Chapter 43 - Replantation Flashcards
What is the goal of digital replantation?
Equivalent or improved function when compared to revision amputation and prosthesis
What are the current indications for digital replantation?
Thumb, multiple digits, single digits distal to FDS insertion, hand at wrist or forearm (sharp), any amputation in a child
What is the appropriate workup for a patient with amputated digit?
ATLS, Do not complete amputation until fully evaluated in OR, wrap part in moist gauze and in plastic bag, place plastic bag in ice. IV antibiotics, Tetanus. Xrays. Consent for possible nerve/vein graft and amp as well as replant.
What is the order for replantation steps?
Bone, Extensors, Flexors, Arteries, Nerves, Veins
What is the order for multiple digit replantations?
Structure by structure (all bones, then all tendons, then all arteries, then all nerves, then veins)
What are the potential advantages in skeletal shortening in digital replantations?
May enable more secure bone fixation, may minimize need for vessel or nerve grafting
What are the options for skeletal stabilization in digital replantation?
K wires, 90-90 wiring, miniplates and screws, intramedullary bone pegs
What are the functional deficits associated with ray amputations of the index finger?
Loss of power grip and key pinch
What is the lumbrical plus deformity?
FDP tendon and lumbrical muscle migrate proximally after division of the tendon in trauma. With flexion , tension is exerted on the lumbrical via the radial lateral band causing paradoxical extension of the PIP during flexion of the MP joint
What is the treatment for lumbrical plus deformity?
Division of the lumbrical insertion
What is the most common cause of digital replantation failure?
Arterial insufficiency
What is the treatment of arterial insufficiency after digital replantation?
- If any concern about arterial insufficiency, return to OR
- Loosen dressings
- Heparin
- Antivasospastic meds (thorazine)
- Sympathetic blocks
What is the treatment for venous congestion after digital replantation?
- Removal of dressings
- Leeches
- Heparin
- Nail bed bleeding with heparin-soaked sponges
- Revision of venous anastamosis
Which tissue is most sensitive to warm ischemia
Skeletal muscle
What is the maximum cold ischemia time reported for digital ischemia?
30-40 hours
When should prophylactic fasciotomies be performed in upper extremity replantation?
With any replantation proximal to the wrist (because of increased skeletal muscle present)
What is the quadriga effect?
Weakness in flexion of the fingers secondary to excess pull of one FDP tendon of the amputated finger
What is the maximum nerve gap for use of a neural tube (PGA)?
2.5cm
What nerves are available for donor grafting?
Posterior interosseous, sural, superficial radial, superficial peroneal
What is the treatment of choice for a tip amputation through the nail bed without bone exposed?
Local dressing changes (healing by secondary intention)
What is a good option for failed thumb replantation at the MCP level?
Revision amputation followed by toe to thumb transfer at a later date
What donor vessel is the toe-to-thumb transfer based on?
First dorsal metatarsal artery from the dorsalis pedis artery or plantar digital artery from the lateral plantar artery
What is a good option for a thumb-tip amputation with exposed bone?
Moberg flap
How much advancement can be obtained from a Moberg flap?
1.5cm
What are contraindications to digital replantation?
Severe concomitent injuries, severely crushed or mangled part, multilevel amputations, significant comorbidities (relative), prolonged warm ischemia time, Mentally instable/self-mutiliation (relative), single finger proximal to FDS insertion
How many arteries and veins are needed for a digital replantation?
One artery and one vein (two is preferred if possible)
Is an artery-only digital replantation possible?
Yes. Leeching and/or bleeding of the nail bed can be used to relieve venous congestion
How many places can you find a digital vein?
Two. Dorsal and volar.
What is the concern in avulsion amputation vs guillotine amputation?
Zone of injury is much greater in avulsion injuries
What is the red stripe sign?
A red streak along an artery indicating severe intimal injury along the length of the vessel
What is the best method for treating the zone of injury of an artery or vein in the case of crush or avulsion injuries?
Resection of the compromised vessel and vein grafting
Where can veins be found on the hand dorsum?
Proximal to each webspace
What vascular pattern exists in a finger that was crushed and has the appearance of venous congestion and low capillary refill?
Loss of proper digital artery inflow, intact venous flow
Eight months post digital replantation, what operation would you offer the patient with minimal active or passive ROM?
Extensor tenolysis and open capsulotomy
What operation would you offer s/p digital replantation with minimal active ROM but good passive ROM?
Flexor tenolysis
What is the greatest danger in digital reoperation after replantation?
Injury to the neurovascular bundle embedded in the scar
What is fluorimetry?
a method of monitoring tissue perfusion by injecting fluorescein dye intravenously and using a fluorometer to quantitatively measure rise and fall of fluorescein in tissue
What if there is a two to threefold rise but no fall in the number on fluorimetry?
Signs of venous congestion
What if the absolute number (on fluorimetry) is very low and remains low, but the digit clinically looks viable?
Thick skin or heavily contaminated skin can alter the numbers
When is the highest likelihood of a thrombotic event at the microanastomosis?
Within 24-48 hours
At the microanatomosis, what is the most prominent cell layer on day 3?
Platelets
At the microanatomosis, what is the most prominent cell layer on day 4-14?
Pseudointima
At the microanatomosis, what is the most prominent cell layer on days 14+?
Intima
One year status post replantation at the PIPJ level with severe arthritis or fusion at the PIPJ. What surgery can you offer the patient?
PIP Joint arthroplasty
Which Urbanik class of ring avulsion is considered a relative contraindication to replantation?
III - complete degloving or complete amputation
What type of flap can be used if there is a soft-tissue defect in a Type II ring avulsion injury?
Venous flow through flap
What is the average two point discrimination of a replanted thumb
9-11mm
What is the average two point discrimination of a replanted digit?
8-15mm - depending on sharp vs avulsion
What is the “no reflow phenomenon”?
Inability to maintain perfusion to he replanted tissue despite restoration of blood flow through a technically acceptable anastomosis. Thought to be the result of inschemia-induced endothelial injury
What is a common long-term sequelae of digit replantation?
Cold intolerance. This occurs commonly in the adult population but can also affect peds
How much time should you tell a patient they will have to wait for cold intolerance symptoms to resolve?
2 years, maybe never
What is the scientific name for medical leeches?
Hirudo medicinalis
Action of Hirudin?
Binds activated thrombin (1:1)
Inhibits conversion of fibrinogen to fibrin
Blocks activation of Factors V, VIII, XI, and vWF.
Decreases activation of tPA, protein C and plasmin
Prolongs thrombin-dependent coagulation tests (PTT, TT, ACT, ECT)
There is no direct effect on platelets or endothelial cells
Can monitor by thrombin time and PTT
Excretion of hirudin?
Renal
Organisms to cover while patient is on leech therapy?
Aeromonas hydrophilia - enteric organism that can cause severe soft tissue infection.
What medications to use with leech therapy?
Third generation cephalosporin (Cefizox) or aminoglycosides (tobramycin, gentamicin) in adults. Bactrim or cipro in peds.
What is the mechanism of heparin?
Action primarily via activation of serum antithrombin III and lowering blood viscosity, increases AT III activity
Mechanism of dextran
Polysaccharide - molecular weight 40,000 and 70,000
Decreases platelet aggregation by imparting a negative charge on the platelets, inactivating vWF
Modifying the structure of fibrin
Altering rheologic property of blood
Possible complications of dextran
Possible complications: antigenic test of <5ml must be given before full dose
Renal failure - volume expansion
Noncardiogenic pulmonary edema
What is the mechanism of aspirin?
Acetylates cyclooxygenase enzyme
Decreases arachnodonic acid, thromboxane, and prostacycline
Decreases platelet aggregation and vasoconstriction
What is the mechanism of Thorazine?
Potent vasodilator
What is the mechanism of papaverine?
Salt of opium alkaloid. Smooth muscle relaxant especially with cerebral and peripheral ischemia associated with arterial spasm
What is the mechanism of lidocaine?
Potent local vasodilitation. Commonly used at 2% dilution
What is the definitive role of anticoagulation in microsurgery?
Controversial. Not enough RCT. Common uses: high-dose heparin irrigation during microanastomosis. IV heparin after a thrombotic event with anastomotic revision
