TF Prosthetic Components and Suspension Systems (1)

Question 1

components

Answer 1

foot, ankle, shank

knee

socket

suspension

Question 2

components –> foot, ankle, shank

Answer 2

same as for TT prosthesis

Question 3

components –> knee

Answer 3

“heart” of the TF prosthesis

Question 4

what is the prosthetics knee controlled by

Answer 4

hip mechanics and alignment of the prosthesis

Question 5

fxn w/in the prosthetic knee

Answer 5

attaches shank/foot to socket

allows/controls flexion in swing phase and sitting

supports leg and allows for extension during stance

strong enough for kneeling

Question 6

normal knee fxn

Answer 6

stability/stance

mobility/swing

Question 7

stability/stance –> normal knee –> HS to MS

Answer 7

quads control eccentric/concentric

Question 8

stability/stance –> normal knee –> MS to HO/PO

Answer 8

begin to flex knee as hip flexes

Question 9

stability/stance –> normal knee –> where is max flexion

Answer 9

in stance

20 degrees

Question 10

mobility/swing –> normal knee –> produced by

Answer 10

momentum and mm action

controlled by mm action

Question 11

mobility/swing –> normal knee –> max flexion in swing

Answer 11

65 degrees

Question 12

how would you describe a TF prosthetic knee joint (in order)

Answer 12

axis –> swing control –> stance control –> extension aide

Question 13

knee joint axis

Answer 13

single or polycentric

Question 14

single axis knee joint

Answer 14

rotation around one axis

hinge

Question 15

advantages –> single axis

Answer 15

simple few moving parts

low cost

low maintenance

quiet, low weight

Question 16

disadvantages –> single axis

Answer 16

poor cosmesis of gait

normal knee

Question 17

polycentric axis

Answer 17

instant axis

Question 18

advantages –> polycentric axis

Answer 18

inherent stability

normal appearance of knee motion

Question 19

disadvantages –> polycentric axis

Answer 19

more complex mechanically

higher cost/weight

too stable late stance

Question 20

swing control(list)

Answer 20

swing control

need for resistance

Question 21

swing control

Answer 21

resistance to flexion and extension

Question 22

in normal knee at the beginning of swing

Answer 22

knee is flexing to midswing then extends

forces acting on knee = mm and gravity

Question 23

during acceleration –> swing

Answer 23

beginning of knee flexion d/t PO

gravity pulls knee down to resist flexion

quads resist flexion

Question 24

mid-swing –> swing normal

Answer 24

gravity helps

muscles initiate extension

Question 25

deceleration --> swing normal

Answer 25

gravity pulling straight down resists extension, hamstrings eccentrically

Question 26

in the prosthetic knee

Answer 26

mm absent must use mechanics to control knee flexion/extension

Question 27

need for resistance --> swing --> what would happen w/o resistance

Answer 27

get free swinging knee okay if walking speed stays constant

Question 28

need for resistance --> swing --> if walking speed changes

Answer 28

heel rise will increase time for knee to reach full extension will increase leg may be in flexion at HS --> UNSAFE

Question 29

need for resistance --> swing --> what do need to decrease

Answer 29

heel rise during swing phase

Question 30

need for resistance --> swing --> what is the answer

Answer 30

friction

Question 31

swing control --> friction control

Answer 31

friction requirements vary at different points in the gait cycle

Question 32

swing control --> friction control --> when would you need the most friction

Answer 32

when mm would be the most active

Question 33

swing control --> friction control --> friction is

Answer 33

mechanical analogue of quads at HS

Question 34

swing control --> friction control --> where must friction be greatest

Answer 34

mid-swing

Question 35

types of frictional control

Answer 35

constant variable hydraulics

Question 36

constant --> frictional control

Answer 36

same level of friction throughout swing

Question 37

advantage of constant frictional control

Answer 37

simple cheap quiet light decrease m

Question 38

disadvantage of constant frictional control

Answer 38

not cadence responsive doesnt have good cosmesis of swing w/ varying speeds of gait adjusted 1 time to pt speed

Question 39

single axis and constant frictional control

Answer 39

single-axis constant friction w/ weight activated brake and extension assist

Question 40

what does the pt need to moderate -->single-axis constant friction w/ weight activated brake and extension assist

Answer 40

voluntary control of the prosthesis

Question 41

single-axis constant friction w/ weight activated brake and extension assist

Answer 41

single speed ambulation for basic ADLs adjustable weight activated stance control for stability

Question 42

polycentric constant frictional force

Answer 42

pt needs low voluntary control single speed walkers limited community ambulation

Question 43

polycentric constant frictional force is good for

Answer 43

hip disarticulation short transfemoral hemipelvectomy pts

Question 44

variable frictional control

Answer 44

greater friction at beginning and end of swing stimulating quad and HS control

Question 45

example of variable frictional control

Answer 45

mating surfaces provide for variable friction

Question 46

mating surfaces provide for variable friction --> extension to flexion

Answer 46

45-70 degrees most friction

Question 47

mating surfaces provide for variable friction --> flexion to extension

Answer 47

90-10 degrees little friction 10-0 degrees = most friction

Question 48

hydraulics --> frictional control

Answer 48

variable friction w/ hydraulics instead of mechanical friction

Question 49

what is resistance based on --> hydraulics

Answer 49

physical laws of fluid viscosity

Question 50

"the law" --> hydraulics

Answer 50

resistance to the flow of a fluid varies w/ the square of its velocity

Question 51

resistance --> hydraulics

Answer 51

varying resistance throughout swing

Question 52

example --> hydraulics

Answer 52

mauch

Question 53

resistance encountered is dependent upon --> hydraulics

Answer 53

types of oil used rate of fluid flow characteristics of channel viscosity of fluid

Question 54

rate of fluid --> resistance encountered is dependent upon --> hydraulics

Answer 54

increase rate --> increase resist decrease rate --> decrease assist

Question 55

stance control

Answer 55

normal knee prosthetic knee

Question 56

normal knee --> stance control

Answer 56

quads at HS control knee to MS later --> quads control flexion at HO and PO

Question 57

prosthetic knee stance

Answer 57

whats needed could be achieved via components/alignment

Question 58

prosthetic knee stance --> can align prosthesis w/

Answer 58

hip and ankle --> anterior to knee create an extension moment at knee

Question 59

prosthetic knee stance --> how can the axis move

Answer 59

axis of the knee posterior as done in polycentric through its changing axis