A posterior cruciate ligament (PCL) injury happens when the biomechanical
limits of this major knee ligament are overextended. This injury may be the result of
a blow to a bent knee, falling hard on a bent knee, or from an overextension the
knee. An injury to the PCL can involve mild to severe ligament damage and is often
associated with other knee injuries.
The knee joint is a complex hinge joint connecting the thighbone (femur),
which is the longest bone in the body, to the second longest bone in the body, the
shinbone (tibia). It is the largest joint in the body and acts in coordination with the
pelvis, hip, upper leg, lower leg, ankle and foot to facilitate a complete range of lower
body movements. The knee is a strong weight-bearing joint that allows the leg to
flex, extend, and twist slightly from side to side.
There are four major ligaments in the knee. The two located at the sides of
the knee are known as the collateral ligaments and the two crossing each other
within the joint are the cruciate ligaments. These four ligaments, along with help
from the quadriceps muscles in the front of the thighs and the hamstrings in the
back of the thighs, act to stabilize the knee and keep it moving in the proper
direction. The posterior cruciate ligament runs along the back of the knee joint from
the bottom of the thighbone to the top of the shinbone. It helps to insure proper
alignment of the knee and keeps the shinbone from moving too far backwards.
The posterior cruciate ligament is the strongest of the four major stabilizing
ligaments in the knee and the least frequently injured. An injury to this ligament
requires a powerful force. Consequently, the knee trauma that produces a PCL
injury is often severe enough to damage other ligaments and associated structures
within the knee.
The PCL become injured from a direct blow to the flexed knee. Smashing
your knee in a car accident or falling hard on a bent knee in a sports activity are
often sources of PCL damage. Hyperextension of the knee following an awkward
landing from a jump may also injure the ligament.
Symptoms of a PCL injury may include:
- Pain and swelling
- Stiffness in the joint
- Tenderness in the knee (specifically the back of the knee)
- Instability in the knee joint
- Difficulty walking
Evaluating for PCL damage begins with a thorough history of the injury and
the performance of a physical exam. During the clinical examination the doctor will
check for pain and tenderness in the knee as well as assess the joint as the knee is
moved in a variety of directions. Imaging tests may be ordered to evaluate the PCL
in detail, to check for associated damage, and to rule out other disorders.
Treatment depends on the extent of the injury. For minor injuries the
ligament may heal without complications. Non-surgical treatment following the
injury may include RICE (rest, ice, compression, and elevation), a period of
immobilization with a brace and possibly crutches, as well as physical therapy.
If the symptoms are not alleviated with conservative treatment, if the damage is
significant or if there are combined injuries in the knee, then surgery may be
recommended. With surgery the torn posterior cruciate ligament can be rebuilt.
Recovery time from a surgical procedure depends on the severity of the injury.
Combined injuries take a longer time to heal. Physical therapy is an essential part of