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Prosthetic Knees
Overview of Prosthetic Knees
Generic Class Knee | Basic Function | Primary Indication | Major Advantages | Chief Limitations |
---|---|---|---|---|
Single axis (constant friction) | Simplicity | Single speed walking, only if hip control is "good" or better, or when duability is required | Inexpensive, durable | Fixed cadence, low stability |
Stance control (weight activated locking) | Increased weight-bearing stability | General weakness or infirmity; poor hip control | Improved knee stability | Delayed swing phase; must unload fully to flex or sit |
Polycentric | 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 availabe for knee disartic | Stable without disrupting swing phase; sitting cosmesis | Increased weight, maintenance, cost |
Manual lock | Knee of last resort | Ultimate knee stability | Eliminates knee flexion | Abnormal gait; awkward sitting |
Fluid-controlled | Permits cadence change; micro-processor control offers most normal gait pattern | Able to vary walking speed | Variable cadence; more natural gait; hydraulic stance control adds stability | Increased cost; possible weight or maintenance increase |