Gait Analysis

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Gait Cycle Essentials - Stepping Stones

  • Gait Cycle: Heel strike (one foot) to subsequent heel strike (same foot).
  • Two Main Phases:
    • Stance Phase (60%): Foot on ground.
      • Sub-phases: Initial Contact (Heel Strike) → Loading Response (Foot Flat) → Midstance → Terminal Stance (Heel Off) → Pre-swing (Toe Off).
    • Swing Phase (40%): Foot in air.
      • Sub-phases: Initial Swing → Mid Swing → Terminal Swing.
  • Double Support: Two periods (~10% each, total ~20%); both feet on ground.
  • Stride Length: Distance of one full gait cycle.
  • Step Length: Heel strike (one foot) to contralateral heel strike.

⭐ Stance phase: 60%; Swing phase: 40% of gait cycle. Double support time ↓ with ↑ speed, absent in running (replaced by float phase).

Gait Cycle Phases and Sub-Phases Diagram

Gait Parameters & Determinants - Measuring Motion

  • Spatial (Distance) Parameters:
    • Stride Length: Heel contact of same foot to next (Avg: 1.4m).
    • Step Length: Heel contact of one foot to opposite foot (Avg: 0.7m).
    • Step Width (Base of Support): Lateral distance between feet (Avg: 5-10cm).
    • Foot Angle (Angle of Progression): Toe-out (Avg: 5-7°).
  • Temporal (Time) Parameters:
    • Cadence: Steps/minute (Avg: 90-120).
    • Velocity: Speed (Avg: 1.37 m/s or ~80 m/min).
    • Cycle Time: Duration of one full gait cycle (Avg: ~1 sec).
  • Kinematics: Study of motion (e.g., joint angles, ROM).
  • Kinetics: Study of forces causing motion (e.g., Ground Reaction Force - GRF).
  • Determinants of Gait (Saunders, 1953): Mechanisms for efficient, smooth gait by ↓ Center of Gravity (CoG) excursion:
    • Pelvic Rotation (transverse plane)
    • Pelvic Tilt (coronal plane - towards swing leg)
    • Knee Flexion in Stance Phase (approx. 15°)
    • Foot & Ankle Mechanisms (rockers)
    • Knee Mechanisms (interaction with foot/ankle)
    • Lateral Pelvic Displacement (minimized)

Gait parameters: stride, step length/width, step angle

⭐ The six determinants of gait collectively reduce the vertical displacement of the body's Center of Gravity (CoG) during walking from a potential 9.6 cm to approximately 4.5 cm, conserving energy.

Pathological Gaits Part 1 - Wobbles & Limps

  • Antalgic Gait (Painful Gait)
    • Cause: Pain in a weight-bearing structure (e.g., hip, knee, ankle).
    • Mechanism: ↓ stance phase duration on affected limb; ↓ swing phase on unaffected limb.
    • Appearance: Limp with shortened stride length to minimize painful joint loading.
    • Goal: Reduce weight-bearing time and force on the painful side.
  • Trendelenburg Gait (Gluteal Insufficiency Gait)
    • Cause: Weakness of hip abductors (gluteus medius & minimus).
    • Nerve: Often due to superior gluteal nerve injury/palsy.
    • Uncompensated: Pelvis drops on contralateral (swinging) side during stance phase on the affected side.
    • Compensated: Trunk lurches towards the affected (ipsilateral) side to maintain balance and level the pelvis.
    • 📌 Mnemonic: "SOUND" - Superior gluteal, Opposite dip, Unilateral stance, Nerve/muscle, Dip.
    • Trendelenburg gait vs normal gait

    ⭐ Trendelenburg Sign: Positive if, when standing on one leg (the affected side), the pelvis drops on the unsupported (swinging) side.

  • Short Limb Gait
    • Cause: True (structural) limb length discrepancy (LLD).
    • Appearance: Pelvic dip towards the shorter limb during its stance phase; shoulder may also dip.
    • Compensations: Equinus (toe-walking) on shorter side, ↑ flexion of contralateral knee/hip during its swing, or circumduction of longer limb.

Pathological Gaits Part 2 & Analysis - Stumbles & Scans

  • Ataxic Gait (Cerebellar):
    • Wide-based, unsteady, staggering, irregular steps.
    • Difficulty with tandem walking; titubation common.
    • Cause: Cerebellar lesions (e.g., stroke, tumor).
  • Sensory Ataxic Gait:
    • High steppage ("stomping gait"), feet slap ground.
    • Positive Romberg's sign (worse with eyes closed).
    • Cause: Loss of proprioception (e.g., dorsal column lesion, neuropathy).
  • Spastic Gait (Circumductory/Scissors):
    • Hemiplegic: Leg stiff, extended; circumduction to clear foot.
    • Diplegic (Scissors): Legs stiff, adducted; slow.
    • Associated with UMN lesions.
  • Gait Analysis - Clinical:
    • Observation: Symmetry, step/stride length, base, arm swing, turning.
    • Tests: Tandem gait, heel/toe walk, Romberg.
    • ⭐ Timed Up and Go (TUG) Test: Rise from chair, walk 3m, turn, return, sit.

      A TUG time > 13.5 seconds indicates ↑ fall risk in older adults.

  • Key Gait Parameters (Adult Normals):
    • Cadence: 90-120 steps/min.
    • Walking speed: 1.2-1.4 m/s.
    • Step length: 70-80 cm. Comparison of Ataxic and Hemiplegic Gaits

High‑Yield Points - ⚡ Biggest Takeaways

  • Gait cycle: Stance phase (60%) and Swing phase (40%).
  • Double support (both feet on ground) occurs twice during stance.
  • Normal cadence: 90-120 steps/minute. Stride length is two step lengths.
  • Trendelenburg gait: From gluteus medius weakness; pelvis drops on swing side.
  • Foot drop/Steppage gait: From tibialis anterior weakness (e.g., common peroneal nerve palsy).
  • Antalgic gait: Shortened stance phase on the painful limb.
  • Center of Gravity (COG) displaces approx. 5cm vertically and 5cm laterally during normal gait.
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Practice Questions: Gait Analysis

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