P - Prosthetic Devices Intro Flashcards
what typical cause for an amp has a better outcome/recovery time
traumatic amp
- better, quicker/easier healing
why is a pre-amp consult encouraged and what pt pop is this especially recommended in
helps them know what comes next and takes fear out of it
esp in vascular cases
how long is the healing process after amp and how can this vary
4-6wks
- longer if vascular
what is probably the most important thing to get from a prosthetic eval
functional level
other than insurance justification, what are the K levels classifications used for and what is this preventing
to determine before fitting the patient what their functional level will be w the prosthesis
- will determine which prosthesis is appropriate
stops MDs from putting high level prostheses on low level pts
how big/important is the difference between K3 and K4
no difference according for insurance coverage
- just a classificaiton
how big/important is the difference between K2 and K3
huge difference
- difference between someone who is a community amb and needs a prosthesis to accomplish that and someone who can’t and doesn’t need that
what are the majority of UE amps and what is a major consideration of this pt pop
fingers
never get referred for care
what are the 3 physics guided prosthetic design principles
- pressure = force/area
- torque = force*distance
- sum of forces = 0
what does it mean that pressure = force / area
increased surface area is more comfortable and effective
force = body weight
area = surface area of socket
longer limb -> dec pressure bc more surface area
shorter limb -> higher amt of pressure bc dec surface area (harder to fit)
what does it mean that torque = force x distance
larger moment arms dec amt of force needed to control a device
longer residual limbs = more efficient
what does it mean that the sum of forces = 0
the sum of opposing forces is equal
more of an orthotic principle
what are 5 key prosthetic considerations
- properly distribute body forces thru prothesis
- protect limb via shock absorption
- reduce energy expenditure thru appropriate fit and lowest possible prosthetic wt
- prevent mvmt of prosthesis on limb via adequate fit and suspension
- provide cosmetic satisfaction for pt
cosmetic satisfaction is dependent on pt preference (you get this from IE and what their body image is)
what are 4 types of prosthetic design
- passive (cosmetic)
- preparatory
- endoskeleton
- exoskeleton
what is a passive prosthetic design
for cosmetic purpose
say passive for insurance purposes, still difficult to get coverage
what is a preparatory prosthetic design
shape of residual limb isn’t fully defined yet bc pt hasn’t fully healed and there is still some swelling
what is an endskeletal design
almost all parts of the prosthesis you can see
what is an exoskeletal design
hard, laminated, solid
* can’t make adjustments to it
* virtually indestructible
not frequently seen any more
if used, often in people who farm/fish
why are there adjusters built into the socket of a prosthesis
allows the pt to adjust as day goes on bc can lose some mass thru the loss of fluid
what are examples of consumable parts of a prosthesis
- liner
- suspension sleeve
- prosthetic socks
- liner-liner (sheath)
as the residual limb loses mass throughout the day, what are ways to modify the prosthesis appropriately
- adjusters in socket
- sock liners
sock liners are good for protecting skin and absorbing sweat
why is total contact needed in the socket design
prevents 3 issues
- edema
- socket migration
- compromised prosthetic control
what is one of the most important parts of ensuring a positive prosthetic outcome
good fitting socket
if a socket is ill-fitting, what does this cause
think of socket as foundation of building
see problems up and down the limb
what are 3 examples of casting methods
- traditional (plaster)
- aqua-cast
- direct socket
computer scanning is a newer tech (rarely used) instead of casting
what is an aqua-cast casting method
uses hydrostatic pressure to capture shape of person’s limb under full WBing
what is the traditional casting method
casting method which utilizes plaster bandages to capture impression of pt’s limb in a non-WBing position
why is plaster preferred or used more frequently as a casting method
it is inexpensive
bc we are cheap mofos
what is a pro to using an aqua-casting method
dec amt of adjustments needing to be made (sometimes 0)
with plaster casting, prosthetist guesses based off mold what will it need/look like when person stands up
what is a direct socket casting method
fabrication process that allows a definitive socket to be produced directly on the pt w/i short time frame
when do you use a direct socket casting method
usually see this for an initial socket
initial socket won’t last long bc volume dec w/i days to months
what is socket fit the most important component in? what is an inherent challenge to achieving this?
- achieving good prosthetic control
- socket is a static device we attempt to fit to a constantly changing limb
what should be avoided in the socket fit? what different problem can have a similar presentation to this?
- excessive distal contact (aka “bottoming out”)
- lack of total contact can manifest w similar sx
what is important to think about when noticing skin irritation on residual limb in pt using a prosthesis
skin irritation only tells part of the story
what are 4 things to look at when assessing socket fit
- positioning of limb w/i socket
- resistance during donning
- rotation of socket on limb during amb
- stability during amb
what are 4 types of TT suspension methods
- passive suction w/ sleeve
- pin locking/lanyard
- seal in suction
- elevated vacuum
passive suction & elevated vacuum are suspension methods unique to TT
**elevated vacuum: **what is it? what is a pro to this suspension method? who is an appropriate candidate and why?
- TT suspension method that motion activated w how much air is sucked out of socket
- see less fluctuation in shape of limb bc pulls skin out
- would only do on pt w amp from years ago, new amp has too much shrinkage
what are 4 types of TF suspension methods
- skin fit suction
- seal in suction w linter
- lanyard/pin locking
- silesian belt / hip joint
skin fit suction and silesian belt/hip joint are suspension methods unique to TF
who is appropriate for a silesian belt/hip joint
low activity TF amp patients
what is adaptable componentry limited by
available build height
if long residual limb, dec amt of space to fit everything in before the ground
what does adaptable componentry allow for
clinically necessary changes to alignment to optimize gait
important to consider additional weight added to device
what is adaptable componentry rated by
body weight
how does the functional K level impact the prosthesis
the lower the functional level, the more simplistic the prosthesis
K1 prosthetic foot
- make up
- differential function
- pros/cons
- solid ankle cushion - heel (SACH); most basic type of prosthetic foot available
- transfers or limited amb
- pro: solid ankle and soft heel absorb impact at heel strike
- con: provides minimal energy return
what are qualities needed in a K1 prosthetic foot and why
needs to absorb heel strike
needs to PF for push off
needs to be soft to allow ankle rolling mvmts
K2 prosthetic foot
- make up
- differential function
- pros/cons
- lightweight, foam-rubber heel cushioning, flexible keel, multi-axial ankle
- allows more PF, little more inv/eve
- pros: provides some energy return, adjustible flexibility
- con: inc maintenance
K3 prosthetic foot
- make up
- differential function
- pros
- carbon fiber composite, lightweight, flexible, durable
- variable cadence amb, better for slopes, more functional
- pros: energy storing, dynamic response, dec energy expenditure, dec sound side compensation, features to inc shock absorption and dec forces on limb
K3 prosthetic feet - microprocessor
- differential function
- cons
- active response to changes in environment: sense inclines, provide active PF in late stance, powered DF to assist in swing
- cons: heavier, requires charging, may make sounds, can’t expose to water/dust/heat
K4 prosthetic feet
what are they
activity specific feet (ex: running, climbing, water sports, etc.)
* unique designs and configurations based on specific activity
what is the TT prosthetic “bench” alignment
37mm ant to ankle bolt/malleoli
12mm lat to center of heel
what is the TT prosthetic alignment in sagittal plane
center of socket/proximal part of prosthetic below knee should align with the first 1/3 of the foot
10deg too much in either extension or flexion motion
what is the significance of an adjustable heel height in a TT prosthetic
prosthetic ankles allow for 3/8’’ heel height
* higher than this can place ankle into excessive flexion, flatter could be excessive extension
adjustable ankles allow you to change the angle depending on the shoe you wear which is very important to maintain TT alignment
what is the most common characteristic of a K1 prosthetic knee and what type is an appropriate example
stability, safety
manual locking
manual locking prosthetic knee
- indications
- characteristics
- function
- pros/cons
- K1, new amps, very weak users, blind users
- fully locked mechanical single axis knee
- locked in full ext for all phases of gait (only unlocked to sit)
- pros: max mechanical stability in stance
- cons: no flex in swing causes gait deviations
single-axis constant friction prosthetic knee
- indications
- characteristics
- function
- pros/cons
- K2, long residual limbs w good muscular control
- simulates simple hinge w fixed center of rotation
- allows prosthetic shank to freely swing in flex and ext, stance phase accomplished thru proper positioning of knee unit in relation to weight line and adequate ms control of user
- pros: lightweight, durable, inexpensive, low maintenance
- cons: no mechanical stability, no safety features
weight activated stance control prosthetic knees
- indications
- characteristics
- function
- pros/cons
- K2, new amps, short residual limbs, users w weak hip extensors
- acts like single axis knee in swing
- braking mechanism - locked during stance, unlocked during swing ; prevents unwanted flex during stance and more natural swing pattern
- pros: lightweight, inexpensive, stability in stance, natural swing pattern
- cons: unable to respond to varied cadence
how does the line of force in a prosthetic knee impact stability
line of force from knee if posterior to proximal limb will thus be behind weight line of pt = more inherent stability
if anterior to weight line, less stability and more likely to buckle
polycentric prosthetic knees
- indications
- characteristics
- function
- pros/cons
- long residual limbs, short residual limbs, users w weak hip extensors
- mechanical knee w moving center of rotation via 4-bar linkage system
- allows for relative “shortening” of prosthetic shank during swing, posterior/prox ICOR inc stance phase stability
- pros: lightweight, inexpensive, more cosmetic for longer limbs
- cons: less durable d/t more moving parts
ICOR = instantaneous center of rotation
hydraulic prosthetic knees
- indications
- characteristics
- pros/cons
- higher k-levels, more experienced users
- single axis or polycentric knees which use hydraulic fluid to provide frictional resistance
- pros: responds to changes in cadence, stims a more normal gait pattern
- cons: heavier, inc maintenance, higher cost, temp dependent
pneumatic prosthetic devices
- indications
- characteristics
- pros/cons
- higher k-levels, more experienced users
- single axis or polycentric knees which use air pressure to provide frictional resistance
- pros: responds to changes in cadence, stims more normal gait pattern, less expensive & lighter than hydraulic knees
- cons: less precise cadence control, inc maintenance, higher cost than mechanical knees
why are falls such a prevalent issue in the TF amp pt pop
if you land on a bent knee, you will fall
* falls used to be daily occurrence if TF amp tripped on something
how has a prosthetic knee w microprocessor control dec the amt of falls? why is this sometimes easier to get insurance coverage for?
microprocessors responsible for most of the recent change seen in prosthetic knees
multiple sensors in knee to sense how much weight
* allows prosthesis to vary resistance to amt of wt placed
* angle sensor to know if knee is bent or straight
* can detect speed and direction person is moving
= stumble recovery
good thing to justify to insurance as it dec falls and dec cost to them in the future
microprocessor control prosthetic knees
- indications
- characteristics
- pros/cons
- higher K-levels, experienced users
- single axis hydraulic knees equipped w sensors which monitor knee position, angle, and load throughout gait cycle
- pros: responds to change in cadence, inherent safety feature, better accommodation to stairs/ramps/slopes
- cons: highest cost, most maintenance, least durable, heaviest, requires charging and cognition to use
how should TF coronal/frontal plane alignment look
center of malleoli/foot attachment should be directly under femoral head
too far in or too far out can create instability
what role can the prosthetic attachment play in TF alignment
microprocessor can mask minor alignment discrepancies
what is a strategy to determine with analyzing TF sagittal plane alignment?
use of projecting lasers to determine where the weight line is
what is the 3 legged stool analogy to troubleshoot if it is an issue w the prosthetic
- socket fit
- suspension problem
- alignment change
if there is a problem w the prosthesis, where should you start?
with the socket fit
if there is a problem with the prosthesis, what would make you think it is an issue with the suspension
is it moving when walking or in swing phase
do you see drop or pistoning
if there is a problem with the prosthesis, what would make you think it is an issue with the alignment
pt is saying everything feels great but when they walk “it feels off”
troubleshoot: when is it a medical issue?
4 issues
- skin problems
- infections
- neuromas
- bone spurs
neuroma = ball of fibers at end of nerve and causes pain
bone spurs = heterotopic ossification at end of limb
troubleshoot: when is it a physical therapy issue?
3 issues
- ROM limitations
- weakness/muscular imbalance
- balance issues
for a holistic patient-centered care approach, what must be addressed
4 fields
- mental health
- occupational health
- family/peer support
- nutritional ed
