Knees

Question 1

What are the generic classes of knees?

Answer 1

• Single Axis (constant friction)
• Stance-control
• polycentric
• manual lock
• fluid controlled

Question 2

What is basic function, primary indication, advantages/disadvantages for single axis knees?

Answer 2

• simplicity
• single speed walking only if hip contrl is good or better or when max durability is required
• improved knee stability
• fixed cadence and low stability

Question 3

What is basic function, primary indication, advantages/disadvantages for stance control knee?

Answer 3

• increased weight bearing stability
• general debility, poor hip control
• improved knee stability
• delayed swing phase, must unload fully to flex or sit

Question 4

What is basic function, primary indication, advantages/disadvantages for polycentric knees?

Answer 4

• positive stability and ease of flexion for swing phase, special design available that provides sitting cosmesis for long residual limbs
• to enhance knee stability, special design for KD, stable w/o disrupting swing phase, special design provides cosmesis for long limbs
• increased weight maintenance, initial cost

Question 5

What is basic function, primary indication, advantages/disadvantages for manual lock knees?

Answer 5

• knee of last resort
• ultimate knee stability
• eliminates knee flexion
• abnormal gait, awkward sitting

Question 6

What is basic function, primary indication, advantages/disadvantages for fluid controlled knees

Answer 6

• permits cadence change, mpk offers most normal gait pattern
• able to vary walking speed
• variable cadence, more natural gait, hydraulic stance control adds stability
• increased initial cost, may involve increased weight or maintenance