Lower extremity amputation operatives

Indications:

• Acute ischaemia
  • Irreversible ischaemia
  • Severe ischaemia with no revascularisation options
  • Following unsuccessful attempts at revascularisation
• Chronic ischaemia
  • Failure of revascularisation (most common)
  • Lack of suitable conduit or target arteries
  • Severe patient comorbidities
  • Poor functional status
  • Extensive foot gangrene or infection such that foot salvage is not possible
• Foot/leg infection
  • Pedal sepsis without ischaemia
• Severe traumatic injury
• Skeletal or soft tissue malignancy

Major amputation pathway:

• Pre-op:
  • Offer consultation with amputee rehabilitation services if possible
  • Crossmatch 2 units
• Post-op hospital (3-10 days)
• Rehab 4-8 weeks post-op
  • Wound healing
  • Early rehab
• Recovery
  • Starts when the wound is fully-healed
  • Prosthetic fitting
  • Changes in limb volume due to use
  • Extends 4-6 months from the healing date
• Transition to stable stage
  • Extends 12-18 months after initial healing
  • Some adjustments in prosthesis may be required

Selecting level of amputation

• Goals:
  • Eliminate all infected, necrotic and painful tissue
  • Achieve uncomplicated wound healing
    • Adequate vascular supply to heal wound
      • The extent of gangrene/infection dictates the maximal achievable level, but dependent rubor should be considered analogous to gangrene in this case
      • Palpable pulse immediately proximal to amputation level predicts successful healing in nearly 100% of cases, but absence of a pulse does not necessarily predict failure. Sole reliance on pulses would lead to unnecessarily proximal amputation.
      • You need a patent EIA to heal an AKA and a patent PFA to heal a BKA
      • Objective skin temperature measurements can be helpful
      • Pressure measurements:
        • Ankle pressure >60mmHg predicts healing of BKA with accuracy 50-90%
        • Universal failure of healing in minor amputations for diabetics with toe pressures <38mmHg.
      • Transcutaneous oxygen - reliable and easy, with accuracy of 87-100%. In general, readings >40mmHg are associated with healing and readings <20mmHg are associated with failure.
    • Muscle coverage to move remaining joints
    • Viable skin for flaps
  • Have an appropriate remnant stump that can accommodate a prosthesis
• Energy requirements:
  • Toe/ray amputations - minimal difference
• Prosthetic use:
  • BKA - 50-100%
  • AKA - 10-30%
    • Elderly AKA ambulation rate is <10%
  • True rate of ambulation is much lower than that of prosthesis use
• Ambulation rate:
  • BKA 80%
  • AKA 38-50%

Physiological cryoamputation

• Indicated in patients requiring an amputation who are moribund
• Umbilical tape tied around the affected limb just proximal to the diseased area
• Large plastic bag placed over the distal leg and filled with dry ice, circumferentially covering the leg
• Dry ice bag wrapped with blankets and secured with adhesive tape
• Heating pad placed proximal to ice bag and opposite leg covered in numerous blankets
• Frost line and frozen limb checked frequently by nurses
• This process alleviates time pressures, controls infection and allows optimal treatment of associated conditions
• When the patient's status improves, they are taken to the OT for a one-stage amputation

Hip disarticulation

• Technique:
  • Semilateral position
  • Anterior racquet incision (2.5cm medial to ASIS, extending towards the pubic tubercle, and continues posteriorly distal to the ischial tuberosity and gluteal crease, then anteriorly, medial to the greater trochanter and AIIS before joining back at the origin) or a posterior long flap incision
  • Skin and soft tissues incised down to external oblique aponeurosis and deep fascia of the thigh
  • Femoral vessels suture ligated and the femoral nerve transected and allowed to retract
  • Hip joint muscles are divided, starting with the sartorius at its origin and iliopsoas at its insertion. Pectineus divided at its origin. Gracilis and three adductors are divided at their origins. Obturator neurovascular bundle is divded. Obturator externus muscle divided at its insertion. Hamstrings transected at the ischial tuberosity. TFL, gluteus maximus, and rectus femoris divded.
  • Ligamentous attachments and capsule of the hip divded.
  • Sciatic nerve transected and allowed to retract
  • Specimen passed off
  • Posterior quadratus femoris sutured to anterior iliopsoas and lateral gluteus medius sutured to medial obturator externus
  • Subcutaneous closed suction drains
  • Gluteal fascia sutured to inguinal ligament and skin loosely closed with staples
  • Prevena works well.

Above-knee amputation

• Principles
  • Divide femur at the junction of middle and distal thirds, or approximately 12cm proximal to the condyles
  • If necessary, division can be more proximal as long as tissue coverage exists
  • Aim for equal anterior and posterior flaps
  • There is a tendency for the hip flexors to abduct and flex the hip because the adductors are not attached, and therefore can't oppose it. These muscles need to be detached from the femur.
• Technique:
  • Consider tourniquet, unless doing it for ischaemia
  • Prep leg with U drape underneath and stockinette on foot
  • Mark thigh - divide femur at junction of middle and distal thirds, with the corners of the fish mouth at the same level, and the distal extent of the flap as far as possible
  • Fish-mouth incision (see below)
  • Dissect through subcutaneous tissue with diathermy (watch out for GSV medially - ligate)
  • Divide muscle with diathermy, leaving medial to last
    • Remaining gracilis, sartorius, semimembranosus, and semitendinosus are divided approximately 1-2cm distal to the point of transection of the femur.
    • Detach quadriceps proximal to the patella, leaving some of the tendinous portion intact. Reflect the vastus medialis laterally off the intermuscular septum to expose the adductor magnus, and sharply divide it off the medial epicondyle, and it is reflected medially to expose the femoral shaft.
  • Identify SFA bundle lateral/deep to sartorius. Transfix and ligate the vessels traversing the Hunter canal (SFA and femoral vein).
  • Femur transected proximal to the corners of the fish-mouth incision using a mechanical saw. File back edges to smooth them as needed.
    • Myodesis - optional (may benefit patients more likely to ambulate with a prosthesis):
      • Wrap adductor magnus over the end of the bone, with the femur held in maximal adduction, then anchored using the lateral holes.
      • Quadriceps muscles then wrapped over the end of the femur and anchored posteriorly.
  • Sciatic nerve stretched, divided and allowed to retract.
  • ?sciatic block/catheter
  • 10Fr Blake's drain
  • Closure - fascia with 2/0 Vicryl, skin with nylon if dirty or monocryl if clean
  • Dressings - clear opsite, velband, crepe
• Post-op:
  • See BKA section below
• Complications:
  • See BKA section for full list
  • Wound infection
    • Higher rate than BKA
    • Leave dressings intact for 5 days unless clinically compelled to remove them earlier.
  • Inability to ambulate
    • <10% of elderly AKA ambulate effectively
  • Mortality
    • 16%
    • One year survival approx 50%

BKA

• Most common technique - posterior flap
  • Principles
    • Divide tibia at least 12-15cm distal to the tibial tuberosity for optimal ambulation
      • As little as 5cm of residual tibia can work in certain circumstances
    • Anterior incision should go approximately two-thirds of the way round the leg
    • Length of posterior flap is one-third the leg circumference, and should be shaped in a gentle curve to reduce dog-ears
    • Consider previous vascular interventions (such as bypasses) and orthopaedic history such as plates
  • Pitfalls
    • Wrong stump length
    • Trauma either to flaps or shear injury to deeper tissue
    • Pressure necrosis from underlying bony tissue
    • Stump trauma from an overly tight dressing
    • Flexion contracture of the knee
  • Equipment
    • Sterile tourniquet
    • Wedge
    • IDC
    • Power saw
  • Technique
    • Use wedge to keep leg medially rotated
    • Catheter
    • Prep entire leg and groin, generally with alcoholic iodine unless infected wounds in field (assistant will need to hold leg up by foot, then use huck towel to help get leg into stockinette and wrap it in place with a sterile bandage); huck towel over genitals then U-drape and square drapes
    • Marking: mark out flaps
    • Venous exsanguination with Esmark and inflation of thigh tourniquet to 250 or 300 (don’t need tourniquet if doing it for ischaemia)
    • Start with anterior transverse incision. Incise skin, subcutaneous tissue and fascia. Then extend along posterior flap (make a very long posterior flap, passing longitudinally down the leg, and it can be sized later, to avoid the risk of making it too short). Just watch out for GSV medially).
    • Divide anterior and lateral compartment muscles (look out for anterior tibial vascular bundle in between tibialis anterior and EDL, just anterior to the interosseous membrane between tibia and fibula; this should be transfixed)
    • Incise periosteum of tibia and clear proximally with large periosteal elevator (Bristow), get a pack underneath for protection and divide tibia with the bone saw. Bevel the anterior edge and rasp down smoothly.
    • Divide fibula approximately 1-2cm proximal to tibia (removing too much will result in conical stump). Can do it with either power saw or bone cutter.
    • Incise tissue off the posterior tibia and fibula, unroll the stockinette and dispose of the amputated leg
    • Bluntly dissect (may need diathermy too) in between gastrocnemius and soleus. Most of soleus will be debulked proximally.
    • Identify PT and peroneal vascular bundles, and transfix them
    • Sharply divide tibial and peroneal nerves, and allow to retract proximally. Transect sural nerve (in subcutaneous tissue posteriorly, alongside SSV) at least 5cm proximal to skin edge to prevent neuroma formation.
    • Trim posterior flap of gross excess, but leave it fairly bulky to make a good cushion. If it's TOO bulky, can trim soleus to the level of the tibial osteotomy. Preserve gastrocnemius though - this is where the blood supply to the skin of the flap comes from.
    • Release tourniquet and haemostasis
    • Irrigate to remove bone dust
    • Approximate deep fascia with interrupted absorbable sutures. Cover the tibia without tension.
    • Close skin with staples or interrupted monofilament suture, avoiding tightly compressing the flap. Unnecessary to remove dog ears because the stump rapidly remodels.

Post-op

• Mostly dress with a firm compression bandage, drain tube on suction, and nerve sheath catheters
• Five days IV ABx
• Don't take the bandage or dressing down unless need to check for infection or bleeding (usually comes down day 3-5)
• Can arrange rigid removable dressing through orthotics if requested.
• Rigid dressing CAN be done immediately post-op, but makes it harder to check the wound and can be difficult to organise.
• Keep BKA limb straight and don't prop up on pillows
• Tendency to flex the knee joint due to pain, which can lead to a flexion contracture
• Patient can be transferred to amputee rehabilitation when the wound looks good, drain and nerve sheath catheters are out, and the patient has no other medical issues

Complications

• Haematoma - evacuate if significant to prevent infection
• Stump ischaemia - coolness, pallor, pain, necrosis/blisters on skin (consider local pressure as cause)
• Infection - more likely in AKA and in patients with pre-existing infection
  • Superficial infections treated with antibiotics and removal of skin sutures
  • Deeper infections will need aggressive drainage and debridement, and often VAC application
• Knee contracture - 3-5% - early PT prevents formation
  • Fixed flexion >15 degrees at the knee prohibits effective prosthetic ambulation, and can be impossible to correct with PT once it forms
• Cardiac complications are very common, along with respiratory
• DVT - 50% if no LMWH, 10% if LMWH
• Pain
  • 95% have some form of chronic pain, either confined to residual limb, or phantom pain
  • Consider pain due to ischaemia, bone spurs, chronic OM, neuroma (usually well-localised, and can be transiently or permanently blocked with LA injection), neurospinal sources
  • Phantom pain 5-85%, with gabapentin most effective
• Outcomes:
  • 20-30% fail to heal primarily, and 50% of those can be salvaged at the same level. 10-20% need higher amputation.
  • 55% fully healed 100 days post-op

Follow-up

• With amputee rehab - not with vasc, unless they have other issues

Guillotine amputation

• Indicated in patients with severe sepsis
• Two-stage operation
• Mixed results in the literature

Midfoot and hindfoot amputations

• Considerations:
  • Note that many surgeons recommend BKA as next step from TMA
  • Results in dramatically altered foot biomechanics
  • Short-leg plaster cast applied over the sterile dressings on the operating room table, and changed weekly
  • Weight bearing after 4-6 weeks
• Lisfranc tarsometatarsal disarticulation
  • See below for incision
  • First, third, fourth and fifth TMTJs are diarticulated
  • Second metatarsal divided 1-2cm distal to the medial cuneiform
  • Variation - preserve the base of the fifth metatarsal and the insertion of peroneus brevis to prevent equinovarus deformity
  • Achilles tendon released by either transection or Z-plasty
  • Plantar fascia on the flap approximated to the dorsal periosteum with absorbable sutures
  • Skin closed
• Chopart midfoot amputation
  • Performed through talocalcaneonavicular joint and the calcaneocuboid joint
  • Achilles tenectomy recommended
  • EHL and tibialis anterior tendons reattached to talar neck
  • EDL reattached to calcaneus
• Syme amputation
  • Advantage is the preservation of limb length - can sometimes get away without a prosthesis for short periods of weight-bearing
  • Less cosmetically-appealing prosthesis than for a BKA

Trans-metatarsal amputation

• Anatomy:
  • Proximal metatarsals articulate with three cuneiform bones and the cuboid laterally
  • Collectively the tarsometatarsal (Lisfranc) joint connects the midfoot and forefoot
  • Appropriate for wounds involving the entire forefoot, or when multiple rays are considered
  • TMA offers the ability to wear standard footwear with near-normal ambulation
  • Contraindicated with severe bony deformities of midfoot and hindfoot which would lead to structural instability
• Technique:
  • Transverse incision of dorsum of the foot at the level of the distal metatarsals, with corners at the first and fifth metatarsal heads, and extending on the plantar surface to the base of the toes
  • Extensor tendons divided at skin level
  • Periosteum incised
  • Metatarsals divided with a bone saw - each 3-4mm shorter than the last, moving laterally. Add a gentle bevel to plantar surface to facilitate ambulation and reduce risk of ulceration.
  • Plantar myofascial attachments to the metatarsal heads divided
  • Remove tendons and sheaths in plantar flap
  • Some surgeons recommend calcaneal tendon lengthening or transection to reduce risk of recurrent ulceration

Ray amputation

• Anatomy:
  • Resection of the digit and variable length of the associated metatarsal
  • Simultaneous first and second rays will significantly alter gait
  • Isolated first ray is prone to recurrent ulceration in 60% of patients
  • Some surgeons advocate TMA instead of first and second rays, but no conclusive data according to Rutherford's
• Technique:
  • Can use racquet incision, as below
  • Through skin with 15 blade and down to bone
  • Sesamoid bones and flexor tendons excised

Toe amputation

• Anatomy:
  • Note generally medial and lateral sesamoid bones in flexor tendon of hallux
  • Hallux has two phalanges, whereas other toes have three
  • Joint capsules surround the interphalangeal and metatarsophalangeal hinge joints
• Technique:
  • Prep - alcohol if closed, betadine if open
  • Mark out racquet incision (with the handle of the racquet pointing dorsally for toes 2-4 and medially/laterally for first and 5th toes respectively) at approximately the level of the bone division, and preserving as much healthy skin as possible
  • Set up with Ray-tecs to pull other toes away and sharp towel-clip on end of toe
  • Cut with smaller blade - 15 blade - perpendicular and down to bone
  • Disarticulate through the joint with the knife
  • Haemostasis - big arteries only
  • Use bone cutters to divide bone - wiggle back proximally. Send metatarsal head chips for MCS +/- histo.
  • Nibble back sharp edges/exposed bone - check texture of bone for persistent OM.
  • Remove tendons and sesamoids
  • Hydrogen peroxide/saline
  • Haemostasis (just stop what you can and dress firmly - even an inaccessible bleeding digital artery will stop with firm packing)
  • LA
  • If closing - 3/0 nylon to skin, interrupted, loose. Jelonet/gauze/velband/crepe.
  • If leaving open (if there's pus or active infection) - saline gauze/jelonet/gauze/velband/crepe.