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 10-15% 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. The need to maximize rehab potential and minimize need for revision has led to the investigation of optimal method of level selection.

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 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