Finger Replant

In this Article

1. Indications for Replant
2. Replant Viability
3. Transport of Finger
4. Surgical Technique
5. Post-Operative Care\
6. References

Indications for Replant

These are relative indications and other factors should be considered – such as, patient preferences, patient motivations, overall health, and expectations.

Indications and Contraindications for Finger Replant

The general indications and contraindications for replantation are summarized in the following table.

Supporting Evidence for Indications

• Thumb provides 40-50% of hand function. A thumb with limited movement is more functional than other reconstructive procedures or prosthetics^​1​
• Multiple Digits amputations results in major functional issues. A preference is to prioritise thumb and middle finger (important for pinch grip)
• Single-digit proximal to FDS (zone 2) is an ongoing debate. Evidence suggests that a replanted finger with limited function has an overall negative effect on dexterity^​2​ , especially with a poorly-functioning PIPJ. This is controversial.
• Single digit distal to FDS insertion (zone 1) is often attempted. The function of the finger with a preserved PIPJ is enhanced by the additional length, even if the distal interphalangeal joint is stiff or fused^​3​
• Mid-palm amputations should generally be replanted, as any successful procedure will have superior function compared with a prosthetic device. A major issue is intrinsic muscle function recovery. Evidence suggests palmar arch replantations more successful than at common digital arteries^​4​

As a side not, the issue of litigation and replantation should be considered. The majority of the patients who filed claims do so because of the decision not to replant^​5​.

Replant Viability

The viability of replanting a finger amputation is centred on 4 main factors: mechanism of injury, ischaemia time, location and the patients conditions. Over time, evidence has changed and traditional teachings evolved.

Mechanism of Injury

Finger amputations are most commonly caused by 3 types of mechanisms: a “sharp, clean cut”, crush or avulsion. The type of injury is a key determinant of replant viability^​2​ .

The correlation between survival and injury can be seen in the table below^​6–8​

The relationship between mechanism of injury and survival rates/replant viability

Location of Finger Amputation

An important landmark in finger amputations is the FDS insertion. This defines zone 1 and zone 2. These zones of the hand have traditionally defined the relative indications and contraindications for performing a finger replant.

The following table compares the impact of location on replant viability^{​3,9–11​}

The importance of distal and proximal to FDS insertion point

As finger replantations have become more successful over time, a question has arisen – how distal do we go? Comparative studies using Tamai and Ishikawa Classifications for distal fingertip amputations have suggested the following^​11,12​:

• Advantage of distal tip replantation include length, protective sensation, increased DIPJ motion.
• No difference in grip strength between distal tip replant and revision amputation.
• No major difference in cold intolerance.

Ischaemia Time

Traditionally, irreversible ischaemia occurs in muscle after 2-4 hours warm, 6-8 hours cold. In fingers, it is more likely to be 6-12 hours warm and 12-24 hours cold ischaemia^​13​.

Key points to understand in relation to ischaemia time are:

• Fingers lack muscle tissue – this is a positive factor to prolong ischaemia time
• Evidence suggests cold ischaemia should not be involved in the decision-making process^​14​
• Successful replants have been reported up to 3 days post injury^​15​

This table summarise the impact of time on replant viability – please note this evidence comes from different research papers and thus different cohorts of patients and surgeons.

The impact of time on replant success

Ultimately, more data are needed regarding the effect of prolonged ischemia on functional outcomes and survival is needed.

Patient Factors

There have been traditionally 4 common patient-related factors which influence finger replantation:

1. Young Age: Children show better functional recovery than adults^​16​
2. Smoking Status: Evidence is inconclusive^​2,8​
3. Comorbidity: Diabetes

Surgical Technique

The literature supports a standardised, step-wise and sequence approach to finger replantation. This should be adaptable to different mechanisms and injury presentations.

A Step-wise Sequenced Approach for Replantation

There is a general consensus on the step-wise and sequenced surgical approach to finger replantations. The following is a guide and can change depending on finger configuration and surgical preference.

1. Bone: Osteosynthesis/bone fixation with or without shortening of bone with K-wires, Interosseous wires, mini-plates or screws.
2. Tendon Repair: Flexor and Extensor Tendon repair
3. Nerve Repair: not necessary in distal fingertip amputations^​17,18​
4. Artery Anastomosis +/- Vein Graft
5. Vein Anastomosis: A strong predictor of survival^​10​
6. Skin: also has a role in venous drainage

Tip: The amputated part can be aseptically prepped under Loupes prior to patient entering theatre.

Vein Grafting in Finger Replants

Vein grafts are a reliable option in digital replantation. They provide a back-up and level security for both aterial and venous anastomosis

Vein grafts are often used for the following reasons:

1. Creating tension-free anastomosis (if bone shortening not performed)
2. Do not increase rate of thrombosis ^​19​
3. Do no decrease replant survival^​19​

Vein grafting is commonly indicated in amputations because:

1. Degree of intima damage (in avulsion injuries this can extend passed transection^​20​)
2. Anastomosis to be performed outside zone of injury
3. Large thrombosis within zone of injury

Vein grafts from the volar wrist often match the calibre of the digital arteries.

Interestingly there is evidence to support an arterial-only replantation, when venous outflow can not achieved. This can be reliable if low-resistance flow through the replant is maintained until venous outflow is restored naturally^​21​. Other options include:

1. Check for volar veins
2. Create an AV fistua – digital artery eill backflow to a vein.

Post-Operative Care

The post-operative regimen for finger replantation should focus on thromboprophylaxis, monitoring of complications, medical optimisation and rehabilitation.

Thromboprophylaxis

The purpose of thromboprophylaxis is to interfere with platelet function, to counteract the effects of thrombin on platelets and fibrin, and to decrease blood viscosity

Current practices demonstrate substantial variability between surgeons regarding systemic anticoagulation and duration of therapy^​22​. T

Current practices include:

1. Aspirin^​23​
2. Intravenous heparin^​24​
3. Subcutaneous Low molecular-weight heparin (LMWH)^​25​
4. Local Heparin referred to as the “chemical leech”^​26,27​
5. Intravenous dextran^​28​
6. No Thromboprophylaxis ^​29​

There is little evidence to guide perioperative anticoagulation finger replants. Current literature is limited by low-level evidence^​30​. The timing of medication is also non-standardised to pre-, intra- and post-operative options^​31​.

Complications

Venous Insufficiency and Arterial Thrombosis are the two commonest complications in finger replantations surgery. 90% of these complications occur within the first 72 hours^​32​.

This table compares these two arterial and venous complications^​32​:

Venous vs Arterial complications in finger replant

Other complications to be aware of are:

• Infection from wound or leeches (cover Aeromonos hydrophila infection with Ciprofloxacin)
• Reperfusion Injury (Allopurinol to decrease Xanthine production)
• Cold Intolerance

Rehabilitation post-replant

No standardised post-operative rehabilitation program. This is a multi-disciplinary effort with the physiotherapy, occupational therapy and most importantly, the patient.

Rehabilitation requires appreciation of:

1. Bone Healing and bone stability
2. Tendon Adhesion and their prolonged avascular state
3. Joint contracture

There is evidence to suggest rehabilitation should being as early as possible^​33,34​. Ultimately, it should be tailored to the specific injury^​35​.

The functional outcomes is dependent on age, mechanism of injury, level of injury, and rehabilitation compliance^​36​

Tip: Patients often undergo secondary surgeries to overcome the issues of delayed rehabilitation. To increase functional use options include: flexor tenolysis, and DIP joint arthrodesis

Bibliography

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