Vascular: Amputation

Amputation

Basics

  • Largest Risk Factors: PAD & DM
  • Should Generally Be Viewed as a Definitive Reconstructive Option, Not a Treatment Failure

Indications

  • Acute Ischemia:
    • Irreversible
    • Severe with No Revascularization Options
    • Failed Revascularization Attempts
  • Chronic Ischemia:
    • Failed Revascularization Attempts
    • Severe with No Revascularization Options
    • Severe Comorbidities
    • Poor Functional Status
    • Extensive Gangrene/Infection that is Not Salvageable
  • Severe Infection Causing Pedal Sepsis
  • Severe Traumatic Injury
  • Malignancy

Amputation Staging

  • Formal Amputation – Definitive Single-Stage Procedure
  • Guillotine Amputation – Two-Stage Procedure
    • First: Straight Amputation with Open Site
    • Second: Formal Amputation a Few Days Later

Amputation Levels

  • Podiatric Procedures:
    • Partial Toe Amputation – Part of a Toe
    • Toe Amputation – Entire Toe
    • Ray Amputation – Toe & Corresponding Metatarsal Bone
    • Transmetatarsal Amputation (TMA) – Partial Foot Across the Metatarsal Bones
    • Tarsometatarsal (Lisfranc) Amputation – Forefoot Amputation Across the Tarsometatarsal Line
    • Midtarsal (Chopart) Amputation – Forefoot & Midfoot Amputation Sparing the Proximal Talus & Calcaneus
    • Ankle Disarticulation (Syme’s Amputation) – Through Ankle Joint
  • Major Leg Amputations:
    • Transtibial – Below-Knee Amputation (BKA)
    • Transfemoral – Above-Knee Amputation (AKA)
  • Orthopedic Hip Procedures:
    • Hip Disarticulation – Entire Leg
    • Hemipelvectomy – Entire Leg & Ipsilateral Hemipelvis

Testing to Determine Site

  • Objective Data Can Supplement but Not Replace Clinical Judgment
  • Transcutaneous Oxygen (tcPO2)
    • Generally Considered the Best Objective Test
    • Sensor Placed on Skin, Heated to Decrease Flow Resistance & Oxygen Partial Pressure Measured
      • Approximates True Arterial Oxygen Pressure at Questioned Site
    • Values:
      • < 16-20 mmHg: Likely to Fail
      • ≥ 20-30 mmHg: Likely to Heal
  • Other Less Reliable Objective Tests
    • Skin Temperature – Not Reliable
    • Ankle Brachial Index (ABI)
    • Arteriography – Poor Correlation to Healing Potential

Foot Amputations

Leg Amputations

Outcomes

  • General Outcomes:
  Healing Rates Mortality
Overall – 8%
BKA 80% 5-7%
AKA 90% 10-15%
Hip Disarticulation – 50%
    • 10-20% of BKAs Require Revision to AKAs
    • 10-20% Eventual Risk for Major Amputation on Contralateral Side
  • Ambulation:
  Increased Energy Expenditure to Walk Ambulation Rate
BKA 10-40% 70-80%
AKA 60-70% 35-50%
Hip Disarticulation 80% 0-10%

Complications

  • Most Common Cause of Death: MI
  • Contracture
    • Risk: 3-5%
    • Inhibits Proper Prosthetic Ambulation
    • Prevention:
      • BKA: Rigid Dressings
      • AKA: Brief Periods of Prone Positioning
  • Bleeding
    • Risk of Reoperation for Bleeding Control: 4-8%
  • Infection
  • DVT
    • Up to 50% Risk Without Prophylaxis
  • Chronic Pain
  • Phantom Pain – Poorly Understood
  • Post-Traumatic Stress Disorder
    • 5% Risk for Vascular Amputations
    • 20% Risk for Traumatic Amputations

Transtibial – Below-Knee Amputation (BKA)

Posterior Flap Technique

  • Skin/Fascia Incision:
    • “Two-Thirds/One-Third” Approach
    • Anterior Incision:
      • Two-Thirds of Leg Circumference
      • Start Just Past the Planned Tibia Incision
      • Straight Transverse Incision
    • Posterior Incision:
      • One-Third of Leg Circumference
      • Flap Length: Additional One-Third of Leg Circumference
      • Slightly Curved Incision
  • Bone Transection:
    • Tibia: ≥ 12-15 cm Below Tibial Tuberosity
    • Fibula: 1-2 cm Proximal to the Tibia
  • Neurovascular Management:
    • Major Blood Vessels: Suture Ligate
      • Consider Tourniquet to Decrease Blood Loss
    • Nerves: Divide Sharply & Allow Retraction
  • Modification & Closure:
    • Bevel Bones to Avoid Sharp Edges – Particularly the Anterior Tibia
    • Consider Myodesis of Gastrocnemius to Tibia
    • Irrigate Prior to Closure
    • Close Deep Fascia with Interrupted Absorbable Suture
    • Close Skin with Staples

BKA Wound Dressing

  • Soft Gauze with Elastic Wrap
    • Most Commonly Used
    • Remain Non-Weight Bearing for 4-6 Weeks Until Fit for Prosthesis
  • Thigh-Level Rigid Plaster Cast
    • Shorter Rehabilitation Times
    • Similar Pain, Healing Rates & Prosthetic Use
    • Can Include a Temporary Immediate Postoperative Prosthesis (IPOP)
      • May Have Improved Primary Wound Healing & Shorter Rehabilitation Times

BKA Incision

Transfemoral – Above-Knee Amputation (AKA)

Fish-Mouth Technique

  • Skin/Fascia Incision:
    • “Fish-Mouth” Incision Made with Equal Anterior & Posterior Flaps
  • Femur Transection: 12 cm Proximal to Femoral Condyles
    • May Need to be More Proximal if Lacking Adequate Tissue Coverage
  • Neurovascular Management:
    • Major Blood Vessels: Suture Ligate
      • Consider Tourniquet to Decrease Blood Loss
    • Sciatic Nerve: Stretch & Divide Sharply, Then Allow Retraction
  • Modification & Closure:
    • Bevel Bones to Avoid Sharp Edges – Particularly the Anterior Tibia
    • Consider Myodesis of Adductor Magnus & Quadriceps Muscles
    • Irrigate Prior to Closure
    • Close Deep Fascia with Interrupted Absorbable Suture
    • Close Skin with Staples

AKA Incision