Knee
PCL Avulsion 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.
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 avulsion 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) or meniscal injuries. 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 injured.
How common are PCL avulsion injuries?
While the majority of PCL injuries are intrasubstance tears, a small subset of injuries involves avulsion fractures off the femoral or tibial attachment of the PCL. PCL avulsion fractures at the femoral attachment are much less common than tibial-sided avulsion fractures.
What are the symptoms of a PCL avulsion 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 avulsion 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 avulsion 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 avulsion injuries are rare, imaging studies, such as an MRI, are important to evaluate the full extent of your injuries and rule out concomitant ligamentous or meniscal injuries.
Moreover, to help evaluate the functionality of the injured PCL, a special test called kneeling stress x-rays may be ordered to determine the severity of your PCL injury. These special x-rays allow for objective quantification and diagnosis (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.
PCL Avulsion Injuries Non-Surgical Treatment
Can a PCL avulsion injury be treated without surgery?
In cases of minimally displaced PCL avulsion injury, conservative treatment can sometimes be considered. For patients who are candidates for conservative treatment based off the degree of displacement of the avulsion fracture, 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 PCL avulsion fracture 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 Avulsion Injuries Surgical Treatment
What are the surgical treatment options for a PCL avulsion injury?
For patients with cases of a displaced PCL avulsion injury or for those that remain symptomatic despite conservative treatment, surgery is recommended. In a recent systematic review and meta-analysis study published by Dr. Bryan Penalosa and his research team in 2023, it was found that surgical treatment of PCL avulsion fractures achieves a high rate of fracture union with excellent restoration of posterior tibial translation. Surgical PCL repair can be completed either as an open or arthroscopic procedure. The study published by Dr. Bryan Penalosa suggested that displaced PCL avulsion fractures treated with either open or arthroscopic surgery will lead to the best outcomes and patient satisfaction.
During PCL repair, Dr. Bryan Penalosa will reduce the avulsion fracture back to the footprint of the PCL attachment. Since it is most common for the PCL avulsion injury to occur at the tibial attachment, the repair usually involves reducing the fracture at the PCL tibial attachment site.
During open PCL avulsion repair surgery, it is most common for the avulsed bone to be secured using a screw and washer fixation. For patients treated arthroscopically, typically a technique known as a transtibial suture pull-out fixation is used. In this case, sutures secured on the fractured bone piece are passed through a small tunnel in the tibia, pulling the piece of bone fragment back down to the tibia. Once the correct tension is set to keep the bone fragment in its correct anatomical place, a non-metal anchor or cortical button is used for fixation.
Recovering from PCL Avulsion Surgery
How long is the recovery from a PCL avulsion injury?
Your recovery from a PCL repair 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 Dr. Bryan Penalosa’s PCL repair 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.
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.
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