L05. Lower Extremity Prostheses

Question 2

What are the cut offs for long, standard, and short below knee amputations

Answer 2

Long: 6” below knee
Standard: 5-6” below knee
Short: <4”

Question 3

What are the main components for a below knee prothetic?

Answer 3

Socket, Adapters, Pylon (Shank), Foot

Question 4

What functions would you want in a foot prosthetic?

Answer 4

1. Surface adaptation
2. Shock absorption following heel strike
3. Knee stabilization
4. Limb shortening during swing

Question 5

Is knee more mechanically stable if the ankle is anterior or posterior?

Answer 5

Anterior

Question 6

What is a SACH foot?

Answer 6

Solid ankle cushion heel

• wooden keel and polyurethane foam heel wedge

Question 7

What does the single axis foot allow?

Answer 7

• Limited uni-axial motion in plantar- and dorsi- flexion (but better than SACH foot)

Question 8

What does the multi-axis foot allow for?

Answer 8

• Motion in plantar-, dorsi-, inversion, eversion, and pronation/supination planes

Question 9

What is the advantage and disadvantage of multi-axis foot

Answer 9

Advantage: Good for surface adaptation
Disadvantage: Stability

Question 10

What is the jaipur foot?

Answer 10

• Made of vulcanized rubber with a wooden keel
• has 3 inserts for the length of the foot and ankle of laminated wood
• Flexibility in 3 planes
• Good for walking on uneven terrain

Question 11

Benefit of an energy storing prosthetic foot?

Answer 11

1. Prostheses feels more lively
2. Reduces energy consumption and cardiovascular load

Question 12

Benefit of a microprocessor controlled prosthetic foot

Answer 12

1. Greater adjustment to surfaces
2. Provide greater push off at end of stance (dorsiflex)
3. Ankle adjustment makes sitting more comfortable
4. Better for active amputees

Question 13

Purpose of prosthetic shank

Answer 13

Connects and transfers weights from the socket to the foot

Question 14

Purpose of prosthetic socket

Answer 14

Interface between remaining limb and prosthesis

• Allows for load bearing comfortably
• Preventing rotation or sliding off

Question 15

Which above knee amputation has the best and worst power transmission efficiency?

Answer 15

Best: Long above knee
Worst: Short above knee

Question 16

What are the components for an above knee prosthetic

Answer 16

1. Socket
2. Knee
3. Shank
4. Foot/Ankle

Question 17

What are the main functions of the knee during gait?

Answer 17

1. Stability and support
2. Shock absorption

Question 18

Benefits and drawbacks of locked knee prosthetic

Answer 18

Benefits: Complete stance phase stability
Drawbacks:
- No swing phase knee flexion
- Likely requires a compensatory mechanism for foot clearance during gait

Question 19

What are the 3 gait deviations in above knee amputees

Answer 19

1. Curcumduction
2. Vaulting
3. Hip Hiking

Question 20

How does the polycentric knee work?

Answer 20

• Moves the center of rotation posteriorly at full extension
• When flexion is desired, center of rotation moves forward and ground reaction force promotes flexion

Question 21

How does a fluid controlled knee work?

Answer 21

• Motion of the knee is regulated by viscous fluids using pneumatic/hydraulic systems
• Doesn’t lock during stance

Question 22

How does the powered knee work?

Answer 22

Enables more flexible control by adjusting the mechanical resistance based on the exerted load