Abnormal Foot Motion - More Correctly referred to as Gravity Drive. This motion is observed in the Rothbarts Foot and PreClinical Clubfoot Deformity

  • Internal hip rotation no longer pronating the ipsilateral foot  
  • External hip rotation no longer supinating the ipsilateral foot
  • The Pull of Gravity drives the pronation pattern of the foot

Discussion

  • From Foot Flat to Mid-stance, the foot (subtalar joint) is pronating (due to the pull of gravity on Rothbarts Foot).  The forefoot remains unlocked. 
  • At Toe Off the foot is unstable (loose bag of bones syndrome).

Hip Drive Mechanics

Hip Drive - Right Foot

Right foot is supinating at Midstance due to the rotation of the ipsilateral hip.

Gait Analysis

Hip Drive - Observed in the Plantargrade Foot

Gravity Drive - Observed in Rothbarts Foot or

The Preclinical Clubfoot Deformity

Gravity Drive - Left Foot

Left foot is pronating at Midstance due to the pull of gravity on the structurally unstable foot.

Gravity Drive Mechanics 

Normal Foot Motion - More Correctly referred to as Hip Drive.   This motion is observed in the Plantargrade Foot.

  • Internal hip rotation, pronates the ipsilateral foot  
  • External hip rotation, supinates the ipsilateral foot

Discussion Above Animation

  • From Heel Strike to Flat Foot, the foot (subtalar joint) is pronating (due to internal hip rotation).  This unlocks the forefoot and allows it to adapt to uneven ground surfaces.
  • From Flat Foot to Heel Off, the foot (subtalar joint) is supinating (due to external hip rotation).  This locks the forefoot and allows it to function as a rigid lever at Toe (Push) Off (Zitzlesperger, 1960).



References

    Zitzlesperger S 1960.The mechanics of the foot based on the concept of the skeleton as a statically indetermined space framework. Clinical Orthopedics, 16:47-63
    Rothbart BA 1973. Part I. Biomechanical analysis of a normal gait pattern.  Journal Canadian Podiatry Association, (3):3-7.
    Rothbart BA 1973. Part II. Biomechanical analysis of a normal gait pattern.  Journal Canadian Podiatry Association, (4):1-12.