The posterior-lateral corner of the knee stabilizes the knee against forces that are directed externally. These injuries are very uncommon; however, when they do occur they can affect an athlete's performance in a very big way. Injury to the posterolateral corner causes pain at the posterior and external portion of the knee. Around 50% of the injuries are due to sporting activities. Traumatic accident is one more common cause for PLC injury.
About Posterolateral Corner (PLC)
The Posterolateral Corner (PLC) is formed of numerous ligamentous and tendinous structures present about the knee. Tendon is defined as a connective tissue which joins a muscle to a bone. A ligament is defined as a fibrous tissue that joins two bones together. The Posterolateral Corner (PLC) is located in the posterior-lateral corner of knee. There are many structures covering the Posterolateral Corner (PLC) of which the main structures are the following: Biceps femoris muscle, LCL, popliteus muscle, popliteal-fibular ligament, fabellofibular ligament, and posterolateral joint capsule. These structures are responsible to stabilize the joint of knee from external rotation forces on the knee.
Signs and Symptoms of Posterolateral Corner (PLC) Injury
The symptoms of this injury are dependent on the degree of the injury. The symptoms gradually increase in severity over time.
- Pain at posterior and external portion of knee.
- Swelling in the posterior and external portion of knee.
- Tenderness on the lateral side of knee.
- Instability of the knee.
- Hyperextension of knee.
- Affected people ambulate with the knee consistently bent so as to prevent hyperextension.
Causes and Classifications of Posterolateral Corner (PLC) Injury
The knee region generally gets injured due to hyperextension force from the front and inner part of the joint of knee. In the case of injuries during sporting activities, generally the soft tissue structures are torn from their bony attachments resulting in an injury. Posterolateral Corner (PLC) Injuries commonly happen in combination with other knee injuries, especially to the ACL and PCL and with tibial plateau fractures. Depending on the severity and degree of injury, Posterolateral Corner (PLC) Injuries are divided into grade 1, 2 or 3. This classification depends on the degree of joint gapping when the lateral joint is manually stressed along with the end feel when doing this movement.
The Following Are The Different Grades Of Injury:
- Grade 1 Injuries: They have a 5 mm gap with clear endpoint.
- Grade 2 Injuries: They have a 10 mm gap but with clear endpoint.
- Grade 3 Injuries: They have more than 10 mm gap with a very soft or even absent end-feel.
Treatment for Posterolateral Corner (PLC) Injury
Treatment of a Posterolateral Corner (PLC) Injury is determined by the intensity of the injury and the time lapsed after the injury and when the injury is diagnosed. Conservative treatment can be followed for grade 1 and mild grade 2 injuries. The knee is kept immobile in a hinged brace which allows complete range of motion and controlled weightbearing using a crutch or a cane for a period of a month. Subsequently, a progressive rehab program can be done concentrating on building strength and recovering full knee motion. Surgical treatment may be necessary for severe grade 2 and grade 3 injuries.
Acute injuries can be treated with repair whereas surgical reconstruction may be required for more chronic injuries. Repair cannot be done after acute period passes as there is development of scar tissue along with joint misalignment. Reconstructive procedures consist of a graft which may be taken from Achilles tendon, IT band, patellar tendon, semitendinosus tendon, or anterior or posterior tibialis tendons to reconstruct the torn structures.