A 65-year-old man undergoes transfemoral (above-knee) amputation for peripheral vascular disease. On rehabilitation, the prosthetic knee joint most suitable for a community ambulator with moderate activity demands (K3 level — variable cadence walking, terrain variation) is:

• A Hydraulic/pneumatic swing-and-stance control knee ✓
• B Single-axis, constant-friction mechanical knee
• C Polycentric (four-bar linkage) knee joint
• D Microprocessor-controlled (C-Leg type) knee joint

Explanation

The K classification (K0–K4) rates amputee functional level; K3 indicates community ambulation at variable cadence with ability to negotiate most environmental barriers. A hydraulic or pneumatic swing-and-stance control knee accommodates variable walking speeds (the hydraulic cylinder modulates swing phase resistance proportionally to cadence) and provides stance-phase stability — making it the appropriate choice for K3 activity level. Single-axis constant-friction knees only control swing phase at fixed cadence and are suitable for limited household ambulators (K2). Microprocessor knees (K3–K4) provide the best control but have higher cost, weight, and maintenance requirements. Polycentric knees offer inherent stance stability and are preferred for bilateral amputees or K2–K3 users with high instability concerns.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

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Written and medically reviewed by the StethoPrep medical team.