What anatomy is crucial to understand for a tibial thrombectomy with possible bypass?

Critical Anatomy for Tibial Thrombectomy with Possible Bypass

Understanding the tibial arterial anatomy and surrounding structures is essential for successful thrombectomy and bypass procedures to optimize limb salvage outcomes.

Tibial Arterial Anatomy

Popliteal Artery and Trifurcation

• The popliteal artery bifurcates at the lower border of the popliteus muscle into:
  • Anterior tibial artery
  • Tibioperoneal trunk (which further divides into posterior tibial and peroneal arteries)
• This trifurcation is the critical anatomical landmark for both thrombectomy and bypass procedures 1

Tibial Arteries

1. Anterior Tibial Artery:

   • Courses anteriorly through the interosseous membrane
   • Runs along the anterior compartment of the leg between tibialis anterior and extensor digitorum longus
   • Continues as the dorsalis pedis artery at the ankle
   • Access requires careful navigation around the interosseous membrane 2

2. Posterior Tibial Artery:

   • Runs posteriorly along the medial aspect of the leg
   • Located deep to the soleus muscle proximally
   • Becomes more superficial distally as it passes behind the medial malleolus
   • Terminates by dividing into medial and lateral plantar arteries 1

3. Peroneal Artery:

   • Runs along the medial border of the fibula in the deep posterior compartment
   • Provides important collateral circulation when other tibial vessels are occluded
   • Can be accessed through posterior approach between flexor hallucis longus and peroneus brevis 3

Venous Conduit Anatomy

Greater Saphenous Vein (Primary Choice)

• Originates at the medial malleolus and ascends medially along the leg and thigh
• Optimal conduit for tibial bypasses with 70% 5-year patency rate 1
• Assess for:
  • Adequate diameter (≥3mm)
  • Absence of varicosities
  • Previous harvesting or stripping

Alternative Venous Conduits

• Lesser (Small) Saphenous Vein:

  • Originates at lateral foot, ascends posteriorly along calf
  • Accessible through posterior approach when patient is prone 3

• Arm Veins (cephalic, basilic):

  • Important alternative when leg veins are unavailable
  • May require splicing for adequate length

• Composite/Spliced Veins:

  • Used when single-segment autogenous vein is unavailable 1

Surgical Approaches and Anatomical Considerations

Medial Approach

• Standard approach for posterior tibial artery access
• Provides exposure to distal popliteal and proximal posterior tibial arteries
• Requires identification of the tibial nerve which runs adjacent to the vessels 1

Posterior Approach

• Useful for simultaneous access to popliteal and anterior tibial arteries
• Patient positioned prone
• Dissection between two heads of gastrocnemius
• Allows harvest of small saphenous vein in the same field 3

Medial Popliteal Extension

• Allows "poplitealization" of the proximal anterior tibial artery
• Avoids lateral counterincision and protects peroneal nerve
• Particularly useful for in situ saphenous vein bypass 2

Critical Anatomical Relationships

Neurovascular Structures

• Tibial Nerve:

  • Runs parallel to posterior tibial artery
  • Must be identified and protected during dissection

• Peroneal Nerve:

  • Wraps around fibular neck
  • At risk during lateral approaches to anterior tibial artery

Compartmental Anatomy

• Anterior compartment: Contains anterior tibial artery
• Lateral compartment: Contains peroneal muscles
• Deep posterior compartment: Contains posterior tibial and peroneal arteries
• Superficial posterior compartment: Contains gastrocnemius and soleus

Technical Considerations for Thrombectomy

• Access Points:

  • Femoral approach for proximal control
  • Direct tibial access may be necessary for distal thrombi not retrievable through femoral approach 4

• Vessel Wall Integrity:

  • Tibial arteries have thin walls prone to injury during thrombectomy
  • Risk of pseudoaneurysm formation with excessive force during Fogarty catheter use 5

Bypass Considerations

• Inflow Source Selection:

  • Common femoral artery (most common - 50%)
  • External iliac artery (43%)
  • Superficial femoral artery (8%) 6

• Outflow Target Selection:

  • Choose the least-diseased tibial artery with continuous flow to the foot
  • Target vessel must provide uncompromised outflow to the foot 1
  • Distribution: anterior tibial (21%), posterior tibial (35%), peroneal (44%) 6

• Conduit Placement:

  • Anatomic tunneling preferred to avoid kinking
  • Subcutaneous tunneling for easier surveillance

Pitfalls and Caveats

1. Vessel Fragility: Tibial arteries are thin-walled and prone to injury during thrombectomy. Use gentle technique with appropriately sized Fogarty catheters to prevent vessel perforation 5.

2. Collateral Preservation: Identify and preserve collateral vessels, especially when the target vessel has limited outflow.

3. Conduit Selection: Always prioritize autogenous vein for tibial bypasses. Prosthetic grafts have significantly lower patency rates (27% vs 70% at 5 years) 1.

4. Distal Anastomosis Technique: When prosthetic conduit must be used, consider distal vein patch technique to improve patency 6.

5. Complete Thrombectomy: Ensure complete clearance of thrombus from tibioperoneal and plantar arteries, as limb salvage correlates directly with the number of available runoff vessels 1.