Foot Drop

Differential Diagnosis

Top to Bottom:

  1. Brain:
    • CVA (Cerebrovascular Accident).
    • Space-occupying lesion.
  2. Spine:
    • Spinal dysraphism.
    • L4/5 far lateral or L5/S1 posterolateral disc lesion.
  3. Hip:
    • Post Total Hip Replacement (THR) iatrogenic injury.
    • Trauma.
  4. Knee:
    • Post Total Knee Replacement (TKR) iatrogenic injury.
    • Compression neuropathy under Biceps femoris fascia.
    • Trauma (fracture, knee dislocation).
    • Mass (popliteal cyst, tumor).
    • Direct nerve injury (penetrating injury).
  5. Other Causes:
    • Neural tumor (e.g., neurofibroma).
    • Mass lesions.
    • Neurological conditions (e.g., Polio, Spina Bifida).
    • Achilles tendon rupture.

Examination

Look

  • Gait:
    • Loss of 1st rocker.
    • Compensatory pelvic tilt, lateral bend, or leg circumduction.
    • Compensatory hip and knee flexion for foot clearance during swing.
    • Toes make initial contact instead of the heel.
    • Heel lands with a characteristic slap.
  • Muscle Appearance:
    • Wasting of anterior and peroneal compartment muscles.
    • Fasciculations in affected muscles.
  • Scars and Masses:
    • Inspect hip, knee, leg, and spine for scars or masses.
  • Deformities:
    • Identify any deformities.
    • Compare with the other leg.

Feel

  • Sensory Assessment:
    • Test dermatomes and peripheral nerves.
  • Tinel’s Sign:
    • Perform from proximal to distal.
  • Popliteal Fossa:
    • Palpate for masses.
  • Achilles Tendon:
    • Assess for abnormalities.

Move

  • Neurological Function:
    • Assess myotomes and peripheral nerve motor power:
      • Tibialis Anterior (TA).
      • Tibialis Posterior (TP).
      • Gastrocnemius-Soleus (GS).
      • Peroneal muscles.
  • Differentiation Tests:
    • Distinguish between L5 root involvement and peripheral nerve injury by testing Gluteus Medius (GM).
  • Spinal Irritation Tests:
    • Straight Leg Raise (SLR).
    • Cross-over test.
  • Upper Motor Neuron (UMN) Signs:
    • Babinski sign.
    • Clonus.

Finishing Steps

  • Obtain a detailed history.
  • Conduct a vascular examination to rule out vascular causes.
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