MT: Prosthetic Knee Control- Fluid

Question 1

In fluid control units…

Answer 1

the flow of the fluid through the system provides resistance

Question 2

Swing phase control

Answer 2

• cadence responsiveness
• limit heel rise
• have an extension bias

Question 3

Stance phase control

Answer 3

• resist knee flexion when the knee is loaded in flexion

Question 4

Fluid Control Principles

Answer 4

1. Gases are compressible;liquids are not

Question 5

Pneumatic

Answer 5

• gas can be compressed
• this cannot create enough resistance to flexion during stance phase to provide stance phase control
• this can create resistance during swing phase AND/OR can act as an extension assist during swing

Question 6

Hydraulic

Answer 6

• liquid cannot be compressed
• creates resistance during swing phase
• may be able to resist knee flexion during stance phase
• may be able to stop knee flexion

Question 7

Pneumatic Knee Indications

Answer 7

• lightweight, quiet
• variable candence walker
• smooth swing
• indicated for moderate to light users

Question 8

Pneumatic Knee Disadvantages

Answer 8

• stance control must be provided through other means
• air spring effect can occur at higher walking speeds
• active users can outwalk the knee

Question 9

Pneumatic Swing Control

Answer 9

Stance control: mechanical, polycentric design
Swing flexion resist: fluid
Swing extension resist: fluid
Swing extension assist: mechanical

Question 10

Hydraulic Knee Indications

Answer 10

• can provide swing and stance resistance
• cadence responsiveness
• yielding rate
• incompressible hydraulic fluid can create a block against motion in some knees
• high activity users

Question 11

Yielding Rate

Answer 11

• stance flexion resistance
• can be adjusted to optimize stumble recovery, decline walking, and sitting

Question 12

Hydraulic Knee Disadvantage

Answer 12

• bulky
• fluid leakage

Question 13

Fluid Control benefits

Answer 13

fluid swing control permits variable cadence walking