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 is one of four main ligaments in the knee that provides stability to the knee. Both the ACL and PCL criss-cross the knee providing support and preventing the knee from moving forwards and 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 ‘dashboard’ injuries in reference to car collisions when the knee hits the dashboard directly. Also, in sports, we see a PCL tear when athletes fall directly on the front of the knee. Other mechanisms include sudden bending of the knee, causing the knee to hyperflex.

Often, a Knee PCL tear is associated with injuries to other structures such as the posterolateral corner of the knee, 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 producing only minimal pain and swelling. However, the knee often doesn’t feel right 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 MCL, LCL, ACL, and posterolateral corner to ensure you don’t have other injuries. In most cases, there is a limited range of motion and swelling in the knee.

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: Grade 1 injury indicates a sprain, a grade 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 treatment.

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

However, higher grade 2 and grade 3 injuries 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 a knee brace 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, how long one should wear a PCL Jack brace is not known.

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. Generally, 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, for non-operative treatment, a PCL tear can take up to 6 months to recover. 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 mish. 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 leads to greater forces on the kneecap and medial (inside) compartment. Over a few years, this increased pressure can lead to cartilage damage and 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. These avulsions can be reattached if detected early, 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