Lower extremity amputation

First performed therapeutically by Hippocrates?

Think of it as another therapeutic option in a patient with critical limb ischaemia, which can improve and QoL through pain relief, and return functionality

Indications

• Preservation of life through prevention of ascending infection and tissue loss
• Relief of ischaemic pain
• Removal of a neurologically malfunctioning foot

Types

• Minor
  • Digit
    • For minor tissue loss - confined to distal phalanx
    • Tolerated well, apart from great toe
    • Loss of third digit is barely even missed
  • Ray
    • Removal of entire phalanx
    • Indications - involvement of proximal phalanx/web space/metatarsal head
  • Transmetatarsal
    • Infectious process extends into forefoot
    • Multiple toes are involved
  • Chopart
    • Midtarsal joint amputation - calcaneocuboidtalonavicular level (preserves calcaneus and talus)
  • Syme
    • Used in severe foot trauma
    • Contraindicated in patients with neurotrophic ulcers or ischaemic vascular disease
    • Can ambulate without a prosthesis
• Major
  • Transtibial/BKA
    • 30-60% increase in energy required to ambulate with a prosthetic
    • 75% chance of ambulating with a prosthetic
  • Through-knee
    • Rarely performed
    • Sometimes done emergently for ascending infection, then converted to transfemoral amputations once the infection has cleared
  • Transfemoral/AKA
    • Can't have BKA because of tissue loss/muscle ischaemia/poor rehab potential
    • 60-100% increase in energy required to ambulate
    • 40% chance of ambulating with a prosthetic
  • Hip disarticulation
    • Proximal thigh ischaemia/trauma

Choice of amputation

• Energy expenditure
• Likelihood of healing - of course more likely to hear as you move more proximally
  • Palpable pulse proximal to site to level of amputation is a reliable indicator that it will heal
• Check soft tissue integrity, joint mobility, muscle strength
• There are a few other special tests like scintigraphy that MAY be of assistance in predicting which amputations will heal

Complications

• DVT
  • Chemoprophylaxis within 24-48 hours
• Wound infection
• Trauma secondary to falls
  • Rigid dressings such as plaster or KIWI may help prevent damage to wound
• Contractures - need to start rehab early
• Pain
  • Residual stump pain
  • Phantom limb pain
    • Cause unknown
    • 25% get it
    • Try pharmacotherapy, nerve stimulation, behavioural therapy
• Contralateral amputation
  • Overall 12.5% chance of major contralateral amputation within 5 years