CLINICAL FOOT ORTHOPEDICS
FOOT ORTHOSES
James McGuire DPM, PT, LPed, FAPWHc
Clinical Professor
Departments of Podiatric Medicine and Biomechanics
Temple University School of Podiatric Medicine
Suggested Textbook
Definitions:
• Orthosis - A device utilized to assist, resist, facilitate, stabilize or improve range of
motion and functional capacity of mechanically based musculoskeletal pathologies in
the body.
• Functional Foot Orthosis - A custom or prefabricated device utilized to treat
mechanical pathologies of the foot that may be structural or functional in nature.
• Accommodative Foot Orthosis - An orthotic device that supports the foot but does
not attempt to align the joints of the foot during stance or gait.
• Custom Foot Orthosis - A device derived from a three-dimensional mold of the
patient's foot. This device may be functional or accommodative and is based on a
prescription.
Proper use of the terms
• Foot Orthosis - A mechanical intermediary between the foot and
shoe
• Orthoses – more than one
• Orthotic - adjective (i.e. orthotic device)
• Orthosis - noun (i.e. functional orthosis)
Definitions:
• Rigid Functional Orthosis - A functional foot orthosis made to maximally
prevent abnormal motion or abnormal position of the foot and leg during gait.
The device should be made with a rigid material that displays minimal flexibility
during use. Material rigidity is a function of material thickness, intrinsic rigidity
of the material, orthotic plate size, patient weight, and the degree of instability
of the foot.
• Semirigid Functional Orthosis - A functional foot orthosis used to partially
control abnormal motion or abnormal position of the foot and leg during gait.
This device is made from a material that displays moderate flexibility during
use. Material rigidity is a function of material thickness, intrinsic rigidity of the
material, orthotic plate size, patient weight, and the degree of instability of the
foot.
• Flexible Functional Orthosis - A functional foot orthosis is used to partially
control abnormal motion or abnormal position of the foot and leg during gait.
This device is made from a material that displays significant flexibility during
use. Material rigidity is a function of material thickness, intrinsic rigidity of the
material, orthotic plate size, patient weight, and the degree of instability of the
foot.
Definitions
• Brace: An orthopedic appliance applied to the body to support the
weight of the body, to correct or prevent deformities, or to control
involuntary joint movements.
• Splint: A rigid or flexible appliance for fixation of displaced or
movable parts designed to support an injured or displaced body part.
Definition: Prosthetist/Prosthetic
• Prosthetic: An artificial device that replaces a missing body part, which may be lost
through trauma, disease, or congenital conditions.
• Prosthetist: A licensed, certified professional who measures, designs, fabricates,
fits, or services a prosthesis as prescribed by a licensed physician, and who assists in
the formulation of the prosthesis prescription for the replacement of external parts
of the human body lost due to amputation or congenital deformities or absences
Definition: Pedorthics/Pedorthist
• Pedorthics is the management and treatment of conditions of
the foot, ankle, and lower extremities requiring fitting,
fabricating, and adjusting of pedorthic devices. Pedorthics
uses footwear to help ease and treat these foot-related
problems
• Pedorthist is a licensed certified professional who has
specialized training to modify footwear and employ
supportive devices to address conditions which affect the feet
and lower limbs as prescribed by a licensed physician
Definitions
• Prefabricated Foot Orthosis (PFO) - A mass-produced foot orthosis
made in various sizes and fit to a patient based on the size of their
foot. A variety of materials and options are available.
• Functional Prefabricated Foot Orthosis - A prefabricated orthosis that
is designed to alter foot function and to align the joints of the foot.
Includes many features commonly found on custom orthoses
including valgus forefoot support, rearfoot posts, and medial skives.
Also referred to as a Customizable PFO
THE ORTHOSIS SHOULD BE SELECTED AND DESIGNED
TO ACCOMPLISH ONE OR MORE OF THE FOLLOWING
OBJECTIVES ?
• Transfer forces from high to low pressure areas
• Reduce shock and shear forces
• Modify force transfer patterns
• Correct positional ( flexible ) malalignments
• Accommodate fixed ( rigid ) deformities to prevent
abnormal motions/ compensations from occurring
• Limit motion of painful, inflamed, or unstable joints
Pros and Cons OTC Prefabs
• Pros
• Dispense Immediately
• Less messy
• Less expensive
• Cons
• General sizes
• Average shapes
• Less aggressive due to need for general acceptance
Pros and Cons Custom Orthoses
• Pros
• Specific fit and functional control
• Physician directed process
• Fits odd shapes and sizes
• Cons
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•
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Expensive
Delays in implementation
Messy process
Requires the use of an outside lab – control issue
Orthotic Indications
• Proximal Lower Extremity Pathology Responsive to Foot Orthoses
• A. Shin Splints
• B. Tendonitis (Tenosynovitis)
• C. Posterior Tibial Dysfunction
• D. Chondromalacia Patella
• (Runner's Knee, Patello-femoral Syndrome)
• E. Iliotibial Band Syndrome
• F. Limb Length Discrepancy
Orthotic Indications
• Arthritides
• A. Inflammatory Arthritis,
• Rheumatoid Arthritis, Psoriatic Arthritis,
• Other Inflammatory Arthritides
• B. Osteoarthritis
Indications
• Mechanically Induced Pain and
Deformities
• A. Pes Cavus, Haglund's Deformity
• B. Hammer Digit Syndrome
• C. Functional Hallux Limitus,
Hallux Limitus and Hallux Rigidus
• D. Plantar Fasciitis
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•
•
•
•
•
•
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E. Equinus
F. Sinus Tarsi Syndrome
G. Tailor's Bunion (Bunionette)
H. Hallux Abducto-Valgus
(Hallux Valgus, Bunion)
I. Pes Planus
J. Metatarsalgia
K. Sesamoiditis
L. Morton's Neuroma
(Intermetatarsal Neuroma)
Indications
• Pediatric Conditions
•
•
•
•
A. Calcaneal Apophysitis
B. Genu Varum and Genu Valgum
C. Tarsal Coalition
D. Metatarsus Adductus
• Sensory Neuropathies
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•
•
•
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A. Peripheral Neuropathy
B. Charcot Neuroarthropathy
(Charcot Foot)
C. Tarsal Tunnel Syndrome
Alcoholic and Drug-related Neuropathy
Contraindications to the Use of Custom Foot
Orthoses
• Other modalities have not been tried: Prefab devices, shoe
modifications, physical therapy
• Literature supports the use of alternative
therapies/devices/modalities
• Medical or Surgical Management is more appropriate
Anatomy of a Functional Orthosis
Plate or Shell = A thermoplastic material molded to a neutral
position plaster cast
Post = A correcting platform designed to help place the shell in
the desired functional position
extrinsic post the material is added to the outside of the
shell
intrinsic post, corrective posting is incorporated into the
shell
Forefoot Extension = A layer of protective or accommodative
material extending from the distal end of the orthotic shell to
either the digital sulcus (3/4 length) or to the tips of the toes (full
length)
Top Cover =The top layer of material which may offer additional
cushioning if desired and is in direct contact with the foot
Casting Choices What types?
Clean, Fast
Studies Show Repeatable,
Consistent Results
Repeatable, Consistent
Results
Repeatable, Consistent
Results
Difficult To Find
STJ Neutral
Technology Is Key
Fast
Reference Standard
Higher Volume Necessary
Sizing Is Key
Messy
Results not
repeatable
Expensive
CASTS
• Negative Cast - A plaster molding or digital scan of the patient’s foot
in a particular position. This is sent to an orthotic laboratory for use in
manufacturing custom orthoses.
• A foam impression is occasionally used for this purpose but only to
fabricate custom accommodative orthoses.
Cast Corrections
• Modifications to the mold of the
patient’s foot based on the
orthotic prescription. These
modifications change the shape of
the positive mold in order to
change the function of the foot
once an orthoses is made from
this mold. They include:
•
•
•
•
arch fill
heel expansions
balance platforms
lateral expansion.
Why do we add each of these corrections?
Minimal Fill vs Maximal Fill
CAD / CAM Cast Correction
• The use of computer-aided design to perform the same corrections
on computer that would be done on a plaster positive cast. Once the
computer-generated positive cast is completed, a physical positive
cast can be milled out of a block of wood, or the orthosis itself can be
milled directly out of a block of polypropylene from a “virtual”
positive.
Digital Rendering and Modification
*
Extrinsic Rearfoot Post
Stabilizes/ Inverts/ Everts Shell After Forefoot Post Is Applied
0°
0° Rearfoot Post Stabilizes
Shell And Is On The Same
Plane As The Parabola
4°
4° Varus Rearfoot Post
Inverts Shell. Causes
Forefoot To Rearfoot
Motion Of 4°
Milling and Finishing
Prefabricated Orthoses
(Over The Counter/OTC or Professional)
• OTC orthoses are increasing in number and
claims of therapeutic benefits.
• OTC devices which have been objectively
evaluated with clinical patient studies should be
given greater consideration for use I.e *Scholl’s
Heel Guard®, *Dynastep®
• Prefabricated orthoses which may be
customized by the clinician may provide
excellent biomechanical control and comfort for
the patient.
Prefabricated Orthosis
• This prefabricated orthotics are extremely versatile devices
that may be custom balanced to meet many patient
functional support needs.
• This orthosis is comprised of an 1/8” Aliplast #10 firm
topcover material overlying a 5/16” thick Plastazote #2
molded support base. Other combinations include Cork
and EVA, Cork and Leather, and Plastazote and Poron
• The neutral-posted base material may be left alone or
ground to produce the desired frontal plane varus or
valgus posting.
• The orthosis is easily modified with the addition of
thermoplastic balance elements to increase medial
longitudinal support or frontal and/or sagittal plane
posting..
Prescription Foot Orthoses (Flexible)
• Flexible or “Accommodative” type
orthoses are generally prescribed for
patients at risk of soft tissue or osseous
injury.
• Materials such as Plastizote, PPT, SBR,
Aliplast may be laminated together to
provide for optimal cushioning and
accommodation.
Prescription Foot Orthoses
(Semi-Rigid)
• Patients who need support but also require
motion to function optimally or without pain.
• Semi-rigid materials such as Thin Polypropylene
and Subortholen allow for shock absorption and
foot elongation during gait while preventing
pathologic ranges of motion.
• The degree of rigidity is often based on the
material thickness.
Prescription Foot Orthoses
(Rigid)
• Designed to limit and control motion
associated with abnormal compensation
patterns.
• Prescribed for patients requiring a high
degree of biomechanical control and
support.
• Materials may include Polypropylene,
Polydur©, Rohadur®, Metal, Fiberglass, and
carbon-graphite composites.
Heel Elevator
Most orthotics come back
from the lab posted on the
flat bench top however most
shoes have at least a little
heel elevation built into them
Orthotics must be manufactured on an
elevator or a block that is equal to the heel
height or the orthotic will rock in the shoe
Dynamic Molding
• When a material molds to the foot in response to pressure and body
heat it is referred to as “dynamic molding”.
Heel Stabilizer
A rearfoot posted orthosis that
incorporates high medial and
lateral flanges for increased
frontal plane control
Gait Plate
• A foot orthosis that is designed to induce in-toe or out-toe
Out-Toe Orthosis
• Deep Heel Seat - to a height just
inferior to the lateral maleolus
• Lateral Flange - to just proximal to
the base of the fifth metatarsal
• Medial Flange - to the mid-point of
the first metatarsal shaft
• Distal Plantar Edge - ending at the
mid-point of the first ray medially
and at the end of the fifth toe
laterally.
• Forces the child to out toe to
progress over the distal edge
In-Toe Orthosis
• Deep Heel Seat
• Lateral Flange
• Medial Flange
• Distal Plantar Edge - ending at the
mid-point of the fifth metatarsal
ray laterally and at the sulcus of
the hallux medially
• Forces the child to in-toe to
progress over the distal edge
•
UCBL Foot Orthosis
FUNCTION: To reduce or prevent problems
related to compensatory STJ pronation,
collapsing mid-foot deformity and internal
(medial) leg rotation.
• Orthosis functions primarily as a transverse
plane stabilizer by exerting force against
the shaft of the fifth metatarsal and
sustentaculum tali. Sagittal and frontal
plane support are provided through arch
bracing and molded deep heel cup.
Direct Mold Orthoses
The Direct Mold Orthosis (DMO) is an easily fabricated, readily adjustable
device that can be made in the office setting on the day of the patient’s
visit if desired. It is an extremely versatile orthosis that may be utilized for
biomechanical control, protective accommodation, or bracing purposes.
Direct Mold Orthosis
Direct Mold Orthosis
Direct Mold Orthoses
(Modified Carville Healing Sandal Dr. Paul Brant)
• The Carville Healing Sandal has proven to be an effective
time tested ulcer healing technique at the Hansen’s Disease
Center for thousands of patients
• We have found a modified version of the Carville Sandal to
also be very effective in the management of plantar foot
ulcerations
• The Diabetic Direct mold orthosis is fabricated as previously
described and trimmed to an exact surgical shoe fit
• The Direct Mold Orthosis should be fastened to the surgical
shoe with rubber cement to facilitate easy removal for
future modifications
Orthosis Material Selection
Vacuum-Formed Polypropylene
• Used for the shell of a custom functional orthosis. It is made from a
sheet of polypropylene, heat formed over a corrected positive mold
of the foot. This positive can be made of plaster or milled from a
block of wood.
Direct-Milled Polypropylene
• Used for custom functional orthosis. The shell is milled directly out of
a block of polypropylene based on the corrected “virtual” positive
mold. Direct-milled polypropylene is more rigid compared to the
same thickness of vacuum-formed polypropylene.
Graphite
• Used for custom functional orthoses, graphite is extremely thin and
lightweight with variable rigidity within the shell for localized strength
in high-force areas. Orthoses made with this material are intended to
fit in low-volume footwear such as dress shoes and footwear used for
cycling, soccer, skating and skiing.
EVA (Ethyl Vinyl Acetate)
• A closed-cell foam available in a medium (40
durometer) or firm (70 durometer) density.
Used as an orthotic shell material for
accommodative custom orthoses, or as a
material for topcover or firm EVA rearfoot
post.
• P-Cell is a closed-cell EVA foam used as a
topcover material for foot orthoses.
Plastazote®
Closed cell cross-linked polyethylene foam
• Low to High durometer #1, #2, #3
• Commonly used for accomdative
orthoses for diabetes and arthritis
• Good for shock absorption but bottoms
out quickly unless laminated to another
material such as poron/PPT
• Easy to clean with water and mild soap.
• Several thicknesses available, ranging
from 1mm to 6mm.
Material
Selection by
Weight and
Flexibility
Requirements
Primary Factors Used in Selection of Materials for Foot
Orthotics
• Weight (weight to thickness ratio)
• Activity level/sport/work requirements
• Available ROM
• Amount of control needed
• Amount of Accommodation required
• Inherent Material Characteristics. Density, Flexibility, Fatigability,
Memory, Thickness
Primary Factors Used in Selection of Materials for Foot Orthotics
•Footwear
•Previous experience with a
given material or orthosis
design
•Patient concerns: color, etc.
•Cost
•Orthotic Lab recommendation
Materials Selection
Materials Selection
AGE
RIGID
5
15
30
Reverse-of-Deformity Theory
What is This?
45
60
75
FLEXIBLE
Definitions Shore Durometer
• Durometer is one of several measures of the hardness of a
material.
• Hardness may be defined as a material's resistance to permanent
indentation.
• The durometer scale was defined by Albert F. Shore, who
developed a measurement device called a durometer in the
1920s. The term durometer is often used to refer to the
measurement, as well as the instrument itself. Durometer is
typically used as a measure of hardness in polymers, elastomers,
and rubbers.
• Shore A Scale: For determining the hardness of softer materials such as EPDM rubber,
elastomers, neoprene, silicone, polyurethane
• Shore D Scale: For determining indentation hardness of harder materials such as pipeline
coating epoxy, plexiglass, vinyl, cellulose acetate, and other similar materials.
• Depending on the intended use; types A, B, C, D, DO, E, M, O, OO, OOO, OOO-S, and R.
Each scale results in a value between 0 and 100, with higher values indicating a harder
material
Grindability
• Defines whether or not the orthotic material can be used on
a grinder, such as the Sanigrinder.
Laminate
• This is the number of layers or materials glued together to form a single
sheet.
• Material laminates possess some distinct advantages over single layer
materials. A characteristic, which is poor in one material, may be offset by
the same characteristic, which is strong in another material.
• Laminating two such materials together, or otherwise using them in
conjunction, produces a better functioning material. Materials used in this
manner possess all of the good qualities and none of the weaker qualities of
its' component materials.
CMO Laminate
Nickleplast-Subortholen-EVA
Superform®
Nylon Reinforced Polypropylene
Acrylics: Polydor, Rohadur
• An acrylic thermoplastic material designed for use in
orthotic devices
• Manufactured in the United States by Spartech Polycast.
There is a Polyfilm protective masking on two sides.
Top Cover Characteristics
• Wearability – Naugehyde
• Breathability - Plastazote
• Stainability - Naugehyde
• Odor-Retention - Leather
• Accommodation – EVA, Plastazote, Nickleplast
• Adherence – Silicones will not adhere
• Appearance – color, texture, pattern
Open vs Closed-Cell Materials
• OPEN Cell: Interconnections between individual air cells within the
material
- breathes well
- compresses – dynamic molding
• CLOSED Cell: No interconnections between individual air cells
- impermeable
- non-compressible
- excellent recovery (Shock absorption)
Rubbers
• Latex
• Rubber Butter
• Commercial Cork and Latex Combinations
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Cushion Cork
Korex
Orthocork
Thermocork and Thermocork Lite
Synthetic Rubbers
• SBR styrene butadiene rubber
• Nickleplast
• Spenco
closed cell urethane
• Lynco
open cell urethane
• Sponge