What the LCL does
The LCL is a strong band on the outer side of the knee. Together with other structures of the posterolateral corner, it resists forces that push the knee outwards (varus stress) and helps control rotation. The common peroneal nerve runs close by, around the top of the fibula.
How the LCL is injured
- A blow to the inner side of the knee pushing it outwards.
- Twisting or pivoting with the foot planted.
- Landing awkwardly from a jump.
- Contact sports, wrestling, skiing and gymnastics.
- Road traffic accidents and falls.
Symptoms of a torn LCL
- Pain and tenderness on the outer side of the knee.
- Swelling and bruising.
- Stiffness and difficulty bending.
- A feeling that the knee buckles outwards when walking or turning.
- Numbness, tingling or weakness lifting the foot, if the peroneal nerve is affected.
Outer knee pain that starts gradually in runners is more often iliotibial band irritation; see IT band stretches.
Grades of LCL injury
- Grade 1: stretched ligament, tenderness, no instability; 1 to 3 weeks.
- Grade 2: partial tear, some looseness; 3 to 8 weeks.
- Grade 3: complete tear, clear instability, often with other injuries; may need surgery.
How it is diagnosed
A physiotherapist or doctor examines the knee, gently stressing the outer side with the knee straight and slightly bent to assess looseness, and checks the cruciate ligaments, meniscus and nerve function. X-rays rule out fractures, including a small fragment pulled off the fibula. MRI shows the extent of the tear and any associated injuries.
First steps
- Rest from sport and painful activity.
- Ice for 15 to 20 minutes several times a day.
- Compression and elevation.
- Crutches if walking is painful.
- Simple painkillers if appropriate.
Non-surgical treatment
Grade 1 and 2 LCL injuries usually heal without surgery. A hinged knee brace protects the ligament from outward stress while allowing bending. Weight-bearing is increased as comfort allows, and rehabilitation starts early to restore movement and strength.
Compare with MCL injury on the inner side of the knee.
Rehabilitation exercises
- Early: quad sets, heel slides and straight leg raises.
- Strength: mini squats, bridges, hamstring curls, step-ups and leg press.
- Hip strength: side-lying leg lifts and clamshells.
- Balance: single-leg standing, progressing to unstable surfaces.
- Sport: jogging, side-stepping, cutting and jumping when cleared.
See hamstring stretches and quad stretches.
When surgery is needed
Surgery is considered for complete tears with significant instability, injuries to the posterolateral corner or cruciate ligaments, or a bone fragment pulled away. Repair is best done within a few weeks of injury; later, reconstruction with a graft may be needed. Return to sport typically takes 6 to 12 months.
See meniscus tear for another common associated injury.
Recovery time and return to sport
Return to sport is based on criteria rather than time alone: no swelling, full movement, strength close to the other leg, good balance and confidence with sport-specific movements. Returning too early increases the risk of re-injury.
Injuries that often come with an LCL tear
- Posterolateral corner injury: damage to the structures at the back and outside of the knee, which can cause rotational instability.
- ACL or PCL tears: particularly with high-energy injuries.
- Meniscus tears.
- Peroneal nerve stretch: causing foot numbness or weakness.
Missing these injuries can lead to ongoing instability, which is why severe LCL tears need a thorough assessment and MRI.
Using a knee brace
A hinged brace limits outward movement of the knee while allowing it to bend. It is usually worn for 2 to 6 weeks depending on the grade, during walking and activity. Your physiotherapist will advise when to wean off it, and some athletes use a brace when returning to sport.
When to seek urgent help
- Inability to lift the front of the foot (foot drop) or numbness on the top of the foot.
- A very unstable knee or obvious deformity.
- Inability to bear weight.
- Severe swelling soon after injury.
- A cold, pale or blue foot.
Key points to remember
- The LCL stabilises the outer side of the knee.
- Most grade 1 and 2 tears heal with bracing and rehab in 2 to 8 weeks.
- Complete tears with other damage may need surgery.
- Foot numbness or weakness needs prompt assessment.
Questions about LCL tears
These answers are general information and do not replace an examination or individual medical advice.
How long does a torn LCL take to heal?
Grade 1 takes 1 to 3 weeks, grade 2 about 3 to 8 weeks; surgery means 6 to 12 months.
Can you walk with a torn LCL?
Often yes, with a brace and sometimes crutches.
Does an LCL tear need surgery?
Most do not; complete tears with other injuries may.
Is an LCL tear worse than an MCL tear?
LCL tears are less common and more often occur with other injuries.
What does a torn LCL feel like?
Pain on the outer knee and a feeling of buckling outwards.
Can an LCL tear heal on its own?
Partial tears usually heal with protection and rehab.
Why does my foot feel numb after a knee injury?
The peroneal nerve near the LCL may be stretched; get it checked promptly.
Can I drive with an LCL injury?
When you can brake firmly and safely without pain and are not wearing a restrictive brace on the driving leg.
What is the difference between LCL and MCL?
The MCL is on the inner side of the knee; the LCL is on the outer side.
Sources
- OrthoInfo (AAOS) · Collateral ligament injuries
- NHS · Knee pain
- OrthoInfo (AAOS) · Anterior cruciate ligament (ACL) injuries
This guide is for general information and does not replace medical advice. How a problem is diagnosed and treated depends on your examination and medical history. If you think you have an emergency, contact your local emergency services.