Prosthetic Knee Chart Flashcards
Alignment stability: manual locking
Most
Alignment stability: outside hinges
Least
Alignment stability: single axis
Low
Alignment stability: polycentric
High
Amputee stability: manual locking
None needed
Amputee stability: outside hinges
High
Amputee stability: conventional
High
Amputee stability: polycentric
Low
Indications: manual locking
- last resort
- usually for post-op instability
Indications: outside hinges
Knee disarticulation ONLY
Indications: conventional
- long limb with good voluntary control
- rarely used
Indications: polycentric
- knee disarticulation
- short or long TF RL
Indications: polycentric (K levels
K 2-4 for low-mod impact activities
Advantages: manual locking
Most stable
Advantages: conventional
- durable
- inexpensive
Advantages: polycentric
- excellent stability
- knee center symmetry
- good swing clearance
Disadvantages: manual locking
- gait deviations
- needs to be short to facilitate swing
Disadvantages: outside hinges
- poor cosmesis
- knee axis asymmetry
Disadvantages: conventional
Poor stability
Disadvantages: polycentric
- not heavy duty
- increased weight
- requires charging
Pneumatic, hydraulic, and microprocessor knees all fall under this category
Polycentric
Swing control types
- extension aid and mechanical friction
- pneumatic
- hydraulic
- microprocessor controlled
Advantages: extension aid and mechanical friction
- durable
- low cost
Advantages: pneumatic
- increased resistance with increased cadence
- unaffected by temp changes
Advantages: hydraulic
- increased resistance with increased cadence (very slow to very fast)
Advantages: microprocessor
- adjusts resistance instantly based on flex/ext angle and foot contact
- allows controlled descent
- more knee flexion ROM
Disadvantages: extension aid and mechanical friction
- constant speed (doesn’t adjust to cadence)
- may loosen
- debris may interfere
Disadvantages: pneumatic
high speeds may overpower available resistance
Disadvantages: hydraulic
- high cost
- high weight
Disadvantages: microprocessor
- high cost
- high weight
- sensitive to moisture
- etc.
Braking (stance control): manual locking
N/A (locked)
Braking (stance control): outside hinges, conventional, ext aid and friction, pneumatic, hydraulic
- stance control: knee in ≤ 15˚ flexion
- aka weight activated or “safety knee”
Braking (stance control): microprocessor knee
- Active
- ≤ 35˚
