Pronation
Over-pronation of
the foot: 
A complex motion including outward rotation of the
heel and inward rotation of the ankle.
Normal pronation, or "rolling
inward" of the foot is necessary as the foot adapts
to uneven ground. Excessive pronation, however causes the
arch to flatten and soft tissues such as ligaments to stretch.
Excessive pronation causes
the joint surfaces to function at unnatural angles to each
other, resulting in increased rates of ‘wear and tear’
and joint deformities such as bunions and hammer toes.
When pronation occurs, joints
that should be stable now have an increased range of motion
and become overly flexible.
Initially, excess pronation may cause a
wide range of problems such as many problems such as muscle
fatigue or ankle sprains.
Prolonged strain on the muscles, tendons,
and ligaments of the lower limb can cause permanent problems
and deformities such as bunions or excessive wear beneath
the kneecap.
Casted
foot orthotics are the most effective way of
dealing with excess pronation. They work by holding the
joints in their ‘neutral’ position; that is,
the position the joint would be in if it were not pronating.
Pronated
Feet: Note the excessive inward curve/sag of the
inside ankle
Feet
Corrected with orthotics: Note that there is no
longer an inward curve and that the axis of the joint is
now vertical
