TT 3 Flashcards
Which is better to prevent rotation? PTB or TSB?
PTB
Why is PTB better for prevention of rotation within a socket?
more contours
Why are the forces on a prosthetic limb important to consider?
need to account for skin breakdown and function to improve a person’s functional ability
What are the types of forces we need to consider for prosthetic fitting?
- pressure
- shear
- friction
What is pressure?
force perpendicular to the skin
Our typical amputee pt has these types of issues
circulation (think DM)
Excessive pressure causes
- circulation loss
- pain
- skin problems
What is shear?
skin and prosthesis/surface are rubbing in OPPOSITE directions
What does shear occur between?
- dermis
- subcutaneous tissue
What does friction cause?
blisters
What does friction occur between?
- prosthesis
- skin surface
What are the two “effects” we talked about?
- heel effect
- contracture effect
What is the heel effect?
- prosthesis behaves like a SAFO (no ankle joint)
- Where the heel goes, the ankle follows
What does the heel effect affect?
forces on the knee
What is the contracture effect?
- There is a fixed relationship between the pylon and socket
- Where the pylon goes, the socket follows
What are some disadvantages to a pin and shuttle?
- excessive shear (all weight pulls down during swing phase)
- fluid “milking” down to distal end
What is the TKA line equivalent to?
GRF
TKA =
Trochanter
Knee
Ankle
When is a flexion moment created?
knee is anterior
Does a flexion moment mean the knee will go into flexion?
not necessarily
When is an extension moment created?
knee is posterior
What can happen if the prosthesis is too big? (safety concerns)
it will slide down and cause issues during swing phase
- increased leg length
- poor foot clearance
- trip and fall
