A posterior cruciate ligament injury (PCL) is less common than other types of knee ligament injuries, like an ACL tear or a LCL tear, but it still can limit or prevent you from doing the things that you already enjoy. You might feel a mild or achy feeling in the back of your knee when you kneel, climb up and down the stairs, or walk. There might be even some swelling behind your knee but you feel no pain or movement restriction.
Since the symptoms likely overlap with other causes, like hamstring strain or a Baker’s cyst, it is important to understand the nature of the pain behind your knee and what you can expect at a doctor’s visit.
The PCL is the strongest knee ligament and is made up of two parts: anterolateral and posteromedial bands. Like all ligaments, these bundles of fibrous tissues have a poor blood supply, which makes lesions to the PCL longer and more difficult to heal than most other structures.
It originates from the side and front of the medial condyle of the femur at the intercondylar fossa (the notch of the thigh bone that gives its familiar shape) and inserts into the back of the tibia’s flat surface.
The PCL’s job is to prevent the femur from sliding horizontally across the tibia and limit excessive abduction (varus) and adduction (valgus) of the knee.
PCL tear causes
The primary cause of a PCL tear is trauma to the knee joint, particularly an impact to the shin bone near the knee joint while the knee is flexed. One 2003 study from Rochester, Massachusetts, of nearly 500 patients found that about 45% of the PCL tear is caused by a vehicle accident and 40% are caused by athletic injuries. About 28% of these accidents are from motorcycles and 25% of the athletic injuries are from soccer.
Although non-contact injuries are low, it can still happen among certain populations. One Norwegian case-control study of 104 patients with a PCL tear found that those who had a non-contact injury had a higher tibial slope at the proximal tibia than the control group. This may increase the risk of a PCL tear when the knee sharply rotates while the knee is hyperextended.
The prevalence of an isolated PCL tear is quite low compared to other types of knee pain and injuries, but it is rather common among different types of PCL injuries. While the Rochester study said that the prevalence of PCL tears is “rare”—2 out of 100,000 people—a Scandinavian study in 2015 found that isolated PCL tears occurred among more than one-third of the total number of PCL injuries. Soccer players ranked as the highest prevalence among all sports (13.1%).
Dissection of the posterior knee, including the posterior cruciate ligament.
PCL tear symptoms
Although the symptoms of a PCL tear may feel like other types of pain behind the knee, research has shown that in many cases, the torn PCL can be asymptomatic. Symptoms, however, can vary among each person. These include swelling behind the knee, achiness in the back of the knee, dull pain during movement, and instability in the knee, which may feel “looser” than normal.
PCL injuries can occur with other types of knee injuries, such as torn knee meniscus, osteoarthritis, and—in rare instances—ACL tears. Thus, each person may have different symptoms of posterior knee pain because of a combination of different causes.
PCL tear diagnosis
Acute and chronic pain from a PCL tear or injury would require different tests, and they can be challenging for clinicians to diagnose because there may be one or more causes of pain besides the PCL injury. Thus, clinicians may likely use multiple physical examinations to make a correct diagnosis.
Posterior drawer test
One common test that a clinician might use is the posterior drawer test, which has a high sensitivity rate of 90%. This means that it has a high accuracy rating of identifying a PCL tear.
A clinician would have you lie on your back on the examination table, and flex your hip at about 45 degrees and your knee flexed at 90 degrees. Then the clinician would push sharply at the tibia near your knee joint while the femur is stabilized. If there is a PCL tear, the tibia would slide horizontally relative to the femur. The amount of movement would depend on the grade of the tear: 0 to 5 millimeters for grade 1; 6 to 10 millimeters for grade 2; 11-plus millimeters for grade 3.
Named after Dr. William Clancy, Jr., of the University of Wisconsin in the early 1980s, a positive result of the Clancy sign means that the clinician cannot feel the bony projections to either side of the tibial plateau beneath the femur’s condyles.
The dial test measures the external rotation of the tibia while the femur is stabilized. While you lie on your stomach on the examination table with your knee flexed at about 30 degrees, the clinician places one hand on the back of your thigh to keep your upper leg in place. Then your ankle and foot are manually rotated externally.
If there is more than 10 degrees of external rotation compared to the opposite, uninjured knee, then there might be a PCL injury. Chahla et al. cited that if the same test was done with the leg flexed at 90 degrees and there is a greater external rotation, then there might also be injury to the posterolateral complex of the knee (PLC). This area includes—but not exclusively—the popliteus tendon and muscle, lateral collateral ligament, popliteal ligament, and the biceps femoris.
The sensitivity of the dial test, however, may not be reliable. A cadaver study from South Korea found that it may not be able to detect injury to one or two posterior knee structures. The researchers suggested that “comprehensive diagnostic methods including the patient’s history, other physical examinations, radiographs, and magnetic resonance imaging should be used to diagnose posterolateral rotatory instability.”
Reverse pivot-shift test
(Sensitivity refers to the ability to correctly identify people with a disease; specificity refers to correctly identifying those without a disease.)
A clinician would flex your knee to 90 degrees while you are lying on your back on the examination table. Then the clinician extends your knee while applying pressure to abduct your knee and externally rotate your foot. In a positive test, the tibia plateau is partially “out” of the knee joint as the knee flexion is reduced between 20 to 30 degrees. The clinician should not compare your affected leg with the opposite leg.
Posterior sag test
Sometimes called the Godfrey test, the posterior sag test is performed with you lying on the table with your hip and knee flexed at about 90 degrees. The clinician examines your affected leg by checking to see if there are any excessive concaveness of the upper tibia near the tibial plateau. Normally, there should be a small protrusion of the tibial plateau below the knee joint. If there is none, it is likely a sign of a PCL tear.
Details in the video below by PhysioTutors.
There are several more tests that a clinician might perform on you, and feel free to ask what these tests do and how reliable are they in detecting a PCL tear. Any single manual test, no matter how accurate it may be, is not enough to make a clear diagnosis. Clinicians must consider your health history, imagings, and other manual tests to rule out other potential factors before making a diagnosis.
PCL tear treatments
The type of treatment you get would depend on various factors, such as whether the symptoms of the PCL tear are acute or chronic, or if the injury is at the posterior cruciate ligament only or if there are injuries at other parts of the knee.
The majority of the scientific literature seems to favor operative interventions rather than non-operative ones, but generally speaking, the jury is still out. A 2018 review by Pache et al. from the Steadman Philippon Research Institute in Vail, Colorado, stated that which type of treatment patients get depends on the degree of the torn PCL. The researchers cited several studies that partial PCL tears have mixed results in outcome from conservative treatments, such as exercise and knee bracing, while surgery repairs of full PCL tears are recommended. However, there is still a debate on which type of surgery is better than another.
“Most authors agree that partial isolated PCL tears should be treated nonoperatively,” Pache et al. wrote. “Complete PCL tears treated nonoperatively have been reported to increase the risk of degenerative changes of the medial and patellofemoral compartments at long term, and were associated with poor function.”
They also noted that there has not been any long-term research on whether a PCL reconstruction surgery can prevent the onset of knee osteoarthritis.
A nationwide Taiwanese study that was published in late 2018 also favors operative interventions over non-operative ones. Researchers Wang et al. from the National Defense Medical Center in Taipei reviewed narly 4,200 diagnoses of PCL tears from 2000 to 2015. They found that those who had surgery were more likely to get knee osteoarthritis, total knee replacement, and meniscus tear, than those who had conservative care.
“These results raise concerns regarding the need to restore stability with PCL reconstruction to avoid progressive degeneration,” they wrote.
The point of having a PCL reconstruction is to restore normal biomechanics and knee loading to minimize the risk of getting meniscus tears and other types of knee degenerative diseases. The evidence from several studies that Wang et al. cited seem to defeat that purpose.
However, this does not mean the patients with a PCL reconstruction cannot resume normal lives and activities. Wang et al. cited several studies that many patients can recover within two to five years.
For example, in one South Korean study in 2006, subjective evaluations reported that all 61 patients (45 men, 16 women) were “normal or near normal” while objective evaluations reported all but two patients as “normal or near normal.”
In a 2009 Belgian study that followed up with 25 patients (22 men, 3 women) who had a PCL reconstruction surgery in 1995 to 2001, 75% of them tend to have more damage to the knee cartilage than those who had a reconstruction within one year.
This is congruent with Wang et al.’s findings that any delay of a PCL reconstruction surgery of more than one year will have a higher risk of getting osteoarthritis than those who had a surgery in less than a year after getting a PCL tear.
“These findings show that patients who undergo PCL reconstruction experience a satisfactory return to daily activities,” they wrote.
However, Wang et al. pointed out that the data they used were claims-based, meaning that they information was sorted from insurance companies, doctor’s offices and bills, and other similar paperwork. They do not inform the researchers the degree of the PCL tear or the severity of the other knee symptoms.
Even those conservative treatments may underscore surgeries for a torn PCL, they still have their place in the treatment spectrum. Pache et al. If the PCL tear is an isolated incident (no other tears or injury in the knee) and acute, then non-operative treatments may be an option for some patients.
One American study in New York City in 2007 found that there was no pain among 38 out of 58 knees examined (57 patients total), while there was mild pain among 14 knees and moderate pain among 6 knees. About 91% had swelling in the knee. The researchers reported that only two patients failed conservative treatment because of “clinical deterioration of symptoms” and had reconstruction surgery. They were able to return to play their favorite sports where one had a 38-month follow-up while the other patient had a follow-up nearly eight years later.
Another study in Indianapolis, Indiana, in 2013 followed up with 68 patients who had conservative care for their acute PCL tear. Although 11% of them had developed knee osteoarthritis, all of the patients were “active, have good strength and full knee range of motion, and report good subjective scores.”
Like most types of knee pain, treatment for a PCL tear or injury should be tailored to the individual, including how clinicians communicate to the patient. Considering that pain is biopsychosocial in nature, and a PCL tear itself is biological, how patients perceive their injury, what it means to them, and how the healthcare infrastructure on how well patients get treated all play important roles in pain and disability outcomes.