The Lateral Collateral Ligament (LCL) is one of the knee joint’s key stabilisers and it prevents excess varus stress and posterolateral knee rotation. An LCL injury is one of the least common to occur in the knee when compared to ACL and MCL injuries. Despite this, injuries to the LCL can occur with high-energy blows to the anteromedial knee, combining hyperextension and extreme varus force. The LCL is very rarely injured in isolation, but is injured alongside other knee structures in 7% – 16% of all ligamentous injuries. Contact sports make up for 40% of LCL injuries and other mechanisms of injury may be motor vehicle accidents or falls.
Risk factors for LCL injuries include female gender and participation in high contact sports. These sports may include soccer, tennis, and gymnastics. Following an incident, sudden lateral knee pain and swelling will occur. You may also experience lateral lower extremity paresthesias and weakness, or foot drop.
An LCL injury will be classified into one of three grades, depending on the severity:
- Grade 1: mild sprain with localised lateral knee tenderness and without instability or mechanical symptoms.
- Grade 2: partial tear with severe, localised lateral and posterolateral knee pain and swelling.
- Grade 3: complete tear causing variable pain and swelling with mechanical and laxity symptoms present. This usually involves the PLC or other structures.
Frequently Asked Questions
How is a lateral collateral ligament injury diagnosed?
Your physiotherapist will collect a full medical history including previous knee injuries, previous surgeries, your occupation, recreational activities and living situation. A physical examination will include observation and palpation of the injured knee, as well as an assessment of your knee range of motion. Special tests can be used to diagnose an LCL injury, where a Varus stress test is the most helpful in assessing an LCL injury. Other tests that may be useful are external rotation recurvatum test, posterolateral drawer test and reverse pivot test.
If deemed necessary, you may be referred for imaging of your injured knee to determine the severity of the injury and observe any damage to surrounding structures. An MRI is the gold standard when diagnosing an LCL injury. However, an ultrasound can be used to quickly identify any damage to the LCL.
How is a lateral collateral ligament injury treated with physiotherapy?
An LCL tear will not self-heal and so the severity of the injury as well as damage to other structures are critical in determining the need for surgical intervention. Acute management may include compression, ice and anti-inflammatory medications to control pain and swelling.
Grade 1 or 2 LCL injuries with no instability at 0o knee flexion can be non-surgically managed. Immediately after an LCL injury, you should be non-weight bearing for 1 week and be placed in a hinged knee brace for 3-6 weeks.
A grade 3 tear will almost always be surgically repaired. For grades 1 and 2, or post-surgically for grade 3 LCL injuries, physiotherapy will begin with strengthening exercises of the quadricep and hamstring muscles as well as partial weight bearing activities to restore normal walking patterns. By week 4, these strengthening exercises will progress to closed kinetic chain exercises like squats, leg press and step ups to continue to load the joint and supporting muscles. Following week 8 and depending on the progress of your rehabilitation, you may begin sport-specific training, plyometric and dynamic exercises to challenge agility, balance and the stability of the knee. At 3-6 months post-injury, you may gradually return to your normal activities.