Subtalar Joint (Neutral Position) – the position of the subtalar joint in which the foot is neither pronated nor supinated. When the hind foot is neutral, the bisector of the calcaneus is the 90 to the supporting surface. 

Subtalar Joint Pronation – is a coordinated tri-plane motion of the foot that involves three planes of motion: abduction, dorsiflexion and eversion.    

Subtalar Joint Supination – a coordinated tri-plane motion of the foot that involves three planes of motion: adduction, plantar flexion and inversion.

Pronated and Supinated – adjectives that describe the position of the foot (they do not describe the action of pronation or supination). Thus a “pronated foot” is one that is in a pronated position as compared to a neutral position.

Degrees of Pronation and/or Supination – this is measured by the degrees of inversion (in the case of supination) or eversion (in the case of pronation) away from the neutral position.

Gait Cycle – a complete gait cycle when the foot is in contact with the ground (weightbearing). See the figure below.

  1. Stance Phase ­– a portion of the gait cycle when the foot is in contact with the ground (weightbearing).
  2. Swing Phase – the portion of the gait cycle when the foot is in the air (non-weightbearing).

Normal Center of Pressure Line (Gait Line) – this is the average vector of all forces that act on the bottom of the normal foot as it goes through the stance phase of gait.