Updated: 10/9/2017

RETIRE Transtibial Below the Knee Amputation (BKA)

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Pearls & Pitfalls
 
Orthobullets Technique Guides cover information that is "not testable" on ABOS Part I
  • Preparation
    • evaluate vascular status, wound healing potential, soft tissue injury, infection, neuropathy, and trauma
    • standard OR table, sagital saw, and amputation knife
  • Positioning
    • supine with feet at end of bed
      • bump under ipsilateral thigh and thigh tourniquet
  • Approach
    • anterior and posterior approaches to midshaft tibia 
      • anterior incision 10cm distal to tibial tubercle and posterior incision long enough to ensure flap coverage
  • Limb Preparation
    • identify anterior tibial, posterior tibial, and peroneal neurovascular bundles
      • tie off vessels and cut nerves proximally
  • Amputation
    • tibial cut 2-3cm proximal from anterior skin edge with sagital saw perpendicular to bone and fibula cut 1cm proximal
    • bevel distal tibia cut at 45° then rasp edges with saw or rasp
  • Soft Tissue Management
    • deflate tourniquet and coagulate or tie off any bleeding vessels
    • need to approximate edges for even soft tissue distribution
  • Postoperative
    • 2 wks non-weight bearing in well padded knee immobilizer or U-shaped splint
    • 3-6 mo fit for prosthesis and advance rehabilitation
 
Planning & Preparation
  • Patient Evaluation
    • evaluate vascular status, wound healing potential, soft tissue injury, infection, neuropathy, and trauma
      • vascular exam with Doppler (ischemic index), ABI, transcutaneous oxygen pressure, toe pressures
      • if severe vascular dysfunction may require revascularization procedure prior to amputation
      • wound healing potential check with nutrition labs: albumin, prealbumin, transferrin, total lymphocyte count
      • infection check with CRP, ESR
      • severe soft tissue injury has the highest impact on decision whether to amputate or reconstruct lower extremity in trauma cases
      • need to assess associated injuries and comorbidities (diabetes)
    • documental baseline neurovascular exam
    • traditional short BKA increases baseline metabolic cost of walking by 40%
      • traumatic BKA 25%
  • Imaging 
    • AP/Lat views of foot, ankle, and tibia/fibula
    • may require MRI to evaluate extent of infection or soft tissue damage
Equipment & Positioning
  • Equipment
    • large sagital saw
    • amputation knife
    • 2.5mm drill, 3.5mm cortical screws (Synthes Small Fragment Set)
      • if Ertl osteomyoplastic procedure performed
  • Position
    • patient supine with feet at the end of the bed
      • bump under ipsilateral thigh and thigh tourniquet
    • betadine scrub and prep extremity thoroughly
      • particularly in infection cases
  • OR Setup
    • standard OR table
Approaches
  • Anterior and Posterior Approaches to Tibia
    • mark out tibial tubercle and planned anterior and posterior incisions with gradual rounded edges
    • anterior incision 10cm distal to tibial tubercle
      • 15cm from knee joint line
      • anterior incision 2/3 total circumference
    • posterior incision length long enough to ensure adequate flap coverage
      • posterior incision 1/3 total circumference
Surgical Technique
  • Approach 
    • in infection cases do not exsanguinate limb
      • elevate and inflate tourniquet
    • 10blade through skin down to fascia
      • cauterize fascia circumferentially
  • Limb Preparation 
    • on anterior surface need to find anterior tibial neurovascular bundle
      • tie off vessels with 2-0 silk x2
      • 2-0 silk on needle through vessel
      • cut nerve sharply as proximally as it goes for retraction
      • can inject nerve lidocaine/marcaine to reduce phantom pain post-op
    • repeat process above for posterior tibial and lateral peroneal neurovascular bundles
  • Amputation
    • tibial cut 2-3cm proximal from anterior skin edge with sagital saw perpendicular to bone
    • fibula cut at least 1cm proximal to avoid skin irritation
    • bevel distal tibia cut at 45°
      • rasp edges with saw or rasp
    • can perform Ertle procedure to create fibula strut
      • Ertle osteomyoplastic technique creates a weight-bearing strut from the tibia to fibula from a piece of fibula or osteoperiosteal flap
      • secure strut with 2.5mm drill and 3.5mm bicortical screw
    • use amputation knife to cleanly debulk distal extremity
    • trim posterior flap and debulk with knife to ensure adequate closure
  • Soft Tissue Management
    • deflate tourniquet with laps packed into wound for initial hemostasis
    • carefully remove laps one at a time
      • coagulate or tie off any bleeding vessels
    • deep fascia closure with 0-vicryl
      • need to approximate edges for even soft tissue distribution
      • can leave “dog ears” to preserve blood supply to flap
      • avoid excessive stripping of soft tissue as this devascularizes tissue
    • place deep drain bluntly without sharp end to avoid injuring vessels during placement
      • pass drain with hemostats from medial to lateral under fascia
  • Extremity Check
    • check limb length and soft tissue coverage
Closure
  • Irrigation & Hemostasis
    • irrigate wounds thoroughly
    • recheck for remaining peripheral bleeders
  • Closure
    • subcutaneous with 2-0 vicryl
    • skin closure with 2-0 nylon (vertical/horizontal mattress)
      • do not want to overly tighten skin as this can necrosis edges
  • Dressing & Splint
    • soft incision dressing well padded to reduce pressure in incision
    • knee immobilizer or U-shaped splint
    • crutches or walker for ambulation
Postoperative Care
  • 2 Weeks 
    • wound check and remove sutures
    • place in stump shrinker and stump cast if incision healed
  • 3-6 Months 
    • remove stump cast and fit for prosthesis
    • advance rehabilitation
Complications
  • Document Complications 
    • wound breakdown (worse in diabetics, smokers, vascular insufficiency)
    • superficial and deep infections
    • recurrent infection requiring revision amputation or AKA
    • phantom limb pain
 

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