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The
Quad D Foot-Type is a moderately over-pronated foot-type. This
foot-type occurs when a Compensated Rearfoot Varus exists with a normal
or neutral forefoot alignment.
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Point of Propulsion |
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OBSERVATIONS
- Low Arches
- Minimal/Neutral Toe Out
- Abnormal Pronation Through Midstance
- Midfoot Sag
- Functional Hallux Limitus
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Click on Image to go to Orthotic that is right
for Quad D Foot Type
quad d
orthotic
 
 
 
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The D Quad foot-type
is congenitally a partially unstable foot and is often diagnosed in
children as developmental flat foot. Make no mistake, if you
think that this child will “out-grow the deformity,” just ask Mom and
Dad and their older siblings to take off their shoes and socks. If
family members demonstrate similar foot characteristics, chances are
that this child is not going to develop an arch. During gait,
this foot begins to pronate at the subtalar joint in contact phase, and
continues to pronate throughout midstance. In propulsion, the 1st ray
will plantarflex to load the medial column of the foot and allow the
foot to re-supinate.
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Contact Phase
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At
initial contact, the calcaneus strikes the ground in a slightly
inverted alignment relative to the ground. Since the rearfoot
varus is primarily compensated, the subtalar joint immediately pronates
at heel strike causing the calcaneus to evert to a vertical position,
which in turn unlocks the midtarsal joint. Ideally, the midtarsal
joint should only partially unlock to allow for shock absorption, and
help the foot adapt to uneven terrain during contact period. In
this foot-type however, the foot is a little too unstable. One
more important observation is that during gait, the foot progression
angle is fairly linear or mildly toe-out at best.
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Midstance Phase
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Normally
in gait, co-contraction of the peroneals and the gastrocsoleus should
create a pronatory twist of the forefoot, and re-supination of the
subtalar joint. This is known as the midtarsal joint locking
mechanism. This mechanism provides the stability necessary to
lock up the midtarsal joint in preparation for propulsion.
Unfortunately, in the D Quad foot-type, there is a persisting state of
subtalar joint pronation that prohibits this from happening. The
midtarsal joint remains unlocked and mobile, while the overall height
of the arch drops in a vertical direction. This decrease in arch
height is often referred to as navicular drop.Alternatively, we refer
to this motion as midfoot sag, to more clearly differentiate it from
medial shelfing (i.e. medial or horizontal displacement of the arch
that is evident in the E and F foot-types). Additionally, along
with all this pronation and midfoot sag, there is increased tibial
internal rotation, creating strain on the posterior tibial tendon and
often leading to the development of medial shin splints, or posterior
tibial tendonitis
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Propulsion Phase
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As the heel lifts off the ground, initiating the propulsion phase of
gait, the lateral column should remain straight and stable.
Instead, in the D Quad foot-type, you may notice that the foot is
“bending backwards” at the level of the midtarsal joint. What you are
actually seeing is dorsiflexion and slight abduction of the forefoot
about the oblique midtarsal joint axis, a further sign that the midfoot
is still unlocked. Since the forefoot is neutral in this
foot-type, it is possible for the peroneals to initiate plantarflexion
motion of the 1st ray during early propulsion, thereby enabling loading
of the 1st Metatarsal head. Once the 1st metatarsal is stabilized
on the ground, then the foot can begin to re-supinate (better late than
never!).
Unfortunately,
since the foot enters propulsion in a flexible state, some damage is
being done with each and every step. Over time, 1st ray mechanics
become impaired and the peroneals will lose their efficiency.
Eventually the 1st ray will be driven dorsally, causing the development
of functional hallux limitus, and possible dorsal spurring at the 1st
metatarsalphalangeal joint. Once this happens, weight will
partially transfer to the 2nd metatarsal head and there will be a
partial reversal of the transverse metatarsal arch. Callosities
will be present at the 2nd MTH and in the sulcus of the hallux.
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