Uncommon Knee Injury Easily Missed on Diagnosis

From the WebMD Archives

Feb. 3, 2000 (Lake Worth, Fla.) -- Most commonly found in runners who stop short after running at full sprint, or after a fall on the knee which pushes the tibia, the front leg bone, into the ligament, posterior cruciate ligament (PCL) injuries are often difficult for physicians to diagnose. Therefore, it's important for doctors to take a detailed patient history and perform a specific in-office test to make an accurate diagnosis.

The posterior cruciate ligament is a cross-like ligament located at the back of the knee. "Some of the disability that relates to the PCL injury oftentimes is just misconstrued as having a sore knee or an achy knee," Robert S. Gotlin, MD, tells WebMD.

A study appearing in a recent issue of Sports Medicine and Arthroscopy Review points out the importance of an accurate diagnosis. "The most important thing is to learn to recognize [PCL injuries], and that means doing a good history and physical examination, which would include the posterior drawer test," study co-author K. Donald Shelbourne, MD, tells WebMD. Shelbourne and a colleague, John J. O'Shea, MD, studied 133 patients who came through the Methodist Sports Medicine Center in Indianapolis, where Shelbourne is a knee specialist. Through their experience, they determined that the most important diagnostic test used to diagnose this injury is the "posterior drawer test."

In the posterior drawer test, the physician looks at both of the patient's knees held in a 90-degree position and applies force on the shin (tibia) with both thumbs to determine if there is any amount of step-off, or misalignment of position, between the tibia and the femur (thigh bone) in the injured leg. It is important to compare the affected knee with the normal knee.

The important outcome of the study was that these injuries rarely need surgery, and most of the patients returned to their pre-injury activity -- half of them at the same level and a third at a lower level of activity. Only one-sixth of the patients did not return to their pre-injury activity.

Gotlin, director of orthopaedic and sports rehabilitation in the department of orthopaedic surgery at Beth Israel Medical Center in New York, provided WebMD with an objective analysis of the study. He explains that the way the PCL is injured is involved with its primary function, which is to prevent the knee from going backward. When a person is running full out and stops short, that momentum tries to push the knee backward. Sometimes, this is when most people realize they've injured their knee. Also, falling on the knee can push the tibia into the PCL and cause injury.

Continued

What often happens with the PCL is that, once it tears, "it scars and scars the structures around it, and it almost self-heals, if you will," Gotlin explains. "People who have loose knees or tight knees with the PCL do equally well, and [this] study shows that."

"The most appropriate treatment is not an operation, but to manage any new swelling and to get full range of motion. Once full range of motion is attained, work on getting the quadriceps and hamstrings strengthened," Shelbourne explains.

There is no way to prevent this type of knee injury. Gotlin encourages athletes to exercise in a way that will strengthen and stretch the quadriceps and hamstring muscles. They should also learn to land in a spring-like fashion, with both the knees and waist bent.

The good news is that PCL injuries do heal. "These patients generally end up with good knees, but not great knees," Shelbourne says.

Vital Information:

  • PCL injuries most often occur in runners who stop short after sprinting or who fall on their knee.
  • Most patients who have this type of injury do not need surgery and can return to their normal activities.
  • Physicians often misdiagnose PCL injuries, but using the posterior drawer test is an effective way to make an accurate diagnosis.
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