what-when-how
In Depth Tutorials and Information
1
must first have a reference position. The foot has a wide range of so-called
'neutral' reference positions. The neutral position is deemed to be the
position at which the foot or one of its joints is in its normal alignment, or
ideal alignment or parallel to another. There is little consensus as to the
value of these neutral positions and much evidence that because they
rely heavily on manual palpation, they cannot be identified consistently by
different clinicians. It follows that if their identification is not repeatable
between clinicians, then the position is not of any real value with regard
to diagnosis of foot problems and design of foot orthoses.
The so-called subtalar joint neutral position is rapidly becoming obso-
lete. A more consistently achievable reference position is foot posture
when a person is standing relaxed, and this should be largely repeatable
between clinical visits and less susceptible to operator error. Inter-subject
comparisons of relaxed standing position are difficult since each person
will naturally adopt a different posture for the foot when standing; however,
it remains the primary position of reference for assessing foot posture.
motion at the ankle and subtalar joint
The ankle is formed by the superior aspect of the talus and inferior end
of the tibia and fibula; the subtalar joint by the calcaneus and inferior
surface of the talus. Since they share the talus, these joints are often
described together. Also, what we know of their movements comes from
experiments that describe the heel relative to the leg (
Leardini et al 2007
);
this movement comes from the combined motions at these two joints.
Traditionally these joints were described as having quite different func-
tions but contemporary research suggest otherwise (
Lundgren et al 2008
,
Nester et al 2007,
Arndt et al 2004
). Both are capable of considerable
movement in the frontal and transverse planes - in the region of 10-15
degrees in each case, although this appears to vary between people.
The frontal and transverse plane movement between the heel and leg
that is described in the literature is a result of frontal and transverse plane
motion at both joints, with each often making comparable contributions
to the motion in each plane. Traditionally it was considered that frontal
and transverse plane motion came from the subtalar alone.
In the sagittal plane, it is clear that the ankle is able to provide far
greater movement than the subtalar joint: approximately 40-60 degrees.
motion at midtarsal and forefoot joints
The most recent research has demonstrated that the joints between the
navicular and talus, cuboid and calcaneus, cuneiforms and navicular, and
