Posterior Cruciate Ligament (PCL) Injuries
The posterior cruciate ligament, or PCL, is one of the four main ligaments that stabilize the knee. It sits deep inside the knee joint and connects the thigh bone (femur) to the shin bone (tibia). Its primary job is to prevent the tibia from moving too far backward under the femur. When the PCL is stretched or torn, the knee can become unstable, painful, and weak.
Compared to ACL tears, PCL injuries are less common, but they can still significantly affect knee function. The PCL is thicker and stronger than the anterior cruciate ligament (ACL). Because of this, it typically requires a stronger force to injure it. The classic example is a direct blow to the front of the knee while it is bent. This type of injury is often referred to as a “dashboard injury” because it commonly happens during car accidents when the shin strikes the dashboard injuries can range from mild stretching of the ligament to a complete tear.
PCL injuries are classified based on severity:
- Grade I (Mild Sprain) – The ligament is stretched but not torn. The knee may feel sore but remains stable.
- Grade II (Partial Tear) – The ligament is partially torn. There may be moderate pain, swelling, and some looseness in the joint.
- Grade III (Complete Tear) – The ligament is completely torn. The knee may feel unstable, especially when walking downhill or descending stairs.
In some cases, the PCL is injured along with other structures in the knee, such as the ACL, medial collateral ligament (MCL), lateral collateral ligament (LCL), or meniscus. These combined injuries are more serious and may require more advanced treatment.
Symptoms can vary depending on the severity of the injury. Some people with mild PCL injuries may not realize they have significant ligament damage at first.
Common symptoms include:
- Pain in the back of the knee
- Swelling that develops within hours after the injury
- Stiffness and difficulty bending the knee
- A feeling of instability or looseness
- Trouble walking on uneven surfaces or going downstairs
With a complete tear, the knee may feel unstable during everyday activities. Some individuals describe a sensation that the knee is “giving out.” Over time, untreated PCL injuries can lead to abnormal joint movement, which increases the risk of cartilage wear and early arthritis.
Because symptoms may not always be dramatic, some patients delay evaluation. At Orthollinois Knee Center, a thorough knee examination can determine whether instability is present, even when swelling has improved.
PCL injuries are usually caused by a strong impact or force that pushes the shinbone backward. Unlike ACL injuries, which often occur during twisting movements, PCL injuries more frequently result from direct impact.
Common causes include:
- Car accidents, especially when the knee strikes the dashboard
- Sports injuries, such as falling on a bent knee
- Football tackles where the front of the knee is hit
- Landing awkwardly from a jump
- High-energy trauma such as skiing or contact sports
Athletes in contact sports are at higher risk, but anyone can sustain a PCL injury during a fall or collision. Motor vehicle accidents remain one of the leading causes.
Accurate diagnosis begins with a detailed history of how the injury occurred. The mechanism of injury often provides important clues. During the physical examination, the orthopedic specialist will assess swelling, range of motion, and stability. Specific hands-on tests are used to determine whether the tibia moves excessively backward compared to the opposite knee. One common test is the posterior drawer test, where gentle pressure is applied to evaluate ligament stability.
Imaging studies are often necessary to confirm the diagnosis and determine severity. X-rays may be ordered first to rule out fractures or bone avulsion injuries, where a piece of bone is pulled off with the ligament.
Magnetic resonance imaging (MRI) is the most useful test for visualizing the PCL. An MRI can show whether the ligament is partially or completely torn and can also identify associated injuries to cartilage, menisci, or other ligaments.
Because combined ligament injuries are possible, a complete assessment is critical. At OrthoIllinois Knee Center, advanced imaging and comprehensive orthopedic evaluation allow for an accurate diagnosis and individualized treatment planning.
While some mild PCL injuries can heal with non-surgical management, more severe injuries can lead to long-term instability if left untreated. Persistent instability places abnormal stress on the knee joint, increasing the risk of cartilage damage and early degenerative changes.
Early diagnosis allows for appropriate bracing, physical therapy, and monitoring. In cases of complete tears or multi-ligament injuries, surgical reconstruction may be recommended to restore knee stability and protect long-term joint health.
Even if swelling improves and pain decreases, instability may remain. Ignoring symptoms can lead to chronic knee problems.
OrthoIllinois Knee Center is a leading bone and joint provider serving communities throughout northern Illinois. The team offers comprehensive knee care, from initial injury evaluation to advanced treatment options.
If you experience knee pain after a fall, collision, or sports injury—especially if the knee feels unstable or swollen—prompt evaluation is important contact OrthoIllinois Knee Center to schedule a consultation. Accurate diagnosis and timely treatment can protect your knee function and reduce the risk of long-term complications.
Posterior cruciate ligament injuries may be less common than ACL tears, but they should never be overlooked. With expert evaluation and comprehensive care, patients can return to daily activities and athletic performance with improved stability and confidence.
