Orthotic Design for Foot Pathologies
Top Contributors - Carin Hunter, Jess Bell, Kim Jackson, Stacy Schiurring, Tarina van der Stockt, Vidya Acharya and Lucinda hampton
Non-pathological Foot[edit | edit source]
- No underlying condition
- Normal foot structure
- Pain
- Musculoskeletal issues
- Trauma
- Tendon dysfunction
Congenital Paediatric Problems[edit | edit source]
o Flexible pes planus
o Accessory Navicular – Congenital 12% pop., pain,
redness, PTTD
o Vertical talus – Congenital, may have other conditions,
rocker bottom foot
o Freibergs Disease – Forefoot pain, stiffness, 2nd MPT,
rare
o Cavus foot – High arch, CTEV
The Child’s Foot – flexible pes planus
o Flexible Pes Planus – Jacks Test, arch recreates
Off the Shelf (OTS) Insoles
oGenerally std neutral position
oStd arch support
oDifferent densities
oLow profile
oShock absorption
oMinimal correction
oNo accommodation of deformity
oGood starting point
| 36
Adult Non-pathological Foot – Common Problems
o Adult Acquired Flat Foot (AAFF)- most common caused by
o PTTD - occurs when the posterior tibial tendon becomes inflamed or
torn. As a result, the tendon may not be able to provide stability and
support for the arch of the foot,
• (PTTD) is characterized by degeneration of this tendon and is
progressive if not treated.
• 5 stages
o Can be associated with tear or stretching of spring ligament.The spring
ligament functions as static restraint of the medial longitudinal arch, it
supports the head of the talus from planter and medial subluxation
against the body weight during standing. Can be ruptured or torn.
PTTD
• Posterior Tibial Tendon Dysfunction
I. Acute
II. Flexible (FFO)
III. Fixed –Arizona
IV. Chronic –AFO
V. Chronic – surgery
• The treatment plan for posterior tibial tendon tears varies depending on
the flexibility of the foot.
38
PTTD I & II
• Posterior tibial tendon dysfunction characteristically is a slow onset
condition mainly affecting women older than 40 years of age.
• Risk factors include obesity, hypertension, diabetes, steroid use
and seronegative arthropathies.
• Patients may complain of pain and swelling around the medial
ankle, difficulty mobilizing or exacerbation of an existing limp.
• Examination may show tenderness along the course of the tendon,
A change in the shape of the foot. The heel is everted and the arch
collapsed. Flexibility reduced
• Test - “too many toes” when feet are viewed standing from behind.
• Difficulty performing a single heel raise. Heel remains in everted
position
PTTD Orthotic Prescription
• Goal - reduce the excessive pronatory forces acting across
the subtalar joint (STJ) axis.
• Design - The orthoses must control pronation with
significant surface area contacting the foot. The
modifications should increase supinatory torque across the
STJ axis.
• Polypropylene Shell - semirigid
• Deep Heel Cup
• The deep heel cup increases surface area medial to the
STJ axis applying a supinatory torque
• Medial Heel Skive – 4mm or 6mm
• The medial heel skive increases force medial to the STJ
axis to reduce excessive STJ pronation and heel eversion.
Measurement of FFO
• Cast, foam box, scan to capture shape of foot
• Modify intrinsically in w/shop or lab
• Extrinsically posting/adaptions can be added
• Often off site manufacture
• Low profile- full, 3⁄4, court, sports
• Limited shock absorption or accommodation
41
Design/Prescription of FFO
o Based on Exam/assessment
o Main issue- part of gait cycle, ie MS or push off
o Determine what mechanism for problem
o Pes planus, arch support
o STJt rotation, wedging
o Problems higher up, compensation
o Weakness/tightness, hips, knees
Principle of orthotic design
o Position of heel/forefoot and STJt rotation
o Medially rotated STJt
o Increased pronation moment/ decreased supination moment
o Rebalance by moving GRF medial, increasing supination moment,
reducing medial rotn
o Laterally rotated STJt
o Increased supination moment, decreased pronation moment
o Rebalance by moving GRF closer to STJt, to increase pronation
moment of GRF
o Not this simple, look at tibia and knee hip alignment
Adult Non-pathological Foot – General foot
problems
o Plantarfascitis – inflammation of plantar fascia
o Windlass test +/-, common symptoms, pain , am, n/splints
o Hallux rigidus/limitus – Flexibility of 1
st MTP
o Test, to ax limitus or rigidus, try to encourage flexion by inc p/f 1st ray
o Metatarsalgia – Prominent bony structures, pain
o Mortons Neuroma – Mulder’s test
o Heel spurs – Specific heel pain, treat with off load device
o Claw/ hammer toes Fixed/mobile, pain, callousing,shoes
o Arthritis- shock absorption, support off load
Functional Foot Orthosis (FFO)
o Heel Skives- intrinsic (on model)
o Medial (Kirby)- shifts force applied laterally, supinates/inverts –
o PTTD, Plantarfacsitis
o Lateral shifts force applied to heel medially and pronates/everts
o Inversion of the positive cast increases arch height under the base of
the first metatarsal resulting in plantarflexion of the first metatarsal -
FnHlimitus
Functional Foot Orthosis (FFO)
o Arch Fill – can increase or decrease arch support, be
careful.
o 1
st ray /1st met cut out- allows the 1st ray to plantarflex-
key for normal gait, windlass. Not always necessary if
corrected cast used- FnHl, Plantar flexed 1st ray
Functional Foot Orthosis (FFO)
o Mortons extension ( not to be confused with Mortons neuroma)
o extra material added under 1st met heads only to increase plantar
pressure and flex 1st met head, Can be Rigid or flexible useful in
treating HR, to reduce painful mvt, protect stiff joint also shoe mod
can help
o Reverse- extra added under 2-5 to allow plantarflexion of 1st ray-
FnHR, allows p/flexion of 1st ray and increases flexion MTP, windlass.
Non-pathological Foot - Injury /Trauma
o Shin splints – Med. Tibial Stress Syndrome
o Overuse injury, Tib post./Tib ant-
o Support, reduce overuse by balance, shock absopt and rest
o Inversion injury/Lat ankle sprain-
o Ant/post TaloFibL, CalcFibL- lateral wedge, increase
pronation to stabilise.
o Eversion – Deltoid, less common
o Lisfranc Injury/Trauma
o Achilles Tendon injuries- relieve with heel post, stretch
Pathological Foot
• Neurological/Motor
• Sensory
• Neuropathy
Pathological Foot – Associated Conditions
o Neurological
o CP
o Stroke
o MS
• Motor
o Ataxia
o Dystonia
Pathological Foot
o Sensory/ Neuropathy
o Diabetes
o HSMN- CMT
o Downs
o ASD
TCI’s - Measurement
o Custom made – usually E.V.A. – High, Medium
& Low Density
o Cast, foam box, scan
o Workshop manufactured or Lab
o Intrinsic modification/ extrinsic posting
o Can be bulky
o Support, correct, Accommodate
o Shock absorbing
Total Contact Insoles (TCI)
o Design from Examination as per FFO
o Support- through shape and density of materials
o Accommodation - fixed deformities, ground to meet feet or feet to
ground, blocks test, easier due to construction than with FFO
o Shock absorption – better than FFO due to materials.
o EVA (Ethyl Vinyl Acetate)
Most common pathological foot
The Diabetic Foot
• Sensory
• Neuropathic issues
• Pressure areas
• PTTD
• Charcot foot
• At Risk
Diabetic Treatment
Off -Loading Diabetic Ulcers
Charcot Foot
Orthotic Insoles
| 58
Diabetic Spec – Toe fillers amputation
Pathological conditions-
more complex as all joints/muscles affected
• Look at hip knee position
• Feet ankles will adapt to ground
to support structures higher up
and compensate for bony
abnormalities
Pathological Foot- Valgus Deformities
o Rocker Bottom Foot- accommodate, support.
o Hyper-mobility- if OTS does not work for
paediatric hypermobility
o Escape Valgus – Accommodate for tight TA
Escape Valgus
oCompensatory movement- heel
pulls into valgus/eversion
oOver pronates mid foot
oDriven by tight TA
oCan alter foot structure
oCan result in long term issues
61
Cavus/Varus Deformity
o Cavo Varus deformity can be the result of a plantar
flexed first ray (forefoot-driven), a deformity of the
hindfoot (hindfoot-driven), or a combination of
both.
o Weakness in tibialis anterior & peroneal brevis
( which dorsiflex and evert)
o Tight plantar fascia
o Over-active peroneus longus, pulls 1st ray into
p/flexion
o Plantar-flexed first ray
o C.T.E.V./HMSN
Fore foot v Hind foot Deformity
• In midstance, plantarflexion of the first ray leads to a
compensatory varus heel, supination of STJt and
reduced shock absorption.
• During heel-off (terminal stance), the plantarflexed first
ray causes a supination of the forefoot that increases the
varus deformity of the hindfoot.
• In hindfoot-driven cavo-varus deformity, the subtalar
joint may compensate for varus deformities above the
ankle joint.
• Overload of the lateral soft tissue structures (eg, lateral
ligament complex, peroneal tendons) and degenerative
changes (eg, medial ankle osteoarthritis, midfoot
arthritis) may occur over time.
Coleman Block Test
Lateral Forefoot Wedge
In summary
o Anatomy- complex mechanism to allow standing, balance,
walking, running, jumping, lifetime of external factors
o Assessment / history, passive, static, dynamic
o No one correct solution, watch, listen and learn
oPatient and clinical education
oOrthotics in combination with other MDT treatments
