LE Prosthetic Componentry Part 2: Alignment Considerations & Gait Deviations Flashcards
what is the typical bench alignment for TTA?
right in the middle
- middle of ant-post and M-L
when a prosthetist looks at the device alone (not worn by the patient) on a level surface:
bench alignment
what are you looking for in a static standing alignment assessment for TTA?
equal weight distribution
level pelvis (ASIS, IC, PSIS)
foot in plantigrade (foot is in contact with ground)
knee position
pylon position
pain?
what is the purpose of adjustable heel height in a prosthetic?
to accommodate different styles of shoes
typically, what is the transverse plane foot rotation set to be?
anatomically normal of 5-7 degrees of toe out
what is the purpose of socket flexion in TTA?
mimics foot translated posteriorly
may be to accommodate knee flexor contracture
socket flexion TTA:
– dampens _____ and smooths _____
– prevents _____
– resists tendency of residual limb to:
– no change in ______ moments
– shock ; COM rise and fall
– genu recurvatum
– slide into socket and potentially bottom out
– sagittal plane
what is the purpose of socket extension in TTA:
to attempt to correct knee flexion contracture
mimics foot translated anteriorly & PF
increased knee extension moment
anterior translation of socket (socket flexion) =
posterior translation of socket (socket extension) =
posterior translation of foot
anterior translation of foot
for socket adduction, the foot must be _____
for socket abduction, the foot must be _____
laterally displaced
medially displaced
socket adduction:
– increased _____
– mimics:
socket abduction:
– increased _____
– mimics:
– knee valgus moment
– medial translation of the socket
– knee varus moment
– lateral translation of the socket
foot lateral to socket / socket medial to foot:
– ______ BOS
– increases:
– widens
– knee valgus moment
foot medial to socket / socket lateral to foot:
– _____ BOS
– loads more pressure on ______
– decreases:
– increases:
– maintains fairly normal
– medial residual
– pressure on fib head
– knee varus moment
single axis mechanical knee joint:
– ___ mechanism
– k level:
– lightweight or heavy?
– hinge
– K1
– light weight
polycentric mechanical knee joint:
– K level:
– have ____ or more pivoting bars
– provide __(more/less) knee stability than single axis
– K2
– 4
– more
constant friction knee joint:
– K level:
– friction amount (does/does not) change
– used for:
– K1/2
– does not
– set cadence/walking speed
variable friction knee joint:
– K level:
– friction amount changes during ____ phase
– K3/4
– swing
describe the variable friction knee joint changes during each level of the swing phase:
—> initial swing: high friction to prevent excessive knee flexion
–> midswing: friction decreases to allow the knee to swing easily
–> terminal swing: increase in friction to prepare for initial contact
** increase, decrease, increase
what are the two prosthetic knee types that are friction control systems?
pneumatic (air)
hydraulic (fluid)
describe how the pneumatic (air) knee works:
compresses air as knee is flexed –> stores energy –> then energy is returned to put knee in extension
hydraulic (fluid) knee:
– provides:
– cons:
– uses:
– more friction and smoother gait
– heavier, expensive, more maintenance
– liquid medium such as silicone
microprocessor knees:
– k level:
– sensors detect ______, then adjusts _____ as needed
– benefits:
– cons:
– movement and timing ; pneumatic or hydraulic control
– decreases falls, more active, enhanced confidence
– heavier, expensive, need a battery
socket flexion TFA:
– accommodates:
– weight line shifts _____
– increased ____ moment
– hip flexor contracture
– posterior to knee joint center
– knee flexion
what are 4 control mechanisms used for knee stability for TFA?
- alignment of knee joint axis in sagittal plane
- inherent mechanical stability of knee
- voluntary control swing muscular power
- microprocessor controlled
