chapter 3d orthotics and pros the tics

3.4 Orthotics and ProstheticsBy Ellen Sobel, DPM, PhD & Lauren Jones, DPM

Foot OrthosesOrthosis means to straighten. There are orthoses for every part of the body from the head to the toe. An ortho-

sis is named for the joints that it crosses. The type of orthosis used in podiatric orthopedics for arch support andcushioning for painful submetatarsal calluses is a foot orthosis (FO). The ankle foot orthosis (AFO) crosses theankle. An orthosis that crosses both the ankle and the knee is called a knee-ankle foot orthosis (KAFO).

Functional Foot OrthosisThe Functional Foot Orthosis is designed to place the foot morphology in its most functional position, decrease

the amount and rate of subtalar joint pronation, control function of the midtarsal joint, and support compensatoryosseous deformities of the forefoot.

The patient must be casted off weight bearing in the subtalar joint neutral position and then the foot will takeon a three dimensional shape generally with more of an arch and a compensatory forefoot supinatus. The rootFunctional Foot Orthosis consists of a thermoplastic shell made of polypropylene, polyethylene, acrylic, or compos-ite materials. Angular posts added to the plantar aspect of the shell maintain the position of the rearfoot around thesubtalar joint neutral position and support compensatory deformities of the forefoot. The Root Functional FootOrthosis may be made with a shallow or deep heel seat.

Materials for the Functional Foot Orthosis

Thermoplastics soften as they are heated and harden each time they are cooled.

Polypropylene thermoplastic is the most common material composing the shell of the rigid foot orthosis.

Polypropylene is a thermoplastic polymer with low specific gravity and good resistance to chemicals and fatigue.

The polymer structure gives polypropylene high stiffness and good tensile strength.

Polyethylene thermoplastic is the most common material used for the semirigid foot orthosis shell.

Acrylics (Rigidur, Plexidur, Nyoplex) are polymerized from methymethacrylate polymers. They are a stiff,

dense, tough material. Acrylic shells are commonly 3-5 mm thick.

Composites are combinations of different plastics into one form. A composite of carbon fiber and acrylic is a

popular combination used in foot orthosis shells called Carboplast. Combining acrylic plastic with carbon fibers

creates a plastic sheet as rigid as acrylic and polypropylene, but with only half the thickness.

Leather is a flexible animal hide material, which is used in flexible foot orthoses and is very easy to modify.

Most leather foot orthoses are chrome-tanned.

Orthopedics | Orthotics and Prosthetics 139

Table 1. Materials for Foot Orthosis ShellCharacteristic Material Rigid Polypropylene

RigidurComposite

Semi-Rigid PolyethyleneSubortholenComposite

Flexible ToprelleLeatherMolded EVA

Rubber is an elastic substance produced from the milky sap (latex) of tropical plants or made synthetically.Rubber is tough, resilient, and a high shock absorber. The three classes of rubbers are expanded, sponge, and latex.Microcellular rubber,Ethylvinylacetate (EVA) is a hollow material that creates an internal network of air cells used toconstruct lightweight shock absorbing insoles of low density. Toprelle is a hybrid of rubber and thermoplastic whichmakes a lightweight relatively flexible orthotic shell.

Closed-cell expanded rubber (spenco). Closed-cell expanded rubber or spenco is manufactured by the introduc-tion of nitrogen gas under pressure to the rubber mix. External pressure is lowered allowing absorbed gas to expandand form thousands of individual closed cells. Spenco has a nylon top cover and is a very common flexible insolematerial.

Open-cell sponge rubber (Lynco). Open-cell sponge rubber (Lynco) is formed by mixing a blowing agent into arubber compound. Gas is liberated during the vulcanization process forming open cellular structures. It is a verysoft material used for foot insoles.

Rubberized cork known as cushion cork or korex is cork combined with a rubber binder that makes the corkmore flexible, reducing cracking and adding additional shock absorption.

Polyethene foams (e.g., Plastazote) is a closed cell polyethylene foam manufactured from a block of polyethyl-ene plastic that is placed in a mold, then in an oven, and expanded.

Felt (Orthofelt, Hapads). Platform felt is a fabric made of wool fibers matted together by steam and pressure.Adhesive-backed, precut felt can be used as heel, arch, metatarsal, and callus pads which can be placed directly onthe foot or onto the foot orthosis.

Viscoelastic polymer made from polyurethane elastomers create rubber like insoles, heel pads, and footorthoses. They are rather heavy and difficult to cut. The SofSpot Viscoheel (Bauerfeind USA, Inc, Atlanta, GA) is asilicone polymer heel cushion that has a built in area of softer durometer specially designed to disperse weightaround the plantar medial tubercle of the calcaneus, the site of inflammation in plantar fasciitis. Viscoelastic heelpads have been reported to reduce the impact of heel strike on the leg and low back by as much as fifty percent. TheTuli heel cup (Tuli International Comfort Products, San Marcos, CA) is a soft rubber heel cushion with trademarkwaffling. In patients with heel pain caused by fat pad atrophy, hard plastic heel cups (M-F Athletic company,Cranston, RI) theoretically position the heel pad underneath the calcaneus restoring the natural cushioning andcompressibility.

Poron and PPT are open-cell polyurethane foams made that are commonly used as soft shock absorbing insolesand as a soft top cover over the rigid shell of the functional foot orthosis.

Orthotic Device ModificationsA POST is a wedge that is added beneath the exterior surface of the orthotic shell (extrinsic opost). The post

may be made by making modifications to the shape of the positive impression itself (intrinsic posting).

Rearfoot Varus PostA rearfoot varus post is an added wedge under the medial heel of the orthotic shell (Table 2). The thickness or

apex of the post is under the medial side. The rearfoot varus post is the most common type of posting added to theFunctional Foot Orthosis. The indications are for a flexible pronated foot type to prevent subtalar joint pronationand to hold the rearfoot in a more inverted position. The rearfoot varus post may be an extrinsic post, which isadded to the shell of the orthosis, or it may be an intrinsic post, which is built into the shell of the orthosis.Generally the rearfoot varus post is no greater than four degrees.

Figure 1. Rearfoot Post

140 The 2005 Podiatry Study Guide

Table 2. Orthotic ModificationsBIOMECHANICAL Limit subtalar joint pronation Deep heel seat

Rear foot varus posting (for flexible foot type)High medial heel cupBlake orthosis modification Kirby heel skive

Limit midtarsal joint motion Forefoot postingForefoot balancingCalcaneal pitch

Accommodation of 1st ray 1st ray cut outproblems-hallux rigidus, Kinetic Wedge sesamoiditis Accommodation of ankle Heel liftequines Solid ankle foot orthosis

BY PATHOLOGY For plantar fasciitis Plantar fascial grooveheel liftWhale padU-padDonut pad

Figure 2. Forefoot Post

Forefoot Varus PostA forefoot varus post is an added wedge under the medial forefoot of the orthotic shell (Table 2). The thickness

or apex of the post is under the medial side of the forefoot. The forefoot varus post is used with a rearfoot varuspost if the rearfoot varus post is insufficient to hold the foot in the corrected position. The forefoot varus post sup-ports a compensatory rigid forefoot supinatus deformity.

Forefoot Valgus PostA forefoot valgus post is an added wedge under the lateral forefoot of the orthotic shell (Table 2). The thickness

or apex of the post is under the lateral side of the forefoot. A forefoot valgus post is indicated for prevention ofankle sprains and for a rigid forefoot valgus deformity.

Rearfoot Valgus PostA rearfoot valgus post is an added wedge under the lateral rearfoot of the orthotic shell (Table 2). The thickness

or apex of the post is under the lateral side of the rearfoot. This type of post is the least commonly used as it willincrease subtalar joint pronation. Indications for the rearfoot valgus post include prevention of ankle sprains and toaccommodate a rigid equinovalgus deformity such as occurs in neuromuscular such as disease-cerebral palsy.

Zero Degree PostThe zero degree post stabilizes the heel in a vertical position in situations in which the total rearfoot varus

deformity is less than 8 degrees, but exaggerated pronation is still a concern, and the rearfoot may be posted to zerodegrees.


Bar PostA bar post is a flat forefoot post that may effectively decrease pressure on the metatarsal heads by supporting

the metatarsal necks. It is common to request a two-five bar post when treating a plantar flexed 1st ray.

Biplanar GrindThe biplanar grand is a grind down wedge on the distal medial portion of the extrinsic rearfoot post, which

theoretically maintains ideal osseous alignment through the unaltered rearfoot post but allows the rearfoot to

pronate the necessary four degrees for shock absorption during the contact phase of gait.

Deep Heel SeatThe heel cup height is the vertical distance between the heel contact point of the positive cast and the circum-

scription line of the heel cup on the positive representation of the foot. A deep heel seat especially a high medial heel

cup is used to limit excessive subtalar joint pronation as manifested by eversion of the calcaneus.

Calcaneal Inclination Angle (Calcaneal Pitch)The calcaneal inclination angle involves removing one-fourth inch to one-half inch of material from the plaster

positive and then forming the shell to this contour. The calcaneal inclination angle (calcaneal pitch) is used to con-

trol sagittal plane motion at the midtarsal joint by supporting the head of the calcaneus.

Lateral FlangeThe lateral flange is an increase in the height of the orthosis on the lateral side of the foot starting lateral to the

heel and continuing distally at viable length usually not beyond the 5th metatarsal head. The height is variable but

no higher than inferior to the lateral malleolus. Indications for a lateral flange are for prevention of ankle sprains, to

prevent lateral slide off of the foot, and to control and support rigid rearfoot varus deformity such as in clubfoot. In

general when the rearfoot valgus deformity is flexible, it can be corrected with a rearfoot varus post, however, if the

rearfoot varus deformity is rigid such as in clubfoot or long-standing equinovarus deformity of neuromuscular dis-

ease, a lateral flange will control the rigid varus deformity of the rearfoot.

Lateral ClipThe lateral clip is an increase in the height of the orthosis on the lateral aspect of the foot starting proximal and

lateral to the center of the heel and ending distally at the proximal aspect of the 5th metatarsal base. The height is

variable, but should be no higher than the inferior surface of the lateral malleolus. Indications are the same as for a

lateral flange.

Medial FlangeThe medial flange is an increase in the height of the orthosis on the medial side of the foot starting medial to

the heel and extending distally with increasing height with the apex near the navicular and then decreasing in height

to end along the first metatarsal shaft. Indications for the medial flange are for control of pronatory problems espe-

cially when they are rigid. To tolerate a medial rearfoot post, there must be some flexibility to the foot with a range

of motion, however, a rigid rearfoot valgus deformity such as occurs in endstage flatfoot disorders with no range of

motion may be controlled somewhat with a high medial flange.

Toe CrestA toe crest may be used to treat hammer toe or claw toes. By supporting the central portions of the second

through fifth digits, toe crests function to reduce pressure beneath the metatarsal heads and distal toes by distribut-

ing pressure over a larger surface area. Also, because toe crests effectively stabilize the distal phalanges, their addition

helps improve the propulsive period function of the flexor digitorum longus, which does not function properly

(Flexor stabilization) when digital contractures are present.

First Metatarsal Head CutoutThis is complete removal of the orthotic shell under the first metatarsal head. Indications for the first metatarsal

head cutout include: sesamoiditis, forefoot valgus deformity, and hallux limitus.


Kinetic WedgeThis is a cutout under the 1st metatarsal head replaced with softer durometer material. The shape of the cutout

with a wide medially shaped wedge angle similarly to the 1st ray axis. The kinetic wedge is indicated to promote

plantarflexion and eversion of the 1st ray for Functional Hallux Limitus deformity.

Morton’s ExtensionMaterial is added under the orthotic shell extending through the 1st ray and crossing the 1st metatarsopha-

langeal joint to immobilize the joint. Indications for a Morton’s Extension modification are for a painful hallux limi-

tus/rigidus for splinting and immobilization. See Table 2 for summary of Foot Orthoses Modifications.

Figure 3. Kinetic Wedge Figure 4. Morton’s Extension

Cuboid PadA cuboid pad is a small pad placed directly beneath the cuboid, used with prefabricated orthotics to accommo-

date plantarflexed 4th or 5th rays. Some orthotic companies put a cuboid pad on all orthotics claiming that it sup-

ports the “lateral arch.”

Figure 5. University of California Biomechanics Laboratory Orthosis (UCBL)

University of California Biomechanics Laboratory Orthosis (UCBL)

See Figure 5. The UCBL is used to treat flexible flat foot, plantar fasciitis, and calcaneal spurs. The UCBL is cast-

ed in the full weight-bearing position. The device elevates the arch by holding the foot in a position of forefoot

adduction and hindfoot inversion. In one study-patients wearing a UCBL orthosis for three months had a 60-100%

relief of heel pain. The UCBL orthosis was found to reduce the degree and duration of abnormal pronation during

the stance phase of gait in flatfoot patients. The UCBL orthosis with medial posting has been successfully used to

treat posterior tibial tendon dysfunction.


Dynamic Stabilizing Insole System (DSIS)

This foot orthosis is unique for having a split forefoot plate for individual function of the medial and lateral

column. It has a 5 degrees intrinsic varus offset heel. The orthosis is indicated for children’s flatfoot pronatory con-

ditions.

Figure 6. DSIS

Orthotic Devices for Arthritis Patients

The arthritic foot generally demonstrates stiffness with loss of passive range of motion at the subtalar joint.

Typical foot problems of the arthritis patient include metatarsalgia and hindfoot valgus.

MetatarsalgiaThe patient with pain under the metatarsals usually has painful burning calluses under the metatarsal heads

and atrophy of the plantar fat pad. Foot orthoses for forefoot pain generally consist of soft materials such as closed

celled polyethylene foam (plastazote) and open cell polyurethane foam (PPT) and microcellular rubber (spenco).

Metatarsal pads can be placed proximal to the metatarsal heads on the orthoses to unload painful plantar callosities.

If subluxation at the metatarsophalangeal joint has occurred with plantar-plate rupture, a stiff, full-length insole that

limits hyperextension of the metatarsophalangeal joint may be helpful. Examples include a thin carbon fiber ortho-

sis. Shoe corrections for metatarsalgia include a metatarsal bar to unload painful metatarsal heads and a rocker bar

to facilitate motion over the metatarsophalangeal joint. The heel of the shoe should be low in the arthritic patient

with metatarsalgia.

Hindfoot ValgusSince the calcaneus is lateral to the weight-bearing axis of the tibia, most midfoot and ankle problems in

arthritic patient result in hindfoot valgus deformity. The goal of the orthosis is generally to prevent further prona-

tion of the midfoot and valgus of the hindfoot. If the hindfoot valgus is still somewhat flexible, a rearfoot varus post,

Kirby heel skive, or Blake-inverted orthosis modification may be added to the foot orthosis. If the patient has a rigid

hindfoot valgus, then a high medial flange may offer support to a rigid foot. Shoe corrections for the patient with

rigid hindfoot valgus include medial offset heel, medial buttress, stiff heel counter, rigid shank and high top.

Ankle ArthritisWhen arthritis affects the ankle, a solid ankle foot orthosis may be indicated, either of plastic or metal. A solid

AFO may also be indicated for the totally collapsed arch with painful bursa under the talar head or for severe insta-

bility of the subtalar and/or ankle joint. When a solid AFO is worn immobilizing the ankle, shoe corrections need to

be added to accommodate the limitation of ankle motion. Shoe corrections for the painful arthritic ankle include a

Solid Ankle Cushion Heel (SACH), which facilitates plantarflexion at heel strike and cushions the heel from heel

strike to midstance. It attenuates shock and reduces ankle range of motion from heel strike through midstance to

toe-off. A rocker bottom sole is usually worn with the SACH heel to facilitate roll over. Elastic ankle wraps, the

Aircast Stirrup, and a cloth lace-up gauntlet type ankle braces (Swedo-ankle brace) may be helpful in immobiliza-

tion and support of the painful arthritic ankle.


Ankle Foot OrthosisOrthotic Devices for Neuromuscular Disease

IndicationsThe AFO is the most common type of orthosis used. The AFO is also known as: short leg brace, drop foot

brace, Klenzak ankle brace, and coil spring brace. It may be fabricated as a metal double upright or as a plastic shoe

insert orthosis.

The main indications for the AFO is for individuals with neuromuscular disease who have a flaccid drop foot or

spastic equinus. The AFO provides ground clearance during the swing phase of gait. The brace also provides stabili-

ty during the stance phase of gait for patients with weakness, spasticity, and instability. For patients who are nonam-

bulatory the AFO is utilized to maintain position and prevent contractures. See Table 3 Bracing the Neuromuscular

Patient on page 137 for a summary of indications for Ankle Foot Orthoses.

Table 3. Bracing the Neuromuscular PatientGROUP PROBLEM BRACING SOLUTION ADULTS Flaccid drop foot with isolated Posterior Leaf Spring (PLS)

dorsiflexor weaknes Ankle Foot Orthosis (AFO) (May be plastic or metal)

Flaccid drop foot with dorsiflexor Solid Ankle Foot Orthosisand plantar-flexor weakness (May be plastic or metal) Spastic ankle equinus Semirigid or Solid Ankle Foot Orthosis

(May be plastic or metal)Spastic equinovarus Semirigid or Solid Ankle Foot Orthosis

with correction for varus, which mayinclude lateral t-strap, lateral calf flange(Only the metal orthosis has the t-strap)

Patient with insensitivity, or AFO Double upright metal edema, or previous ulcers from plastic AFO

CHILDREN Mild ankle equinus/drop foot Posterior Leaf Spring AFOwith poor dorsiflexion Spastic ankle equines with good Articulated Ankle Foot Orthosis dorsiflexion power Medial/lateral ankle instability Supramalleolar Orthosis


Figure 7. Double Upright Ankle Foot Orthosis (AFO)

Metal Double Upright Ankle Foot Orthosis

Before the introduction of plastic the metal double-upright AFO (See Figure 7) was the standard brace used for

drop foot, and all upper and lower motor neuron conditions requiring a below knee leg brace. The double upright

metal AFO is still considered the safest orthosis for patients with sensory loss and edema who cannot tolerate the

hard margins of plastic against the skin (See Table 3 for summary of the indications of Ankle Foot Orthoses).

The ankle joint of the metal brace is usually set at 90º with the foot perpendicular to the leg. The ankle joint

can be positioned at 10 to 15º dorsiflexion to increase the toe pickup during the swing phase and avoid tripping.

However a 10 to 15º dorsiflexed ankle brace tends to increase the flexion moment at the knee during stance phase

and reduces the degree of genu recurvatum produced from the ankle equinus. The dorsiflexed brace may cause the

knee to buckle. There is a direct trade-off between the amount of toe pickup and the amount of knee instability,

which a dorsiflexed ankle setting position will create. The more toe pick up that the orthosis provides, the greater

the instability at the knee. The brace may help to achieve maximum stability of the knee over most of stance by set-

ting the ankle in mild plantar flexion (5-10º plantarflexed). However, this setting provides the least toe clearance.

When the knee extensors are weak, mild ankle equinus deformity and genu recurvatum may be useful to the

hemiplegic patient as a means of providing stability of the knee during weight bearing. The ankle of an AFO may be

set in five to ten degrees of plantarflexion to create a recurvatum moment at the knee to compensate for weak

quadriceps muscles. When the knee is very unstable a knee-ankle-foot orthosis (KAFO) may be necessary.

The variations in the double-bar AFO function are achieved by adjustments at the ankle joint. A FREE

MOTION ankle allows motion in any direction. The ankle joint may be set to prevent all motion (“STOP”), which is

indicated when immobilization is required to alleviate pain and to enhance stability, such as in patients with painful

arthritis. A metal AFO with a rigid ankle is known as a Solid Ankle Foot Orthosis.

The ankle joint of the metal AFO may be fixed so that plantar flexion can not go past 90º (foot perpendicular to

the leg). This is known as a 90º posterior plantarflexion stop. The 90º posterior plantarflexion stop is helpful for

patient with severe spastic ankle equinus.

The anterior (dorsiflexion) stop limits dorsiflexion, thus acting as a calf muscle substitute. It blocks dorsiflexion

during the end of mid-stance and push-off. The anterior stop prolongs mid-stance and delays heel-rise. It mechani-

cally assists push-off. When active plantarflexion is present, a spring assist may be added to return the ankle to neu-

tral and attain ground clearance during swing.

The double upright AFO is generally worn with a blucher oxford shoe. A leather T-strap may be attached to the

shoe and buckled around the medial or lateral upright to correct varus or valgus deformity. In the pronated (valgus)


foot, the T-strap is attached on the medial side and buckled around the lateral upright. In the varus foot, the T-strap

is attached to the lateral side and buckled to the medial upright to pull the foot out of varus.

There are several advantages of the double upright AFO over the plastic variety. The double upright AFO is the

best orthosis for patients who have sensory deficit and are likely to ulcerate with a plastic AFO. The metal AFO may

tend to be sturdier than the plastic type. The solid ankle variety is excellent for stroke patients with severe spasticity.

The chief disadvantage is that it is usually only possible to wear one pair of shoes, which are attached to the

uprights.

In some patients with hemiplegia who have markedly limited active hip and knee flexion, toe-drag will not be

eliminated by an AFO. When the patient has markedly limited hip and knee flexion, it is impossible to clear the toe

on swing-through even though the AFO is adequate. In this case, it is useful to raise the heel and sole of the con-

tralateral shoe sufficiently to allow clearance of the involved side on swing-through, usually one-quarter to one-half

inch being enough.

Figure 8. Solid AFO on left, PLS on right, Semirigid AFO center

Plastic Ankle Foot Orthosis

The plastic AFO designs (see Figure 8) consist of

• Posterior Leaf Spring Orthosis (PLS)

• Solid ankle foot orthosis

• Articulated (jointed) ankle foot orthosis

• Total contact ankle foot orthosis (with anterior shell)

• Supramalleolar orthosis (short orthosis) with proximal trim lines cut just above the malleoli

Figure 10. Arizona Brace

Figure 9. Posterior Leaf Spring (PLS) Orthosis


Posterior Leaf Sprint Plastic Ankle Foot Orthosis

The polypropylene Posterior Leaf Spring (PLS) (see Figure 9) orthosis is a lightweight, flexible AFO created by

narrowing the distal posterior ankle of the calf shell so that the trim lines are posterior to the malleoli. This makes

the orthosis more flexible and allows plantarflexion at heel strike and following push-off returns the orthosis to

neutral for the swing phase, providing toe pickup. The orthosis can be strengthened with vertical corrugations built

into the ankle joint and still retain the posterior trim line. For maximal resistance to varus or valgus, a flange may be

placed on the middle third of the calf shell, which creates a three-point pressure system. When placed on the lateral

side, the flange controls varus deformity.

The patient who is prescribed the PLS polypropylene orthosis may have little or no dorsiflexion power. Because

dorsiflexion is only partially resisted by the PLS, it is contraindicated with weak plantar flexors. There should be

good mediolateral stability in stance phase. Passive ankle dorsiflexion to 90º should be possible with the foot becom-

ing plantigrade during midstance. Mild spasticity may be present when prescribing the PLS orthosis. The very thin

polypropylene AFO to correct drop foot does not provide the stability for a weak calf and significant spasticity,

which is present in many stroke patients.

The PLS orthosis will provide toe clearance during swing phase, a mild degree of mediolateral stability during

swing and stance phase, and allow physiologic plantarflexion after heel strike and permit the plantar flexors to func-

tion for push-off. The PLS orthosis is the counterpart of the metal double upright brace with a dorsiflexion assist. A

90º plantarflexion stop should not be used with a PLS orthosis since it will prevent plantarflexion at heel strike.

Figure 11. Solid Ankle Foot Orthosis

Plastic Solid Ankle Foot OrthosisThe solid ankle foot orthosis (see Figure 11) is indicated for patients with significant spasticity, severe weakness

or absence of ankle dorsiflexors and plantar flexors, and mild to severe mediolateral instability during swing andstance. The rigid polypropylene orthosis has been shown to provide the same ankle stability as a fixed ankle doubleupright orthosis. It is also used for painful arthritic conditions in which it is desirable to immobilize the ankle. Thefunction of the solid-ankle polypropylene orthosis is to restrict all motion at the ankle. An anteriorly placed trimline at the level of the malleoli will provide the orthotic with the rigidity required. The solid ankle foot orthosis witha distal filler attachment may be indicated in the case of less stable partial foot amputations. The foot must beplantigrade with no equinus contractures. A partial foot amputee with an edematous stump and/or leg with poten-tial pressure against rigid margins of the shoe insert will not be able to tolerate a plastic insert AFO design. Theabsence of sensation in the diabetic foot will remove a warning signal if irritation should occur and is also a con-traindication to the use of a plastic shoe insert AFO. External orthoses are preferred when there is significant fluctu-ating edema or an absence of sensation.


Figure 12. Articulated Ankle Foot Orthosis

Articulated Ankle Foot OrthosisThe Articulated Ankle Foot Orthosis (see Figure 12) has an ankle joint built into the plastic orthosis. The artic-

ulated AFO is used in adults and in children with spastic cerebral palsy. The articulated AFO is also used as a tonereducing night splint. There are several tone reducing features of the articulated AFO which include: 1. 15 to 20º ofmetatarsal phalangeal extension in the foot plate; 2. Recessing area under the metatarsal heads in order to reducestimulation under the plantar surface to reduce the plantar grasp and decrease the positive support reflex; 3. Buildup of the medial aspect of the foot plate to control foot valgus and recess slightly at the lateral areas of the calcaneusto elicit inversion reflex; 4. Build up of the lateral side of the foot plate for the foot to be in inversion, eliciting ever-sion reflex; 5. Figure of eight ankle strap; 6. Fixed five degrees dorsiflexion for patients with extensor tone.

Disadvantages of the articulated AFO include compromised ability to control varus and valgus, problems withthe structural integrity for the aggressive walker who puts enormous forces on the ankle joint area; Less cosmeticallyacceptable as it is bulkier, utilizes more plastic and is much more difficult to disguise. Skin breakdown at joint artic-ulations when varus or valgus is severe; as i the inability of elderly patients to tolerate this brace.

Figure 13. Total Contact Insert (TCI) AFO with Toe Filler

Also Known as Chopart Clam Shell Prosthesis


Figure 15. Ritchie Brace

Total Contact Ankle Foot Orthosis

The Total Tontact Ankle Foot Orthosis (Figure 13) consists of a plastic solid ankle foot orthosis with an anterior

shell added for further reinforcement. The total contact AFO was modeled after the total contact plaster cast and the

orthosis tries to reduce pressure by completing surrounding the foot.

Figure 16. Supramalleolar Orthosis

Supramalleolar Orthosis (SMO)

The Supramalleolar Orthosis (SMO see Figure 16) is a plastic orthosis with proximal trim lines ending right

above the malleoli. The orthosis offers good medial and lateral stability. It is good for treating ankle sprains and for

children’s neuromuscular disease.


Orthotic Devices for the Diabetic Patient and Partial Foot AmputationOrthotic devices for people with diabetes mellitus have focused on reducing plantar weight bearing pressure on

the foot. Orthotic devices include prefabricated foot inserts and custom foot orthoses, the prefabricated walking

brace, Patellar Tendon Bearing orthosis (PTB), and Charcot Restraint Orthotic Walker (CROW) Orthosis.

Figure 17. DH Pressure Relief Prefabricated Walking Brace

Prefabricated Below Knee Walking Brace

The prefabricated below-knee walking braces (see Figure 17) including the DH-Pressure Relief Walker (Royce

Medical Co., Camarillo, CA), Equalizer Premium Walker (Royce Medical Co., Camarillo, California), and Aircast

Pneumatic Walker (Summit, New Jersey) formerly used for lower extremity trauma, have recently been found to be

effective in reducing plantar pressure in the diabetic foot and have become very popular unweighting devices.

Average peak forefoot pressures were reduced greater than 51% using the Equalizer Premium Walker and Aircast

Walker. In contrast to the total contact cast they are relatively easy to use, inexpensive, and allow easy access to the

wound for dressing changes. The prefabricated walking brace provides the necessary stability while allowing easy

donning and doffing for physical therapy sessions, washing and sleeping. A rocker sole or ankle joints may be added

to facilitate ambulation. The prefabricated walking brace can be used for immobilization of the charcot foot in dia-

betic patients.

In one study the DH Pressure-Relief walker (Royce Medical Orthopaedics, Carmarillo, CA) reduced plantar

pressures under all the metatarsals and the great toe significantly better than several other off-loading devices tested

and reduced forefoot pressure equally as well as the total contact cast. In another study comparing the DH Pressure

Relief Walker with the total contact cast in the reduction of plantar pressure, the DH Pressure Relief Walker reduced

plantar forefoot pressure 85% from baseline as compared to 76% reduction in plantar pressure with a Total Contact Cast.


Figure 18. Pneumatic Air cast Prefabricated Walking Brace

Aircast Pneumatic Walker

The Aircast Pneumatic Walker (Figure 18) because of it air bladders in the rigid shell has the advantage over

other prefabricated below-knee walkers of a total contact fit to reduce edema and shear forces. In a study comparing

the Aircast Pneumatic Walker with the total contact cast, the Aircast Pneumatic Walker decreased peak plantar foot

pressures to an equal or greater degree than the total contact cast in all tested locations of the forefoot, midfoot, and

hindfoot in 10 healthy male volunteers.

Although these prefabricated walking braces have been found to reduce plantar weight-bearing pressure in

healthy and diabetic subjects, their effectiveness in actually healing diabetic ulcers in random clinical trials has not

yet been demonstrated.

Figure 19. Charcot Restraint Orthotic Walker (CROW) Orthosis


Crow Orthosis

For patients with charcot foot too deformed to fit into an extra depth shoe, the Charcot Restraint Orthotic

Walker (CROW) may be indicated (see Figure 19). The CROW orthosis is a rigid, custom full-foot enclosure ankle-

foot orthosis that provides immobilization and protection during the prolonged healing of diabetic neuroarthropa-

thy. The orthosis is constructed with a total posterior and anterior shell that includes the foot so that a patient does

not need to wear a shoe with the brace as would be necessary with a regular plastic AFO or PTBO.

Figure 20. PTB Orthosis

Patellar Tendon Bearing Orthosis

The Patellar Tendon Bearing Orthosis (PTBO) is one of the original orthoses for unweighting the rearfoot and

the leg (see Figure 20). The PTBO is constructed with a pretibial component in which the patient rests his upper leg

and knee when ambulating. Patients are trained to walk by sinking their weight into the pretibial shell and the

weight is transferred down the uprights to the floor, bypassing the leg and the rearfoot. When patients walk properly

with the PTB and a cane, it has been found to reduce weight bearing on the leg and rearfoot up to 60%. The PTB

was originally indicated for patients with fractures of the leg and rearfoot, and to unweight a painful diabetic char-

cot rearfoot. It has been used to unweight patients with painful chopart joint amputations.

Patients are able to walk with the PTBO while the ulcer is healing and once the ulcer has healed the brace can

be used prophylactically. The PTBO has the advantage over total contact casting of being removable and is easier to

maintain. It comes in metal and plastic varieties and must have a solid ankle and rigid anterior shell closure to work

properly. It is also helpful to have a heel-shoe clearance of 3/8 inch to one inch and a rocker sole. The advantage of

the metal double upright variety is that patients with diabetes with neuropathy, who are most likely to use this

orthosis, may not be able to tolerate a plastic orthosis directly against the skin even if the orthosis is lined with pelite

or plastazote foam.


Figure 21. Half-Shoe With Dorsiflexory Wedge

IPOS Postoperative Half Shoe/Healing Sandal

The IPOS postoperative shoe (see Figure 21) was originally designed to take all pressure off the forefoot for use

after surgery. The shoe has a 10∞ doriflexory wedge and the heel is elevated four centimeters to avoid any forefoot

contact with the ground when walking. The shoe cannot be worn by individuals with ankle equinus or used for

bilateral ulcers. Half shoes were shown to heal ulcers faster and be associated with fewer serious infections than

patients treated with standard wound care therapy.

Figure 22. Silicone Cosmetic Foot Prosthesis

Partial Foot Amputations

For the patient with partial foot amputations, the orthotic/prosthetic prescription varies depending upon the

level of amputation. The patient missing one or more lesser digits does not need any special orthosis or prosthesis.

In fact a toe filler is likely to rub against the remaining toes and result in further ulceration and amputation. The

patient with an amputated great toe lacks push-off. These patients require a sturdy shoe. Some patients with hallux

amputations require a toe filler, but usually the hallux deviates medially after a while and no toe filler is required.

Figure 23. Foot Insert with Toe Filler


Partial foot amputations from the level of all toes, ray amputations, transmetatarsal amputations to Lisfranc’s

amputation level generally can be accommodated very well by a foot orthosis with toe filler (Figure 23) in conjunc-

tion with either a sturdy blucher oxford, running shoe, or high-top shoe. Patients with transmetatarsal amputations

frequently require a high-top shoe.

Figure 24. AFO with Toe Filler

Patients with amputations of one or more rays of the foot have what is known as longitudinal amputations.Amputation of one lateral ray can be accommodated by a custom-foot orthosis with toe filler and a sturdy shoe.However when several rays have been resected or when the entire 1st ray is resected, the foot becomes narrow andunstable. An ankle foot orthosis with toe filler and/or high-top shoe may be required to add stability (Figure 24).

Individuals with chopart amputation have just the talus and calcaneus left on the foot. The remaining footstump tends to develop equinus contractures, ulcerate and a higher revisional amputation is required. The chopartamputation without equinus contractures, which has been stabilized with tendoachilles lengthening and/or anklefusion, may be accommodated by a solid ankle foot orthosis with toe filler. For patients with chopart amputationswith equinus contractures, a clambshell partial foot prosthesis is required.

The final level of foot amputation is the Syme Amputation, which involves the removal of the entire foot. A spe-cial prosthesis, the Syme Prosthesis is required for amputation (see Figure 25).

Figure 25. Syme Opening Window Canadian Amputation Prosthesis


Orthoses for Sports Medicine

Figure 26. Tension Posterior Night Splint

Posterior Tension Night Splint

Recently the Tension Posterior Night Splint (Figure 26) has been used in the treatment of recalcitrant cases of

plantar fasciitis. During sleep, the unbraced foot and ankle assumes a plantarflexed position due to the normal tone

in the gastrocsoleus muscles. This nonfunctional plantarflexed position results in tightness of the posterior muscle

group and the plantar fascia is thought to account for the severe pain that patients with plantar fasciitis experience

upon their first step out of bed in the morning as the plantar fascia resumes its functional weight-bearing length.

Stress relaxation is the decrease in stress with time once a material under loading has deformed to a constant length.

This is due to the viscoelastic nature of all biological tissues. Similarly, when the plantar fascia is kept in a dorsi-

flexed, stretched position by the night splint, the biomechanical phenomenon of stress relaxation occurs and the

plantar fascia relaxes in the new stretched position. The tension night splint maintains the foot in a dorsiflexed atti-

tude while sleeping, thereby preventing tightness and contractures of the Achilles tendon and plantar fascia that

occurs as a result of the plantarflexed posture of the foot during sleep.

The tension night splint is typically used in combination with other treatments for heel pain. A night splint in

conjunction with stretching, viscoheels, and nonsteroidal antiinflammatory medications was more effective in the

treatment of plantar fasciitis than the same treatments without the night splint. This study used an office made plas-

ter night splint constructed with the ankle in maximum dorsiflexion. These authors felt that their splint produced

both ankle dorsiflexion and toe extension, which they considered critical to maintain tension in the plantar fascia.

Figure 27. Aircast Stirrup


Ankle Braces

The Aircast Stirrup (Figure 27) and a variety of cloth lace-up gauntlet type ankle braces have become popular

in the treatment of ankle sprains and other sports injuries about the ankle. Some of these sports ankle braces may

even take the place of a plaster cast for a simple non-displaced ankle fracture.

Ankle braces prevent active and passive inversion at the ankle, improve proprioceptive capability, and have been

shown to be more effective than taping for prevention of ankle injuries. Athletes also report that they are more com-

fortable in an air-stirrup brace than adhesive ankle taping. More importantly, ankle braces have not been shown to

inhibit athletic performance. Ankle braces are effective in the treatment of lateral ankle instability and ankle frac-

tures. Traditionally, the treatment for stable lateral ankle fractures was a below-knee walking cast until five to six

weeks after the trauma. In one study, 66 adult patients with supination external rotation ankle fractures were suc-

cessfully treated with either an aircast air-stirrup ankle brace or DonJoy R.O.M.-Walker brace for five weeks with an

average time until return to work of sex weeks. In a study of 0 patients with acute inversion ankle sprains, 10

patients were treated with a “dynamic” orthopaedic ankle brace after a 10-day plaster immobilization, and a control

group of 10 patients was treated with a weight-bearing, short-leg plaster cast for 25 days. An earlier and more func-

tional recovery occurred in the “dynamic” brace group. Similarly, patients treated with an Air-Stirrup ankle brace

were more mobile and had shorter sick leave time than patients treated with a compression bandage.

PRESCRIPTION FOOT WEARBasic Terminology

LastThe Last is a three-dimensional model on which the shoe is made. The shape of the toe box, the instep, the

girth, and the foot curvature are determined by the last. A Single Last shoe consists of a last with the heel in propor-

tion to the forefoot. A double (or combination) last is when two different sizes or two different proportions are used

in constructing a model for shoe fabrication. The last of the shoe can also be an Out Flare Last which accommodates

an abducted forefoot or painful bunion or an In Flare Last which accommodates an adducted forefoot or a foot in

slightly fixed varus. A Straight Last shoe is well-aligned in the forefoot and rearfoot. The straighter the last, the more

medial support is provided; therefore a straight last shoe is recommended to help control overpronation. Because

most feet have a slight inward curve, most companies that make athletic shoes use a last that is curved inward

approximately seven degrees.

Figure 28. Shoe Last

A board-lasted shoe has a hard fibrous board on its innersurface that provides stability and is more appropriate

for individuals who overpronate. The board-lasted shoe is stiffer and may lead to an Achilles tendon injury. In a slip-

lasted shoe, the upper is stitched into a one-piece moccasin and then glued to the sole. These shoes provide less sta-

bility but are lighter, more flexible, and roomier in the toe box (making them an excellent choice for individuals

with cavus foot types). The combination last usually consists of a board-lasted heel for rear foot stability with a

board-lasted forefoot for flexibility.


Shoe closures include the Blucher in which the shoe quarters extend forward over the throat of the vamp and

are therefore loose at the inner edge. The Blucher adds room in the shoe and is preferred for insole modifications,

foot orthoses, and to be worn with braces. The Blucher Oxford is the classic orthopedic style shoe. The Balmoral

shoe closure has the vamp sewn over the quarters of the front of the throat. This is more of a dress shoe and the

shoe does not open as easily or as fully.

In-Depth ShoeThe in-depth shoe is usually oxford style and has a Blucher closure. The shoe is designed with a minimum of

3/16 inch to 1/4 inch depth thoughout the shoe. The in-depth shoe usually has a deep broad high toe box, a full

length wedge sole with longitudinal arch support, and a stiff counter. Work boots, even with steel toes, “comfort”

shoes and athletic shoes are being made in expanded size with removable insoles and high wide toe box and func-

tion as in-depth shoes.

Figure 29. In-Depth Shoe

Custom-Molded Shoe A custom-molded shoe is made from a cast of the patient’s foot to accommodate or support a specific foot

deformity. The last is a solid form over which the shoe materials are stretched to conform to the shape of the foot.

The last for a molded shoe is made by taking a cast of the foot, and once dry, filling the cast with plaster to make a

positive mold of the foot and leg. Custom-molded shoes are required when the foot deformity is such that a conven-

tional, extra-depth shoe cannot be modified to accommodate the deformity or when there are special functional

requirements. Custom shoes are often prescribed for patients with residual clubfoot deformities, proximal partial

foot amputations, severe neuropathic arthropathy (charcot foot), nonplantigrade foot conditions such as severe

equinovarus foot of neuromuscular disease, and end stage Rheumatoid arthritis foot.

Figure 30. Custom-Molded Shoe


External Shoe Modifications

Solid Ankle Cushion Heel (SACH)The Solid Ankle Cushion Heel (SACH) heel is a wedge interposed into the heel of the shoe made of compressi-

ble foam material. The SACH heel simulates plantarflexion on heel strike and absorbs stress and impact diminishing

the force to the heel. The SACH heel actually limits motion at the heel on heel strike simulating plantarflexion and is

therefore good for painful ankle and heel conditions including ankle arthritis, and postoperatively for ankle fusions.

Rocker Bottom SoleThe anterior half of the sole is curved upward toward the end of the shoe, with the apex of the curve just proxi-

mal to the metatarsal heads allowing for more smooth transmission of weight bearing from heel to toe during

stance phase of gait and decreases the weightbearing load beneath the metatarsal heads. The rocker bottom sole

must be made of a rigid material. The rocker bottom sole is useful for relieving metatarsalgia, hallux limitus, and

plantar forefoot ulcers. The rocking action of the sole compensates for lost ankle motion and is useful for patients

with ankle arthritis, following fusions of the hindfoot, or attached to a solid ankle foot orthosis. The rocker bottom

sole should be added to any shoe requiring an extended steel shank.

Figure 31. Heel Rocker

Toe Spring Toe spring is the upward curve of the distal midsole representing a modified rocker bottom that serves to short-

en functional length of the shoe while allowing the metatarsophalangeal joint to move through a lessened range of

motion during propulsion.

A negative heel rocker is a toe rocker with a negative heel and may be helpful for patients with the foot fixed in

the calcaneus position.

Rigid SoleA rigid sole consists of either adding a rigid sole bar such as adding a steel spring or fiber glass plate inter-

spersed between the midsole and outsole. It extends from the midpoint of the heel to the sulcus of the toes. It pre-

vents dorsiflexion at the metatarsophalangeal joints. It must be used with a rocker sole. Indications for a rigid sole

include hallux limitus, arthritis, metatarsal ulcers and forefoot amputations.

Extended Heel CounterThe counter is the stiff material in the heel portion of the upper that helps control the alignment of the hind-

foot. Extended counters on either the medial or lateral side are used when additional hindfoot control or stabiliza-

tion is necessary. An extended medial counter is used for ponation deformities with hindfoot valgus. If the foot is

rigid with a severe heel valgus or varus on weight bearing (relaxed calcaneal stance position), a stiff countered shoe

may result in pressure sores and ulceration on the medial or lateral aspect of the foot inferior to the malleoli espe-

cially in the patient with neuropathy. **Do not use with rigid deformity.

Sole WedgesLateral heel and sole wedges are used to correct flexible hindfoot varus deformities and decrease varus instabili-

ty with lateral ankle sprains. Neuromuscular conditions that may be managed partially with lateral sole wedges


include post-polio syndrome, and Charcot-Marie Tooth disease. Medial sole sole wedges help control excessive

pronation and flexible hindfoot valgus deformities. The apex of the wedge is generally one-eighth inch to one-

fourth inch thick. **Do not use sole wedges with rigid deformity.

Sole/Heel FlareA sole flare is an extension of the edge of the sole material in either a lateral or medial direction to make the

shoe more stable. The flare increases the surface area in contact with the floor by 1/4 inch to one inch. Medial sole

flares are used to decrease medial tilting of the shoe in severe pronation deformities and can be used with rigid

deformity. Lateral sole or heel flares are used to reduce lateral ankle ligament instability and to decrease lateral tilting

of the shoe in severe hindfoot varus deformities such as occurs in rigid clubfoot and equinovarus deformities of

neuromuscular disease. A large lateral heel flare (as seen on some running shoes) increases both the range and speed

of initial subtalar joint pronation. **Heel and sole flares can accommodate rigid fixed deformities.

Heel Buttress (OFFSET)The heel buttress (offset) is firm density soling material added to the lateral or medial side of the shoe. A medial

heel buttress resists pronation force and a lateral heel buttress resists varus force. **Heel buttresses can be used to

manage rigid fixed deformities.

Sole ElevationsSole elevations are useful to accommodate severe limb-length deficiencies. Blocks of material of known thick-

nesses can be placed beneath the short leg until the pelvis appears level. Usually 1/4 inch to 1/2 inch less than the full

amount of the leg length difference is added to the sole to allow easier swing through of the foot during walking.

Thomas HeelThe Thomas heel has an anterior medial extension of at least one-half inch longer than the standard heel. It is

designed to give added support under the sustentaculum tali and the medial longitudinal arch for symptomatic pes

planus. The Reverse Thomas heel has the lateral portion of the heel extending anteriorly under the calcaneal cuboid

joint and externally rotates the foot.

Figure 32. Thomas Heel

Metatarsal BarThe metatarsal bar is an external shoe correction that involves placing a firm material with the apex just proxi-

mal to the metatarsal bar on the sole of the shoe. Metatarsal bars unload the metatarsal heads and are indicated for

painful metatarsalgia conditions including metatarsal calluses, sesamoiditis, and neuroma.

Internal Shoe ModificationsThe shank of the shoe is equivalent to the arch of the shoe. Internal shoe modifications such as the steel shank,

cookie pad, navicular scaphoid pad, longitudinal arch support, and extended medial counter all support the medial

longitudinal arch.


chapter 3d orthotics and pros the tics

Documents

equalizer

calcaneal

total contact

deep heel

aircast pneumatic

rocker bottom

extended medial

cell sponge