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Amputation indications and levels

Indications for amputation and levels including foot amputation and hip disarticulation

27 questions 3 source pages 1 images 1 fact-check flags

Images appear with the first question taken from each source page — tap a question to open it.

27 questions
Q1What are the indications for lower limb amputation?▸
  • DM/PVD
  • Trauma
  • Tumour
  • Paediatric malformation/infection
Q2How is the level of amputation chosen?▸
  • Balance between pathology, wound healing and energy expenditure
  • Ideal level: best for prosthesis fitting while minimising energy expenditure
Q3What is the increase in energy consumption at each amputation level?▸
  • Generally inversely proportional to remaining length
  • Symes 15; BKA traumatic 25, vascular 40; through knee 50; AKA traumatic 70, vascular 100
  • Bilateral BKA 40; BKA + AKA 120; bilateral AKA >200
Q4What makes a good amputation stump?▸
  • Ideal stump: mobile nonadherent muscle mass covered by full thickness skin tolerating weightbearing and shear
  • Skin: scar mobile and away from bony edges, as sensate as possible
  • Soft tissue: cylindrical or conical stump without excessive tissue
  • Muscle: myodesis (muscle to bone) versus myoplasty (muscle to fascia)
  • Nerve: clean section and retraction into soft tissue; bone ends bevelled and contoured
Q5How do you perform a below-knee amputation (BKA)?▸
  • Decide level (15cm below medial joint line); check pulse/healing and no contracture
  • Bone cut 10-15cm from medial joint line; skin incision 15cm distal to tibial tubercle, posterior flap ~1.5x anterior flap (anterior 2/3, posterior 1/3)
  • Section tibia, fibula 1cm above; bevel cut; Ertle osteomyoplasty fibula strut (paediatric)
  • Ligate anterior and posterior tibial vessels and peroneal nerves; meticulous soft tissue balance; U slab to avoid knee contracture
Q6What are the complications of amputation and the differential for pain in the missing limb?▸
  • Unfit prosthesis - sore; neuroma; bone impingement; phantom limb
  • Phantom limb risk factors: traumatic, young patients, upper limb, bilateral
  • Ddx primary: neuroma, phantom limb pain, HO, bone impingement
  • Ddx secondary: recurrence of primary pathology (tumour), CRPS, radiation pain from elsewhere
Q7What are the key steps after the skin incision in a below-knee amputation?▸
  • Position supine with tourniquet and hip support
  • Divide anterolateral muscle down to intermuscular septum; ligate anterior tibial vessels and peroneal nerves
  • Section tibia, and fibula 1cm above
  • Dissect posterior soft tissues distally to the posterior transverse incision
  • Ligate posterior tibial and peroneal vessels and the posterior tibial nerve
  • Bevel cut; meticulous soft tissue balancing; do not trim dog-ear; U slab to avoid knee contracture
Q8Compare the long posterior flap and sagittal flap for BKA.▸
  • LPF: better flap blood supply from gastrocnemius; limited by proximal extent of infection/tumour
  • SF: versatile, less infection in DM (Christensen JBJS 1989)
  • SF disadvantage: tibial bone close to wound
  • Ruckley J Vascular Surgery 1991: no difference
Q9What are the length guidelines for transtibial and transfemoral amputation?▸
  • Transtibial optimal 8cm for every 1m of height
  • Transtibial shortest 7.5cm below medial joint line
  • Transfemoral shortest 8cm below pubic rami
  • Transfemoral longest 15cm above medial joint line
Q10How is an above-knee amputation (AKA) performed?▸
  • Bone: level of cut 8cm below pubic ramus to 15cm above joint line, smoothened and bevelled end
  • Skin: AP flap
  • Soft tissue: myodesis to counterbalance muscle pull and prevent contracture
  • Myodesis of adductor and hamstring to prevent flexion and abduction deformity
  • Not to do myodesis in vascular compromise
  • Nerve: clear cut under gentle tension and allow retraction to prevent neuroma
Q11What are the important considerations in the length of an AKA?▸
  • Longer gives a better lever arm for control of the prosthesis
  • Balance accommodation of the prosthesis
  • Myoplasty/myodesis of adductor preserves 70% adductor power --> decreases AL drift
Q12What are the indications and technique of through-knee amputation?▸
  • Life saving
  • Paediatric: preserve distal femur physis for longer lever arm
  • Non-ambulatory patients
  • Technique: suture patellar tendon to cruciate ligament
  • Gastroc muscle (gastrocnemius) used as soft tissue envelope
Q13What are the advantages of through-knee amputation?▸
  • Less bleeding, faster OT
  • Most thigh muscle preserved
  • Long lever arm
  • Broad end bearing surface
  • Stable suspension
  • No bony outgrowth
Q14What are the disadvantages of through-knee amputation?▸
  • Different levels of knee joint, less modularity
  • Bulbous shape, less cosmetic
  • Less room for error for flap (cannot cut more bone)
Q15What did the LEAP study show for through-knee amputation?▸
  • Similar pain to AKA/BKA
  • Reduces walking speed and return to work
  • Asymmetric knee + limited knee component choices
  • Reduces satisfaction
Q16What is direct versus indirect load transfer in an amputation stump?▸
  • Direct - through knee/through ankle: wide metaphysis distributes the force of weight bearing
  • Direct: less stiff bone at metaphysis dampens GRF at heel strike
  • Indirect - BKA/AKA: terminal surface incapable of weight bearing; stiff bone
Q17What is the pathophysiology and treatment of phantom limb pain?▸
  • Pathophysiology: corresponding primary somatosensory cortex deprived of sensory input --> reorganization via increased expression of previously marked inputs - maladaptive plasticity model
  • Physio: mirroring, USG, TENS, massage, immersive virtual reality
  • Pharmacological: opioids, anticonvulsants, antidepressants, botulinum agents
  • Surgical: stump revision, intrathecal implants, trigger point injections, dorsal column tractotomy
Q18What are the types of foot amputation?▸
  • Transmetatarsal
  • Lisfranc (TMTJ disarticulation)
  • Chopart
  • Syme
  • Boyd
Q19Describe transmetatarsal amputation and its problems.▸
  • Lowest energy expenditure; no tendon transfer
  • Bone cut >=3cm to MTB; preserve MT cascade; 5MTB
  • Problem: equinus from loss of extensor lever arm; solution TA lengthening
Q20How are Lisfranc and Chopart amputations balanced?▸
  • Lisfranc: PB to cuboid transfer to reduce varus / shell out 5MTB to preserve PB insertion
  • Lisfranc: +/- TA lengthening to reduce equinus
  • Chopart: tib ant to talus transfer to reduce equinus and cavus; +/- TA lengthening
  • Chopart problem: unstable hindfoot
Q21What are the prerequisites and indications for Syme amputation?▸
  • Patent posterior tibial artery (ischemic index >0.5)
  • Healthy heel pad
  • Indication: forefoot pathology - tumour/trauma/congenital; DM/infection
  • Contraindicated in PVD
Q22Describe the Syme amputation technique.▸
  • Fishmouth flap 1cm distal + anterior to intermalleolar line; anterior through ankle joint, posterior through CCJ
  • Ligate PTA as distal as possible
  • Malleoli cut at 6cm proximal to joint line (see factcheck)
  • Posterior flap anchored to distal tibia through drill holes to prevent heel pad posterior migration
  • Preserve tibia articular surface for a resilient limb; avoid vigorous trimming of dogears
Q23What are the advantages and disadvantages of Syme amputation, and what is Boyd amputation?▸
  • Adv: end bearing stump (walk on unsupported stump); Self regulated walking speed, more natural gait pattern
  • Adv: longer lever arm --> reduce energy expenditure
  • Disadv: technically difficult; limited indication; fat pad migration; socket fabrication challenging
  • Boyd = modification of Syme: talectomy + calcaneal tibial fusion; no heel pad migration
  • Boyd disadv: bulky stump increases rehab time and nonunion
Q24Describe the racquet-shaped incision for hip disarticulation.📷▸
Hip disarticulation
Hip disarticulation
  • Anterior: ASIS to hip
  • Medial: parallel to inguinal ligament to inferior pubic rami (adductor origin)
  • Posterior: transverse 5cm distal to ischial tuberosity to 8cm distal to GT
  • Lateral: curve up to anterior incision
Q25What are the anterior dissection steps in hip disarticulation?▸
  • ASIS: detach sartorius; AIIS: detach rectus femoris
  • Divide femoral NAV at femoral triangle
  • LT: detach iliopsoas (hip ER) and obturator externus
  • Superior PR: detach pectineus (0.6cm residual cuff), divide obturator AVN underneath
  • Inferior PR: detach adductors + gracilis; ischial tuberosity: detach hamstring
Q26What are the posterior dissection steps in hip disarticulation?▸
  • Divide fascia lata and glut max along posterior incision
  • GT: detach glut med and min
  • Trochanteric ridge: detach short ER
  • Divide sciatic nerve
Q27How is the stump covered after hip disarticulation?▸
  • Deep myoplasty: obturator externus to glut med at acetabulum (GMOE)
  • Superficial myoplasty: iliopsoas to quadratus femoris (IQ)
  • Fascia: glut fascia --> inguinal ligament

Fact check

In Syme amputation the malleoli are cut at 6cm proximal to the joint line — incorrect level — Classic Syme divides the tibia and fibula ~1-1.5cm above the ankle joint (or flush with the plafond) so the distal articular surface is preserved; 6cm would be a transtibial level — source
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