LE Prosthetic Componentry Part 2: Alignment Considerations & Gait Deviations

Question 1

what is the typical bench alignment for TTA?

Answer 1

right in the middle
- middle of ant-post and M-L

Question 2

when a prosthetist looks at the device alone (not worn by the patient) on a level surface:

Answer 2

bench alignment

Question 3

what are you looking for in a static standing alignment assessment for TTA?

Answer 3

equal weight distribution
level pelvis (ASIS, IC, PSIS)
foot in plantigrade (foot is in contact with ground)
knee position
pylon position
pain?

Question 4

what is the purpose of adjustable heel height in a prosthetic?

Answer 4

to accommodate different styles of shoes

Question 5

typically, what is the transverse plane foot rotation set to be?

Answer 5

anatomically normal of 5-7 degrees of toe out

Question 6

what is the purpose of socket flexion in TTA?

Answer 6

mimics foot translated posteriorly
may be to accommodate knee flexor contracture

Question 7

socket flexion TTA:
– dampens _____ and smooths _____
– prevents _____
– resists tendency of residual limb to:
– no change in ______ moments

Answer 7

– shock ; COM rise and fall
– genu recurvatum
– slide into socket and potentially bottom out
– sagittal plane

Question 8

what is the purpose of socket extension in TTA:

Answer 8

to attempt to correct knee flexion contracture
mimics foot translated anteriorly & PF
increased knee extension moment

Question 9

anterior translation of socket (socket flexion) =
posterior translation of socket (socket extension) =

Answer 9

posterior translation of foot
anterior translation of foot

Question 10

for socket adduction, the foot must be _____
for socket abduction, the foot must be _____

Answer 10

laterally displaced
medially displaced

Question 11

socket adduction:
– increased _____
– mimics:

socket abduction:
– increased _____
– mimics:

Answer 11

– knee valgus moment
– medial translation of the socket

– knee varus moment
– lateral translation of the socket

Question 12

foot lateral to socket / socket medial to foot:
– ______ BOS
– increases:

Answer 12

– widens
– knee valgus moment

Question 13

foot medial to socket / socket lateral to foot:
– _____ BOS
– loads more pressure on ______
– decreases:
– increases:

Answer 13

– maintains fairly normal
– medial residual
– pressure on fib head
– knee varus moment

Question 14

single axis mechanical knee joint:
– ___ mechanism
– k level:
– lightweight or heavy?

Answer 14

– hinge
– K1
– light weight

Question 15

polycentric mechanical knee joint:
– K level:
– have ____ or more pivoting bars
– provide __(more/less) knee stability than single axis

Answer 15

– K2
– 4
– more

Question 16

constant friction knee joint:
– K level:
– friction amount (does/does not) change
– used for:

Answer 16

– K1/2
– does not
– set cadence/walking speed

Question 17

variable friction knee joint:
– K level:
– friction amount changes during ____ phase

Answer 17

– K3/4
– swing

Question 18

describe the variable friction knee joint changes during each level of the swing phase:

Answer 18

—> 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

Question 19

what are the two prosthetic knee types that are friction control systems?

Answer 19

pneumatic (air)
hydraulic (fluid)

Question 20

describe how the pneumatic (air) knee works:

Answer 20

compresses air as knee is flexed –> stores energy –> then energy is returned to put knee in extension

Question 21

hydraulic (fluid) knee:
– provides:
– cons:
– uses:

Answer 21

– more friction and smoother gait
– heavier, expensive, more maintenance
– liquid medium such as silicone

Question 22

microprocessor knees:
– k level:
– sensors detect ______, then adjusts _____ as needed
– benefits:
– cons:

Answer 22

– movement and timing ; pneumatic or hydraulic control
– decreases falls, more active, enhanced confidence
– heavier, expensive, need a battery

Question 23

socket flexion TFA:
– accommodates:
– weight line shifts _____
– increased ____ moment

Answer 23

– hip flexor contracture
– posterior to knee joint center
– knee flexion

Question 24

what are 4 control mechanisms used for knee stability for TFA?

Answer 24

• alignment of knee joint axis in sagittal plane
• inherent mechanical stability of knee
• voluntary control swing muscular power
• microprocessor controlled

Question 25

what is the progression for prosthetic training for a patient with bilateral TFA?

Answer 25

1. build confidence (strength, endurance, weight management, psychological stress)
2. start with stubbies without knee joint
3. gradually progress to increase prosthetic height
4. progress to full-length/long prosthetic limbs with knee component

Question 26

what are advantages to starting your bilateral TFA patient with short prosthetic limbs?

Answer 26

COM lower to ground –> easier to maintain balance
reduce fall risk
require less energy expenditure
help improve strength

Question 27

what are 2 prosthetic hip joint options?

Answer 27

hydraulic
mechanical, single axis

Question 28

stance time: prosthetic ___ intact
step length: prosthetic ___ intact

Answer 28

<
>

?? don’t understand what she means here

Question 29

what are contributing factors to step length/single stance time asymmetries?

Answer 29

patient confidence
pain
proper weight shifting
needs gait training

Question 30

if a short step length is observed on prosthetic side, what is the possible cause?

Answer 30

knee flexion contracture

Question 31

what are 3 swing phase gait deviations?

Answer 31

contralateral vaulting
hip hike
circumduction

Question 32

what are anatomical causes for a contralateral vaulting gait deviation? (4)

Answer 32

residual limb discomfort
fear of stubbing toe
short residual limb
painful hip/residual limb

Question 33

what are anatomical causes for hip hike gait deviation? (2)

Answer 33

weakness of hip flexors
difficult initiating knee flexion

Question 34

what are anatomical causes of circumduction gait deviation? (5)

Answer 34

abduction contracture
poor knee control - inability to initiate knee flexion
weakness of hip flexors
lack of confidence/training to flex knee
painful anterior distal residual limb

Question 35

what are prosthetic causes for swing phase gait deviations? (5)

Answer 35

long prosthesis
locked knee
inadequate suspension
loose socket
foot plantarflexed

Question 36

what is the functional significance for swing phase gait deviations?

Answer 36

assists with foot clearance
increases energy expenditure due to displacement of COM

Question 37

what are prosthetic causes for an ipsilateral lateral trunk lean during prosthetic limb stance?

Answer 37

prosthetic length too short
sharp or high medial wall (TFA/KD)
prosthesis aligned in abduction (TFA/KD)

Question 38

what are anatomical causes for an ipsilateral lateral trunk lean during prosthetic limb stance?

Answer 38

poor gait training
inadequate loading of prosthesis
abduction contracture
weak abductors
hip pain
instability
short residual limb
lack of proprioception
poor balance
hypersensitive or painful residual limb

Question 39

what is the functional significance to having an ipsilateral lateral trunk lean during prosthetic limb stance?

Answer 39

increased energy expenditure

Question 40

** outcome measure learning activity ???