Skip to Main Content

Condition/Disorder Synonyms

  • LCL sprain

ICD-9-CM Code

  • 844.0 Sprain of lateral collateral ligament of knee

ICD-10-CM Code

  • S83.429A Sprain of lateral collateral ligament of unspecified knee, initial encounter

Preferred Practice Pattern

Key Features


  • Tear of the lateral collateral ligament of the knee

  • Graded based on extent of damage

    • Grade I: localized tenderness with no instability

    • Grade II: localized tenderness, moderate fiber disruption, slight to moderate abnormal motion

    • Grade III: complete fiber disruption, noted instability

Essentials of Diagnosis

  • Injury is generally traumatic, can occur at any age; trauma usually a high-impact force applied to the medial knee

  • Clinical diagnosis generally made through history of injury and knee varus stability testing

  • Diagnosis may be confirmed with MRI

General Considerations

  • Lateral collateral ligament is most taut in extended knee position


  • Injury to lateral collateral ligament less common than to medial collateral

  • Most common in young athletic population

Clinical Findings

Signs and Symptoms

  • Lateral knee pain

  • Pain with palpation over lateral knee

  • Pain with varus force to knee

  • Pain with extension

  • Feeling of instability or “giving way” in the knee

Functional Implications

  • Pain with swinging legs in/out of car or bed

  • Decreased stability while walking on uneven surfaces

  • Decreased stability with change of direction

Possible Contributing Causes

  • Usually related to traumatic varus stress applied to the knee

    • Sports injury

    • Motor vehicle accident

  • May be related to severe, degenerative osteoarthrosis

Differential Diagnosis

  • Joint-line pain related to knee osteoarthrosis

  • Iliotibial band syndrome

  • Biceps femoris tendinopathy or strain

  • Arcuate-popliteal complex

  • Anterior cruciate ligament sprain or tear

  • Posterior cruciate ligament sprain or tear

  • Proximal tibiofibular joint pathology

  • Referred pain to hip, low back, sacroiliac joint

Means of Confirmation Diagnosis

Laboratory Tests

  • Knee varus stress test in 30˚ knee flexion

  • Grading of laxity2

    • 1+ = 3-5 mm laxity

    • 2+ = 6-10 mm laxity

    • 3+ = greater than 10 mm laxity


  • MRI

  • Valgus stress radiograph3

    • Isolated injury of LCL

      • Increased lateral joint gap of 2.7 mm

    • Grade-III posterolateral corner injury

      • Increased lateral joint gap of 4.0 mm

Findings and Interpretation

  • Pain, tenderness, swelling in lateral knee from tissue disruption and inflammatory process

  • Possible laxity with varus force to knee, depending on extent of tissue disruption

  • Reports of “giving way” ...

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.