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Knee Ligament Injury

LCL Injury

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Posted 1 year ago


Last updated: 29/11/2022


by James McCormack

James McCormack
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The LCL is the lateral collateral ligament, in this article we will be discussing the LCL of the knee. There is also a lateral collateral ligament at the elbow, which will not be covered. A ligament is a thick strong band of connective tissue, that attaches one bone to another. Their function is to keep the bones together but allow for movement in some directions while preventing movement in others.

Diagram of lateral collateral ligament

Anatomy and Function of the LCL

The LCL is located on the outside of the knee, connecting the femur bone of the thigh, to the fibular bone of the shin. The main function of the LCL is to provide lateral stability to the knee by preventing varus movement. The attachment of the LCL to the fibula is interlinked with the iliotibial band which also provides lateral stability to the knee.

In addition to lateral stability, the LCL’s function is also to help prevent unwanted rotation of the knee and hyperextension. This action is particularly important if the cruciate ligaments are injured.

Common Symptoms:

  • Pain located at the outside of the knee
  • Swelling at the outside of the knee
  • Bruise on the outside of the knee and upper outer calf
  • Instability, feeling your leg might give way or buckle
  • Tightness in the quadriceps and lateral leg muscles

Less Common Symptoms:

  • Clicking or catching
  • Locking, the knee feeling stuck in a position

LCL Tear Symptoms

Injury to the lateral collateral ligament can range from minor strains to compete tears. The ligament is stretched beyond its capacity and there can be damage to the fibres of the ligament.

Tears are graded 1 to 3 relating to the level of injury to the ligament.


Grade 1:

Minor ligament damage with no laxity. Symptoms will include pain, minor swelling, minor bruising if any and no instability.

Grade 2:

Moderate ligament damage with laxity. Symptoms will include pain, significant swelling, significant bruising and instability.

Grade 3:

Severe ligament damage or complete rupture. Symptoms will include pain, extensive swelling, extensive bruising and instability and loss of varus control.

Photo of football tackle

How are LCL injuries Caused?

Most lateral collateral ligament injuries are caused by impact and force to the inside of the knee, pushing it outwards. While injury to the LCL is relatively uncommon, compared to other knee injuries it is seen often in contact sports such as football, rugby and wrestling sports such as jiu-jitsu. Or from falls with sports such as skiing, climbing or gymnastics.

This study found that of all knee injuries in the sporting population only 1% were to the LCL (Majewski et al, 2006).

Due to the high force needed to injure this ligament, it is most commonly seen in the younger athletic population than any other.

Diagnosis of LCL Injury

Assessment of a suspected LCL injury is best done by an experienced physical therapist or sports doctor, as they will need to consider differential diagnoses that can have similar symptoms. There are several other injuries that can present with pain and swelling to the outside of the knee, such as iliotibial band syndrome or a lateral meniscus injury. Your doctor or physical therapist will discuss with you the mechanism of your injury and the symptoms you have experienced to direct the physical examination.

Diagnosis can be confirmed with radiological imaging such as MRI or ultrasound scans.

Photo of ultrasound of knee

Knee LCL Test

One of the important tests to be included during an examination of a suspected LCL injury is the adductor or varus stress test. A positive test will reproduce the patient’s pain and in many cases laxity of the joint, or excess varus movement. 


The femur is held stable while the shin (often held at the ankle) is adducted, and moved inwards. This knee LCL test should be carried out with the knee in full extension and in 20-30º of flexion.

Physiotherapy with James McCormack

This is not medical advice. We recommend a consultation with a medical professional such as James McCormack. He offers Online Physiotherapy Appointments for £45.

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