Courtesy: Mary Lloyd Ireland M.D.
Associate Professor
University of Ketucky
Lexington, KY, USA

Biomechanics of Gait

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Overview

• Understanding gait biomechanics is essential for:
  • Walking
  • Running
  • Return to sports after injury

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Clinical Importance

• Restoration of normal foot and ankle motion is critical for:
  • Functional recovery
  • Normal gait pattern

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Basic Gait Cycle

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Phases

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Double Limb Support

• Both feet on ground
• ~10% of gait cycle

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Walking vs Running

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Phases of the Gait Cycle

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1. Heel contact (initial contact)
2. Forefoot contact
3. Midstance
4. Heel off
5. Toe off (propulsion)
6. Swing phase

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Foot and Ankle Biomechanics

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Key Joints

• Ankle joint
• Subtalar joint
• Transverse tarsal joint

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Oblique Axis of the Ankle

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Effect of Movement

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Significance

• Allows rotational movement between foot and leg

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Tibial Rotation with Foot Motion

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Subtalar Joint Mechanics

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Axis

• ~45° to horizontal

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Coupled Movements

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Transverse Tarsal Joint

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Components

• Talonavicular joint
• Calcaneocuboid joint

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Function

• Adapts foot to ground

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Behavior

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Windlass Mechanism

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Mechanism

• Toe dorsiflexion – plantar fascia tightens

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Effect

• Elevates longitudinal arch
• Converts foot into rigid lever

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Function

• Essential for push-off

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Stance Phase Biomechanics

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Interval 1: Heel Strike – Foot Flat

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Function

• Shock absorption

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Movements

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Effect

• Flexible foot

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Interval 2: Foot Flat – Heel Off

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Function

• Stability

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Movements

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Effect

• Foot transitions to rigidity

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Interval 3: Heel Off – Toe Off

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Function

• Propulsion

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Movements

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Windlass Role

• Stabilizes arch
• Enables push-off

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Body Weight Distribution

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• Rapid increase after heel strike
• Peak load may exceed 100% body weight
• Decreases toward toe-off

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Key Biomechanical Patterns

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Early Stance (DIEP)

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Push-Off Phase (PERS)

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Important Concept

• Talus moves opposite to foot and tibia

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Gait as a Controlled Fall

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• Walking = continuous forward fall
• Balance maintained by alternating limb support

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Clinical Gait Assessment

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Methods

• Visual observation
• Treadmill analysis
• Video recording
• Gait lab analysis

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Hip Mechanics in Gait

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Normal Finding

• Pelvis tilts upward on opposite side during stance

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Abnormality

• Suggests:
  • Trendelenburg gait

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Biomechanics of Running

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Key Concepts

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• Foot must alternate between:
  • Flexibility – shock absorption
  • Rigidity – propulsion

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• Coordination required between:
  • Ankle
  • Subtalar joint
  • Transverse tarsal joint

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Clinical Insight

• Loss of motion in these joints – abnormal gait