Understanding PCL Tear: Causes, Symptoms, and Treatment

Most people have heard of an ACL injury suffered commonly by amateur and elite athletes of all ages. However, a posterior cruciate ligament (PCL) injury accounts for up to 20% of acute knee injuries. So what is a Knee PCL tear, and how do we treat it?

What is the posterior cruciate ligament?  

The posterior cruciate ligament (PCL) is one of four main ligaments in the knee that provides stability. Both the ACL and PCL crisscross the knee, providing support and preventing the knee from moving forward or backward. Generally, the main role of the PCL is to prevent the tibia from sliding back against the femur.

How does a Knee PCL tear occur? 

The most common mechanism of injury is when a force hits the front of the tibia, forcing the tibia backward and tearing the PCL. Often, a torn PCL is referred to as a ‘dashboard’ injury in reference to car collisions when the knee hits the dashboard directly. We also see PCL tears when athletes fall directly on the front of the knee in sports. Other mechanisms include sudden knee bending, causing the knee to hyperflex. 

A PCL tear is often associated with injuries to other structures, such as the lateral knee corner, ACL, or meniscus.

Diagnosis of PCL tear

Often, but not always, a torn PCL is associated with sudden pain, swelling, and a feeling of instability. Sometimes, people hear a pop or a sense of giving way. If instability develops, people report feeling they can’t trust the knee or that the knee gives way with specific movements. 

Sometimes, a PCL tear may be subtle, particularly in partial tears that produce minimal pain and swelling. However, the knee often feels wrong and fails to recover quickly.

Your doctor will examine your knee to see if the PCL is intact. The most reliable test is the posterior draw test. Other tests include the posterior sag sign and reverse pivot shift. In addition, we must test other ligaments, such as the MCL, LCL, ACL, and posterolateral corner, to ensure you don’t have other injuries. In most cases, the knee has a limited range of motion and swelling.

Generally, we use X-ray and MRI to confirm the diagnosis of a torn PCL and rule out other damage to ligaments and cartilage.

Overall, a PCL tear is graded according to injury severity: A grade 1 injury indicates a sprain, a grade 2 injury indicates a partial tear, and a grade 3 injury indicates a full tear.

Treatment of PCL tear 

Treatment of PCL injuries – especially grade 3 injuries – is controversial, as there is little agreement as to the best form of therapy.

Generally, simple treatments are first started for grade 1 and mild grade 2 injuries. These include ice, ibuprofen, compression, and range-of-motion exercises.

However, higher grades 2 and 3 are often treated with a knee brace to help stiffen the knee.

Knee support for PCL tear

While there is controversy about whether a knee brace will help after a PCL tear, most doctors recommend wearing one for six weeks following an injury. Typically, the knee brace pushes the shin bone forward, allowing a torn PCL to heal. One example is the PCL jack brace. This knee brace limits movement from 0 to 90 degrees and should only be used in the early stages of rehab. However, the length of time one should wear a PCL Jack brace is unknown.

PCL exercises  

Strengthening and balance exercises are essential to regain knee function. Generally, we start with range-of-motion exercises and then move to non-weight-bearing and weight-bearing quadriceps and calf exercises. It would be best to avoid hyperextension and exercises that push the shin bone backward, such as isolated hamstring exercises (prone knee curls). The aim is to restore strength, balance, and control before restarting running and sports-specific training.

Surgery

In general, surgical reconstruction is uncommon in a torn PCL except in the following circumstances:

• A grade 3 injury with symptoms of instability
• A grade 3 injury with other injuries such as posterolateral corner or LCL tear

PCL reconstruction is technically more complex than the more common ACL reconstruction and needs at least 12 months of rehab.

Frequently asked questions about a PCL tear.

How long does it take to recover from a PCL injury? 

Generally, a PCL tear can take up to 6 months to recover for non-operative treatment. Sometimes, recovery can take longer as the knee takes time to get used to not having a PCL. In some cases, the forces on the kneecap or the medial compartment increase, leading to early arthritis in these joints. Generally, these problems settle with good solid rehab. Sometimes, cortisone, hyaluronic acid, or PRP injections are needed.

ACL vs. PCL injury: how can you tell? 

Both injuries can occur from a sporting mishap. However, unlike a PCL injury, an ACL injury occurs from a sudden stop, direction change, or awkward landing. Generally, on examination, there is looseness in moving the shin bone forwards on the thigh bone – also called Lachman’s test. Typically, ACL rupture requires surgical reconstruction in young people, while most PCL tears can be treated without surgery.

Does a PCL tear lead to early arthritis? 

A PCL injury causes greater forces on the kneecap and medial (inside) compartment. Over a few years, this increased pressure can damage cartilage and cause early arthritis. Generally, rehab to keep the muscles strong will protect the knee from further damage.

How do we treat PCL avulsion? 

In teenagers, the top attachment of the PCL with a small piece of bone can tear, leading to a PCL avulsion. If detected early, these avulsions can be reattached, meaning the PCL functions normally. Therefore, it is always crucial to X-ray a teenager with a swollen knee after trauma.

Does a grade 1 or 2 PCL injury need surgery?

Generally not. We suggest surgery only for grade 3 PCL injuries, especially if combined with other injuries such as a posterolateral corner or medial meniscal injury. Ususally, grade 2 injuries should be OK with rehab.

Related conditions:

• torn meniscus
• meniscus injections 
• MCL injury