Which vessels and nerves should be ligated during a lower extremity above‑knee amputation?

Above-Knee Amputation: Vessel and Nerve Management

During an above-knee amputation, the femoral artery and vein should be ligated, while the femoral nerve, saphenous nerve, tibial nerve, and common peroneal nerve should NOT be ligated but instead managed with targeted muscle reinnervation (TMR) to prevent neuroma formation and chronic pain.

Vascular Management

Vessels to Ligate:

• Femoral artery: Ligate proximally with secure suture ligation
• Femoral vein: Ligate separately from the artery to prevent arteriovenous fistula formation
• All arterial side branches: Identify and ligate individually before vessel division

The femoral vessels are the primary vascular structures requiring ligation in above-knee amputation. These should be dissected free from surrounding tissue, individually ligated with non-absorbable suture, and divided cleanly 1. The key principle is to ligate vessels separately rather than en masse to ensure hemostasis and prevent postoperative bleeding complications.

Nerve Management: Modern Approach

Critical Paradigm Shift:

DO NOT ligate the major nerves. Despite older textbook recommendations suggesting nerve ligation, this practice is contraindicated based on current evidence showing it produces neuropathic pain similar to experimental nerve ligation models 2.

Nerves Requiring Active Management:

Primary nerves in above-knee amputation:

• Femoral nerve
• Saphenous nerve
• Tibial nerve
• Common peroneal nerve (fibular nerve)

Recommended Technique: Targeted Muscle Reinnervation (TMR)

TMR should be performed at the time of amputation to provide motor targets for sensory nerves and prevent symptomatic neuroma formation 3, 4, 5.

Specific TMR Coaptations for Above-Knee Amputation:

1. Tibial nerve → Transfer to motor branches of:

   • Gastrocnemius muscle
   • Semimembranosus muscle
   • Semitendinosus muscle

2. Common peroneal nerve → Transfer to motor branches of:

   • Biceps femoris muscle

3. Saphenous nerve → Transfer to available motor branch in proximal thigh

Surgical Approach Options:

Through-the-wound approach 4:

• Performed through the amputation stump itself
• Shorter operative time (mean 200 minutes vs 326 minutes)
• Fewer TMR coaptations possible (1.5 vs 2.6 per patient)
• May require supplemental RPNI (regenerative peripheral nerve interface) for nerves without suitable motor targets
• Avoids patient repositioning and additional incisions

Posterior approach 4:

• Separate posterior incision in proximal thigh
• Requires intraoperative repositioning
• Allows more complete TMR coaptations
• Better access to recipient motor nerves in proximal third of thigh

Clinical Outcomes

TMR at time of above-knee amputation significantly reduces:

• Overall pain: 41.5% vs 67.2% without TMR (p=0.01) 3
• Residual limb pain: 26.8% vs 44.8% without TMR (p=0.04) 3
• Phantom limb pain: 19.5% vs 43.1% without TMR (p=0.02) 3

Critical Pitfalls to Avoid

1. Never ligate major nerves: This outdated practice creates neuromas and chronic neuropathic pain 2

2. Don't perform simple nerve transection: Cutting nerves without providing motor targets leads to symptomatic neuroma formation in up to 85% of cases 5

3. Preserve the femoral vein: While some animal models describe preserving femoral vein and nerve 1, in human above-knee amputation, the vein must be ligated but should be handled separately from the artery

4. Individual vessel ligation: Avoid mass ligation of vessels and nerves together—each structure requires separate identification and management

Practical Algorithm

Step 1: Expose femoral vessels in the proximal thigh

• Dissect artery and vein free from surrounding tissue
• Identify all side branches

Step 2: Ligate vascular structures

• Double-ligate femoral artery with non-absorbable suture
• Separately ligate femoral vein
• Ligate all side branches individually

Step 3: Identify major nerves

• Femoral nerve, saphenous nerve, tibial nerve, common peroneal nerve
• Trace proximally to healthy tissue

Step 4: Perform TMR coaptations

• Transfer tibial nerve to motor branches of hamstring muscles
• Transfer common peroneal nerve to motor branch of biceps femoris
• Transfer saphenous nerve to available motor target
• Use microsurgical technique with 8-0 or 9-0 suture

Step 5: If motor targets unavailable, perform RPNI as backup for remaining sensory nerves

This approach prioritizes long-term quality of life by preventing chronic pain syndromes that plague traditional amputation techniques.