Lateral Collateral Ligament Injury of the Knee

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This article is currently under review and may not be up to date. Please come back soon to see the finished work! (2 May 2024)

Definition/Description

An injury to the lateral collateral ligament (LCL) of the knee can be caused by varus stress, lateral rotation of the knee when weight-bearing or by repeated varus stress . An injury of the lateral collateral ligament most often occurs from a varus force or by twisting the knee. Such an injury occurs in sports with a lot of quick changes in direction or with violent collisions. Examples are soccer, basketball, skiing, football or hockey.

The LCL can be sprained (grade I), partially ruptured (grade II) or completely ruptured (grade III) .

Additional damage of the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL) and medial knee structures is possible when the lateral knee structures are injured .

Clinically relevant anatomy

The LCL is a structure of the arcuate ligament complex, together with the biceps femoris tendon, popliteus muscle and tendon, popliteal meniscal and popliteal fibular ligaments, oblique popliteal, arcuate and fabellofibular ligaments and lateral gastrocnemius muscle.

The LCL is a strong connection between the lateral epicondyle of the femur and the head of the fibula, with the function to resist varus stress on the knee and tibial external rotation and thus a stabilizer of the knee. When the knee is flexed to more than 30°, the LCL is loose. The ligament is strained when the knee is in extension.

See LCL anatomy for more detailed anatomy.

Epidemiology/Etiology

Injuries to the lateral and medial collateral ligaments are common, however, MCL injuries occur more often than the LCL injuries.

25% of patients in the United States with an acute knee injury in emergency rooms have a collateral ligament injury. Adults aged between 20-34 and 55-65 years old have the highest incidence.

LCL (and MCL) injuries occur equally for men and women.

These injuries are normally successfully treated with conservative methods.

Surgery can be necessary in extreme cases, however, there is a good prognosis.

Characteristics/Clinical presentation

Acute

• Knee swelling
• Pain
• Lateral joint line pain
• Pain with varus stress test
• Increased varus movement with varus stress testing
• Reduced ROM
• Difficulty to fully weight bear
• Weakness of the quadriceps and inability to straight leg raise.
• Instability and giving way
  

Sub-acute

• Lateral knee pain
• Stiffness end of range flexion or extension
• Weakness of effected leg
• Possible further giving way

Persistent/chronic

• Unspecific knee pain
• Significant weakness in whole of kinetic chain
• Potential giving way
• Mal-adaptive movement patterns

Differential diagnosis

• Injury at the posterolateral corner
• PCL tear
• ACL tear
• Meniscus tear/ injuries
• Popliteus avulsion
• Iliotibial Band Syndrome
• Distal hamstring tendinopathy
  

The LCL is not connected with the lateral meniscus, so it is not automatically associated with a meniscal tear.

LCL injuries often occurs along with other ligament injuries, including ACL, PCL, and MCL, and is frequently seen along with knee dislocations.

Diagnostic procedures

Diagnosis can usually be made following the subjective assessment depending on the mechanism of injury. LCL injury is normally accompanied by ACL or posterio-lateral corner injury so ensure screening of these are completed see ACL screening.

Objective assessment

1. Observation
2. Palpation
3. Active range of movement (ROM)
4. Muscle testing
5. Gait analysis
6. Special tests including ligament laxity testing: varus, valgus, anterior/posterior draw, lachmanns

7. Neurological exam (if required)

In objective assessment it may be useful to grade the level of sprain:

Grade I:

• Mild tenderness and pain over the lateral collateral ligament
• Usually no swelling
• The varus test in 30° is painful but doesn’t show any laxity (< 5 mm laxity)

Grade II:

• Significant tenderness and pain on the lateral collateral ligament and on lateral side of the knee
• Swelling in the area of the ligament
• The varus test is painful and there is laxity in the joint with a clear endpoint. (5 -10mm laxity)

Grade III:

• The pain can vary and can be less than in grade II
• Tenderness and pain at the lateral side of the knee and at the injury
• The varus test shows a significant joint laxity (>10mm laxity)
• Subjective instability
• Significant swelling

The peroneal nerve can also be injured which can be identified by a foot drop. of the patient while he is walking or when the patient feels a numbness or weakness in the foot.

Outcome measures

International Knee Documentation Committee Subjective Knee Form

Oxford Knee Score

Medical management

Conservative management

Conservative management of LCL injuries can be considered in grade I or II sprains.

This approach mainly consists of physiotherapy which is discussed in the following paragraph.

Surgical management

Grade III sprains are more severe, the anterior cruciate, posterior cruciate ligaments or posterio-lateral corner may also have become damaged. In this case surgery can be needed to prevent further instability of the knee joint.

The goal of surgical management is to achieve a stable, well aligned knee with normal biomechanics.

Surgical management of LCL injuries normally involve reconstruction of the LCL sometimes using ITB.

Post operative rehab

Post operative rehabilitation can involve an altered weight bearing status for the first six weeks. This is likely to be partial-weight bearing but when extensive additional surgery has been undertaken it could be non-weight bearing.

A knee immobiliser may also be used to limit valgus/varus stresses on the knee as well as stop the knee flexing during gait.

Early ROM exercises should be encouraged in a non-weight bearing position.

After the initial post operative phase normal rehab can start as detailed in the physiotherapy management. It is useful to note that if a mensical repair is also done deep squats should be avoided for the initial four months.

Physiotherapy management 

For general: Ligament injury management

Initial management:

• POLICE or RICE
• Analgesia
• Bracing in a knee immobiliser or adjustable brace which allows limited flexion but full extension.
• Early mobilisation of the knee should be encouraged
• Quadriceps activation exercises
• Electrical stimulation can also prevent the muscles wasting due to immobilisation. 

Strength:

A combination of open and closed kinetic chain exercises is used to increase hamstrings, quadriceps, gluteal and triceps sural strength. The goal of these exercises is to improve the control of the knee joint with weight-bearing activities.These exercises must not produce patellofemoral pain or increase collateral ligament pain. Once the patient is ambulating in full weight bearing, stork standing (Therapist flexes patients hip on the involved side to 90 degrees and applies direct downward force through the femur while stabilizing sacrum) and other balance activities can begin.The patient can be treated with specific techniques, including isometric, isotonic, isokinetic and eccentric exercices. 

Normal range of motion:

If full motion is not achieved by around week 5 or 6, joint mobilization techniques and prolonged stretches may be required.

Aerobic conditioning:

Walking on the treadmill with progression to jogging occurs once a normal walking gait has been achieved. Jogging then progresses to running and sprinting as long as pain and edema are avoided.

Static bike or cycling can be started in the early part of rehab due to the limited weight bearing of activity, this can also help to promote ROM.

Swimming or pool walking can also be introduced in the early rehab stages due to reduced weight bearing, however it is advisable not to do breast stroke due to the rotational elements.

Proprioceptive retraining:

Just as with others injured areas, balance, agility, and coordination must be restored following knee injury or surgery. Proprioception is the element basic to these parameters. Early proprioception exercises before weight bearing can include a variety of activities. For example, with eyes closed the patient can move the involved knee to mimic the uninvolved knee’s position, or with eyes closed can position the knee at a designated angle.

Most of the time an injury of ligaments will take quite a long time, because of the difference in density. It’s important to work as well psychical as physical. The patient has to be motivated and encouraged for a longstanding, intensive rehabilitation.

LCL injuries can be grouped into classes. Grade I injuries show normal or up to 5 mm of joint space opening with a solid endpoint. A similar solid endpoint is observed with grade II injuries, but opening up to 10mm. Grade III injuries demonstrate greater than 10 mm of joint space opening and often are associated with other ligament injuries. There are differences in treatment in the classes. With grade I and II injuries, a brace at 45 degrees for 4-6 weeks is enough. Progressive range of motion after 3 weeks as comfort allows enables progression in rehabilitation. But with an injury grade III there is a surgery necessary due to rotational instability, because they usually involve the posterolateral cornor of the knee. After the surgery, you need a brace and physical therapy for prevent the instability.
Periodic evaluations at 2 to 4 weeks are required for operative and nonoperative management

Clinical Bottom Line

An injury to the lateral collateral ligament of the knee can be caused by varus stress, lateral rotation or by degeneration. Additional damage of the ACL, PCL, posterio-lateral corner and medial knee structures is possible with an LCL injury. In case of a grade III sprain, surgery may be needed to prevent further instability of the knee joint. Conservative management is always the initial treatment choice.  

Resources

LCL knee anatomy

Ligament injuries