what-when-how
In Depth Tutorials and Information
6
There may very well be combinations of these factors, further complicat-
ing the issue.
Variation in heel wear
Normal heel wear is influenced by the fact that the heel strikes the ground
approximately 2 degrees inverted as a component of normal late swing
phase subtalar joint supination. The wear mark is to the lateral side of the
posterior border of the heel.
If the foot is flexible and pronated throughout the gait cycle, the main
heel wear mark will be along the outer border of the heel and may even
move towards the medial side of the midline. This type of foot is so
unstable that apropulsive gait is likely, with a consequent reduction in the
severity of heel wear.
Excessive heel wear on the inner border indicates a rigid everted,
pronated rearfoot. Conversely, excessive wear on the outer border indi-
cates a rigid inverted rearfoot associated with a non-compensating rear-
foot varus deformity. Heel strike in this case tends to be heavy and heel
wear is more severe than usual.
Variation in tip wear
Excessive tip wear may occur for a number of reasons:
1.
Loss of toe function because of forefoot instability, a cavus foot with
retraction of the toes (that is, an excessively supinated foot) or
extremely short footwear.
2.
Uncompensated ankle equinus deformity.
3.
Excessively long shoes.
4.
Rigid soles with inadequate built-in toe spring.
5.
Foot drop associated with anterior tibial muscle paresis or posterior
calf muscle spasticity.
In addition there may be alteration in the position of the wear marks. This
can occur more medially because of:
•
excessive pronation during the propulsive period of gait
•
a large angle of gait or
•
hallux abducto valgus.
Conversely, more lateral wear on the tip can occur because the foot is
excessively supinated, and is a feature of compensated forefoot valgus
and primary plantar flexed first ray deformity.
