Lecture on Gait and Gait Cycle

Key Terminologies

• Step Length: Distance between the heels of two different legs (right heel to left heel).
• Stride Length: Distance between the heels of the same leg (left heel to next left heel on the ground).
• Step Width: Distance between the centers of each foot, representing the base of support during gait.

Gait Cycle

Phases of the Gait Cycle

1. Stance Phase

   • Heel Strike (Initial Contact): Heel touches the ground.
     • Hip: 20° flexion
     • Knee: 5° flexion
     • Ankle: 0° dorsiflexion
   • Loading Response: Stance leg begins to bear weight.
     • Knee absorbs shock with eccentric contraction by quadriceps.
     • Hip extensors stabilize lower extremity.
     • Ankle moves from dorsiflexion to plantar flexion.
   • Mid Stance: Body weight shifts to stance limb.
     • Hip: Neutral
     • Knee: Slightly flexed
     • Ankle: Eccentric contraction by plantar flexors to prevent falling forward.
   • Terminal Stance (Heel Off): Body weight shifts from stance limb to the other leg.
     • Hip: 20° extension
     • Knee: 5° flexion
     • Ankle: 10° dorsiflexion
   • Pre-Swing (Toe Off): Emphasis on ankle for foot clearance.
     • Ankle: Plantar flexor pushes off body against the ground.
     • Knee: Flexes due to plantar flexor contribution.

2. Swing Phase

   • Initial Swing: Leg rises and moves forward.
     • Ankle: Moves from 15° plantar flexion to 5° dorsiflexion.
     • Knee: Flexes to 40°.
     • Concentric contraction by ankle flexors.
   • Mid Swing: Swing leg moves forward.
     • Knee flexor (hamstring) performs eccentric contraction to prepare for landing.
   • Terminal Swing: Prepares for landing.
     • Hamstring slows down leg for safe landing.

Gait Patterns

• Step-to Gait: Step one foot and the other foot matches it at the same level.
• Step-through Gait: Step one foot and the other foot passes it.

Assistive Device Gait Patterns

• Four-Point Gait: Four points of contact (e.g., both crutches and both legs).
• Three-Point Gait: Three points of contact (e.g., both crutches and one leg).
• Two-Point Gait: Two points of contact (e.g., both crutches together and one leg).

Weight Bearing Instructions

• NWB (Non-Weight Bearing): No weight on the limb.
• Partial Weight Bearing: Partial weight is tolerated.
• Full Weight Bearing: Full weight is permitted, although patient may not follow.

Deviations in Gait

• Scissoring Gait: Often seen in cerebral palsy due to tight hip adductors.
• Hemiplegic Gait: Common post-stroke, with one side of the body weaker.
• Parkinsonian (Shuffling) Gait: Leaning forward and shuffling, common in Parkinson's disease.
• Vaulting Gait: Compensation for a fused knee by raising stance leg to allow swing limb to pass.

Key Points

• Understanding normal gait cycle aids in analyzing patients' gait.
• Different gait patterns and deviations have specific underlying causes and characteristics.