Prosthetic Knees and Keel

Question 1

What is the keel?

Answer 1

Supportive structure of the prosthetic foot that provides stability to the user.

Question 2

• The keel can be rigid, flexible, or _________.

- The more rigid the keel, the less ________ it is.

Answer 2

• dynamic

- dynamic

Question 3

The length of the keel is important to gait and has what upstream effects?

Answer 3

• Toe lever
• Heel rise/toe break
• Knee flexion/stability

Question 4

The toe lever is the distance from the center of the socket to the end of the keel. What does a long/short keel/toe lever do?

Answer 4

Long- makes it difficult to initiate pre-swing knee flexion

Short- causes knee flexion too early in stance phase, can result in drop off in TT and knee instability in TF.

Question 5

What are the 2 goals of prosthetic knees?

Answer 5

• Stance phase control (knee doesn’t buckle)

- Swing phase control (controls speed of pylon)

Question 6

What are the types of prosthetic knees from simple to complex?

Answer 6

• Single Axis
• Polycentric
• Manual Locking (exception, variation of single axis)
• Pneumatic
• Hydraulic
• Microprocessor

Question 7

Both single axis and polycentric knees are the most basic types of knees and provide for ________ control through alignment, encouraging the GRFV to be ________ to the prosthetic knee to ensure stability.

Answer 7

• stance

- anterior

Question 8

Users of single axis and polycentric knees need good hip ________ control to pull knee joint behind the GRFV.

Answer 8

extension

Question 9

A manual locking knee is the most ______ stance control knee. Does it allow for knee flexion during swing phase?

Answer 9

• stable

- No

Question 10

Hydraulic and pneumatic knees provide for ______ phase control by dynamically adjusting swing speed to user’s _____ speed.

Answer 10

• swing

- gait

Question 11

Hydraulic and pneumatic knees use ________ to control swing speed.

Answer 11

friction

Question 12

What are the benefits of hydraulic and pneumatic knees?

Answer 12

• control on uneven surfaces
• variable cadence and gait speed
• mimics normal gait

Question 13

What is the difference between hydraulic and pneumatic?

Answer 13

Hydraulic uses fluid or oil, while pneumatic uses air pressure.

Question 14

The microprocessor knee provides _____ and ______ phase control. Sensors measure joint angles, cadence, etc to provide the user with a stable knee that is responsive.

Answer 14

swing and stance

Question 15

What are the benefits of microprocessor knees?

Answer 15

• stumble recovery
• stairs
• power