Inventor and Designer of Postural Control Insoles
Left Gravity Drive - The left foot is pronating (orange-red arrow) as the left hip is externally rotating. Gravity Drive Pronation and Abnormal Foot Pronation are synonymous terms (See Abnormal Pattern Observed in Rothbarts Foot)
Rothbart BA, Esterbrook L, 1988. Excessive Pronation: A Major Biomechanical Determinant in the Development of Chondromalacia and Pelvic Lists. Journal Manipulative Physiologic Therapeutics 11(5): 373-379.
Hip Drive - Timing of the foot's Pronation/Supination is determined by the transverse plane (internal/external) rotations of the pelvis (See Animation below)
Gravity Drive: Gravity pulls the foot inward and downward (pronates the foot) until the entire foot rests on the ground.
Rothbarts (Primus Metatarsus Supinatus) Foot:
Left Hip Drive - Internal (clockwise) rotation of the left hip, internally rotates the left femur and tibia, which in turn, pronates the left foot.
Hip Drive Pronation and Normal Foot Pronation are synonymous terms
Gravity Drive - Timing of the foot's Pronation/Supination is determined by gravity acting on the foot's structure (See Animation below)