LCL / PLC
Lateral Collateral Ligament
Posterolateral Corner
Phone +971-2-4446600
Anatomy
The lateral side of the knee is a complex combination of structures, including several ligaments, the iliotibial band, the proximal tibia-fibula joint, muscles and nerves.
When talking about a lateral sided injury to the knee, it can be everything from a single ligament tear to a combined injury to all these structures.
The primary role of the ligaments is to stabilize the knee in lateral direction and both internal and external rotation. The major muscle, the biceps tendon, attaches on the top of the fibula and helps to externally rotate the lower leg and to bend the knee. The most important nerve in the area, the common peroneal nerve, can result in inability to lift your foot, dropfoot, if injured or stretched during injury.
Injury
Varus force, meaning the knee buckling in a lateral direction, in combination with rotation is the most common way to get a lateral or posterolateral injury to the knee. It usually occurs in combination with ACL and/or PCL tears and requires higher forces to break, for instance a high energy trauma like a car crash or possibly a sports injury commonly involving a tackle of some sort.
As with any ligament tear, the pain and swelling usually subsides, but the main remaining symptom is instability to the knee, specifically lateral buckling of the knee.
However, with a complete posterolateral corner injury, the three structures, lateral collateral ligament (LCL), popliteus tendon and popliteofibular ligament (PFL), are torn resulting in increased varus laxity and external rotation, leaving the knee with significant instability.
Positive LCL Stress X-rays
Evaluation
Often, the history can be diffuse as the trauma was high energy and happened quickly, and therefore examination is crucial in suspecting and identifying lateral injuries. Varus stress test and rotational tests can show the instability, but even just a simple evaluation of your standing position or walk can show signs of lateral injury. MRI is crucial to evaluate these injuries and as they are very rarely isolated, other injuries must be suspected and closely evaluated as well.
X-rays play a significant role as you can put pressure on the knee in any direction and take x-ray images to evaluate what happens during this stress. This will give you further information to grade the instability and is particularly useful when the injury is a bit older.
Increased varus laxity during examination due to posterolateral corner injury
Treatment
Sprains with no or minimal instability can be treated with brace and physiotherapy and has good outcomes.
The lateral ligament complex heals poorly and therefor is commonly, if unstable, treated with surgery. Surgery is planned depending on the evaluation with everything from a single ligament reconstruction, generally LCL or popliteus tendon reconstructions, to a fully open reconstruction of all structures, including three ligaments, biceps tendon reinsertion, fracture reduction and fixation and nerve exploration.
Doing early surgery (within 6 weeks) for these injuries have shown to be beneficial to get back to all activity levels, but even with more chronic instabilities the surgery is aiming to stabilize the knee and increase quality of life.
Image of posterolateral corner reconstruction of both LCL, PFL and Popliteus
Rehabilitation
After surgical reconstruction of the lateral side there is need to offload the knee, meaning you will be non-weightbearing or mildly partially weightbearing for the first 6 weeks and thereafter wean off the crutches. During this first phase of rehabilitation, you will still need physiotherapy to activate the muscles around the knee and work on your range of motion.
After about 8 weeks you can walk and drive a car again, and since these injuries are rarely isolated, the most common progress is to get back to running at 4-6 months and full recovery take up to 9-12 months.