A 65-year-old patient with peripheral vascular disease and a non-healing toe gangrene requires amputation. The most common level of amputation that preserves the best prosthetic function and energy expenditure compared to above-knee amputation is:
- A Syme's amputation (distal tibia, through the ankle joint)
- B Below-knee (transtibial) amputation at the junction of middle and distal thirds ✓
- C Through-knee (transfemoral at the condylar level)
- D Hip disarticulation
Explanation
Below-knee (transtibial) amputation is preferred over above-knee (transfemoral) for vascular disease because energy expenditure for prosthetic ambulation increases dramatically with more proximal amputation: transtibial ~25% extra, transfemoral ~65–80% extra, hip disarticulation ~100% extra vs normal gait. Preserving the knee joint allows use of a dynamic-response prosthetic foot with near-normal gait. The ideal transtibial level is the junction of middle and distal thirds of the tibia (about 12–15 cm below tibial tuberosity), long enough for prosthetic fitting yet with adequate blood supply for healing. Syme's (A) requires intact heel pad vascularity, which is often compromised in PVD.
Reference: Maheshwari Essential Orthopaedics, 6th ed.
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Written and medically reviewed by the StethoPrep medical team.