Management of Severe Limb Ischemia in an Elderly Diabetic Patient
Below knee amputation is the most appropriate management for this elderly diabetic patient with extensive tissue necrosis, complete occlusion of popliteal and infra-popliteal arteries, and no distal runoff. 1
Assessment of the Current Clinical Situation
This patient presents with:
- Elderly female with uncontrolled diabetes mellitus
- Blackish discoloration of left foot for 2 weeks (gangrene)
- No palpable anterior or posterior tibial pulses
- Leukocytosis (suggesting infection)
- CTA findings:
- Severe stenosis of distal superficial femoral artery
- Complete occlusion of popliteal artery
- Complete occlusion of infra-popliteal arteries
- No collaterals
- No distal runoff
Decision Algorithm for Management
1. Evaluate Revascularization Potential
- The complete occlusion of popliteal and infra-popliteal arteries with no collaterals and no distal runoff makes successful revascularization extremely unlikely
- For infra-popliteal revascularization to be successful, there must be at least one target vessel for runoff 1
- Bypass surgery requires adequate target for anastomosis/runoff, which is absent in this case 1
2. Consider Tissue Viability
- Blackish discoloration for 2 weeks indicates established gangrene
- Leukocytosis suggests infection, which increases risk of sepsis
- Uncontrolled diabetes worsens tissue healing potential and infection risk
3. Amputation Level Decision
- Below knee amputation (BKA) is preferred over above knee amputation (AKA) when possible
- BKA preserves the knee joint, allowing better mobility with prosthesis 1
- The infragenicular amputation should be preferred because the knee joint allows better mobility with a prosthesis 1
Why Bypass Graft Is Not Appropriate
- Bypass requires adequate target vessel for anastomosis
- Complete occlusion of infra-popliteal vessels with no runoff makes bypass technically unfeasible
- Guidelines indicate that bypass using great saphenous vein is indicated for infra-popliteal revascularization, but only when adequate target vessels are present 1
- Without distal runoff, bypass would have extremely high failure rate
Why Above Knee Amputation Is Not First Choice
- Preserving the knee joint significantly improves functional outcomes and rehabilitation potential
- ESC/ESVS guidelines specifically state: "In any case, infragenicular amputation should be preferred, because the knee joint allows better mobility with a prosthesis" 1
- Above knee amputation should be reserved for cases where BKA would not provide adequate healing or when infection extends above the knee
Additional Management Considerations
- Immediate systemic antibiotics for leukocytosis/infection 1
- Optimal glycemic control is essential before and after amputation 1
- Pain management
- Early rehabilitation planning with prosthesis
- Secondary prevention of cardiovascular events with antiplatelet therapy and risk factor modification
Pitfalls to Avoid
- Delaying amputation when revascularization is not feasible can lead to:
- Progression of infection and sepsis
- Higher level of eventual amputation
- Increased mortality risk
- Attempting revascularization when there is no distal runoff wastes critical time and resources
- Performing above knee amputation when below knee would suffice unnecessarily reduces mobility and quality of life
In conclusion, while limb salvage is always preferred when possible, this patient's extensive disease with no distal runoff makes revascularization attempts futile. Below knee amputation offers the best balance of removing non-viable tissue while preserving maximum function and quality of life.