Q1: Prosthetic Foot and Ankle Components

Question 1

What does the foot do?

Answer 1

• shock absorption
• weight bearing stability
• progression through gait cycle

Question 2

Prosthetic foot goals initial contact

Answer 2

shock absorption

Question 3

Prosthetic foot goals midstance

Answer 3

stability; coronal adaptations

Question 4

Prosthetic foot goals terminal stance

Answer 4

rigid forefoot leverage

Question 5

Prosthetic foot goals pre-swing

Answer 5

new tech; propulsion

Question 6

How do we describe prosthetic feet?

Answer 6

• materials
• heel
• keel
• functional properties/categories

Question 7

Heel

Answer 7

• shock absorption still achieved via knee flexion during loading response
• prosthetic foot incorporates either heel cushion, bumper, or lever to achieve this

Question 8

The Keel

Answer 8

• provides leverage during terminal stance
• length of keel also has an impact on gait

Question 9

Keel Deflection

Answer 9

keel compresses between middle and terminal stance, springs back into place during terminal stance

energy storing

Question 10

SACH foot

Answer 10

Solid Ankle Cushioned Heel

Question 11

Function of Cushioned Heel

Answer 11

• heel compresses during loading response
• shock absorption
• simulates plantarflexion of the ankle to achieve foot flat

Question 12

Advantages of SACH

Answer 12

• low maintenance
• low cost
• various heel heights

Question 13

Disadvantages of SACH

Answer 13

• deterioration of soft material
• no coronal plane “ground compliance”

Question 14

SACH foot Indications

Answer 14

• limited ambulators
• children (durability)
• need for durability (remote location)

Question 15

Single Axis Foot

Answer 15

• axis allows passive ankle PF and DF: increases knee stability during loading response

Question 16

What happens when loading response WITHOUT ankle PF

Answer 16

shanke and socket move with foot and cause abrupt knee flexion

Question 17

Single Axis Indications

Answer 17

• WEAK QUADRICEPS
• limited ambulator

Question 18

Advantages of Single Axis

Answer 18

• promotes sagittal plane knee stability

Question 19

Disadvantages Single Axis

Answer 19

maintenance due to articulating components

Question 20

Flexible Keel

Answer 20

• allows forefoot inversion/eversion
• intended to improve transition to ipsilateral side limb at terminal stance
• plantar bands allow for smooth rollover

Question 21

Flexible Keel Advantages

Answer 21

• smooth rollover properties
• forefoot inversion/eversion (coronal plane movement)

Question 22

Multiaxial Foot

Answer 22

• allows passive motion in TWO or more planes
• most common sagittal + coronal motion

Question 23

Multiaxial Advantages

Answer 23

• Sagittal plane: ankle PF motion increases knee stability during loading response; ankle DF motion can soften rollover in late stance
• Coronal plane: accommodation to uneven terrain
• Transverse plane: absorption of rotation forces

Question 24

Energy Storage and Return

Answer 24

• elastic spring keel
• keel deflects under load
• provides subjective sense of push off

Question 25

Heel Spring ESAR

Answer 25

• shock absorption
• simulates ankle PF

Question 26

Keel Spring ESAR

Answer 26

• deflects under load
• stronger sense of push off

Question 27

ESAR Advantages

Answer 27

• reduced energy expenditure
• reduced impact of cyclic vertical loads
• low weight if carbon fiber

Question 28

ESAR Indications

Answer 28

• persons at risk for overuse injury
• persons capable of waalking with variable cadence
• community ambulators

Question 29

Hydraulic Ankle

Answer 29

• single axis feature with hydraulic dampening
• allows for variable resistance
• often combined with ESAR or flexible keel base
• allows for easily adjustable resistance

Question 30

External Power Advantages

Answer 30

• active propulsion
• slope accommodation