Lower Limb Amputations

1
Lower Limb Amputations Level Selection

• Arvind Lee
• Vascular Fellow
• Nepean Hospital

2
Overview

• Integral part of any surgical practice.
• The global lower extremity amputation study group
  
• - wide variations in amputation rates
  worldwide
• - similarities in age and sex distribution
• - very high correlation with diabetes (BJS
  2000)

3
Overview

• Australian data
• - 2629 diabetes related lower limb
  amputations per year
• - 21 male female ratio
• - majority in the 65-79 year age group
• - Highest incidence in SA and NT (MJA 2000)

4
Indications for amputation

• PVD
• Failed revascularisation
• Extensive tissue loss
• Unreconstructable
• Excess surgical risk

5
Indications for amputation

• Diabetes
• Overwhelming sepsis
• Extensive tissue loss
• Excess surgical risk

6
Indications for amputation

• Trauma
• Crush
• Nerve injuries
• Others
• Spina bifida
• Contractures
• Neuropathy
• Bed bound

7
Goals of amputation

• Get rid of all infected, necrotic and painful
  tissue
• Attain successful wound healing
• Have an adequate stump for a prosthetic

8
Attempt limb salvage or primary amputation?

• Extent of tissue loss in foot
• Anatomy of reconstruction
• Associated comorbidities
• ESRD with heel gangrene maybe best treated with
  primary amputation

9
Natural history of major amputation

• 10 perioperative mortality
• 3 year survival after BKA 57 after AKA 39
• Of 440 major amputations 75 died in hospital,
  113 deemed unsuitable for prosthesis. Of 57
  referred for prosthesis at 3years follow up a
  further 54 died, only 10-15 were mobile at home.
  (BJS 1992)

10
Amputation levels and significance

• Major amputation above tarso metatarsal joint.
• Levels
• - BKA
• - Through knee
• - AKA
• - Hip disarticulation

11
Amputation levels and significance

• BKA maximal rehabilitation potential
• - 10-40 increase in energy
  expenditure
• - 15-20 of all BKAs go onto an AKA
  in 3 years (5 periop mortality)
• AKA less rehab potential
• - 50-70 extra energy expenditure
• - Better rates of healing

12
Level Selection

• Subjective
• Clinical exam skin quality, extent of ischemia/
  infection
• Pulses presence of a pulse immedietly above the
  level of amputation almost 100 chance of
  healing
• Clinical judgment alone 80 accurate in
  predicting healing with BKA and 90 in AKA.

13
Level Selection

• Wagner et al (J vasc surgery 1988) clinical
  judgment superior to objective assessments. More
  distal amputations can be achieved with clinical
  measures over objective studies.
• Clinical judgment is central to amputation level
  selection.

14
Level Selection

• Objective tests
• Non invasive
• Doppler pressures maybe unreliable in
  diabetics ankle pressures gt60mm gt50 chance of
  BKA healing.

15
Level Selection

• Non invasive
• 2. Skin perfusion pressures
• Radio isotope washout
• Laser doppler velocimetry
• lt20mm Hg 89 failure of healing

16
Level Selection

• Non Invasive
• 3. Transcutaneous oximetry
• Tested under local hyperthermia
• Correlates with true PaO2
• Threshold value 30mm

17
Level Selection

• Invasive Angiographic scoring
• Poor correlation

18
Level Selection
19
Conclusions

• Amputation is traumatic enoughpoor level
  selection can make it worse.
• Clinical judgement central to proper level
  selection
• Patient factors are more important than objective
  testing

20
Case 1

• 93 yr old from NH
• Bed bound after stroke
• Painful heel ulcer on stroke affected side
• Palpable popliteal pulse

21
Case 2

• 68 yr old male
• CRF on hemodialysis
• Post surgery for NOF bilateral heel ulcers
• Painful, non healing despite multiple
  debridements
• Palpable popliteal pulses