Transcript Lower Limb Amputations – Level Selection

Lower Limb Amputations –
Level Selection
Arvind Lee
Vascular Fellow
Nepean Hospital
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)
Overview
• Australian data –
- 2629 diabetes related lower limb
amputations per year
- 2:1 male: female ratio
- majority in the 65-79 year age group
- Highest incidence in SA and NT (MJA 2000)
Indications for amputation:
•
-
PVD
Failed revascularisation
Extensive tissue loss
Unreconstructable
Excess surgical risk
Indications for amputation:
•
-
Diabetes
Overwhelming sepsis
Extensive tissue loss
Excess surgical risk
Indications for amputation:
• Trauma
- Crush
- Nerve injuries
•
-
Others
Spina bifida
Contractures
Neuropathy
Bed bound
Goals of amputation:
• Get rid of all infected, necrotic and painful
tissue
• Attain successful wound healing
• Have an adequate stump for a prosthetic
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
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 1015% were mobile at home. (BJS 1992)
Amputation levels and significance:
• Major amputation: above tarso metatarsal
joint.
• Levels
- BKA
- Through knee
- AKA
- Hip disarticulation
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
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.
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.
Level Selection:
• Objective tests:
- Non invasive
1. Doppler pressures – maybe unreliable in diabetics;
ankle pressures >60mm – >50% chance of BKA
healing.
Level Selection
• Non invasive
2. Skin perfusion
pressures
- Radio isotope washout
- Laser doppler
velocimetry
- <20mm Hg – 89%
failure of healing
Level Selection
• Non Invasive
3. Transcutaneous
oximetry
- Tested under local
hyperthermia
- Correlates with true
PaO2
- Threshold value –
30mm
Level Selection:
• Invasive – Angiographic
scoring
• Poor correlation
Level Selection
Conclusions:
• Amputation is traumatic enough…poor level
selection can make it worse.
• Clinical judgement central to proper level
selection
• Patient factors are more important than
objective testing
Case 1
• 93 yr old from NH
Bed bound after stroke
Painful heel ulcer on
stroke affected side
Palpable popliteal pulse
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