L7 Prosthetics Components Flashcards
Parts of TT prostheses
socket
pylon
ankle
foot
suspension
Parts of TF prostheses
socket
rotator
knee joint
pylon
foot
Preparatory prosthesis
First prosthesis after amputation
Definitive Prosthesis
provided after limb has matured and shape/volume has stabilized
Bench alignment
done on a work bench in sitting
Static alignment
with patient standing at parallel bars
Dynamic Alignment
after observing gait
Socket anterior
knee easier to flex
Socket posterior
knee more stable, in extension
Foot moved anterior
knee more stable
Foot moved posterior
knee easier to flex
Knee more stable in transtibial alignment
socket posterior
foot moved anterior
Knee easier to flex in transtibial alignment
socket anterior
foot moved posterior
Relative DF
inclines the prosthesis anteriorly
moves the knee joint center forward relative to GRF, promoting knee flexion at LR
Relative PF
inclines the prosthesis posteriorly
moves knee joint center backwards relative to GRF, promoting knee extension throughout stance phase
TT Socket flexion
moves knee joint center anterior relative GRF
promotes knee flexion at LR
TT Socket extension
moves knee joint center posterior relative to GRF, promoting extension throughout LR and stance
Socket flex/ext is named for
alignment it produces in most distal residual joint
prosthetist can align the socket in some initial flexion for an individual with short hip or knee flexors
Transfemoral Bench alignment
proper fit helps pt to not feel weight of prosthetic
Pressure tolerant areas TT
patellar ligament
lateral fibular shaft
medial tibial shaft
lateral tibial shaft
Pressure sensitive areas TT
fibular head (moves as leg flexes)
lateral tibial flare
tibial crest
distal end of fibula/tibia
patella
anterior tibial tubercle
peroneal nerve
adductor tubercle
Pressure Tolerant Areas TF
ischium
soft tissue of residual limb
Pressure Sensitive Areas TF
greater trochanter
pubic tubercle
pubic ramus
pubic symphysis
distal end of femur
perineum
Sockets for Partial Foot amputations
toe filler w/carbon footplate
anterior shell AFO w/toe filler
full laminated socket w/carbon plate
Partial foot prosthesis
toe filler with carbon footplate
Types of Transtibial Sockets
patellar tendon bearing
supracondylar PTB
supracondylar suprapatellar
total surface bearing(indicated for all RL)
Patellar tendon bearing
TT
very extreme modifications to take up weight in specific areas of limb
older version
most weight through front and sides
Transfemoral Socket Types
quadrilateral socket
ischial containment socket
sub ischial socket
Quadrilateral socket
TF
no bony lock
Ischial containment socket
TF
bony lock
Interface types
skin fit
socks and sheaths
TPE gel
silicone
urthane
Skin fit interfaces
mainly just TF sockets and somewhat rare
excellent fit is important
Socks and sheaths
mainly preparatory TT sockets
TPE gel Interface
most common for preparatory and definitive socket
3-9 mm thickness
Silicone Interface
much thinner material than TPE
1-2 mm
Urthane Interface
likely custom liner due to shape or invagination
Joint and Corset Suspension
TT, used rarely, mainly now for short limbs and/or knee instability
KAFO on a prosthesis
Supracondylar Suspension
TT, commonly used on short limbs or for pts having distal skin issues
suspended from condyles
Wait belt with fork strap suspension
TT, indicated for people with distal sensitivity
unable or unwilling to use suspension sleeve
Neoprene or gel suspension sleeve
TT, can be used by itself or with suction suspension
often used on preparatory sockets
Suction with sleeve suspension
TT excellent option for healthy limb and/or active patient
controversially used for wound care
very positive suspension
Pin lock suspension
TT, most commonly used suspension, easy don/doff
Silesian belt suspension
TF
used for low activity suspension
can also be used with other suspension for lateral control
Hip joint and pelvic band
commonly used for short limbs that have problems with conventional suspension
Lanyard suspension
TF
common for preparatory sockets
Types of Transfemoral suspension
vacuum
seal in liners
lanyard
hip and pelvic band
silesian belt
Osseointegration
don’t use a socket b/c it goes directly into the bone
Stiffer heel
creates more rapid DF and increases ease of knee flexion
Soft Heel
provides increased pseudo-PF control and leads to more knee stability
Keel
all but the heel of the prosthetic foot
Length of keel
determines timing of heel rise
when GRF passes in front of keel, it causes toe extension on ant portion of foot
the extension moment will break the toe, the foot bends at the end of solid keel, helping heel to rise
Heel lever
roughly the perpendicular distance from heel cushion to center of socket
Toe lever
roughly the perpendicular distance from center of socket to end of keel
Shortening the heel lever
- Locates the GRF more ant with respect to knee during LR and midstance, causing knee extension
- Increases toe lever, which sustains knee extension. Can prevent knee flexion if too long
Lengthening the Heel Lever
- locates GRF posteriorly to knee at IC, producing knee flexion during LR
- Decreases toe lever, causing knee to flex in midstance or TS. Can cause drop off
Drop off
results if toe lever is too short and knee flexes before the person is ready to accept weight on opposite leg
Forward displacement of socket will
- increase the heel lever, creating GRF flexor moment at LR
- Decreases the toe lever
Heel lever increasing…
desirable for those with TT amputation, helps with knee flexion in LR
not desirable for TF amputation if it makes knee more unstable
Decreasing the toe lever…
shorter lever causes early heel rise and knee flexion
Backward displacement of socket will
- Decrease the heel lever
- Increases toe lever
Decreasing heel lever…
allows GRF to move anteriorly to the knee axis and promotes knee extension during midstance
Increasing toe lever…
delays heel rise and supports knee extension longer in stance phase
Solid ankle cushioned heel
non-articulating with rigid keel
cushioned heel for shock abs
allows for PF at IC
abrupt DF stop after midstance
lacks energy return
cannot accommodate to uneven surfaces
Flexible Keel Foot
allows motion similar to SACH feet
able to conform to uneven terrain, remains supportive and stable during standing and walking
more realistic movements, still relatively rigid
Single Axis Foot
articulated foot w/rubber bumpers simulating PF and DF
allows for motion in singular plane
improved knee stability during weight acceptance
lack energy return if not paired with dynamic response foot
Multiaxial Foot
DF, PF, inversion, eversion, with carbon fiber energy return
adapts to varied surfaces
goes into foot shell
Hydraulic Feet
multiaxis with shockabsorption, carbon foot plate with hydraulic controls
moderate to high energy return
adjusts to varied surfaces
smooth rollover stance phase
Dynamic Response/Energy Return Foot
can be articulating or non-articulating
keel has the capability to store and return energy
may have split keel to allow for improve surface accommodation
Microprocessor ankle
multiaxis
smooth computer controlled response to varied surfaces with some active push-off at different gait speeds
evaluates forces/resistance/surfaces with tech
TKA that passes anterior to knee joint
inherently more stable than TKA that passes through the knee joint, but one that passes through the joint will provide voluntary control
Single Axis Knee
also known as constant friction knee
difficult to reciprocate during gait
constant friction mechanism
single speed swing phase control
no stance control
Polycentric Knee
-four bar linkage system provides for moving axis
-provides some control during stance and swing
-good for long RL, helps with toe clearance
-more fluid gait
-constant friction
-heavier than single axis
Stance Control Knee
-weight activated friction brake stabilizes knee in any degree of flexion
-limited swing phase control, weight has to be off prosthesis to initiate swing
-good knee stability
-good for lower level ambulators that need stability and slow gait speeds
Hydraulic Knee
variable friction for improved swing and stance phase control
greater variability than polycentric knee
more normal gait
Pneumatic Knees
both pneumatic and hydraulic systems mimic muscles of natural knee by responding to varying walking speeds
hydraulic will be heavier than pneumatic, but provide smoother walking pattern
Microprocessor Knee
allows for management of descending stairs and hills
requires charging
computer driven control for improved swing/stance control as well as stumble control
closest to normal knee motion
To maximize stability of prosthetic knee
socket flexion
knee axis posterior to socket
ankle anterior to socket
soft heel cushion
soft shoe heel
low shoe heel
