Replants

Replant 4 FingersReplant 4 fingers post

 

Definition

 

Replant

- reattachment of body part that has been completely severed

 

Revascularisation of incomplete Amputation

- vascular repair is necessary to prevent necrosis of the extremity

- retains some venous and lymphatic drainage albeit small

- revascularisation easier, quicker and better results

 

Mechanism of injury

 

Guillotine

Crush

Avulsion

 

Indications - Urbaniak 1987

 

Thumb 

Multiple digits

Individual digit distal to FDS insertion

Partial hand / through palm

 

Almost any body part in child

 

Wrist or forearm

 

Above or below Elbow 

- only if sharply demarcated

 

Contra-Indications

 

Adult single digit proximal to FDS insertion

- poor results / stiffness

 

Ischaemic time distal to carpus

- > 12 hours warm ischaemia time

- > 24 hours cold ischaemia time

 

Ischaemic time proximal to carpus

- > 6 hours warm ischaemia time

- > 12 hours cold ischaemia time

 

Severe crush or mangled

 

Levels

- through elbow

- high arm

 

Multiple level / segmental injury

 

Other serious injuries/diseases

 

Vessels atherosclerotic

 

Mentally unstable patient

 

Examination 

 

Chinese red line sign 

- red streak along arterial course

- due to severe traction

 

Ribbon sign

- elongated tortuous arteries with pigtail appearance

 

Considerations

 

Thumb

 

Thumb has first priority

- a successfully replanted thumb is always better than any reconstruction

- thumb provides 40% of hand function

- a fixed stump / post is very useful

 

Detipped thumb can be successful

- need dorsal veins in stump

- need 4mm of skin proximal to nail plate

- all efforts should be made to preserve thumb length even up to nail base

 

Multiple amputations

 

Replant best digit to most useful stump

When thumb intact goal is to restore palm width

 

Single digit

 

Does well if FDS intact

- allows immediate mobilisation of digit

 

P1 replants

 

Useful function does not occur

- patient will bypass finger

 

Mid-palm amputations 

 

Absolute indication for replant 

- replant far superior to prosthesis as lose sensation and power grasp

 

Proximal injuries

 

Proximal forearm, EJ and Arm 

- usually avulsion types with extensive muscle injury

- infection and muscle necrosis very common 

- usually replant not indicated

 

Patient factors

 

High demand professionals 

- may push indications eg at P1

 

Age is not a barrier 

 

Patient must be aware of chance at viability, function, time off work etc

 

Premorbid conditions must be taken into account 

- DM, Smoking, HTN, peripheral vascular disease

- patient compliance

 

Ischaemia

 

Key factor in success

 

Duration of allowed ischaemia varies from tissue to tissue

 

Recommended maximum

 

1.  Distal to carpus 

- 12 hours warm, 24 hours cool

 

Digits consist of skin, bone and subcutaneous tissue

- no muscle

- warm ischaemia tolerated for long periods

- freezing not tolerated

- digits have survived for 12 hours or longer of warm ischaemia

- when cooled replants have been performed at 36 hours

 

2.  Proximal to carpus 

- 6 hours warm, 12 hours cool

 

Major limb replants contain large volume of muscle

- only tolerate 4-6 hours of ischaemia

- because of the size of the extremity only its outer part is adequately cooled 

- the deep muscle remains relatively warm

- the allowable 6 hours can't be extended

 

Transport of part

4oC ideal

 

2 Methods

 

1. Wrapping the part in a moistened cloth of Ringer's or Saline

- placing in plastic bag and placing the bundle in ice water

 

2. Immersing the part in one of these solutions in a plastic bag 

- then putting on ice

 

No difference in outcome

 

Most important is to give clear and precise instructions to referring doctors

 

Surgeon

 

Dedicated replant team

 

Should be able to consistently achieve 90% patency rate in 1mm vessels in labratory

 

Operating theatre not the setting for practice

 

Surgical management

 

Operative Sequence for single digit

 

1. Locate and tag vessels and nerves

2. Debride

3. Shorten and fix the bone

4. Repair extensors

5. Repair flexors

6. Anastomose the arteries

7. Repair the nerves

8. Anastomose the veins

9. Obtain skin coverage

 

Set up

- maintain body temperature by warming the patient

- axillary block to block sympathetics

- ABx, tetanus prophylaxis

- IDC

 

Approach

- longitudinal mid-lateral incisions for digital replants

 

Shorten bone

- get out of zone of injury 

- must have no tension on the grafts

- minimum 0.5 - 1cm each side

- alternative is to vein graft but is easier to shorten bone

- Shortening also helps with skin coverage

- ORIF P1

- K wire fusion DIPJ / P2

 

Extensor Tendons

- primary repair

- if inadequate extensor tendon for primary repair perform delayed repair

 

Flexor tendons 

- repaired primarily if at all possible

- otherwise 2 stage 

 

Vascular

- 10/0 nylon interrupted

- key is repair normal intima to normal intima

- adventitia is intensely thrombogenic so ensure none in repair

- strip adventitia for 1-2mm

- repair both arteries if possible otherwise vein graft

- tourniquet acceptable

- micro-clips / bulldog clips should not be applied > 30min due to intimal damage

- heparin boluses to maintain patency (5000IU in 500 mls)

- papaverine antispasmodics

- 2 veins for every artery

 

Nerve repair

- 10/0 interrupted epineural repair

- primary repair if possible

- primary nerve graft if not 

- use medial cutaneous nerve of forearm 

 

Skin

- skin closed under no tension

- digital incisions often left open to decompress repairs

- fasciotomies in larger replants

- bulky above EJ dressing with volar slab unless flexor tendon repair then dorsal slab

 

Replant at level of nail bed

 

Issue

- No dorsal veins 

 

Options

1.   Repair of volar veins (smaller and more flimsy)

2.   Anastomose one distal artery to proximal vein (AV anastomoses)

3.   Backbleeding by removing nail plate and scrapping every 2 hrs with cotton applicator and heparin dressings

4.   Medical grade leeches

 

Post-Op

 

Elevate gallows

- high dependency area

- high fluids

- anticoagulation controversial

- smoking strictly prohibited

- no caffeine

- warm ambient temperature

- colour, pulp, turgor, cap refill, and warmth all used as aids in monitoring the replant

- observations hourly for 72h then q4h

- if concern re myoglobinuria then maintain urine output high and alkalinise the urine

 

Monitoring

- if surface temperature <30°C poor perfusion of replant is certain

 

Reversal of failing patient

 

If appears threatened immediate action necessary

1. Relieve dressings or sutures

2. Either elevate or dependant position

3. Regional block for sympathetics

4. Relieve pain, fear and anxiety

5. Ensure patient warm and adequately hydrated

6. If return to OT necessary then must be within 4-6 hours of ischaemia

 

Results

 

80-85% survivability

 

Urbaniak 1985

- 51/55 survived

- ROM 82o distal to FDS

- 35o proximal to FDS

 

Ring Avulsions

 

Urbaniak Classification

 

I - circulation adequate

II - circulation inadequate

III - complete degloving / amputation

 

Major limb replantation

 

Issues

 

Amputations proximal to metacarpal level have significant muscle bulk

- to prevent myonecrosis immediate arterial inflow is necessary

- following rapid skeletal stabilisation at least one artery must be stabilised then follow sequence for digit

- extensive fasciotomies always indicated

- any exposed vessels must be covered by rotation flap etc

- return to OT at 72 hrs for inspection and DPC

 

2 most common causes of failure in major limb replants 

 

1.  Myonecrosis with subsequent infection

 

2.  Failure to adequately decompress the restored vessels