Lower Limb Amputations Level SelectionArvind LeeVascular FellowNepean Hospital

OverviewIntegral 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)

OverviewAustralian 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:PVDFailed revascularisationExtensive tissue lossUnreconstructableExcess surgical risk

Indications for amputation:DiabetesOverwhelming sepsisExtensive tissue lossExcess surgical risk

Indications for amputation:TraumaCrushNerve injuries

OthersSpina bifidaContracturesNeuropathyBed bound

Goals of amputation:Get rid of all infected, necrotic and painful tissueAttain successful wound healingHave an adequate stump for a prosthetic

Attempt limb salvage or primary amputation?Extent of tissue loss in footAnatomy of reconstructionAssociated comorbidities

ESRD with heel gangrene maybe best treated with primary amputation

Natural history of major amputation:10% perioperative mortality3 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/ infectionPulses presence of a pulse immedietly above the level of amputation almost 100% chance of healingClinical 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 invasiveDoppler pressures maybe unreliable in diabetics; ankle pressures >60mm >50% chance of BKA healing.

Level SelectionNon invasive2. Skin perfusion pressuresRadio isotope washoutLaser doppler velocimetry

Level SelectionNon Invasive3. Transcutaneous oximetryTested under local hyperthermiaCorrelates with true PaO2Threshold value 30mm

Level Selection:Invasive Angiographic scoringPoor correlation

Level Selection

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

Case 193 yr old from NHBed bound after strokePainful heel ulcer on stroke affected sidePalpable popliteal pulse

Case 268 yr old maleCRF on hemodialysisPost surgery for #NOF bilateral heel ulcersPainful, non healing despite multiple debridementsPalpable popliteal pulses

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