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Year 3: Prosthetics and Orthotics > Lecture 10: Lower Extremity Prosthetics > Flashcards

Lecture 10: Lower Extremity Prosthetics Flashcards

1
Q

partial foot and toe amputations are common in what populations

A

those with dysvascular disease and/or diabetes

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2
Q

functional deficits for minor LE amputations (toes, great toe, ray, MTP and proximal)

A

toe = minor gait abnormalities

great toe = loss of push off

ray = decreased gait speed, limited LE ROM

MTP and proximal = decreased stability, decreased gait speed, and other gait deviations

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3
Q

what is a syme’s amputation/ankle disarticulation and type of prosthetic used

A

heel pad attached to distal end of tibia

may include removal of malleoli

complicated prosthetic fit due to limited space

can ambulate without prosthesis

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4
Q

ideal length for transtibial/below knee amputation

A

ideal length = mid tibia
- if <9 cm should consider removing fibula

if < 5 cm should consider knee disarticulation

fibula should be 0.5-1 cm shorter than tibia for prosthetic fit

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5
Q

what is a knee disarticulation

A

uneven functional knee joint centers

distal femur can bear weight

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6
Q

what is a hemipelvectomy

A

resection of part of the pelvis

common due to cancer or trauma

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7
Q

what is a hip disarticulation

A

amputation through hip joint

pelvis remains intact

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8
Q

what are k levels used for

A

to assess pts potential for functional ability

determines reimbursement for componentry

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9
Q

what is a K0 or K level 0

A

does not have ability or potential to ambulate or transfer safely with or without assistance and prosthesis does not enhance their quality of life or mobility

  1. cognitive ability insufficient
  2. prosthesis does not improve mobility or transfer ability
  3. wheelchair dependent
  4. bedridden + no need/capacity to ambulate/transfer
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10
Q

describe K level 1

A

ability or potential to use prosthesis for transfers or ambulation on level surfaces; typically limited to household ambulator

  1. sufficient cognitive ability to safely use prosthesis
  2. capable of safe but limited ambulation in her or on similar flat surface with or without AD and with or without assistance
  3. requires use of WC for most activities outside of residence
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11
Q

describe K level 2

A

ability or potential for ambulation with ability to transverse low level environmental barriers such as curbs, stairs, or uneven surfaces

typically limited to community ambulatory

individual can with or without AD and/or with/without assistance
- perform Level 1 tasks
- ambulate on flat/smooth surface
- negotiate curb
- access public/private transportation
- negotiate 1-2 stairs
- negotiate ramp built to ADA specs

may require WC for distances beyond perimeters of yard/driveway, apartment, etc

only able to increase their generally observed speed of walking for short distances or with great effort

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12
Q

describe K level 3

A

ability or potential for ambulation with variable cadence, typical of community ambulatory who has the ability to transverse most environmental barriers and may have vocational, therapeutic, or exercise activity that demands prosthetic utilization beyond simple locomotion

with or without assistance/AD pt can:
- walk on various textures/level
- negotiate 3-7 consecutive stairs
- walk up/down ramps
- open/close doors
- ambulate through crowded area
- cross controlled intersection within their community within the time limit provided
- access public or private transport
- perform dual ambulation tasks

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13
Q

describe K level 4

A

ability or potential for prosthetic ambulation that exceeds basic ambulation skills, exhibiting high impact stress or energy levels typical of prosthetic demands of the child, active adult, or athlete

with or without AD/assistance they can:
- run
- repetitive stair climb
- climb steep hills
- be a caregiver for another person
- home maintenance

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14
Q

K1 prosthetic components at the foot/ankle and the knee

A

foot/ankle = external keel, SACH or single axis

knee = mechanical knee with constant friction

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15
Q

K2 prosthetic components for foot/ankle and knee

A

foot/ankle = flexible keel feet, multi axial feet

knee = mechanical knee with constant friction OR mechanical knee with variable friction (hydraulic or pneumatic) OR microprocessor

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16
Q

K3 prosthetic components for foot/ankle and knee

A

foot/ankle = flex foot, energy storing feet, multi axial or dynamic response feet

knee = mechanical knee with variable friction (hydraulic or pneumatic) OR microprocessor

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17
Q

K4 prosthetic components for foot/ankle and knee

A

foot/ankle = any, includes microprocessor

knee = any

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18
Q

what outcome measure can be used to predict K levels

A

AMPPRO

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19
Q

describe reimbursement for prosthetic devices

A

every 3-5 years depending on insurance

maintenance to current device allowed

manufacturer warrantees

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20
Q

2 ways to fabricate a socket

A

casting- more traditional

scan

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21
Q

more pressure sensitive areas of residual limb with TTA

A

fibular head

end of fibula

shin bone

hamstring tendon (back)

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22
Q

more pressure sensitive areas of residual limb with TFA/KD

A

greater trochanter
ASIS
pubic tubercle
adductor tendon
IT
pubic ramus
distal femur

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23
Q

what is a patellar tendon bearing socket

A

indentation over the patellar tendon

specific pressure points

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24
Q

describe total surface bearing socket

A

distributed weight bearing

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25
Q

describe a quadrilateral socket for TFA

A

horizontal posterior self for ischial tuberosity and glutes

medial brim same as posterior shelf

anterior and lateral brims 2 1/2 - 3 inches higher

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26
Q

describe an ischial containment socket for TFA

A

medial lateral walls are more narrow

anterior wall lower

can encroach on pelvic alignment resulting in APT

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27
Q

describe a subischial containment socket

A

not as common

“brimless”

soft tissue must be able to tolerate WBing

less APT

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28
Q

what must a socket provide for a hip diarticulaiton or hemipelvectomy

A

adequate coronal support

sagittal capture of pelvic movements

secure comfortable suspension

appropriate weight bearing surfaces and contours

socket will typically encompass affected relics, gluteal tissues, and ITs

medial lateral stability provided by compression of the contralateral pelvis

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29
Q

socket suspension for hip disarticulation and hemipelvectomy

A

use of pelvic band

trim lines above iliac crest

suction or vacuum suspension

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30
Q

describe thigh corset suspension system

A

heavier and may facilitate poisoning

difficult to don

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31
Q

describe pin system suspension system

A

shuttle lock system

helps with poisoning

commonly used

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32
Q

describe the suction suspension systems

A

use a 1 way valve

pistoning can occur

will use liner, can add sock ply as needed for volume fluctuations

COMMON

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33
Q

describe a true suction suspension

A

use a 1 way valve

socket fit must be very snug

worn without a liner

34
Q

benefits of a vacuum assisted sock suspension system

A

promote fluid exchange
reduce moisture build up
regulate volume fluctuations
increase proprioceptive awareness of limb
helps control pistoning
may help with wound healing

*expensive, heavier, and can be noisy

35
Q

what is osseointegration

A

option for pts who do not tolerate traditional prosthetic sockets

common complications = infection and soft tissue irritation at stoma

2020 - FDA approved OPRA implant system for TFA

36
Q

timeline for osseointegration

A

1st sx = fixture implant

bone healing x 6 months

2nd sx = abutment placed

partial WBing x 6 months

Rehab

37
Q

suspension aid examples

A

supracondylar trim lines

outer sleeve

thigh corset

other strapping mechanisms

38
Q

types of non-articulating feet

A

SACH feet (solid ankle cushioned heel)

39
Q

types of articulating feet

A

single axis
multi axis
dynamic response/energy storing feet
multi axial dynamic response feet
hydraulic
microprocessor

40
Q

describe the SACH foot

A

lightweight
inexpensive
low maintenance

wooden or metal keel that extends to MTP joints

rubber heel allows for shock absorption and PF at loading response

41
Q

describe a single axis foot

A

some sagittal motion allowed and controlled by interchangeable anterior and posterior bumpers

no transverse or frontal plane mvmt

no energy return

heavier

More maintenance required than SACH

42
Q

describe multi axial feet

A

allows for some pronation and supination (inversion and eversion) to cope with uneven terrain along with sagittal DF/PF

more expensive

can be heavier

for people who function in areas with uneven terrain, active amputees, golfers, and dancers

43
Q

describe energy storage/dynamic response foot

A

leaf spring (metal or nylon) keel stores energy during 2nd rocker and releases it in the 3rd rocker

as cadence or activity level increases, more spring comes into play resulting in greater return

44
Q

describe multi acial dynamic response feet

A

combo of articulated foot and dynamic response

closest to the functional foot replacement

45
Q

describe hydraulic feet

A

multiaxial with vertical shock absorption

energy return

expensive, not as durable

smooth rollover

46
Q

describe microprocessor/power feet

A

identifies slopes and stairs after first step

during gait, automatically provides DF during swing phase that allows sufficient ground clearance

active ankle motion also allows users to tuck both feet behind their knees when getting up from a chair or sitting down

automatically PFs the foot for more natural appearance when seated

47
Q

advantages of microprocessor feet

A

provides push off

increased self selected gait velocity

9.9% less energy expenditure

48
Q

disadvantages for microprocessor feet

A

poor battery life

heavy

expensive

49
Q

types of alignment to look at for prosthetics

A

“bench” alignment

static = sitting/standing

dynamic = gait, STS, and stairs/ramps

50
Q

things to look at with static standing alignment assessment

A

equal weight distribution?
level pelvis? ASIS, IC, PSIS?
foot in plantigrade?
knee position?
position of pylon?
pain?

51
Q

alignment parameters to look at

A
  1. leg length
  2. heel height
  3. transverse plane foot RT
  4. socket sagittal plane alignment
  5. foot AP alignment
  6. socket frontal plane alignment
  7. foot ML alignment
  8. DF/PF
52
Q

why do some prosthetics have adjustable heel height

A

to accommodate different styles of shoes

53
Q

how is the prosthetic generally placed in transverse plane RT

A

typically mimics anatomical normal of 5-7 deg of toe out

54
Q

why might a socket be placed in flexion and how does this affect the alignment

A

may be to accomodate knee flexion contracture

dampens shock and smooths COM rise and fall

will prevent genurecurvatum

helps resist tendency of residual limb to slide into socket and potentially bottom out

no change in sagittal plane moments

55
Q

why might a socket be placed in extension and how does this affect the alignment

A

to attempt to correct knee flexion contracture

peak knee flexion moments increased

peak knee extension moments decreased

56
Q

anterior and posterior translation of the socket has what effect on the prosthetic foot

A

anterior socket translation = posterior translation of foot

posterior socket translation = anterior translation of foot

57
Q

what happens with socket adduction

A

foot must be laterally displaced

increased knee valves moment

mimics medial translation of the socket

58
Q

what happens with socket abduction

A

foot must be medially displaced

increased knee varus moment

mimics lateral translation of socket

59
Q

what happens with the foot of the prosthetic is placed lateral to the socket (socket medial to foot)

A

widens BOS

increased knee valgus moment

60
Q

what happens when the foot of the prosthetic is placed medial to the socket (socket lateral to the foot)

A

maintains fairly normal BOS and loads more pressure on medial residual limb

decreases pressure on fibular head

increases knee varus moment

61
Q

types of prosthetic knees

A

single axis hinge
ploy centric linkage
constant friction
variable friction
pneumatic
hydraulic
microprocessor

62
Q

describe single axis knee joint

A

simple hinge mechanism

light weight

K level 1

63
Q

describe polycentric knee joint

A

have 4 or more pivoting bars

provide greater knee stability than single axis

64
Q

describe constant friction mechanism

A

amount of friction doesn’t change

for set cadence/walking speed

K1/K2

65
Q

describe variable friction mechanism

A

friction changes during swing

  1. initial swing = high friction to prevent excess knee flexion
  2. midswing = friction decreases to allow knee to swing easily
  3. terminal swing = increase in friction to prepare for IC.

K3/K4

66
Q

describe pneumatic (air) friction control system at the knee

A

compresses air as knee is flexed, stores energy, then energy is retuned to put knee into ext

67
Q

describe hydraulic (fluid) friction control system

A

provide more friction and smoother gait

heavier, more expensive, require more maintenance

use a liquid medium such as silicone

68
Q

describe microprocessor knees

A

K2-K4

sensors detect movement and timing then adjusts pneumatic or hydraulic control as needed

benefits = decreased falls, more active, enhanced confidence

heavier, expensive, need battery

69
Q

why might a TFA socket be placed in flexion and what is the effect

A

to accomodate hip flexor contracture

weight line (TKA line) shifts posterior to the knee joint center = increased knee flexion moment

70
Q

describe the control mechanisms for knee stability

A

alignment of knee joint axis in the sagittal plane

inherent mechanical stability of knee

voluntary control swing muscular power

microprocessor controlled

71
Q

key components of prosthetic training for a pt with bilateral TFA

A
  1. build confidence- work on strength, endurance, weight management, and psychological stress
  2. start with short prosthetic limbs “stubbies” w/o knee joint
    - COM lower to ground
    - reduce fall risk
    - less energy expenditure
    - help improve strength
  3. gradually increase prosthetic height
  4. pt will progress to full length/long prosthetic limbs with knee component
72
Q

commonly observed step length/single leg stance time asymmetries

A

stance time = prosthetic < intact

step length = prosthetic > intact

if short step is observed on prosthetic side, possible cause = knee flexion contracture

73
Q

factors that contribute to step length/single leg stance time asymmetries in pts with prosthetic limbs

A

pt confidence
pain
proper weight shifting
needs gait training

74
Q

causes of contralateral vaulting deviation

A

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

75
Q

causes of hip hike deviation

A

weakness of hip flexors

difficulty initiating knee flexion

76
Q

causes of circumduction deviation

A

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

77
Q

prosthetic causes of swing phase deviations (i.e. contralateral vaulting, hip hike, circumduction)

A

long prosthesis
locked knee
inadequate suspension
loose socket
foot plantar flexed

78
Q

functional significance of swing phase deviations

A

assist with foot clearance

increases energy expenditure due to displacement of COM

79
Q

prosthetic causes of ipspilateral trunk lean during prosthetic limb stance

A

prosthetic length too short

sharp or high medial wall (TFA/KD)

prosthetic aligned in abduction (TFA/KD)

80
Q

anatomical causes of ipsilateral trunk lean during prosthetic limb stance

A

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

Year 3: Prosthetics and Orthotics (10 decks)

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