A patient with a transfemoral (above-knee) amputation is prescribed a prosthesis. The prosthetic knee unit that provides the best functional outcome for a K3-level (community ambulator) unilateral above-knee amputee is:

• A Single-axis rigid knee with manual lock
• B Polycentric four-bar linkage knee
• C Microprocessor-controlled prosthetic knee (e.g., C-Leg) ✓
• D Constant friction swing phase control knee

Explanation

Prosthetic knee unit selection depends on K-level (functional classification): K1 (household ambulator) — manual lock/single-axis; K2 (limited community) — constant friction or polycentric; K3 (community ambulator, variable cadence) — microprocessor-controlled knee (C-Leg, Rheo Knee); K4 (high activity/athletic) — dynamic response microprocessor. Microprocessor knees use sensors and hydraulic systems to adapt swing and stance phase resistance in real time, dramatically reducing falls and energy expenditure for community ambulators. Polycentric knees provide greater stance stability and are suitable for K2 ambulators. The K3-level patient benefits most from the microprocessor knee despite its higher cost.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

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Written and medically reviewed by the StethoPrep medical team.