What are Posterolateral Corner Injuries?
Posterolateral corner (PLC) injuries are defined as damage to a complex area of the knee formed by the association of 3 main structures of the knee, namely popliteus tendon, popliteofibular ligament, and lateral (fibular) collateral ligament. Injuries to the posterolateral corner often occur in combination with anterior cruciate ligament (ACL) or posterior cruciate ligament (PCL) tears with isolated PCL injuries occurring rarely. PLC injuries most commonly occur as a result of motor vehicle accidents and sports activities. Left untreated, it can lead to chronic pain, instability, and early degenerative changes of the knee joint.
The knee is the most complex joint in the body and is formed by the articulation of the thighbone (femur) and shinbone (tibia). A kneecap is present over the front of the joint to provide extra protection. These bones are held together by four strong rope-like structures called ligaments. Two collateral ligaments called the medial collateral ligament (MCL) and lateral collateral ligament (LCL) are present on either side of the knee, which control the sideways movement of the knee. The other two ligaments are the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) present in the center of the knee joint and cross each other to form an “X”. The cruciate ligaments control the back and forth movement of the knee.
Causes of Posterolateral Corner Injuries
Posterolateral corner injuries are sports-related injuries that occur when the knee is forcefully twisted or hyperextended. The injuries are mostly related to direct anteromedial tibial impact trauma but can also be caused by an abrupt directional change when the foot is fixed on the ground or when the deceleration force crosses the knee. Changing direction rapidly, stopping suddenly, slowing down while running, landing from a jump incorrectly, and direct contact or collision, such as a motor vehicle collision or a football tackle can all result in posterolateral corner injuries.
Signs and Symptoms of Posterolateral Corner Injuries
Some of the signs and symptoms of posterolateral corner injuries include:
- Difficulty walking
- A popping sound
- Buckling sensation in the knee
Diagnosis of Posterolateral Corner Injuries
The diagnosis of posterolateral corner injuries are made by reviewing your symptoms and medical history, and performing a thorough physical examination of the knee with gait exam, along with clinical tests such as posterolateral drawer test, varus stress test, dial test, reverse pivot shift test, and external rotation recurvatum test. Other diagnostic tests such as X-rays, MRI scans, stress tests of the ligament, and arthroscopy may also be ordered for detailed examination of the bone structure and soft-tissue injuries.
Treatment of Posterolateral Corner Injuries
Treatment of posterolateral corner injuries is based on the degree or severity of the injuries, which is classified into Grade I, II, and III.
- Grade I: Sprain with no rupture of capsuloligamentous structures
- Grade II: Partial damage to ligament with moderate disruption
- Grade III: Complete disruption of ligament
Grade I and Grade II posterolateral corner injuries usually respond well to non-surgical treatment management, which normally involves immobilization of the knee with full extension for 4 weeks using a hinged knee brace technique followed by physical therapy. Knee immobilization promotes healing of the injury and physical therapy strengthens the ligament. Return to sports may take about 8 weeks.
Surgical intervention is the treatment of choice for those symptomatic patients who have failed non-surgical treatment management and for Grade III posterolateral corner injuries with cruciate tears or in isolation. It is recommended that all three injuries are managed in conjunction when anterior cruciate ligament and posterior cruciate ligament tears are present in order to accomplish the best possible outcome. The most common surgical method employed is the anatomical reconstruction of the posterolateral corner injuries utilizing a hamstring autograft (tissue taken from your own body). Reconstruction using an allograft (tissue taken from a donor) is considered for repair of multiple ligament injuries. The main objective of the surgical repair/reconstruction is to gradually restore range of motion, proprioception, strength, and dynamic function of the knee.