterior to the femur.[10]

An additional test of posterior cruciate ligament injury is the posterior sag test, where, in contrast to the drawer test, no active force is applied. Rather, the person lies supine with the leg held by another person so that the hip is flexed to 90 degrees and the knee 90 degrees.

posterolateral injuries
and collateral ligament injuries.

There are four different grades of classification in which medical doctors classify a PCL injury:

Grade I, the PCL has a slight tear.
Grade II, the PCL ligament is minimally torn and becomes loose.
Grade III, the PCL is torn completely and the knee can now be categorized as unstable.
Grade IV, the ligament is damaged along with another ligament housed in the knee (i.e. ACL).

With these grades of PCL injuries, there are different treatments available for such injuries.[citation needed]

The posterior cruciate ligament is located within the knee

Mechanism

In this medial view of the flexed knee, the lateral femoral condyle has been removed to reveal the structure of the PCL. Because the anterolateral bundle is stretched and the posteromedial bundle relaxed during flexion, excessive flexion in the form of hyperflexion causes tensile stress, shown in red, on the anterolateral bundle of the ACL that leads to ACL injury.

In this position, the PCL functions to prevent movement of the tibia in the posterior direction

adduction of the tibia, which is referred to as varus-extension stress,[7] or that occur while the knee is flexed.[15]

Treatment

It is possible for the PCL to heal on its own. Even if the PCL does not heal normally, it is unusual for surgery to be required. Treatment is usually physiotherapy to strengthen the muscles around the knee; usually they provide adequate stability even without a functional PCL. Only if there are ongoing symptoms down the track, or if there are other injuries in the knee (e.g. posterolateral corner injury) will ligament reconstruction be required.[18] Ligament reconstruction is used to replace the torn PCL with a new ligament, which is usually a graft taken from the hamstring or Achilles tendon from a host cadaver. An arthroscope allows a complete evaluation of the entire knee joint, including the knee cap (patella), the cartilage surfaces, the meniscus, the ligaments (ACL & PCL), and the joint lining. Then, the new ligament is attached to the bone of the thigh and lower leg with screws to hold it in place.[19] Surgery to repair the posterior cruciate ligament is controversial due to its placement and technical difficulty.[20]

It is possible for the PCL to heal on its own without surgery when it is a Grade I or Grade II injury. PCL injuries that are diagnosed in these categories can have their recovery times reduced by performing certain rehabilitative exercises. Fernandez and Pugh(2012) found that following a PCL grade II diagnosis, a

Grafts is the method when addressing PCL injuries that are in need of operative surgery. With grafts, there are different methods such as the tibial inlay or tunnel method.[22]

Other animals

In the

quadruped stifle (analogous to the human knee), based on its anatomical position, it is referred to as the caudal cruciate ligament.[23]

Additional images

  • Head of right tibia seen from above, showing menisci and attachments of ligaments.
    Head of right tibia seen from above, showing menisci and attachments of ligaments.
  • Capsule of right knee-joint (distended). Posterior aspect.
    Capsule of right knee-joint (distended). Posterior aspect.
  • Magnetic resonance imaging evaluation demonstrating normal signal of both anterior and posterior cruciate ligaments (arrows).
    Magnetic resonance imaging evaluation demonstrating normal signal of both anterior and posterior cruciate ligaments (arrows).
  • Anterior view of knee.
    Anterior view of knee.
  • Knee joint. Deep dissection. Anterior view
    Knee joint. Deep dissection. Anterior view

References

  1. ^ Saladin, K. S. 2010. Anatomy & Physiology: 5th edition. McGraw-Hill[page needed]
  2. S2CID 15246937
    .
  3. PMID 1126079
    .
  4. ^
    PMID 23022245
    .
  5. PMID 17349472
    .
  6. ^
    S2CID 3524402
    .
  7. ^
    PMID 16360655
    .
  8. S2CID 42810072
    .
  9. PMID 8106532
    .
  10. ^ MedlinePlus Encyclopedia: Posterior cruciate ligament (PCL) injury
  11. ^ Posterior Sag Test From The University of West Alabama, Athletic Training & Sports Medicine Center. Retrieved Feb 2011
  12. ISBN 0-7216-0013-1
    .
  13. S2CID 24386922
    .
  14. PMID 23181354
    .
  15. ^
    S2CID 23746497
    .
  16. ISBN 978-0-7817-9128-1
    .
  17. ISBN 978-0-7817-9128-1
    .
  18. ^ American Academy of Orthopedic Surgeons. "Posterior Cruciate Ligament Injuries". OrthoInfo. American Academy of Orthopedic Surgeons. Retrieved 7 May 2019.
  19. ^ http://www.orthspec.com/pdfs/PCL-injuries.pdf[full citation needed]
  20. ^ Jonathan Cluett, M.D. (2003-08-05). "Injuries to the posterior cruciate ligament (PCL)". about.com. Retrieved 2006-11-11.
  21. PMID 23204951
    .
  22. S2CID 22150465
    .
  23. ISBN 978-0-7020-2788-8
    . Retrieved September 8, 2009.

External links
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