Knee Ligament Examination

Inspect

  • Wasting: Observe for muscle atrophy.
  • Scars: Look for surgical or injury-related scars.
  • Deformity: Assess for visible abnormalities.

Walk

  • Check for ACL deficiency gait.

Lie Down

  • Range of Motion (ROM): Assess joint movement.
  • Screen for Sag: Look for posterior sag (PCL assessment).
  • Posterior Draw Test: Evaluate posterior cruciate ligament (PCL) integrity.
  • Quads Active Test: If PCL laxity is present, observe tibial movement during quadriceps contraction.
  • Lachman Test: Assess anterior cruciate ligament (ACL) integrity.
  • Collateral Ligaments:
    • Varus and valgus stress tests.
  • Pivot Shift: Dynamic test for ACL laxity.
  • Dial Test: Assess for posterolateral corner injuries.

Finishing

  • Joint Lines and Menisci: Palpate for tenderness and check for meniscal involvement.
  • Pulses and Neurology: Evaluate vascular and nerve function.
  • Full History: Gather a complete patient history.
  • Imaging: Order appropriate imaging for confirmation (e.g., MRI, X-ray).

Pivot Shift Quantification

  • Grade 1: Glide.
  • Grade 2: Clunk.
  • Grade 3: Gross clunk with locking.
  • In extension, the tibia starts anteriorly subluxated.
  • Mechanism:
    • Valgus force tensions the MCL.
    • During flexion, the knee pivots around the MCL.
    • The ITB moves posterior to the knee’s center of rotation (COR), working as a flexor, reducing the tibia with a clunk.

Lachman Test Quantification

  • Position: Perform at 30° flexion when ACL is most lax.
  • Grades:
    • Mild: 0–5 mm translation.
    • Moderate: 6–10 mm translation.
    • Severe: >10 mm translation.
  • Comparison: Always compare with the contralateral knee to determine normal.
  • End Point: Assess the quality of the end point.
  • KT 1000 Testing:
    • Translation of 11 mm or a Lachman delta of 3 mm is diagnostic.
    • High-grade laxity may indicate associated MCL or posterior horn medial meniscus tears.

PCL Sag Sign

  • Grades:
    • Grade 1: Tibia still in front of femoral condyles.
    • Grade 2: Tibia level with condyles.
    • Grade 3: Tibia sagged behind condyles.

Collaterals

  • Varus Opening:
    • At 0°: Suggests LCL and PLC injury (high likelihood).
    • At 30°: May indicate isolated LCL injury (uncommon).
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