What are the surgical intervention options for patients with below knee Peripheral Vascular Disease (PVD)?

Surgical Intervention for Below-Knee Peripheral Vascular Disease

For below-knee PVD requiring surgical revascularization, autogenous vein bypass to the popliteal or tibial arteries is the definitive treatment, with prosthetic grafts reserved only when no suitable vein is available from any source. 1

Indications for Surgical Intervention

Critical Limb-Threatening Ischemia (CLTI)

• Surgical procedures are mandatory to establish in-line blood flow to the foot in patients with nonhealing wounds or gangrene. 1
• Surgery for CLTI (rest pain, ischemic ulcers, gangrene) aims to eliminate symptoms, heal wounds, and preserve a functional limb. 1
• Patients with combined inflow and outflow disease require correction of inflow problems first, followed by outflow revascularization if symptoms persist. 1

Lifestyle-Limiting Claudication

• Surgical intervention is indicated for patients with significant functional disability (vocational or lifestyle-limiting) who fail exercise therapy and pharmacotherapy, with reasonable likelihood of symptomatic improvement. 1
• Surgery should NOT be performed solely to prevent progression to limb-threatening ischemia in claudication patients. 1

Surgical Approach by Anatomic Level

Below-Knee Popliteal Bypass

• Bypasses to the below-knee popliteal artery MUST be constructed with autogenous vein when possible (Class I, Level A). 1
• Prosthetic grafts to below-knee popliteal are reasonable ONLY when no autogenous vein from ipsilateral leg, contralateral leg, or arms is available. 1
• Recent VQI registry data (2024) shows below-knee popliteal-distal bypass achieves 89.0% freedom from amputation at 12 months with low perioperative MI rate (2.4%) and 30-day mortality (1.9%). 2

Tibial/Pedal Artery Bypass

• Femoral-tibial artery bypasses MUST be constructed with autogenous vein, including ipsilateral greater saphenous vein, or if unavailable, other sources of vein from leg or arm (Class I, Level B). 1
• The tibial or pedal artery capable of providing continuous and uncompromised outflow to the foot should be used as the distal anastomosis site. 1
• Composite sequential femoropopliteal-tibial bypass and bypass to isolated popliteal segments with collateral outflow are acceptable when no other form of bypass with adequate autogenous conduit is possible. 1

When Autogenous Vein is Unavailable

• If no autogenous vein is available and amputation is imminent, prosthetic femoral-tibial bypass with adjunctive procedures (arteriovenous fistula or vein interposition/cuff) should be used. 1
• Prosthetic material can be effective for bypass to below-knee popliteal and tibial arteries in CLI patients when endovascular revascularization has failed and no suitable vein exists (Class IIa, Level B-NR). 1
• Femoral-tibial artery bypasses with prosthetic graft material should NOT be used for claudication treatment. 1

Critical Conduit Selection Principles

Patency Rates by Conduit Type

• Autogenous vein grafts achieve 85% patency at 1 year, 80% at 3 years, and 70% at 5 years for below-knee bypasses. 3
• Synthetic grafts for below-knee bypasses have significantly inferior patency: 70% at 1 year, 35% at 3 years, and only 25-33% at 5 years. 3
• Above-knee prosthetic grafts achieve 47-50% patency at 5 years versus 66% for vein grafts. 4, 3

Factors Accelerating Prosthetic Graft Failure

• More distal anastomoses (below-knee vs. above-knee) accelerate failure. 3
• Hemodynamically significant tibial arterial occlusive disease worsens outcomes. 3
• Poor outflow tract beyond the distal anastomosis predicts early failure. 3

Preoperative Evaluation

• A preoperative cardiovascular risk evaluation MUST be undertaken in all patients with lower extremity PAD in whom major vascular surgical intervention is planned (Class I, Level B). 1
• The most distal artery with continuous flow from above and without stenosis >20% should be used as the point of origin for distal bypass. 1

Staged Approach for Multilevel Disease

• A staged approach to surgical procedures is reasonable in patients with ischemic rest pain and multilevel disease. 1
• Aortoiliac (inflow) disease should be treated first with endovascular or surgical reconstruction, depending on lesion characteristics, patient comorbidities, and patient preference. 1
• Combined percutaneous and surgical revascularization typically requires the most proximal procedure performed first. 1

Postoperative Management

• Unless contraindicated, all patients undergoing revascularization for CLI MUST be placed on antiplatelet therapy indefinitely (Class I, Level A). 1
• Patients with aortobifemoral bypass grafts require periodic evaluations recording symptom progression, femoral pulse presence, and ABIs. 1

Common Pitfalls to Avoid

• Do NOT delay revascularization in patients with rest pain or tissue loss—unlike claudication, CLTI requires urgent intervention to prevent limb loss. 4
• Ensure adequate inflow before performing outflow procedures; in multilevel disease, correct inflow problems first. 1, 4
• Avoid primary amputation unless there is significant necrosis of weight-bearing foot portions, uncorrectable flexion contracture, extremity paresis, refractory ischemic rest pain, sepsis, or very limited life expectancy. 1
• Younger patients (<50 years) with claudication have less durable results from surgical intervention due to more aggressive atherosclerotic disease. 1

Outcomes Data

• National trends (1996-2006) show major lower extremity amputation rates declined 29% (from 263 to 188 per 100,000) as endovascular and surgical revascularization increased. 5
• Delay in referral to vascular surgery significantly increases limb loss—patients with rest pain who delayed 14.2 weeks and those seen by primary care (additional 11.7-week delay) had worse outcomes than those seen in Emergency Departments (4-week delay). 6
• Below-knee amputation should be prioritized over above-knee when amputation is necessary, as it dramatically improves mobility and quality of life, with achievable below-knee:above-knee ratios of 3:1. 7