Posterior Cruciate Ligament Injury

Although the anterior cruciate ligament (ACL) is often the primary focus in sports medicine discussions, the posterior cruciate ligament (PCL) is equally essential for knee stability. A PCL tear, commonly called a “dashboard injury,” occurs when a strong force strikes the front of the upper shin, causing the tibia to shift backward.

Symptoms may be subtle because the PCL is the strongest ligament in the knee. Unlike ACL tears, a PCL tear rarely produces an audible popping sound. Instead, symptoms commonly include persistent soreness, swelling, or a feeling of knee instability, especially noticeable when climbing stairs. Without timely treatment, a PCL tear can lead to chronic pain and long-term cartilage wear.

Do not let a PCL injury put your life on hold and undermine your mobility. At Suarez Physical Therapy, our Las Vegas experts develop evidence-based recovery strategies to help you regain strength and confidence.

How Does Your PCL Tear Happen?

A PCL tear requires significant force applied in a specific direction, which determines how the ligament is damaged and how healing will proceed.

Below are the most common injury mechanisms that cause a PCL tear.

1. The Dashboard Injury

If you have had an accident in a motor vehicle, then you might have sustained what the clinicians term a dashboard injury. In a car that abruptly stops, the knee is usually flexed (bent). When the upper section of the shin (tibia) hits the dashboard, the force drives the bone backward in relation to the thigh bone.

This posterior translation places your PCL under enormous tension and prevents exactly this motion. With even slower collisions, the direct blow may cause a partial or complete rupture of the ligament.

2. Sports Trauma

The most prevalent cause, especially among athletes such as football players, soccer players, or rugby players, is a fall on a bent knee. When falling on a flexed, weight-bearing knee, body weight and ground impact force drive the tibia backward, stressing the PCL.

Your PCL tear is more likely to have been caused by a contact event because, unlike an ACL tear, where you can easily pivot without colliding with anybody, your PCL tear was probably caused by a contact event. This occurs when your knee hits the turf or a player with significant momentum.

3. Hyperextension

Although hyperextension is a violent PCL injury mechanism that is less frequent than impact injuries, you might have suffered it. Hyperextension occurs when the knee is forced beyond its standard straightened limit. It may have happened when you stepped over a grassy hole that you did not see, or when you were hit on the front of your leg when your foot was firmly planted on the ground.

When you are on your knees, your PCL is stretched to its maximum. With further force, the ligament can tear or even detach a fragment of bone (an avulsion fracture). The injuries are, in many cases, more complicated and can be accompanied by harm to other elements of your knee.

4. High-Torque Twisting

You might have had a PCL tear due to violent twisting or rotation, as your foot was well fixed. It is common in sports like wrestling or gymnastics. The force in the opposite direction causes the body to move, and the bottom leg remains in place. This will cause the ligament to tear under the stress of rotation.

Why PCL Tears Tend to be Silent

If you have injured your knee but aren’t quite sure of the severity, you are not alone. A posterior cruciate ligament tear is commonly referred to as a silent tear, unlike an anterior cruciate ligament tear, which is typically characterized by dramatic, immediate, and substantial swelling. The strength of the PCL is such that it can not all collapse in one blow, and as a result, the symptoms can be more like a nagging enigma than an emergency.

Understanding these subtle signs can help you determine if your knee issues stem from a PCL tear:

1. The Missing “Pop”

The most baffling element of a PCL injury is what you do not experience or hear. Most patients do not typically experience the loud snapping sound that is characteristic of other ligament ruptures. During the first days after the injury, the pain may not be sharp and painful, but rather dull. Since you may still be able to walk or play a sport for a bit longer, you can minimize the injury to a simple bruise or sprain.

2. Subtle Instability and the “Wobbly” Knee

The characteristic of a PCL tear does not always mean that there is a complete collapse of the joint, but it is an uncomfortable sensation of looseness that is constant. Your knee may feel wobbly, or you may notice that it gives way when you make specific movements. This instability is most evident in the following:

• Descending stairs — You may feel your shinbone sliding too far back as you step down
• Deceleration — Unsteadiness on attempting to decelerate jogging or walking
• Changing direction — A feeling that you change in the joint as you twist around a corner

3. Pain and Swelling Deep and Diffuse

Whereas an ACL tear often causes the whole knee to swell up with fluid, PCL swelling is usually not so severe and is generally located at the back of the knee.

Pain behind the knee can be located in the popliteal (back) part of the knee, causing aching, deep throbbing, and discomfort. You may also experience stiffness. This stiffness is possible when you experience loss of range of motion within the first 24 to 48 hours. You could find it hard to bend and straighten your leg all the way.

Also, common is patellofemoral pain. The altered biomechanics may eventually cause patellofemoral pain during prolonged sitting or squatting.

Several individuals with PCL tears can use a relatively normal gait on a flat surface. You may, however, subconsciously be guarding the knee. What might occur to you, then, is that your leg cannot now be depended on to bear your full weight when your knee is bent slightly. This results in a slight limp or an inclination to keep your leg straight as you move.

Classification of the Severity of Your PCL Injury

When a specialist talks to you about the knee injury, they are most likely to grade your injury based on a system. This is not merely a medical term but the description of not only the physical condition of your ligament but also the amount of what is referred to as laxity (looseness) in your joint. Since the PCL is the main ligament that prevents the sliding of your shin-bone (tibia) in a backwards direction, the extent of the injury is measured by the number of millimeters your tibia sags during an exam.

Knowing these grades will help you know when you will be recovered and whether this injury is a single occurrence or a component of a more complicated trauma.

1. Grade I: The Partial Tear

In a Grade I injury, your PCL has been torn very slightly or stretched, and yet it is still intact.

During clinical testing, your tibia moves backward only 0 to 5 millimeters. The knee remains relatively stable, and the ligament can maintain the joint in its correct position. You will probably experience mild swelling and pain, and the structural stop, which prevents the bone from sliding too far, remains firm.

2. Grade II: The Near-Complete Tear

A grade II injury is a more severe partial tear in which the ligament is partially torn, causing moderate joint laxity. You have a tibia that is lax or moves behind within the range of 5 to 10 millimeters. You may experience a wobble or loss of confidence in your knee during physical exercise.

The PCL is not silent in this case. Instability presents itself in many instances when you attempt to turn rapidly or exit a curb.

3. Grade III: The Complete Rupture

A Grade III injury is a total tear of the ligament. The PCL does not provide any structural support. The tibia goes back farther than 10 mm. This can be seen quite often with the naked eye in the form of a sag sign, in which the outline of your knee appears different when lying in a position.

Grade III PCL injury hardly occurs on its own. In the majority of cases, when the force was sufficient to fully tear the PCL, other structures, including the ACL or the Posterolateral Corner (PLC), are likewise torn.

The knee becomes very unstable, making it difficult to walk without support.

The severity of your injury would determine your rehabilitation route. Grade I and II injuries are rarely surgically addressed. They are repaired using specific strengthening exercises for the quadriceps. On the other hand, grade III injuries require a more rigorous examination to determine whether surgery is necessary to restore the complex function of the knee.

How Professionals Identify a PCL Tear

If you suspect that you have injured your PCL, a clinician will apply a synergistic approach to visual examination, physical maneuvers, and other sophisticated imaging to achieve the diagnosis. The symptoms of PCL are minimal; therefore, these special tests are designed to isolate the ligament and precisely determine how much stability is lost.

1. The Posterior Sag Sign Visual Test

This is one of the most apparent indications of a PCL injury, which you will typically notice yourself most of the time. This is the posterior sag sign (or the Godfrey test).

To do this, lie on your back with your hips and knees bent to a 90-degree angle. In a healthy knee, the tibia is in front of the femur. When your PCL is torn, you will find that the tibia tends to fall under gravity, causing it to sag or drop in comparison to the other knee. This brings about an apparent alteration in the line of your knee, a hallmark that the PCL is no longer providing the bone with its correct position.

2. The Manual Examination

The physical examination of a PCL injury, regarded as a gold standard test, is the posterior drawer test. In this examination, your physician or physical therapist will:

• Have you lain on your back with your knee bent
• Sit on your foot to stabilize the leg
• Place their hands on your upper shin and apply a firm, backward pressure

A normal PCL will have a solid end-feel, which will halt movement abruptly. In the case of a ligament tear, the tibia will slide backward an unreasonable amount. The distance that it covers enables the provider to classify the injury (Grade I, II, or III).

3. MRI vs. Stress X-Rays

An MRI is an excellent tool for imaging soft tissue and identifying the actual tear in the ligament. MRI confirms soft-tissue injury, while stress radiographs are more helpful in measuring functional laxity.

In other instances, your specialist may request that you apply stress X-rays (also referred to as kneeling X-rays). In this process, an X-ray is taken while the knee is subjected to a certain degree of pressure. This enables the physician to record the millimeter movement of the bones. Although the MRI is used to confirm the presence of a tear, the stress X-ray provides the most suitable information for grading the laxity, which is of utmost importance in deciding between physical therapy and surgery.

Non-Surgical Management of a Posterior Cruciate Ligament Injury

If you have been diagnosed with a PCL injury, surgery will likely not be your first, or even your second, option. The PCL is often a strong candidate for conservative (non-surgical) care because it has a more robust blood supply than the ACL, which typically has a lower capacity for self-repair.

In most cases, patients with tears classified as Grade I or Grade II can rely on the body's natural healing process, combined with the use of specialized machines, to help restore knee functionality.

The second aspect that is extremely promising about your PCL is that it is vascular. The blood supply of the PCL is much more adequate than that of most ligaments in the knee. The body can knit the tissue back together if the points of the torn ligament are brought into contact and the knee is stabilized. Due to this remarkable healing capacity, even without reconstruction, many athletes can return to high-level sports.

To enable the PCL to heal itself, the “sag” should be removed. Should you permit your shinbone to rest in an inverted position and the ligament endeavors to close it, it will close in a loose or lengthened condition and hence cause permanent instability.

A dynamic PCL brace applies controlled anterior force to maintain tibial positioning and offload the healing ligament. Unlike a standard knee brace that simply prevents side-to-side movement, a dynamic PCL brace uses a spring-loaded mechanism to apply a constant, gentle forward pressure on the back of your calf. This will push your tibia into its anatomical position, relieving tension on the PCL and allowing the fibers to fill the gap, thereby facilitating healing at this time.

The next part of the healing process involves the quadriceps. Since your PCL is no longer in a perfect state of opposition to the sliding backwards of your shin, your quadriceps muscles have to do that work instead. When the strength of the front of the thigh is increased, you establish a muscular seatbelt around the knee. The compensation is so adequate that most patients who tear their PCL and recover can regain knee stability as it was before the injury.

Note: You will need a lot of patience and follow the bracing guidelines. The ligament has a good chance to stabilize itself by shielding it during the first six to twelve weeks, thereby giving the body the best opportunity to heal the ligament.

Physical Therapy Plan

Quadriceps are your best friend in PCL rehabilitation. Rehabilitation prioritizes quadriceps strengthening because the quadriceps help prevent posterior tibial translation.

Since the PCL's work is to keep your shinbone (tibia) still and prevent it from sliding backward, the work of your quadriceps muscles facilitates the tibia's forward motion. A good set of quads can perform the job of the PCL as a secondary muscle.

Physical therapy will focus on quad-dominant training. This is achieved by contracting the muscles in front of your thigh, making them firmer and more active, which in turn provides a natural tension that maintains the knee joint in proper function. This helps reduce the mechanical load on the healing ligament and prevents sag. This will result in wear of the joint over time.

During the initial recovery (usually during the first 3 to 4 months), isolated hamstring curls should be avoided. Although the hamstrings are significant muscles, they primarily function to pull the tibia backward. A deficit of the ligament has necessitated this movement within a PCL knee due to direct stress on the injured ligament and may reverse weeks of recovery. Your therapist will reintroduce hamstring work in due course. However, the PCL is stable enough to withstand the load only after the ligament is sufficiently healed and stable.

The following precautionary, effective movements will probably pass through your protocol:

• Straight leg raises (SLR) — Strengthening of the quad muscles without exerting any shearing pressure on the knee
• Mini-squats (0° to 60°) — Squatting with a limited range helps alleviate pressure on the PCL and engages the glutes and quadriceps. Deep squats (below 60 to 90 degrees) should be avoided early in training because they enhance PCL tension through deep flexion.
• Leg presses — This is a controlled method of developing power, focusing on the pushing aspect to stimulate the anterior chain.

Half the battle is the battle of strength. An injury to your PCL damages your proprioception, or, to put it another way, your brain is aware of the position of your knee in space without having to look at it. It is necessary to perform balance training on uneven surfaces, like foam pads or Bosu balls. This is what preconditions your nervous system to respond quickly to slips or uneven surfaces. This allows you to return to your everyday life or resume sports without fear that your knee will give way.

Find a Physical Therapist Near Me

A PCL injury may seem like a big blow, and you can be literally left with a gap in the stability of the knee. Whether you have gone through an abrupt sporting collision or have been hit in the dashboard, being able to identify the symptoms like swelling, instability, and deep aching is the first key to recovery. Although the PCL is a knee-supportive giant, it possesses amazing healing powers under the guidance of the appropriate expertise.

Knee pain should not be the determining factor in mobility. At Suarez Physical Therapy, we develop individualized rehabilitation programs designed to help you feel stronger and more confident. Our goal is to improve strength, mobility, and pain levels through individualized rehabilitation plans. Contact us at 702-368-6778.