Editing Lower extremity amputation operatives (section)

== 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.
***

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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