Lower Limb Amputations – Level Selection

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 - 2:1 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 >60mm – >50% chance of BKA healing.

15. Level Selection • Non invasive 2. Skin perfusion pressures • Radio isotope washout • Laser doppler velocimetry • <20mm 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 enough…poor 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