The posterior cruciate ligament (or PCL) is one of the four major ligament

Ligament

In anatomy, the term ligament is used to denote any of three types of structures. Most commonly, it refers to fibrous tissue that connects bones to other bones and is also known as articular ligament, articular larua, fibrous ligament, or true ligament.Ligament can also refer to:* Peritoneal...

s of the knee

Knee

The knee joint joins the thigh with the leg and consists of two articulations: one between the fibula and tibia, and one between the femur and patella. It is the largest joint in the human body and is very complicated. The knee is a mobile trocho-ginglymus , which permits flexion and extension as...

. It connects the posterior intercondylar area of the tibia

Tibia

The tibia , shinbone, or shankbone is the larger and stronger of the two bones in the leg below the knee in vertebrates , and connects the knee with the ankle bones....

 to the medial condyle

Medial condyle of femur

The medial condyle is one of the two projections on the lower extremity of femur.The medial condyle is larger than the lateral condyle due to more weight bearing caused by the center of gravity being medial to the knee. On the posterior surface of the condyle the linea aspera turns into the...

 of the femur

Femur

The femur , or thigh bone, is the most proximal bone of the leg in tetrapod vertebrates capable of walking or jumping, such as most land mammals, birds, many reptiles such as lizards, and amphibians such as frogs. In vertebrates with four legs such as dogs and horses, the femur is found only in...

. This configuration allows the PCL to resist forces pushing the tibia posteriorly relative to the femur.

In the quadruped

Quadruped

Quadrupedalism is a form of land animal locomotion using four limbs or legs. An animal or machine that usually moves in a quadrupedal manner is known as a quadruped, meaning "four feet"...

 stifle

Stifle

Stifle can mean:* To suffocate* To prevent from speaking or to prevent a view being heard. See free speech, gag and gagging.A stifle is also the name for an animal's knee joint. See stifle joint....

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

The PCL is an intracapsular ligament along with the anterior cruciate ligament (ACL) because it lies 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.

Injury

The posterior drawer test

Drawer test

The drawer test is a test used by physicians to detect rupture of the cruciate ligaments in the knee. The patient should be supine with the hips flexed to 45 degrees, the knees flexed to 90 degrees and the feet flat on table. The examiner sits on the patient's feet and grasps the patient's tibia...

 is one of the tests used by doctors and physiotherapists to detect injury to the PCL.

Surgery to repair the Posterior Cruciate ligament is controversial due to its placement and technical difficulty.

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. 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.

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. The main parameter in this test is step-off, which is the shortest distance from the femur to a hypothetical line that tangent

Tangent

In geometry, the tangent line to a plane curve at a given point is the straight line that "just touches" the curve at that point. More precisely, a straight line is said to be a tangent of a curve at a point on the curve if the line passes through the point on the curve and has slope where f...

s 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.

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.

Treatment

The PCL does not heal on its own, so surgery is usually required in complete tears of the ligament. Surgery usually takes place after a few weeks, in order to allow swelling to decrease and regular motion to return to the knee. A procedure called 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.

External links

• http://www.cincinnatisportsmed.com/csm/index.asp?ipath=patedu/knee/pcl.htm
• http://www.orthspec.com/pdfs/PCL-injuries.pdf