What Is a PCL Injury?

A posterior cruciate ligament (PCL) injury affects the posterior cruciate ligament, a strong band of tissue behind the anterior cruciate ligament inside your knee. This ligament connects your thighbone to your shinbone and keeps the lower leg from sliding backward when the knee bends. It also helps control stability during everyday movements like walking, squatting or going down stairs.

Although it is twice as strong as the ACL, the PCL can still tear. Most PCL injuries result from high-energy trauma. A common cause is a car accident when a bent knee slams into the dashboard. 

Sports-related injuries also occur, especially in football, soccer and skiing. Falling onto a flexed knee, landing awkwardly from a jump or twisting under pressure can all stress the ligament beyond its limits.

PCL injuries range from mild overstretching to a complete tear. Sometimes, the PCL is injured along with other ligaments or cartilage. When that happens, the damage becomes more complex and may affect your ability to walk or bear weight.

PCL Injury Symptoms

Symptoms depend on the severity of the injury and how many structures in your knee are affected. You might feel a little discomfort after a mild sprain. A complete tear or multi-ligament injury usually leads to more obvious signs.

Common symptoms:

• Pain that increases with time
• Swelling that limits motion
• A sense that your knee is unstable
• Difficulty walking or stepping down
• Stiffness, especially after rest

In mild PCL injuries, you may still walk, though the joint may feel weak. In more serious cases, your knee might give out or feel like it is drifting backward. People with chronic PCL injuries often describe aching during long walks or pain when their knee stays slightly bent.

Unlike an ACL tear, a PCL injury usually does not involve a loud pop. Swelling tends to build gradually, and bruising is often minimal. This can make it harder to identify without a detailed physical exam.

How a PCL Injury Is Diagnosed

A physical examination is the first step. Your orthopaedic specialist will compare both knees and look for changes in alignment, stability or swelling. 

The Posterior Drawer Test

The posterior drawer test is the most specific method to assess the PCL. When your knee is bent at a right angle, the specialist applies pressure to the shinbone. If it slides backward too far, the ligament may be torn.

Sag Test

The sag sign is another useful clue. When lying on your back with knees bent, the injured tibia often droops lower than the healthy one. This backward shift confirms that the PCL is no longer supporting the knee.

To confirm the diagnosis, your specialist may order imaging. An MRI shows soft tissues clearly and can detect a tear, bone bruises or other ligament injuries. X-rays do not show the ligament itself, but they can reveal if a small piece of bone tore off with the ligament, a condition known as an avulsion fracture.

PCL injuries fall into four grades:

• Grade I: A mild sprain with only a small tear
• Grade II: A partial tear with looseness
• Grade III: A complete tear causing instability
• Grade IV: A complete tear involving other ligaments

PCL Injury Treatments

Your treatment depends on how badly the ligament is damaged and whether other structures in your knee were injured at the same time.

Non-Surgical Treatment:

Most Grade I and II PCL injuries heal without surgery. Your physician may recommend:

• A brace to keep the shinbone from sagging backward
• Crutches to reduce pressure while walking
• Physical therapy focused on strengthening the quadriceps
• RICE therapy: rest, ice, compression and elevation

Surgical Treatment:

Surgery may be needed if:

• Your injury is Grade III or IV
• You feel persistent instability
• You tore multiple ligaments
• You have a large avulsion fracture

Surgical reconstruction involves replacing the torn ligament with a tissue graft. This graft may come from your own patellar or hamstring tendon or a donor. Some surgeons prefer a double-bundle reconstruction to better replicate natural movement. This technique rebuilds both parts of the PCL to restore balance and stability.

Recovery from surgery usually takes six to nine months. During that time, physical therapy plays a key role in protecting the graft, regaining strength and preventing future injury.

When to See an Orthopaedic Sports Medicine Specialist

Do not ignore knee pain or instability after a fall, collision or sports injury. If you have trouble walking, feel your knee shift backward or notice swelling that does not improve, you should consult an orthopaedic sports medicine specialist.

At the University Orthopaedic Associates, we offer the full spectrum of care for PCL injuries. That includes on-site imaging, advanced diagnostics and access to fellowship-trained physicians. We also provide custom rehabilitation plans for athletes, active adults and anyone who wants to return to full function.

Schedule an appointment with University Orthopaedic Associates and take the first step toward lasting knee health.