Prosthetic Knees

Question 1

Single axis/constant friction

Answer 1

Basic function:
-simplicity
Indications:
-single speed walking
-good hip control
Advantages:
-inexpensive
-durable
Limitations:
-fixed cadence
-low stability

Question 2

Stance control

Answer 2

Basic function:
-increased weight bearing stability
Indications:
-general debility
-poor hip control
Advantages:
-improved knee stability
Limitations:
-delayed swing phase
-must unload fully to flex or sit

Question 3

Polycentric

Answer 3

Basic function:
-inherent stability
-ease of flexion for saving phase
-sitting cosmesis for long residual limbs (knee disarticulations)
Indications:
-enhance knee stability
-special design for knee disarticulations
Advantages:
-stable without disrupting swing phase
-cosmesis for long residual limbs
Limitations:
-increased weight
-maintenance
-initial cost

Question 4

Manual lock

Answer 4

Basic function:
-knee of last resort
Indications:
-ultimate knee stability
Advantages:
-eliminates knee flexion
Limitations:
-abnormal gait
-awkward sitting

Question 5

Fluid controlled

Answer 5

Basic function:
-permits cadence change
-microprocessor control offers most normal gait pattern
Indications:
-able to vary walking speed
Advantages:
-variable cadence
-more natural gait
-hydraulic stance control adds stability
Limitations:
-increased initial cost
-may involve increased weight
-maintenance