Foot Orthotics Flashcards
What is a foot orthotic?
A device that is placed in a person’s shoe to reduce or eliminate pathological stresses to the foot or other portions of the lower kinetic chain.
A device used to support the foot, improve function, and improve the alignment of the foot and/or lower extremity
Function of the foot during gait
Provide base of support
Mobile adaptor
Shock attenuation
Accommodation of transverse plane
motion
Provide rigid support
Talocrural joint axis
Through malleoli
Lateral malleolus is inferior & posterior to medial malleolus
Talocrural joint PF
with adduction
talocrural joint DF
with abduction
Subtalar joint OKC pronation
Calcaneus
Everts
Abducts
DFs
Subtalar joint OKC supination
Calcaneus
Inverts
Adducts
PFs
CKC Pronation
o Calcaneus everts
o Talus adducts and PF’s
o Leg internally rotates
o Knee flexes
CKC Supination
o Calcaneus inverts
o Talus abducts and
dorsiflexes
o Leg externally rotates
o Knee extends
Mid-Tarsal Joint Axes
Longitudinal Axis:
- Pronation/Supination (Eversion/Inverson)
Oblique Axis
- PF/DF
** In WB’ing, MTJ follows the STJ (Oblique axis)
Tarsometatarsal Joints
Keep MT heads on the
ground
STJ Pronation
MTJ Pronates with STJ
TMT Joint - Supination Twist
1-2nd MT DF 2° GRF
4-5th MT PF 2° flexor mm
Stance phase includes:
– Initial Contact
– Loading Response
– Mid-stance
– Terminal Stance
– Toe-off
Swing phase includes:
Initial Swing
Mid-Swing
Terminal Swing
3 Functional Goals of the Foot
- Get both calcaneal condyles on the ground
- Get MT heads on the ground
- Provide rigid level for toe off
What position is the STJ in at heel strike?
supination
initial contact is with…
the lateral condyle of calcaneus
What occurs after initial contact?
STJ pronation to get medial condyle of calcaneus on ground
How do you get metatarsal heads on the ground?
STJ pronates, giving forefoot mobility to adapt
to surface
Provide rigid lever for toe off - mid stance:
STJ moves toward neutral, increasing the
stability of the forefoot
provide rigid level for toe off - terminal stance/toe off:
STJ is supinated to provide rigid foot
when does maximum supination occur?
just prior to toe off
motion during gait cycle
Foot is in supination prior to loading response
STJ pronation occurs until 50% of gait cycle
Re-supination initiated during mid-stance, by 60% of gait
Supination (max stability) just prior to toe off
what is subtalar joint neutral
Point at which the talus is neither pronated nor
supinated, relative to the navicular
reliability of subtalar joint neutral
Intrarater – Fair
– Interrater – Poor
– Both can improve with training/experience
Usefulness of subtalar joint neutral
– Consistent starting point
– Intrinsic foot deformities
– Neutral position of the joint
What is “functional” neutral position (resting standing foot position)
– Knees extended
– Arms at sides
– Feet 6 inches apart
– Comfortable amount of toe-out
What does “functional” neutral position do?
More closely approximates the position of the subtalar joint during gait
Compensations
A change in the structure, position, or function of one part to neutralize an abnormal force or a
deviation in structure, position, or function of
another part
Functions of a foot orthotic
Distribute WB forces evenly on the plantar surfaces of the foot
Reduce excessive stresses to the proximal structures from pronation/supination
Reduce the magnitude and rate of excessive pronation
Balance intrinsic foot deformities
Indications for Foot orthotics
- LE/Spine symptoms
- PT goals achieved or pt plateaus
- Course of therapy completed
Intrinsic abnormalities require
more controlling orthotic
extrinsic abnormalities require
more accommodative orthotic
Foot orthotic requirements
Conforms to the contours of the foot
Rigid enough to control pronation, but flexible enough to allow normal motion
Capable of being adjusted with precision
Durable
Comfortable
Does no harm
Cost-effective
Lightweight
normative angle of inclination values
Newborn: 150
Adult: 125
Geriatric: 120
“Normal” subtalar joint neutral
Rearfoot: 0-3° varus
Forefoot: calcaneus perpendicular to MT line
Osseous Deformity
rotation within the calcaneus
Shell
“frame of the eye glasses”
posts
“lens”
Intrinsic
Extrinsic
Shell - Soft
– Goal: pressure relief, shock attenuation
– Material: soft foams
– Extrinsic posts
– Indications: DM, hyposensitivity, pes cavus, supinatory foot
Semi Rigid Shell
– Goal: Motion control, shock absorption
– Material: cork, leather, low-temp plastics
– Posts: intrinsic or extrinsic
– Indications: motion control
Rigid Shell
– Goal: CONTROL
– Material: heat-moldable plastics
– Casting required
– Posting: intrinsic
– Indications: control of excessive pronation
Posting Functions
Control motion, bring ground to the foot
Maintain abnormal joint relationships
Prevent compensation/reduce abnormal motion
Enhance muscle activity
Intrinsic Posting
Within the shell of the orthotic
Forefoot posting is almost always intrinsic
↓’d bulk so better fit in shoe
have to be conservative (50%) difficult to adjust
$$$ custom made
Extrinsic Posting
Most orthotics have extrinsic rearfoot
posting
Stronger
Easier to adjust
Less arch pressure
More bulk in shoe
Varus Post
on medial side of foot
forefoot posting - varus post
on medial side of foot
forefoot posting - valgus post
on lateral side of foot
** forefoot only
0 degree post
extrinsic post without angulation (LIFT)
– Large FF varus, no RF abnormality
Bar post
runs straight, flat across
– Usually extrinsic
– Rigid plantarflexed 1st ray
Bar post under rays 2-4
Posting determination - rear foot
– Approximately 50%
of varus
– Maximum 6º
posting determination - forefoot
- approximately 40%
- maximum 8 degrees
posting determination - age
more conservation with increasing age
posting determination - weight
more aggressive with increasing weight
last thing that determines posting
activities
Accommodative orthotic (soft shell)
Allows significant amount of flexibility
Supinatory foot type
Improve shock absorption
Distribute forces t/o foot
“Bias” – controls motion and lets foot come to ground more easily
What are accommodative orthotics used for?
Congenital malformations
ROM problems
Insensate feet
Diabetic/Rheumatoid feet
Illness, old age, unhealthy feet
rigid PF’d 1st ray
Biomechanics Orthotic (Rigid/semi- rigid)
Increased rigidity of shell
Semi-rigid or Rigid
Durometer – indication of flexibility/rigidity
– Higher number = more rigid
– weight, activity, desired control
what are biomechanics orthotics used for?
- anything else
- pronatory foot problems
Biomechanics orthotic requirements
– Conform exactly to contours of the foot
– Sufficiently rigid to maintain contours with use
– Control abnormal motion
– Allow normal motion to occur in proper sequence
– Stand up to stress and wear
– Capable of being adjusted with precision
Dual Density
Usually semi-rigid shell
Provides control of excessive pronation
Softer, accommodating material on top
Allows shock attenuation
Best of both worlds
Easier for patients to break in
Top cover can be replaced
considerations for selection
Patient condition: Acute/chronic
Pronatory v. supinatory
Intrinsic/extrinsic
deformities
Patient’s footwear
Type of stress you are
trying to reduce
Type of material
Customized v. over-the-
counter
Cost
Fabrication time
Patient information
Bring shoes in
Goals and limitations of orthotics
Not likely an immediate cure
may need adjustments
break in period
Break-in period may vary
Day 1 - 1-2 hrs
Increase total wear time by 1-2 hours/ day
Break-in period will depend on type of orthotic
More rigidity = longer break-in periord
Tolerate ~ 6-8 hrs/ day prior to wearing for sports
Sports: begin 1/3 of time and increase by 1/3’s
Stop if symptoms increase or new sx arise
Longevity
Depends on usage, body weight, and material
Long-term use - evaluate ~ 1-4 years
Semi-rigid ~ 1-2 years
Soft orthotics 6 months to one year (max)
Purchasing new shoes
Wait until they have orthotic
Don’t show it to the clerk
Find an appropriate shoe/fit
Then place orthotic in shoe to
determine if a larger size is
needed
Dress shoes
Difficult to wear orthosisbecause of narrow shank and shallow heel
Dress orthotics are available
As heel height increases, function of the orthotic decreases
Maximum heel height = 2 in
Diabetes - typical changes
Intrinsic Muscle Weakness
Toe deformities (hammer/claw toes)
Prominent MT heads
Fat pad atrophy
Diabetes - Shoe Considerations
- Wide toe box
- Good plantar contact
- Straight last
Orthotic considerations for diabetes
Decrease plantar pressures
– Total contact
1st & 5th MT heads
Talus
Navicular
** Usually accommodative or dual-density
RA shoewear
Probably straight last
Good heel counter
Wide toe box
RA - Hallux rigidus
- rocker-bottom shoe or MT bar
Trouble shooting - primary cause
shoe gear
trouble shooting - sudden recurrence of complaints
– Worn post
– Orthotic fatigue
– Gouging of shoe insole by post
– Physiological changes in the patient
trouble shooting - medial foot callus
– Not fully controlling foot – pronating against orthotic
– Excessively high post
trouble shooting - lateral foot callus
– It’s a good thing
– Actually keeping foot in appropriate position
trouble shooting - postural complaints
– Usually due to not following break-in schedule
– Decrease wearing time
– If symptoms aren’t elimated over time, re-evaluate your patient and/or orthotic
