What artery should be checked before below knee amputation in a case of ischemic limb?

Preoperative Evaluation for Below-Knee Amputation in Ischemic Limb

The popliteal artery is the most critical vessel to evaluate before performing a below-knee amputation in a case of ischemic limb. 1

Rationale for Popliteal Artery Assessment

The popliteal artery is the key vessel to evaluate before below-knee amputation for several important reasons:

1. Anatomical significance: It is the direct continuation of the superficial femoral artery and provides the main blood supply to tissues at the below-knee amputation level 1

2. Healing potential: The presence of pulsations in the popliteal artery indicates an 89% chance of healing for below-knee amputations 2

3. Revascularization potential: If the popliteal artery has adequate flow, it may serve as the inflow vessel for potential bypass procedures to salvage the limb rather than proceeding with amputation 3

Comprehensive Vascular Assessment Algorithm

1. Evaluate popliteal artery patency:

   • Check for palpable pulsations
   • Perform Doppler ultrasound assessment
   • Assess for presence of collateral circulation

2. Measure skin perfusion pressure (SPP):

   • SPP > 30 mmHg: High probability (97%) of BK amputation healing
   • SPP 20-30 mmHg: Moderate risk (54% failure rate)
   • SPP < 20 mmHg: High risk (89% failure rate) 2

3. Imaging assessment:

   • Complete angiography down to the plantar arches is mandatory for proper arterial network assessment 3
   • Evaluate for potential revascularization options before amputation 3

4. Evaluate distal runoff vessels:

   • The most distal artery with continuous flow from above and without significant stenosis (>20%) should be identified 3
   • The tibial or pedal artery capable of providing continuous and uncompromised outflow to the foot should be assessed 3

Why Popliteal Artery is Superior to Other Options

1. Femoral artery (Option A): While important for overall limb perfusion, its status alone doesn't determine below-knee amputation success as directly as the popliteal artery 1

2. Dorsalis pedis artery (Option B): Important for foot perfusion but less critical for below-knee amputation healing 1

3. Popliteal artery (Option C): Directly supplies the below-knee amputation site and its patency is the most predictive of successful healing 1, 2

4. Profunda femoris artery (Option D): An important collateral vessel but not as directly relevant to below-knee amputation site healing as the popliteal artery 1

Additional Considerations

• Multidisciplinary evaluation before amputation is recommended to identify potential revascularization options 3
• Blunt trauma to the popliteal artery carries a higher risk of amputation than penetrating trauma 4
• The presence of infection should be assessed and addressed before amputation 3
• Fasciotomy may be necessary in cases of prolonged ischemia to prevent compartment syndrome 4

Remember that a properly performed amputation can be lifesaving and may be a better therapeutic alternative than an ill-conceived attempt at vascular reconstruction when there are inadequate recipient vessels 5.