Prosthetic Knees

Question 1

Polycentric Advantages

Answer 1

• Alpha stability KC stays behind weight line longer
• Beta stability closer to hip (work source), less hip extensor effort
• Variable swing
• Shortens at mid-swing for toe clearance
• Minimized knee center discrepancy when sitting

Question 2

Constant Friction Knees

Answer 2

• Mechanical friction remains constant
• Ideal for only one walking speed
• Wear on the knee results in decreased friction

Question 3

Fluid Controlled Knee Advantages

Answer 3

• Responsive to variable cadence
• Resistance during early and late swing phase
• Less wear on knee, less adjustments
• Stance phase control available

Question 4

Laminar Flow

Answer 4

Straight, smooth flow offering less resistance

Question 5

Turbulent Flow

Answer 5

An uneven flow offering greater resistance

Question 6

Transitional Flow

Answer 6

A relatively random mixture of laminar and turbulent flow