TT 3

Question 1

Which is better to prevent rotation? PTB or TSB?

Answer 1

PTB

Question 2

Why is PTB better for prevention of rotation within a socket?

Answer 2

more contours

Question 3

Why are the forces on a prosthetic limb important to consider?

Answer 3

need to account for skin breakdown and function to improve a person’s functional ability

Question 4

What are the types of forces we need to consider for prosthetic fitting?

Answer 4

• pressure
• shear
• friction

Question 5

What is pressure?

Answer 5

force perpendicular to the skin

Question 6

Our typical amputee pt has these types of issues

Answer 6

circulation (think DM)

Question 7

Excessive pressure causes

Answer 7

• circulation loss
• pain
• skin problems

Question 8

What is shear?

Answer 8

skin and prosthesis/surface are rubbing in OPPOSITE directions

Question 9

What does shear occur between?

Answer 9

• dermis

- subcutaneous tissue

Question 10

What does friction cause?

Answer 10

blisters

Question 11

What does friction occur between?

Answer 11

• prosthesis

- skin surface

Question 12

What are the two “effects” we talked about?

Answer 12

• heel effect

- contracture effect

Question 13

What is the heel effect?

Answer 13

• prosthesis behaves like a SAFO (no ankle joint)

- Where the heel goes, the ankle follows

Question 14

What does the heel effect affect?

Answer 14

forces on the knee

Question 15

What is the contracture effect?

Answer 15

• There is a fixed relationship between the pylon and socket

- Where the pylon goes, the socket follows

Question 16

What are some disadvantages to a pin and shuttle?

Answer 16

• excessive shear (all weight pulls down during swing phase)

- fluid “milking” down to distal end

Question 17

What is the TKA line equivalent to?

Answer 17

GRF

Question 18

TKA =

Answer 18

Trochanter
Knee
Ankle

Question 19

When is a flexion moment created?

Answer 19

knee is anterior

Question 20

Does a flexion moment mean the knee will go into flexion?

Answer 20

not necessarily

Question 21

When is an extension moment created?

Answer 21

knee is posterior

Question 22

What can happen if the prosthesis is too big? (safety concerns)

Answer 22

it will slide down and cause issues during swing phase

• increased leg length
• poor foot clearance
• trip and fall