The Gait Analysis Part-1

The typical walking gait cycle. There are two phases: stance phase and swing phase. It comprises approximately 62 percent of the gait cycle.

Heel strike : When the foot first touches the floor.

Loading response: Weight bearing on the loaded extremity from heel strike and continues until the toe off.

Midstance: The first half of single-limb support beginning when the opposite leg toe off until weight is over the forefoot.

Terminal stance: starts with heel rise and continues until the opposite heel strikes the ground.

Pre-swing: When heel strikes of the opposite extremity begin and toe-off ends.

Swing phase is divided into 3 parts : 

Early swing: When the extremity accelerated just after pre-swing; this action initiates supination in the opposite stance phase leg.

Mid-swing: largely passive late swing: when the extremity is being actively decelerated which largely through an eccentric action of the involved muscles.

Late swing: When the extremity is actively decelerating largely through an eccentric action of muscles.

How about we start with HEEL STRIKE……

The transfer of weight from one extremity to the other extrimities . This is completed by  four distinct mechanisms:

Ankle plantar flexion: heel strike which is  followed by eccentric contraction of the gastrocnemius and soleus muscles to decelerate foot flat.

Subtalar pronation: The calcaneus and the ground contact increases  the talus slides anterior on the calcaneus while attempting plantar flexion, adducting and eversion. This motion causes concomitant internal rotation of the lower leg.

Knee flexion: This is a reaction to the heel rocker which is a forward motion of the tibia and passive tension in the gastrocnemius and soleus group of muscles. where it is slowed by eccentric contraction of the quadriceps where the abdominals acting as a primary anchor.

Contralateral pelvic drop: This is decelerated by the ipsilateral hip abductors which isprimarily gluteus medius.

What`s happening at biomechanical model ? 

Foot :
The foot should be supinated at this point, as it should be from pre swing. It is dorsiflexed, inverted and adducted.

Ankle:
The ankle should be neutral or slightly dorsiflexed

Knee:
The knee is usually neutral or slightly flexed and the thigh and leg externally rotated approximately 4-6 degrees

Hip:
During the heel strike hip should be flexed 20-30° and the lumbar spine neutral; the opposite hip should be extended 20-30° .

Now when your patient walks into your clinic, Knowing what is normal is the 1st step toward gait cycle.

Reference :

1. Root MC, Orion WP, Weed JH. Normal and Abnormal Function of the Foot. Los Angeles: Clinical Biomechanics, 1977.
2. The Pathokinesiology Service and the Physical Therapy Department. Observational Gait Analysis. Rancho Los Amigos National Rehabilitation Center, Downey, CA, 2001.
3. Perry J. Gait Analysis: Normal and Pathological Function. Thorofare, NJ: Slack 1992.
4. Joint structure and function : Cynthia norkins
5. Foroughi, N., Smith, R., Vanwanseele, B. The association of external knee adduction moment with biomechanical variables in osteoarthritis: a systematic review. Knee. 2009;16:303–309