Posterior cruciate ligament

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Posterior cruciate ligament
Knee diagram.svg
Diagram of the knee
Details
FromAntero-lateral aspect of medial femoral condyle
ToPosterolateral aspect of proximal tibia
Identifiers
Latin ligamentum cruciatum posterius genus
MeSH D016119
TA98 A03.6.08.008
TA2 1891
FMA 44617
Anatomical terminology

The posterior cruciate ligament (PCL) is a ligament in each knee of humans and various other animals. It works as a counterpart to the anterior cruciate ligament (ACL). It connects the 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.

Contents

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 knee joint where it stabilizes the articulating bones, particularly the femur and the tibia, during movement. It originates from the lateral edge of the medial 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. PCL Extension and Hyperextension.png
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. [7] During knee joint movement, the PCL rotates [6] [8] such that the anterolateral section stretches in knee flexion but not in 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

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. [11] The main parameter in this test is step-off, which is the shortest distance from the femur to a hypothetical line that tangents the surface of the tibia from the tibial tuberosity and upwards. Normally, the step-off is approximately 1 cm, but is decreased (Grade I) or even absent (Grade II) or inverse (Grade III) in injuries to the posterior cruciate ligament. [12] The posterior drawer test is one of the tests used by doctors and physiotherapists to detect injury to the PCL. Patients who are suspected to have a posterior cruciate ligament injury should always be evaluated for other knee injuries that often occur in combination with an PCL injuries. These include cartilage/meniscus injuries, bone bruises, ACL tears, fractures, 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 Gray348-2.png
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. PCL Flexion and Hyperflexion.png
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 [4] [13] and to prevent the tilting or shifting of the patella. [14] However, the respective laxity of the two sections makes the PCL susceptible to injury during hyperflexion, hyperextension, [15] and in a mechanism known as a dashboard injury. [6] Because ligaments are viscoelastic [16] ) they can handle higher amounts of stress only when the load is increased slowly. [17] When hyperflexion and hyperextension occur suddenly in combination with this viscoelastic behavior, the PCL deforms or tears. [15] In the third and most common mechanism, the dashboard injury mechanism, the knee experiences impact in a posterior direction during knee flexion toward the space above the tibia. [7] [15] These mechanisms occur in excessive external tibial rotation and during falls that induce a combination of extension and 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 multimodal treatment that spanned the course of 8 weeks consisting of chiropractic lumbopelvic manipulation, physiotherapy, and implementing an exercise program that emphasized eccentric muscle contraction (lunges, 1-leg squats, and trunk stabilization proved to be an effective way to recover from the PCL injury. [21] For Grades III and IV, operative surgery is recommended or is usually needed. 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

Related Research Articles

<span class="mw-page-title-main">Knee</span> Leg joint in primates

In humans and other primates, the knee joins the thigh with the leg and consists of two joints: one between the femur and tibia, and one between the femur and patella. It is the largest joint in the human body. The knee is a modified hinge joint, which permits flexion and extension as well as slight internal and external rotation. The knee is vulnerable to injury and to the development of osteoarthritis.

<span class="mw-page-title-main">Hamstring</span> Any of the three muscles in the thigh

In human anatomy, a hamstring is any one of the three posterior thigh muscles between the hip and the knee.

<span class="mw-page-title-main">Anterior cruciate ligament</span> Type of cruciate ligament in the human knee

The anterior cruciate ligament (ACL) is one of a pair of cruciate ligaments in the human knee. The two ligaments are called "cruciform" ligaments, as they are arranged in a crossed formation. In the quadruped stifle joint, based on its anatomical position, it is also referred to as the cranial cruciate ligament. The term cruciate is Latin for cross. This name is fitting because the ACL crosses the posterior cruciate ligament to form an "X". It is composed of strong, fibrous material and assists in controlling excessive motion by limiting mobility of the joint. The anterior cruciate ligament is one of the four main ligaments of the knee, providing 85% of the restraining force to anterior tibial displacement at 30 and 90° of knee flexion. The ACL is the most frequently injured ligament in the knee.

<span class="mw-page-title-main">Lachman test</span> Clinical test to diagnose injury to ligaments

The Lachman test is a clinical test used to diagnose injury of the anterior cruciate ligament (ACL). It is recognized as reliable, sensitive, and usually superior to the anterior drawer test.

<span class="mw-page-title-main">Popliteal artery</span> Continuation of the femoral artery that supplies the lower leg

The popliteal artery is a deeply placed continuation of the femoral artery opening in the distal portion of the adductor magnus muscle. It courses through the popliteal fossa and ends at the lower border of the popliteus muscle, where it branches into the anterior and posterior tibial arteries.

<span class="mw-page-title-main">Segond fracture</span> Avulsion fracture of the lateral tibial condyle of the knee

The Segond fracture is a type of avulsion fracture from the lateral tibial plateau of the knee, immediately below the articular surface of the tibia.

The drawer test is used in the initial clinical assessment of suspected rupture of the cruciate ligaments in the knee.

<span class="mw-page-title-main">Medial collateral ligament</span> Ligament on the inner side of the knee joint

The medial collateral ligament (MCL), also called the superficial medial collateral ligament (sMCL) or tibial collateral ligament (TCL), is one of the major ligaments of the knee. It is on the medial (inner) side of the knee joint and occurs in humans and other primates. Its primary function is to resist valgus forces on the knee.

<span class="mw-page-title-main">Popliteus muscle</span> Muscle responsible for unlocking the knees during walking

The popliteus muscle in the leg is used for unlocking the knees when walking, by laterally rotating the femur on the tibia during the closed chain portion of the gait cycle. In open chain movements, the popliteus muscle medially rotates the tibia on the femur. It is also used when sitting down and standing up. It is the only muscle in the posterior (back) compartment of the lower leg that acts just on the knee and not on the ankle. The gastrocnemius muscle acts on both joints.

<span class="mw-page-title-main">Medial meniscus</span> Cartilage formation in the human knee

The medial meniscus is a fibrocartilage semicircular band that spans the knee joint medially, located between the medial condyle of the femur and the medial condyle of the tibia. It is also referred to as the internal semilunar fibrocartilage. The medial meniscus has more of a crescent shape while the lateral meniscus is more circular. The anterior aspects of both menisci are connected by the transverse ligament. It is a common site of injury, especially if the knee is twisted.

The knee examination, in medicine and physiotherapy, is performed as part of a physical examination, or when a patient presents with knee pain or a history that suggests a pathology of the knee joint.

<span class="mw-page-title-main">Cruciate ligament</span> Type of ligament shaped like an X

Cruciate ligaments are pairs of ligaments arranged like a letter X. They occur in several joints of the body, such as the knee joint, wrist joint and the atlanto-axial joint. In a fashion similar to the cords in a toy Jacob's ladder, the crossed ligaments stabilize the joint while allowing a very large range of motion.

<span class="mw-page-title-main">Anterior cruciate ligament injury</span> Ligament injury near the knee

An anterior cruciate ligament injury occurs when the anterior cruciate ligament (ACL) is either stretched, partially torn, or completely torn. The most common injury is a complete tear. Symptoms include pain, an audible cracking sound during injury, instability of the knee, and joint swelling. Swelling generally appears within a couple of hours. In approximately 50% of cases, other structures of the knee such as surrounding ligaments, cartilage, or meniscus are damaged.

<span class="mw-page-title-main">Patellar tendon</span> Tendon in the human knee

The patellar tendon is the distal portion of the common tendon of the quadriceps femoris, which is continued from the patella to the tibial tuberosity. It is also sometimes called the patellar ligament as it forms a bone to bone connection when the patella is fully ossified.

<span class="mw-page-title-main">Unhappy triad</span> Medical condition of the knee

The unhappy triad, also known as a blown knee among other names, is an injury to the anterior cruciate ligament, medial collateral ligament, and meniscus. Analysis during the 1990s indicated that this 'classic' O'Donoghue triad is actually an unusual clinical entity among athletes with knee injuries. Some authors mistakenly believe that in this type of injury, "combined anterior cruciate and medial collateral ligament disruptions that were incurred during athletic endeavors" always present with concomitant medial meniscus injury. However, the 1990 analysis showed that lateral meniscus tears are more common than medial meniscus tears in conjunction with sprains of the ACL.

Posterolateral corner injuries of the knee are injuries to a complex area formed by the interaction of multiple structures. Injuries to the posterolateral corner can be debilitating to the person and require recognition and treatment to avoid long term consequences. Injuries to the PLC often occur in combination with other ligamentous injuries to the knee; most commonly the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL). As with any injury, an understanding of the anatomy and functional interactions of the posterolateral corner is important to diagnosing and treating the injury.

<span class="mw-page-title-main">Tibial plateau fracture</span> Medical condition

A tibial plateau fracture is a break of the upper part of the tibia (shinbone) that involves the knee joint. This could involve the medial, lateral, central, or bicondylar. Symptoms include pain, swelling, and a decreased ability to move the knee. People are generally unable to walk. Complication may include injury to the artery or nerve, arthritis, and compartment syndrome.

<span class="mw-page-title-main">Medial knee injuries</span> Medical condition

Medial knee injuries are the most common type of knee injury. The medial ligament complex of the knee consists of:

The anterolateral ligament (ALL) is a ligament on the lateral aspect of the human knee, anterior to the fibular collateral ligament.

<span class="mw-page-title-main">Posterior cruciate ligament injury</span> Medical condition

The function of the posterior cruciate ligament (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. Common causes of PCL 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.

References

  1. ↑ Saladin, K. S. 2010. Anatomy & Physiology: 5th edition. McGraw-Hill[ page needed ]
  2. ↑ Amis, AA.; Gupte, CM.; Bull, AM.; Edwards, A. (Mar 2006). "Anatomy of the posterior cruciate ligament and the meniscofemoral ligaments". Knee Surg Sports Traumatol Arthrosc. 14 (3): 257–63. doi:10.1007/s00167-005-0686-x. PMID   16228178. S2CID   15246937.
  3. ↑ Girgis, FG.; Marshall, JL.; Monajem, A. (1975). "The cruciate ligaments of the knee joint. Anatomical, functional and experimental analysis". Clin Orthop Relat Res. 106 (106): 216–31. doi:10.1097/00003086-197501000-00033. PMID   1126079.
  4. 1 2 3 Chandrasekaran, S.; Ma, D.; Scarvell, JM.; Woods, KR.; Smith, PN. (Dec 2012). "A review of the anatomical, biomechanical and kinematic findings of posterior cruciate ligament injury with respect to non-operative management". Knee. 19 (6): 738–45. doi:10.1016/j.knee.2012.09.005. PMID   23022245.
  5. ↑ Edwards, A.; Bull, AM.; Amis, AA. (Mar 2007). "The attachments of the fiber bundles of the posterior cruciate ligament: an anatomic study". Arthroscopy. 23 (3): 284–90. doi:10.1016/j.arthro.2006.11.005. PMID   17349472.
  6. 1 2 3 Voos, JE.; Mauro, CS.; Wente, T.; Warren, RF.; Wickiewicz, TL. (Jan 2012). "Posterior cruciate ligament: anatomy, biomechanics, and outcomes". Am J Sports Med. 40 (1): 222–31. doi:10.1177/0363546511416316. PMID   21803977. S2CID   3524402.
  7. 1 2 3 Malone, AA.; Dowd, GS.; Saifuddin, A. (Jun 2006). "Injuries of the posterior cruciate ligament and posterolateral corner of the knee". Injury. 37 (6): 485–501. doi:10.1016/j.injury.2005.08.003. PMID   16360655.
  8. ↑ DeFrate, LE.; Gill, TJ.; Li, G. (Dec 2004). "In vivo function of the posterior cruciate ligament during weightbearing knee flexion". Am J Sports Med. 32 (8): 1923–8. doi:10.1177/0363546504264896. PMID   15572322. S2CID   42810072.
  9. ↑ Race, A.; Amis, AA. (Jan 1994). "The mechanical properties of the two bundles of the human posterior cruciate ligament". J Biomech. 27 (1): 13–24. doi:10.1016/0021-9290(94)90028-0. 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. ↑ Cole, Brian; Miller, Mark J. (2004). Textbook of arthroscopy . Philadelphia: Saunders. p.  719. ISBN   0-7216-0013-1.
  13. ↑ Castle, Thomas H; Noyes, Frank R; Grood, Edward S (1992). "Posterior Tibial Subluxation of the Posterior Cruciate-Deficient Knee". Clinical Orthopaedics and Related Research. 284 (284): 193–202. doi:10.1097/00003086-199211000-00027. PMID   1395293. S2CID   24386922.
  14. ↑ von Eisenhart-Rothe, Ruediger; Lenze, Ulrich; Hinterwimmer, Stefan; Pohlig, Florian; Graichen, Heiko; Stein, Thomas; Welsch, Frederic; Burgkart, Rainer (2012). "Tibiofemoral and patellofemoral joint 3D-kinematics in patients with posterior cruciate ligament deficiency compared to healthy volunteers". BMC Musculoskeletal Disorders. 13: 231. doi: 10.1186/1471-2474-13-231 . PMC   3517747 . PMID   23181354.
  15. 1 2 3 4 Janousek, Andreas T.; Jones, Deryk G.; Clatworthy, Mark; Higgins, Laurence D.; Fu, Freddie H. (1999). "Posterior Cruciate Ligament Injuries of the Knee Joint". Sports Medicine. 28 (6): 429–41. doi:10.2165/00007256-199928060-00005. PMID   10623985. S2CID   23746497.
  16. ↑ Hamill, Joseph; Knutzen, Kathleen (2009). Biomechanical basis of human movement. Philadelphia: Wolters Kluwer Health/Lippincott Williams and Wilkins. p. 50. ISBN   978-0-7817-9128-1.
  17. ↑ Hamill, Joseph; Knutzen, Kathleen (2009). Biomechanical basis of human movement. Philadelphia: Wolters Kluwer Health/Lippincott Williams and Wilkins. p. 30. 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%5B%5D
  20. ↑ Jonathan Cluett, M.D. (2003-08-05). "Injuries to the posterior cruciate ligament (PCL)". about.com. Retrieved 2006-11-11.
  21. ↑ Fernandez, Matthew; Pugh, David (2012). "Multimodal and interdisciplinary management of an isolated partial tear of the posterior cruciate ligament: a case report". Journal of Chiropractic Medicine. 11 (2): 84–93. doi:10.1016/j.jcm.2011.10.005. PMC   3368977 . PMID   23204951.
  22. ↑ Wind, William M.; Bergfeld, John A.; Parker, Richard D. (2004). "Evaluation and Treatment of Posterior Cruciate Ligament Injuries: Revisited". American Journal of Sports Medicine. 32 (7): 1765–75. doi:10.1177/0363546504270481. PMID   15494347. S2CID   22150465.
  23. ↑ Blood, Douglas C.; Studdert, Virginia P.; Gay, Clive C., eds. (2007). "Cruciate" . Saunders Comprehensive Veterinary Dictionary (3rd ed.). Elsevier. ISBN   978-0-7020-2788-8 . Retrieved September 8, 2009.
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