O - Foot Orthoses Principles Flashcards
what is a biomechanical orthosis
any device capable of controlling motion path in the foot/leg by maintaining the foot in or close to its neutral subtalar position
not trying to lock the foot at any point
want to help it move more efficiently
what are 5 characteristics of biomechanical orthoses
- conform to all contours of foot
- sufficiently rigid to maintain its contours and angular relationships
- control abnormal/excess motion and allow normal motion
- reasonably comfortable w gradually inc wearing time (breaking in period)
- capable of being worked on or adjusted
what are 4 goals of biomechanical orthoses
- minimize abnormal/excess motion
- encourage healing -> dec load on soft tissues and joints
- dec inflammation
- improve motion (normal mvmt patterns)
what are the 3 main components of biomechanical orthoses
shell/module
posts
top covers
what is the shell/module
off-weight neutral cast which conforms to plantar contours
what is the part of the biomechanical orthosis that will be fabricated
shell/module
via plaster cast, foam box, scanning
where is the shell/module on biomechanical orthoses
begins at heel and extends just prox to MT heads
what are 2 types of material that the shell/module can be made of and why
rigid - carbon graphite, polyethylene
* controls motion
soft - foam
* absorbs shock
depends on what the patient needs
what are posts and where are they placed
fills space created by a deformity and brings ground up to the foot so the foot can function better w/o going thru excessive amts of motion
placed at WB-ing sites (calcaneus, MTs)
* varus = medial wedge
* valgus = lateral wedge
what are the 2 main functions of the posts
stabilize the shell
provide motion control in frontal plane
what are the 2 main types of posts
extrinsic and intrinsic
doesn’t have to be one or the other, can be a mix in the orthosis
what type of post is the most common
extrinsic
what are extrinsic posts?
pros and cons
material added to plantar surface of shell
pros:
* easy to adjust
* excellent strength (can use different materials from shell)
cons:
* adds additional bulk in shoe
extrinsic posts
what is a bias
extrinsic post but made of softer material
* see in pts w hypopronated feet, looking for material to be a little softer
what are intrinsic posts?
pros and cons
positive plaster model of foot is modified to embody deformity and shell assumes the shape
pros:
* less bulk in shoe - shell assuming shape of deformity
cons:
* difficult to adjust (once it’s made, it’s made)
* material of shell determine strength (same material as the post)
extrinsic bar post vs single tip
bar post = goes all the way across
single tip = one side
what is the top cover
covers the dorsal surface of shell and is in contact w the pt
what are the 2 main functions of top covers
comfort
durability
what are the varying lengths the top cover could be
extends to MT heads, to the sulcus, or to toes
depending on pt comfort
why does mr jim prefer full length top covers
can trim it to what you want
* shifts less than the shorter ones
* could also be more comfortable depending on how sensitive the pt is
what are 4 examples of additions to orthoses
deep heel seat
1st ray cut out
flanges/clips
padding
additions: deep heel seat
what is it
function
con
normal is 6-8mm, deep is 12+mm
* deeper = wider
controls calcaneal position
* control excessive amts of calcaneal eversion
con - bulk in shoe
pedi pop could likely tolerate this the best, more aggressive of an intervention
additions: 1st ray cut out
what is it/who is it for
- rigid PF 1st ray - cut out to compensate for that
- flexible PF 1st ray - accomodate for this for MTP joint integ, hallux DF ROM
additions: 1st ray cut out
what is a 2-5 bar post and what is a con to this
allows 1st ray to stay in down position
* does same thing as the cut out
bar post is more bulky bc added material
additions: flanges/clips
what are they
3 indications
extensions of shell and rearfoot posting
- peds
- ruptured tib post
- soft tissue spill over
why is pediatrics an indication for flanges/clips additions
can tolerate more aggressive options
why is a ruptured tib post an indication for flanges/clips additions
foot won’t be able to control pronation/maintain arch
* flanges/clips gives pt ability to not have to compensate as much
why is tissue spill-over an indication for flanges/clips additions
can happen in other orthotics
* this dec it
additions: padding
what is it / where is it
placed on shell and held in place by top cover
* embedded between
additions: padding
3 functions
shock absorption
pain control
pressure relief
additions: padding
3 indications
interdigital neuroma
heel spur
sesmoiditis
where are the 4 locations of posting that you should know
RF valgus
RF varus
FF varus
FF valgus
what is Hoke’s Law
body responds to small increments of change
body reacts to large increments of change
how does Hoke’s law apply to orthotics
if we are too aggressive w the orthosis and post too much –> large change and the pt will react to that
biomechanical vs accomodative orthotics
biomechanical: (rigid)
* change or control position/mvmt
* goal: promote function near neutral position
accommodative: (soft)
* allow compensation
* conforms to foot
* dissipates forces
* designed for comfort
what are 3 contraindications for biomechanical devices
acute path
dec ROM
incomplete eval
why is dec ROM a contraindication for biomechanical orthotics
biomechanical orthotics designed to control motion
* anything additional to someone w less ROM will further dec motion
why is an incomplete eval a contraindication for biomechanical orthotics
need to assess entire kinetic chain
what are the 5 main lower kinetic chain concerns in the geriatric population
- subtalar joint ROM
- equinus influences limiting DF
- pron/sup at midtarsal joints (general midfoot mobility)
- abnormal (varus/valgus) influences at knees
- hip ROM (lose hip ext, some rotation)
geriatric population
what does it mean if someone is chronologically old
large age in years but active and healthy
geriatric population
what orthotics are most appropriate for a chronically old pt pop
biomechanical device that is semi-flexible
* would tolerate this well bc not a huge change
accommodative device that uses more agggressive materials
geriatric population
what does it mean if someone is physiologically old
significant PMH and comorbidities
sedentary, not doing a lot
limited tolerance to change
geriatric population
what orthotics are appropriate for a physiologically old pt pop
accommodative device that is flexible w minimal posting
* don’t want to do too much change bc won’t tolerate well
* wouldn’t do biomech bc wouldn’t tolerate well
additional shock absorption
* add extra to dec GRF
pediatric population
what is the goal with orthotics in the pedi pt pop
objective is to establish normal osseous relationships w the foot
allow normal development and foot function
*need to be familiar w developmental stages
pediatric population
what should you have caution w when using orthotics in this pt pop
caution w early intervention that may prohibit natural derotation from a deformity
born w lot of varus –> derotate w age and walking
have a lot of pronation when little
–> but will not be the same by 8-11yo
pediatric population: neonate
what developmental trends do you see at: hip, knee, ankle, and foot
hip = inc anteversion
**knee **= inc varus bowing of tib
ankle:
* inc DF
* minimal to no external mall position
**foot: ** lot of compensated pronation
* RF = 10deg varus in STJN
* FF = 12-15deg varus
pediatric population: 12mo
what developmental trends do you see at: hip, ankle, foot
hip: fem anteversion 10-15deg
ankle:
* external mall position 10-15deg when lat mall is moving post and inf
**foot: **inc pronation in standing & walking
* RF and FF varus <10deg
* relaxed calcaneal stance position 5deg eve
pediatric population: 5yo
what developmental trends do you see at: hip, ankle, and foot
hip: fem ant 10-15deg
ankle: ext mall position 15-25deg
foot:
* RF varus 2-4deg
* FF varus 0-2deg
* relaxed calcaneal stance position 4deg eve
pediatric population
at what age do you see normal derotation of skeletal maturity
b/w 5-7yo
pediatric population
what is the take home point to know when intervening w orthotics in a pedi pop
under 7yo caution not to over correct and inhibit normal skeletal development and normal derotation
what type of orthotic is appropriate in the running population and what should you avoid
full length top cover that is cushioned
semi-rigid orthosis
avoid very rigid shell or posting materials
* don’t want to fx the shell bc all the impact and pounding of running
think ab impact and loading response, the heel strike
what type of orthotic is appropriate in the aerobic population (ex: crossfit lol) and what should you avoid
cushion FF d/t inc WBing
avoid excessive RF postin d/t abrupt direction changes
what type of orthotic is appropriate in the court sport population and what should you avoid
full length top covers
possible lateral flange (if hx of lat ankle sprains)
avoid aggressive RF posting
basketball and volleyball sneakers have a lot of room to accommodate orthoses well
what type of orthotic is appropriate in the field sport population and what should you avoid
durable cover to withstand elements (ie playing in rain)
avoid anything that will add bulk (ie intrinsic post)
* need to dec bulk and width in cleats
what are red flags to watch for during the break in period of an orthotic
skin integ
joint line pain
what does the break in period look like for an orthotic and what is normal
period of 2 weeks
* inc wear 1-2hrs each day
some achiness is normal bc changing their alignment
what law provides the basis for the break in period for orthotics
hoke’s law
if you walk around w new orthoses for 8-10hrs on first day, body will react
* use gradual schedule –> body will respond
what is the typical cost for orthotics
self pay (insurance won’t cover)
* can cost upwards of 100s
paying for materials, time/skill, lab cost
what is the life expectancy for biomechanical vs accomodative orthotics?
biomechanical - rigid materials
* avg of 2-7yrs (he’s seen up to 15yrs)
accomodative - softer materials
* 6-12 months
depends on the density of the material it is made of
what is a factor that can shorten the life expectancy of biomechanical and accomodative orthotics
shorter in active/athletic population
