Knee
PCL Injuries
There are three bones that make up the knee joint – the femur (thigh bone), the tibia (shin bone), and the patella (kneecap). There are two cruciate ligaments—Posterior Cruciate Ligament (PCL) and Anterior Cruciate Ligament (ACL)—inside the knee joint that cross to form an X. The PCL sits in the back of the knee joint, while the ACL sits in the front of the knee joint. Together, they help control the front-to-back motion of the knee, as well as rotation.
What is the PCL?
The PCL is one of two cruciate ligaments in the knee joint that cross to form an X. It is a vital structure that helps stabilize the knee and control its movement. The PCL is the largest and strongest ligament in the knee. It has two very distinct portions: one that goes from the back of the tibia to the roof of the femoral notch (in the thigh bone) called the anterolateral bundle, and a second smaller portion that goes to the side of the notch called the posteromedial bundle. Both bundles work together to prevent the knee from slipping backward, especially when it is bent. However, as they have different attachments, they have different primary functions, and therefore, it is necessary to reconstruct both bundles when the PCL is torn.
How does the PCL work?
Recall that the PCL has two bundles: the anterolateral bundle and the posteromedial bundle. The anterolateral bundle prevents excessive front-to-back motion of the tibia while the posteromedial bundle prevents excessive rotation of the tibia.
Two important structures associated with the PCL are the meniscofemoral ligaments. These are small ligaments that can sometimes be found in the knee joint. These structures attach to the lateral meniscus and follow a similar course alongside the PCL in order to attach to the femur. One of meniscofemoral ligaments attaches in the front of the posterior cruciate ligament (Ligament of Humphrey’s) and the other attaches in the back (Ligament of Wrisberg). The anterior one is present in 30% of patients and the posterior one is found in 60% of knees. Both ligaments help the PCL and prevent the knee from slipping backwards.
What causes a PCL injury?
Given the PCL’s size and strength, it takes a significantly traumatic injury to tear it. Consequently, a PCL tear by itself, called an isolated PCL tear, is not that common. Instead, PCL injuries are usually associated with other ligamentous injuries (MCL, LCL or ACL). Most isolated PCL tears occur as a result of an injury to the front of the knee when it is bent. Falling on a bent knee while playing sports, slipping on ice, or hitting a dashboard during a traffic accident are some common ways that the PCL is torn.
How common are PCL injuries?
A recent epidemiologic study reported that the incidence of isolated torn PCL’s is 2 per 100,000 in the general population, with more injuries in male subjects. However, the incidence of combined PCL injuries is much higher.
What are the symptoms of a PCL injury?
Patients can present with swelling, discomfort, and pain, typically when the knee is bent. When combined injuries are diagnosed, severe instability can be present. In these cases, arteries or nerves can be compromised, and therefore, it is important to rule these injuries out.
How do you diagnose a PCL injury?
The combination of a detailed history, comprehensive physical examination, x-rays, and an MRI (magnetic resonance imaging) is the key to a successful diagnosis of a PCL injury. Dr. Bryan Penalosa and his team use stability tests as part of the physical exam, including the Posterior Drawer test, Supine Internal Rotation (IR) test, quadriceps active tests, and degree of posterior sag to properly diagnose a PCL Injury.
Because isolated PCL injuries are rare, imaging studies, such as an MRI, are important to evaluate the full extent of your injuries.
Moreover, an important thing to evaluate is the actual posterior cruciate ligament function. While it can look normal and healthy on MRI after 6 months, it can heal in an elongated position. Although it looks “normal” on MRI, it might not be functioning properly in the knee. Think of a rubber band that has been stretched and subsequently cannot return to its previous tautness. To help determine if this has occurred, one special test that is used to determine the severity of your pathology are kneeling stress x-rays. These special x-rays allow for objective quantification and diagnose (based on validated systems) of a partial, complete, or combined PCL injury with millimeter accuracy. With this information, Dr. Bryan Penalosa can provide an accurate diagnosis and treatment plan.
What are the severities of a PCL injury?
PCL injuries can be classified into different types based on the severity and extent of the damage to the PCL fibers. The grading of severity is based on the amount of ligament disruption and the extent of knee instability present following an injury. It is important to accurately diagnose the extent of a PCL injury, as the appropriate treatment plan can vary based off the type of PCL injury that an individual has suffered.
Grade 1 PCL Sprain
This is a small partial tear of the PCL, meaning that the ligament is stretched but not completely torn. The knee may still demonstrate some stability, and conservative treatment such as rest, physical therapy, and bracing can be effective in promoting healing and restoring function.
Grade 2 PCL Sprain
This is a moderate, or near complete tear of the PCL. The ligament may be partially torn, resulting in some instability in the knee joint, although there are some fibers that remain intact. Treatment options may include physical therapy, bracing, and possibly surgery in some cases.
Grade 3 PCL Sprain
This is a complete tear of the PCL in which the ligament is no longer functional. The PCL is fully ruptured, leading to significant instability in the knee joint. Usually, this occurs with injuries to other knee ligaments (most commonly the posterolateral knee structures). Grade 3 PCL tears often require surgical intervention to repair or reconstruct the damaged ligament, followed by rehabilitation and physical therapy to regain knee stability and function.
PCL Injuries Non-Surgical Treatment
Can a PCL injury be treated without surgery?
When it comes to discussing the treatment options for a PCL injury, the first question that comes to mind for many patients is: Can a PCL injury heal on its own? The answer is yes—most isolated PCL injuries (Grade I and II) often heal on their own. This is because the posterior cruciate ligament has a dense sheath that offers protection while it is healing. If the patient only has a PCL injury, conservative treatment can be attempted for partial tears (grade I and II). The conservative approach involves rest, ice, oral analgesia, physical therapy, and a dynamic PCL brace.
For patients who are candidates for conservative treatment, the focus of care will be on reducing pain, swelling, and inflammation, while also improving overall stability and function of the knee.
Rest and Activity Modification:
Initially following the injury, it’s essential to rest the knee and avoid activities that worsen the pain or lead to episodes of instability. Repetitive episodes of instability can lead to further damage of other structures of the knee joint, including the cartilage of the patellofemoral joint (under the kneecap). Therefore, activities that include pivoting, lateral movement, cutting, jumping, or quick deceleration from running may need to be avoided following a PCL injury in order to avoid instability episodes.
Oral Anti-Inflammatories, Ice, and Compression:
Oral anti-inflammatory and pain-relieving medications, such as Meloxicam, Naproxen, Advil, or Ibuprofen, may help to manage the pain and reduce inflammation of the knee following a PCL injury. Applying ice packs and compression to the knee can also help reduce swelling and inflammation. Remember to use a cloth or towel between the ice pack and your skin to avoid frostbite.
Physical Therapy:
A structured physical therapy program can be beneficial for strengthening the muscles around the knee and improving overall joint stability. However, physical therapy for a posterior cruciate ligament injury is somewhat more restrictive than for an ACL injury, as higher degrees of knee flexion can stress the PCL. Therefore, the physical therapy following a PCL injury should be focused on quadriceps muscle activation while avoiding hamstring activation. Too much activity from the hamstrings will pull the tibia backwards, which can stretch the healing of the PCL. It is important to complete any home exercises that your physical therapist provides to you in order to optimize your recovery.
Proprioceptive Training:
Proprioceptive training can enhance knee stability. Proprioception is the body’s ability to sense joint position and movement, and improved proprioception can help with knee stability and control during activities.
Functional PCL Brace:
A functional posterior cruciate ligament (PCL) brace is a specialized dynamic knee brace designed to provide support and stability to the knee joint in cases of PCL injuries or instability. Recall that a higher degree of knee flexion and hamstring activation will pull the tibia backwards, which can stretch the healing of the PCL. For this reason, a brace is usually needed to avoid PCL instability episodes. It is important for the patient to understand this reason for wearing the brace.
While a functional brace cannot fully replace the role of the PCL, it can help limit certain movements that could put additional stress on the knee and reduce the risk of further injury during physical activities. Here’s how a functional PCL brace works:
- Mechanical Support: The brace provides mechanical support to the knee by limiting excessive movements, such as backward sliding of the tibia relative to the femur. Recall, that this is the primary function of the PCL.
- Stabilization: The functional brace helps stabilize the knee joint. The brace typically exerts posterior pressure on the tibia, pushing it forward slightly to mimic the role of the intact PCL in preventing excessive backward movement of the tibia. This helps protect the PCL from further strain while promoting healing.
- Protection: A functional PCL brace is particularly useful for providing support during physical activities and sports that involve jumping, running, or sudden changes in direction. By applying the posterior pressure to avoid the tibia from sliding backwards, the PCL brace can help reduce the risk of further injury and provide confidence to the wearer.
Intra-Articular Knee Injections:
The goal of an intra-articular injection is to manage pain and inflammation of the knee. Therefore, injections may be used as a short-term measure to manage these symptoms following an injury. However, it’s crucial to understand that an intra-articular injection will not heal the torn PCL itself, nor will it provide long-term stability to the knee. Additionally, receiving an intra-articular injection to the knee will delay any surgical intervention for at least 3 months following the administration of the injection.
PCL Injuries Surgical Treatment
What are the surgical treatment options for a PCL injury?
For patients with combined ligamentous injury, chronic cases, or those that remain symptomatic despite the conservative treatment, surgery is recommended. PCL surgery is similar to ACL surgery in that it involves drilling tunnels into your tibia and femur before fixing a graft into those tunnels. However, because the PCL is bigger than the ACL, it typically requires two grafts to truly replicate the anatomy and biomechanics. An Achilles tendon allograft and a hamstring tendon allograft are the two most often used grafts for the double-bundle PCL reconstruction gold-standard technique.
Although a more challenging technique, substantial evidence suggests that the double bundle technique (two grafts) is superior in terms of knee function and stability compared to a single bundle PCL reconstruction. Recall that the PCL has two bundles: the anterolateral bundle and the posteromedial bundle. The anterolateral bundle prevents excessive front-to-back motion of the tibia, while the posteromedial bundle prevents excessive rotation of the tibia. Thus, as the two bundles have different primary functions, it is necessary to reconstruct both bundles when the PCL is torn.
Recovering from PCL Surgery
How long is the recovery from a PCL surgery?
Your recovery from a PCL surgery will begin the first day after your operation. Immediate physical therapy intervention allows for optimal recovery of one’s range of motion and quad re-activation according to the PCL reconstruction protocol. Patients should not bear weight on the operative leg for the first 6 weeks after surgery. After this initial period, they may progress from crutches. Patients can usually return to driving 2-3 weeks after they are able to walk. Endurance and strengthening can be started in the second phase of rehabilitation. Agility exercises start at 4 months along with the running progression if previous stages have been successfully completed. Depending on the severity of the injury and other associated ligament injuries, recovery can be between 6 to 12 months, with return to sport expected no earlier than 9 months post-op. A study was recently published looking at 100 patients that underwent a PCL reconstruction demonstrating excellent outcomes with restoration of the knee kinematics (similar movement and stability to the healthy knee) with a minimum follow up of 2 years.
Effects of Untreated PCL Avulsion
What are the long-term effects of an untreated PCL avulsion injury?
An untreated PCL avulsion injury can have several long-term effects on the knee and overall joint health. The PCL plays a critical role in stabilizing the knee joint, and when it is injured and left untreated, the following complications may arise:
Chronic Knee Instability:
Without proper treatment, a PCL injury can lead to chronic knee instability. This instability can make activities that involve weight-bearing, such as walking and running, difficult and painful.
Progressive Knee Joint Damage:
An untreated PCL injury may lead to further damage to the knee joint over time. This can include additional ligament, meniscus, or cartilage injuries, which can compound the knee’s instability and decrease its function.
Osteoarthritis:
Over the long term, untreated PCL injuries can significantly increase the risk of developing osteoarthritis in the knee, particularly in the patellofemoral compartment. The instability and altered mechanics of the joint can accelerate the degeneration of the articular cartilage, leading to pain, swelling, and reduced joint function.
Decreased Quality of Life:
The cumulative effects of chronic pain, instability, and limited mobility can significantly reduce an individual’s quality of life, making it challenging to participate in everyday activities and sports.