A 40-year-old bilateral above-knee amputee (transfemoral) receives a microprocessor-controlled prosthetic knee (C-Leg). What is the primary advantage of a microprocessor knee over a purely mechanical knee for this patient?

• A Real-time sensor feedback adjusting stance phase resistance to prevent stumbling and reduce fall risk, enabling varied cadence walking ✓
• B Lower cost and easier maintenance compared to passive mechanical systems
• C It eliminates the need for hip flexor muscle function for prosthetic swing through
• D Microprocessor knees are water-resistant and can be used for swimming

Explanation

Microprocessor-controlled prosthetic knees (e.g., C-Leg, Rheo Knee) use real-time sensors (gyroscopes, accelerometers, load sensors) to continuously adjust hydraulic or pneumatic resistance during both stance and swing phases. Key advantages include: prevention of stumbling (automatic stance phase lock when stumble detected), safe controlled descent on stairs/ramps, and the ability to walk at variable cadence. This significantly reduces fall risk in active transfemoral amputees. They are more expensive (not cheaper) than mechanical knees. Hip flexors are still needed for swing initiation. Most versions are not waterproof unless specifically designed.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

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Written and medically reviewed by the StethoPrep medical team.