P - UE Prosthetics Flashcards
what will be a limitation of any UE prosthesis
no prosthesis will be able to replicate all of the intact limbs functions:
* fine & gross motor skills
* communication/body language
* 28 simultaneous deg of freedom
* sightless proprioception - position, heat, moisture, pressure
* visually appealing, lightweight, waterproof, and self healing
what is a consideration when determining the best device for a pt
consider their goals
- the best device may not be the most technologically advanced version
what are the possible UE amputations
- partial hand
- wrist disarticulation
- transradial
- elbow disartic
- transhumeral
- shoulder disartic
- 4 quarter (part of scap and thoracic wall)
how does a UE prosthetic eval differ from a LE
very similar
- emphasis on activity specific devices & pt goals
- cognition important - esp if considering myoelectic device
what is a component of holistic care than can be more important in UE amps than LE
mental health
- harder to hide UE amp than LE
what are the main objectives of acute care
soft tissue mob
scar management
wound care
desensitization (tapping, pressure)
prep limb for prosthesis + manage recovery
similar to LE amp
what are 6 components of pre-prosthetic care (past the acute phase)
- limb shaping
- strengthening
- ROM
- endurance
- mental health considerations
- myoelectric specific training
what are components of limb shaping and what is the goal?
compression devices
ace wrap
want a cylindrical shape and get edema out
what are strengthening components in pre-prosthetic care
sound limb
residual limb
core - so important for function
what are components to myoelectric specific training in pre-prosthetic care and what is the goal
EMG signal training
co-contraction/signal separation
goal - get them to create signals w/i limb
what are the 2 prosthetic options for a finger or partial hand amp
silicone restoration
functional prosthesis
finger/partial hand
silicone restoration benefits
realistic looking, cosmetic
functional:
* provides opposition
* protection if sensitive to touch
* mental health benefits
finger/partial hand
functional prostheses benefits
- functional, durable
- intuitive grasp
- restores length of finger/hand
- returns grip strength
- provides opposition
opposition esp important w a thumb bc 50% of hand function
what are 4 considerations with transradial amputations
residual limb length
- surface area
- leverage
pron/sup ROM
ms strength
krukenberg operation
why is the residual limb length with a transradial amputation an important consideration
inc length = inc SA (inc area for force to be distributed on, relevant for heavy things) = inc leverage (control of prosthesis)
why is pronation/supination ROM an important consideration with a transradial amputation
by maintaining wrist function of pron/sup, dec amt of compensation needed from shoulder
what is the krukenberg operation and what are the benefits
separate ulna and radius to create pincer surface area
gives them ability to grab
still have proprioception/sensation bc of existing residual limb
rare to see today bc of advancement in prostheses
what are 4 considerations of a transhumeral amputation
residual limb length
- surface area
- leverage
- interaction w/o prosthesis (suspension may become an issue)
skin integrity
soft tissue coverage
muscular strength/myodesis
what is a myodesis
ms attaching well to residual limb (into bone)
what is the general rule when it comes to residual limb length
extra length always benefits the pt
what are shoulder disartics often related to (3)
malignant lesions
trauma
congenital etiologies
relatively uncommon
what is an important consideration with a shoulder disartic for prosthetics
patients often reject prosthetic use
- cumbersome, heavy, not very helpful (have to manage 3 joints)
what is a common cosmetic consideration with shoulder disartics
may leave small part of humeral head and neck remaining to preserve cosmesis
- w/o this, very obviously missing shoulder (won’t fill out shirt as well)
what are the 3 prosthetic design principles
- pressure = force / area
- inc SA = more comfortable/effective - torque = force x distance
- larger moment arms dec amt of force needed to control device - sum of forces = 0
- sum of opposing forces is equal
same as LE
what pt pop is no UE prosthesis common in
congenital
what are the 4 options for UE prosthetic designs
passive
body powered
myoelectric
hybrid systems
what are the benefits to body powered prostheses
lightweight
durable
waterproof
no need to charge
improved sensory feedback to user
less expensive
what are 3 types of UE prosthetic suspension systems
harnessing
liner (lanyard/pin)
anatomical suspension
what is the most common UE prosthetic suspension system
anatomical
suspension systems
liner (lanyard/pin): how does it work, pros, cons
liner engages into locking mechanism at end of socket
**pro: **provides additional protection and cushioning
con: can be hot, donning can be challenging
suspension systems
how does anatomical suspension work
donning sleeve is used –> pulls soft tissue in and creates tension on skin against outer wall of socket
- potentially suspend over bony landmarks
passive vs cosmetic UE prostheses
passive - lacks actively controlled grasping capability
cosmetic - visually appealing/lifelike
a passive prosthesis may or may not be cosmetically appealing depending on purpose
what are 4 functions of passive terminal devices
- support/stabilization of objects
- restoration of some bimanual activities
- use of utensils, tools, grooming instruments (stick them b/w fingers)
- functional extension of residual limb to match sound side (good opposition, good balance, good posture)
what are 3 examples of passive terminal devices
- hands
- mitts
- devices designed for sport/rec/vocation
what type of suspension is needed with passive terminal devices
usually no harnessing need bc typically lightweight
body powered terminal devices
voluntary opening vs voluntary closing
opening: closed at rest
- when you activate it, it opens
closing: open at rest
- when you activate it, it closes
body powered terminal devices
how does voluntary opening grip strength work
grip strength remains constant until modulated by user –> have to overcome full grip strength to open no matter what is needed for the task
difficult w delicate objects bc have to maintain appropriate tension to prevent crushing the object
body powered terminal devices
how does voluntary closing grip strength work
graded prehension is possible
user must apply constant cable tension to maintain grip -> more intuitive and natural
- manipulation of delicate objects requires less work
body powered terminal devices
what pts are better candidates for voluntary closing terminal devices and why
longer residual limbs and more distal amp levels bc requires more excursion
body powered terminal devices
what is a huge benefit to utilizing a hook
it has a better visual field than mechanical hands
canted hooks > lyre
body powered terminal devices
what is the locking feature on hooks for
to lock the hook in a certain amt of closure
body powered terminal devices
what are 5 drawbacks of mechanical hands
- not very functional
- frictional loss of force
- glove restriction of motion
- limited pinch force
- contours block visual inspection
someone would probably use as an interchangeable hand for social occasions
body powered terminal devices
what is the typical physical makeup mechanical hands
3 jaw check prehension pattern
terminal devices: wrists
what is the purpose of a wrist prosthesis
attach and position the terminal device
terminal devices: wrists
what do wrist prostheses primarily facilitate
pronation/supination
some units allow flexion, ext, or other mvmts
terminal devices: wrists
what is the significance of having a good wrist unit
reduces amt of sound side compensation
transradial prostheses
what are the 6 types of hinges
- flexible
- single axis
- polycentric
- step up
- residual limb activated locking
- outside locking
transradial prostheses
flexible hinges: indications, function, attachments
long residual limbs
- preserves residual forearm rotation
- permits min of 50% of anatomic sup/pron
prox attach = tricep cuff
distal attach = prosthetic forearm
transradial prostheses
how do single axis hinges function
- provide axial/rotational stability
- doesn’t restrict anatomic flex/ext elbow ROM
- set in pre-flex to prevent elbow hyper-ext (esp when carrying heavy loads)
transradial prostheses
polycentric hinges: indications, function
short limbs
- inc stability
- allows for higher trimlines
- dec tendency of soft tissue bunching
transradial prostheses
step up hinges: indications, function, set up
short transradial limbs
strong pt (requires more force to activate)
amplifies (2xs) anatomic joint motion
requires separate prosthetic socket and forearm sections
transradial prostheses
residual limb activated locking hinges: indications, function
short residual limb
poor strength
poor ROM
poor load bearing capacity
uses residual limb mvmt to operate locking hinges
transradial prostheses
outside locking hinges: indications, function
elbow disartics
long transhumeral w/o space for elbow unit
lock on medial side and controlled manually or via shoulder mvmt
elbow units for ED and transhumeral
friction vs inside locking elbows
friction - requires passive positioning of forearm
inside locking - locking mechanism triggered by cable/string
elbow units for ED and transhumeral
who are friction elbows indicated for
low-impact
pedi
cosmetic restoration
brachial plexus injuries
what is arguably the most important part of ensuring a positive prosthetic outcome
good fitting socket design
harnessing
what are the 2 functions of a harness
- suspension - how prosthesis held to residual limb
- mvmt from intact body segment causes a transfer of force that actuates body powered componentry
- move shoulders to pull on cable to activate terminal device
harnessing
what is force
amt of power body must generate to activate terminal device
harnessing
excursion
distance intact segment of body must travel to activate terminal device
harnessing
what are 3 types of transradial harnesses
figure of 8
shoulder saddle
figure of 9
harnessing - transradial
what 5 components make up a figure of 8 harness
axilla loop - attachment point
ant suspensor strap - hold pro up
control strap - activates cable
harness cross point - anchor
housing - where cable runs
harnessing - transradial
how is power generated in a figure 8 harness
GH flex of ipsi shoulder with biscapular ABD
harnessing - transradial
when is a shoulder saddle indicated for harnessing
when heavy lifting w prosthesis frequently required
harnessing - transradial
what is the function behind the design of a shoulder saddle harness
allows distribution of pressure in areas other than contra deltopectoral groove and axilla
- uses chest wall and ipsi shoulder to support weight/force
harnessing - transradial
when is a figure of 9 harnessing appropriate and what is its function
when socket design is self-suspending
control only, to activate the cable
- not really suspending prostehsis (doesn’t need an ant suspensor strap)
harnessing - transhumeral
what function does a transhumeral harness must have
control both elbow and terminal device function
harnessing - transhumeral
what sequence does the pt usually have to operate the device in
- position forearm - passive, cable system
- lock elbow - pull on strap, specific motion to lock
- activate TD - pull cable again
harnessing - transhumeral
what does it mean that the device has split cable housing
single cable is responsible for 2 actions (at elbow and TD)
harnessing - transhumeral
what are the control motions
GH flex and biscap ABD
- performs both elbow flex and TD activation
same control motions as transradial
harnessing - transhumeral
what are the body motions to lock/unlock elbow
scap depression (down)
GH ext (back)
GH ABD (out)
harnessing - transhumeral
what does it mean that the elbow locking mechanism is cyclical
each pull alternates b/w locked and unlocked
harnessing - transhumeral
where is the elbow locking cable attached to
ant suspension strap
harnessing - transhumeral
how does the elbow being locked or unlocked change the control cable’s function
unlocked = cable activates elbow function
locked = cable activates TD function
harnessing - transhumeral
what are the 2 types of harnessing for transhumeral
shoulder saddle
nudge switch
harnessing - transhumeral
shoulder saddle harnessing: indication, function, drawbacks
heavy lifting required
disperses forces across greater surface area using chest wall and ipsi shoulder
- can use rib cage expansion to strengthen anchor points
con: not as effective force transmission
harnessing - transhumeral
nudge switch: indication, function, set up
insufficient excursion or forces available via harnessing
lever used to create action
typically by socket so pt can push on it w chin
myoelectric prostheses
what about the limb length is important to consider when deciding if someone is a candidate
build height
residual limb length for electrode surface area
myoelectric prostheses
pros and cons
pros:
- doesn’t require gross body mvmts
- inc grip strength
- inc envelop of operation
- improved control
- improved cosmesis
cons:
- reliance on external power source
- inc wt
- susceptible to damage
- inc cost
myoelectric
what are 3 types of terminal devices
single degree of freedom hands
single degree of freedom hooks
multiple degrees of freedom hands
myoelectric
single degree of freedom hand: function and pros
simple open/close prehension
- rigid IP joints
- articulating at MCP and CMC joint
1-2 motors to oppose thumb against digits 2 and 3 (digits 4 and 5 are passive)
cosmetic appearance, simpler
myoelectric
single degree of freedom hooks: function, pros, cons
simple open/close prehension
1-2 motors w rigid orientation for opposition
pros: strong pinch force, inc visual feedback, robust/stronger design
con: sacrifice cosmesis
myoelectric
multiple degrees of freedom hands: indications, function, cons
light/medium duty activities
multi-articulating w inc # of functional graspoing patterns
5-6 motors for more degrees of freedom
- may dec opposition force
- dec battery life
cons: more complicated, heavier
myoelectric
what is the most common prosthetic set up for a transhumeral amputee and why
passive elbow w myoelectric hand
- cuts down on wt and less cumbersome to control
myoelectric
when are myoelectric elbows appropriately indicated
need to have enough ms control to do multiple motions (these are heavy)
myoelectric
what are common cons in almost all myoelectric devices
complicated and heavy
myoelectric
what is required for shoulder componentry
frame that will go against chest wall
myoelectric control
what are myoelectric signals
signals associated w ms contraction in the residual limb which can be picked up by external electrodes placed against the skin inside the prosthetic socket
myoelectric control
what are the 3 possible control strategies
single site
dual site
pattern recognition
myoelectric control
what is single site control
one place where the electrode is, you contract your ms and it does one thing –> you contract again and does the opposite
myoelectric control
what is dual site control
separates the motions
myoelectric control
what is pattern recognition
creating pattern of motion w residual limb and electrodes placed around socket pick up on pattern and create the associated action
myoelectric control
what is a needed component bc of the size of ms activity
need an amplifier to amplify amt of motion seen
myoelectric control
power source vs prosthesis motor
power source = allows it to create motion
prosthesis motor = driven by power source to activate prosthesis
what is targeted muscle reinnervation (TMR)
redirect nerves back to pectoral ms
- so if pt pretends to do motion, activates that nerve associated w the motion –> put sensor on that spot and it will pick up on that to create the action
what pt pop is TMR more targeted for
it is a way for high level pts to have higher control of their prosthesis
what is significant about HiFi socket design
about the interface and creating something that focuses on stabilizing the bone w/i limb and preventing any rotation in the socket
socket design is key to fit and outcome
pros and cons of osseointegration
pros:
- eliminates need for socket
- can still use pattern recognition
- less hot
- more comfortable
- more sensation and feedback
cons: risk of infection
