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If the Shoe Fits …Pedorthic Modifications for Optimal Function
By Séamus Kennedy, BEng (Mech), CPed Billions of pairs of shoes are sold annually in the
US. Human anatomy, although clinically standardized, is certainly
unique from individual to individual. Given both of these
statements, it is no surprise that much of the footwear bought
today may not be a perfect fit for the wearer.
Fortunately there are many and varied ways that shoe
fit can be optimized. Pedorthists dedicate themselves to the study,
fitting, and modifying of footwear and foot orthotics in order to
give the wearer the ideal shoe function. Changes can be made
internally, externally, or a combination of both.
External Pedorthic Shoe Modifications
When shoe modifications are applied correctly, or used in
conjunction with foot orthotics, the results can be quite
remarkable: aiding in the transfer of forces; off-loading at-risk
or sensitive areas of the foot; rebalancing or realigning the
musculoskeletal system; accommodating fixed deformities; and
controlling motion.
Modifying Off-the-Shelf Footwear: Advantages
There are many obvious advantages in being able to modify
off-the-shelf footwear. Whether the shoes are fashionable or
extra-depth, patients like that "factory-made" look. Working with
their store-bought shoes allows them to control, to some degree,
the style, color, and shape of the shoe. These shoes also are less
expensive than custom-made shoes and perhaps will allow for some
variety over time.
Unlike foot orthotics, which can be transferred easily, shoe
modifications, either external or internal, become a permanent
aspect of a particular shoe and make it expensive to modify every
shoe. This may restrict the wearer to a single pair, which is never
an ideal situation. In addition, external adjustments may wear down
quite quickly and lose much of their efficacy, requiring constant
vigilance and refurbishment. The following are some of the more
commonly applied modifications. In the descriptions I have included
some of the possible Therapeutic Shoe Bill (TSB) A-Codes and HCPCS
L-Codes, although this list is by no means complete and should only
serve as a guideline for further investigation.
Flares: If ever you ascend a public staircase,
as I do daily in the subway system of New York City, and observe
the person in front of you, you can quickly tell if he or she rolls
in or out on the shoes. Pronation and supination are readily
obvious. Usually if the eversion or inversion is pronounced, the
entire shoe will have broken down on one side. The sole may be much
worn, the upper may be stretched and sagging over the welt, and the
counter may have broken down. There are several adjustments that
can be made to correct or control such a foot.
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Heel and sole elevation with flares. |
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The mildest change is to add a flare to the sole
of the shoe. A flare is an extension of the base of the shoe, below
the welt, medially or laterally. Usually a flare has a beveled
edge. It may be at the heel only, under the sole only, or it may
run the full length of the shoe. It widens the shoe, resisting
rotation, making it more difficult for the wearer to roll out on
that side. It does not attempt to correct the problem, just to
impede it.
Flares also have the advantage of making shoes more stable.
Patients who present with balance issues may well benefit from
having both medial and lateral flares applied to their shoes.
Although the shoes may look a little clunky, this will provide a
wider base for them to stand on. Flares also are known as "off-set
heels;" this is the term used in the Medicare diabetic TSB, Code
A-5506. (HCPCS L-3390)
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Left: Cork Barton’s wedge. Center and right: Rubber heel wedges. |
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Wedges: If the foot is flexible
and some correction is desired, an external wedge can be applied to
the shoe. Medial or lateral heel wedges add an extrinsic posting to
the sole of the shoe to promote heel varus or heel valgus
respectively. Once again wedges can be at the heel, the sole, or
applied heel to sole. In a case where the patient presents with a
fixed deformity, wedges can be used to accommodate the position of
function, bringing the ground up to the foot. Wedges are covered in
the TSB under Code A-5504. (HCPCS L-3350, L-3360, L-3370, L-3380,
L-3420)
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Left: Scaphoid pad and heel plug. Right: Met bar and heel wedge. |
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External counters: A more
aggressive shoe adjustment to provide motion control is the
addition of an external counter. This also is known as a
"buttress," a "stabilizer," or an "outrigger." External counters
are made by layering firm neoprene or crepe (Durometer >55) from
the ground to up above the welt and onto the quarter of the shoe.
The effect is to fully support the foot and ankle, provide a wider
base, and reduce flexing. This is best used when the patient
presents with a fixed deformity, such as an equinovarus clubfoot,
and the patient will benefit from fairly rigid support. External
counters are not aesthetically attractive, so I recommend only
using them as an option of last resort.
Cushion heels: A cushion heel is often referred
to as a SACH heel (solid ankle cushion heel). This is simply the
replacement of a triangular wedge, taken from the heel, with a
lower durometer sponge rubber. This allows the heel of the shoe to
compress at heel strike and absorbs some of the impact forces.
(HCPCS L-3340, L-3450)
Elevations: Shoe lifts to accommodate
leg-length discrepancies are probably the most
common adjustments seen on regular shoes. This topic was discussed
more fully in an article in the August 2005 edition of
The O&P EDGE.. (HCPCS L-3300, L-3310, L-3320,
L-3334)
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Forefoot rocker sole with slight negative heel |
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Rockers: There are a number of
techniques to transfer and offload plantar pressure and improve
gait. Rocker soles reduce energy consumption as they propel the
body forward after the center of gravity has passed over the apex
of the rocker. Rockers also can help patients with limited ranges
of motion at the ankle or metatarsophalangeal (MTP) joints.
Rockers are created by adding extra crepe to the midsole portion
of the shoe and then beveling it away just proximal to the point of
pressure. Some rockers have a rock at the forefoot only, and others
rock at the anterior and posterior ends of the shoe; all have a
flat stable area at mid-stance. Rockers are listed in the TSB under
code A-5503. There are many styles and types of rocker named in the
pedorthic and orthotic literature, the following list only
indicates the main categories.
Forefoot rockers--Reduce ground reactive forces
to the metatarsal heads, inhibit demand for dorsiflexion at the MTP
joints and assist at toe off. These are good for patients with met
head problems such as metatarsalgia and hallux rigidus or those
with forefoot lesions or ulcerations.
Rearfoot rockers--Lessen the demand for motion
in the ankle joint and reduce impact at heel strike.
Roller sole--This sole has no flat spot in the
midfoot. There is a gentle curve from heel to toe. It allows the
patient to roll through from delayed heel strike to toe off. This
sole modification is similar to that of a CROW boot or CAM walker.
Used in conjunction with a sole stiffener, this will prevent any
flexion of the foot, but some patients may find it unstable.
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Metatarsal bar. |
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Metatarsal bars: Much like rocker
soles the general term "met bars" refers to a whole family of
specific shoe modifications, each with unique names: Jones, Thomas,
Crescent, Mayo, Denver, etc. All met bars are designed to help
metatarsalgia and relieve plantar pressure by adding a wedge of
firm material across the sole of the shoe just proximal to the met
heads. This unloads the pressure from the met heads, allowing for
rapid transfer from the shafts of the metatarsals to the distal end
of the toes, with limited extension of the digits.
Met bars are typically ¼" in vertical height, which can
make them a tripping hazard. They can be made using firm crepe or
leather. Unlike rockers, met bars have a much flatter plantar
surface, providing a broader area of contact with the ground. Met
bars are included in the TSB under code A-5505. (HCPCS L-3400,
L-3410)
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Spring steel sole stiffeners |
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Stiffeners: Sole stiffeners can
be added to almost any shoe to limit flexion. They are usually made
from spring steel or carbon fiber, and they run from mid-heel to
forefoot.
They are added to the midsole of the shoe, layered between the
innersole board and the outsole.
Stiffeners are useful for treating patients with conditions such
as stress fractures, hallux rigidus, and MTP joint arthritis.
Stiffeners are often applied in conjunction with one of the rocker
options so as not to totally restrict motion. They also are helpful
for trans-met amputees using a partial foot prosthesis when you
want to protect the distal foot from impacting the toe filler.
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Toe guard. |
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Toe guards: Patients with
peripheral neuropathy often require shoes with softer, more
pliable uppers. However, they may operate in harsh environments
that will quickly cause the toe box to deteriorate. Examples
include at-risk diabetics working in industry or those engaged in
outdoor activities. Toe guards, also known as "bumper guards," are
the addition of a harder plastic or coating onto the front portion
of the shoe to prevent it wearing down too quickly.
These are some of the many and varied external pedorthic shoe
alterations that are possible. They can be used separately or in
conjunction with one another. The shoe is the final building block
upon which orthotic therapies or even surgical procedures will
rest. Optimizing fit and function with the overall aim to improve
patient outcomes is the pedorthist's mission.
Internal Pedorthic Shoe Modifications
As we all know there are two sides to every story:
having considered the outside, it is now time to look at some of
the changes that are possible inside a shoe. Much like the marvels
of plastic surgery, a little nip here and tuck there can optimize
the feel and fit of a shoe without having to compromise the outward
appearance.
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Heel spur excavation with PPT plug. |
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There is never a bad time to take the pedorthic
high ground, so the first consideration for footwear is to ensure
that it is properly sized in both length and width. If there is not
adequate room inside the shoe, the addition of internal
modifications may only cramp and worsen the situation. The shoe is
the platform upon which any modifications rest; having firm
counters, long-laced eyestays and a sensible heel height (1/2 in.
to 1 in.) will form the best foundation to control the foot.
The advantages of internal modifications are that they are
frequently less expensive, and they are usually easily replaced if
they become worn. They also come into direct contact with the foot,
acting at the site of concern. Internal modifications typically
will not wear down as quickly as external modifications. However,
unlike custom foot orthotics, they often are not transferable, so
you may need to apply one in each pair of shoes, possibly limiting
the footwear available to a patient. In addition, they may reduce
the shoe volume, leading to an unexpected fit issue.
Some of the more popular internal shoe modifications are
discussed below.
Heel cushions: One of the simplest changes to
make to a shoe is to insert a heel cushion. Cushions have been
shown to relieve mild cases of plantar fasciitis or early heel pain
syndrome. Cushions can be made from a wide variety of materials of
various durometers. Foams, sponge rubbers and silicone all are
possibilities. Heel cushions can be effective on two fronts:
providing shock absorption to a sensitive part of the foot and
acting as a slight, albeit compressible, heel raise.
Heel elevations: Shoe lifts to accommodate
leg-length discrepancies are probably the most common adjustments
seen on regular shoes. Internal heel lifts are made from firm cork
or neoprene. This topic was discussed more fully in the article from the August 2005 edition of
The O&P EDGE's "Stepping Out" department.
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Left: Cork Barton’s wedge. Center and right: Rubber heel wedges. |
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Heel wedges: A mild correction
for a pronated foot displaying heel valgus is the insertion of a
"pear" shaped wedge under the medial heel. You can add up to 3/8
in. of firm material, either a crepe or leather, and skive the
distal edges to zero. This is similar to adding extrinsic posting
to a foot orthotic. For supinators with heel varus, the wedge
should be placed on the lateral side. A Barton's wedge is longer
and extends from the heel to just behind the met head on the
effected side.
Metatarsal pads: The addition of metatarsal
pads onto the shoe insole will help alleviate the symptoms of
metatarsalgia by building a met arch, and transferring some of the
weight bearing pressure from the met heads unto the met shafts. Met
pads come in many different sizes, heights, and materials ranging
from spongy PPT and felt to harder orthopedic rubbers. Patients
with neuromas will only benefit from met pads as long as the shoe
has enough volume to accommodate the foot plus the pad!
The main difficulty for the practitioner is being able to
place the pad correctly inside the shoe. It is best to make a trial
fit with a self-adhesive pad or make a transfer mark using lipstick
before permanently bonding the final pad in place.
For patients that require broad metatarsal relief, met bars can
be placed under all five met heads. Likewise sesamoid pads allow a
drop for the first met head and transfer pressure laterally by
raising the second, third, and fourth.
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Left: Scaphoid pad and heel plug. Right: Met bar and heel wedge. |
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Schaphoid pads: These pads also
are known as longitudinal arch pads and used to be referred to as
cookies; they were quite popular in times past. Scaphoid pads can
be made from a variety of materials, firm or soft rubbers or even
leather. They are cemented into the shoe at the medial arch, giving
extra support under the midfoot. When a shoe is too narrow in the
shank to accommodate a foot orthotic, they often are the only
alternative for providing some support.
Excavations: These refer to any depressions or
cutouts created to the inlay or insole to reduce pressure in a
localized area. For example, patients presenting with a calcaneal
spur may benefit from a round plug being removed from the central
aspect of the heel. This then can be filled in with a compressible
PPT or viscoelastic type material.
Stretching: One of the simplest
adjustments to make to any shoe is to stretch it. Shoes can
be stretched in both length and width if necessary, adding slightly
more volume. However, there are limits to what can be achieved as
the innersole board does not stretch, and the shoe upper may begin
to look swollen. There are a number of stretching systems available
on the market from simple manual shoe-tree type units to heated
shoe racks. You will get the best results when using a shoe
stretching liquid, which can be purchased from any shoe finder
wholesaler.
Localized stretching can be achieved with the use of a Ball and
Ring device. These are excellent for creating a mound or bump at a
particular spot on the upper. Although seldom pretty, they can give
significant relief for patients with bunions or severe
hammertoes.
Carbon plates: Patients with met head
fractures, hallux limitus, or turf toe often require restricted
range of motion at the met heads. The insertion of a carbon
footplate into a shoe will limit flexion. This is a good
alternative to cementing a permanent steel shank into the shoe's
midsole as the plate is both transferable and eventually removable.
The thin plates are low bulk and lightweight and they can be used
in conjunction with custom foot orthotics when necessary. They also
have a beneficial energy return component when the plate springs
back into shape at toe off.
There are many other changes that can be made to shoes such as:
relasting to accommodate extra-wide feet; conversions from lace to
Velcro closures; additions of firmer counter materials, etc. Some
of these techniques have been in use in the pedorthic field for
more than 100 years. Skilled shoemakers and cobblers can be quite
ingenious in the methods they employ to adjust shoe fit.
However, there has been a tremendous increase in the variety of
reasonably priced extra-depth shoes, extra-wide shoes, and shoes
with expandable spandex or woven uppers. This market response to
the needs of the diabetic and geriatric populations has made some
of the more sophisticated shoe adjustment techniques
cost-prohibitive. Yet, when used judiciously, internal
modifications can significantly alter a shoe's function without
compromising on style. Séamus Kennedy, BEng (Mech), CPed, is president and co-owner of Hersco Orthotic Labs, New York City, New York. He can be contacted via e-mail: seamus@hersco.com, or visit www.hersco.com 
Table Of Contents - April 2006
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