what-when-how
In Depth Tutorials and Information
B
A
C
E
D
Figure 3.2
Prefabricated foot orthosis - lateral view. Key:
A
= deep heel cup,
B
= top of
arch,
C
= start of arch,
D
= medial/lateral arch,
e
= end of arch. Salford insole HYPERLINK
“http://www.salfordinsole.co.uk/”
casted orthosis another cast may sometimes be required. Owing to vari-
ations in casting technique, this will inevitably produce a different shape
of cast and orthosis, which may not be as effective as the original.
Many will argue that prefabricated orthoses do not lend themselves to
accurate modification, such as the addition of wedge material under the
heel or forefoot, so that the precise biomechanics of the foot can be
altered. In fact, many prefabricated orthoses are supplied with such addi-
tions ready for the clinician to use. Those that do not will often accept
ethyl vinyl acetate (EVA) or other materials being adhered to the base of
the orthosis.
Some argue that casted orthoses are the only means to achieve appro-
priate correction or control of foot motion. There are several counter argu-
ments. First, a foot orthosis is used as a means of achieving successful
clinical rather than biomechanical outcomes. The biomechanical alteration
that occurs is a means to an end, not an end in itself. Second, there is little
evidence of precisely what 'ideal' or 'better' foot biomechanics is, so it is
not clear what the mechanical goal for the orthosis should be. Third, there
is very little evidence to suggest that an orthosis, which matches the shape
of the foot when casted, offers any specific clinical benefits over a prefab-
ricated orthosis. However, there is evidence that orthoses of all types
(including sham and orthoses that are almost placebo in design and effect)
lead to improvements in symptoms, and this outcome, rather than the
biomechanical outcome, should remain the priority.
Key
Concept
A foot orthosis is used as a means of achieving successful clinical
rather than biomechanical outcomes. The biomechanical alteration
that occurs is a means to an end, not an end in itself, and should be a
secondary clinical concern.
