Microvascular replantation of amputated digits · advanced
- Absolute indications: thumb at any level, multiple digit amputations, amputations through the palm, wrist or forearm, and any amputation in a child. A single finger distal to the FDS insertion (distal zone II) is a relative contraindication — revision amputation may give a better functional outcome than a stiff, painful replanted digit.
- The operative sequence is non-negotiable: bone shortening and rigid fixation, extensor tendon repair, flexor tendon repair, arterial anastomosis, venous anastomosis, nerve repair, then loose skin cover. The bone must be stable before microvascular work begins, and arteries are done before veins so inflow is established before outflow.
- Warm ischaemia time is critical: a finger tolerates up to about 12 hours, a thumb up to about 6 hours of warm ischaemia. Cool the amputated part (wrapped in saline-soaked gauze inside a sealed plastic bag, on ice — never in direct contact with ice) and transfer immediately. Cold ischaemia extends digit tolerance to about 24-30 hours.
- The artery-to-vein ratio should favour veins: aim for at least 2 veins per artery. Fewer than 2 patent venous anastomoses is the single greatest predictor of replant failure from venous congestion, which accounts for about 60% of failures. If vessel ends will not reach without tension, use interpositional reversed vein grafts from the volar forearm or dorsal foot.
When & Why
The replantation decision balances the chance of a useful, sensate, mobile digit against the morbidity of a long operation and rehabilitation. Three categories drive it:
Thumb at any level (the loss of a thumb is about 40-50% of hand function); multiple digit amputations; amputations through the palm, wrist or forearm (larger vessels, better functional return); and any amputation in a child.
A single digit proximal to the FDS insertion; a sharp, clean (guillotine) mechanism; a young, highly motivated patient; and amputations of the dominant hand in a manual worker whose livelihood depends on hand use.
A single zone II digit distal to the FDS insertion; severe crush or avulsion; warm ischaemia over the limit (greater than 12 hours for a finger, greater than 6 hours for a thumb); a multilevel (segmental) injury; significant comorbidity (diabetes, vascular disease, smoking, anticoagulants); and self-inflicted amputation pending psychiatric assessment.
The mechanism of injury is the strongest predictor of both survival and function — it dictates how much vessel and soft tissue must be debrided before any anastomosis is possible.
- Survival rate
- 85-95%
- Functional outcome
- Good to excellent
- Key challenges
- Minimal soft-tissue damage; clean vessel ends; standard sequence; fastest rehabilitation
- Survival rate
- 70-85%
- Functional outcome
- Moderate to good
- Key challenges
- Trim vessels back to healthy intima; possible bone comminution
- Survival rate
- 40-60%
- Functional outcome
- Poor to moderate
- Key challenges
- Extensive debridement; bone shortening; soft-tissue coverage; multiple secondary procedures
- Survival rate
- 30-50%
- Functional outcome
- Poor
- Key challenges
- Long vessel gaps needing vein grafts; nerve avulsed from the proximal stump; tendon retraction; highest failure rate
R.E.P.L.A.N.TREPLANT — indications for digit replantation
Transport and cooling of the amputated part - Wrap the amputated part in saline-soaked gauze.
- Place it inside a sealed plastic bag (to prevent maceration).
- Put the bag on ice — NEVER in direct contact with ice, because frostbite damages the microvasculature.
- Warm ischaemia tolerance: about 12 hours for a finger, about 6 hours for a thumb. Cold ischaemia extends digit tolerance to about 24-30 hours.
- Document the time of amputation and the time the part was cooled, and transfer to a replant centre immediately. Setup and consent - Supine, arm on a hand table, forearm tourniquet at 200-250 mmHg, regional or general anaesthesia. Loupe and operating-microscope magnification are essential; two teams shorten a multiple-digit case considerably.
- Pre-assess the part (mechanism, Tamai zone, contamination, vessel and nerve condition) and the patient (age, occupation, dominance, diabetes, smoking, vascular disease, anticoagulants, psychiatric history).
- Consent honestly: overall survival about 70-85% (lower for crush and avulsion), 6-12 months to maximal improvement, a high likelihood of secondary procedures (tenolysis, nerve graft, aesthetic revision), and the alternative of revision amputation.
The Operation
The goal is to restore a stable, sensate, mobile digit: shorten and rigidly fix the bone, repair the extensor then the flexor tendons, re-establish arterial inflow then venous outflow, repair both nerves, and close the skin loosely — performed across two surgical fields (the amputated part and the proximal stump) under magnification.
Operative sequence
- Under tourniquet control, thoroughly debride both the amputated part and the proximal stump: remove all non-viable skin, muscle and fat, and irrigate with copious normal saline.
- On the amputated part, identify and TAG the two digital arteries, two to four dorsal veins, and both digital nerves with 6-0 Prolene. Colour-code them (red for artery, blue for vein, yellow for nerve) — in the chaos of a two-field replant, arteries, veins and nerves look similar once debrided, and tagging prevents wrong-structure repair and wasted time.
- Debride and tag the matching structures on the proximal stump.
- Examine every vessel end under the microscope at 10-25x magnification. Healthy intima is smooth, glistening and intact; crushed intima is ragged, with subintimal haemorrhage and intimal flaps. Trim vessel ends back to healthy intima, extending the dissection by several millimetres if necessary.
- Shorten the bone to (1) remove all non-viable or contaminated bone, (2) let the vessel, nerve and tendon repairs sit without tension, and (3) achieve stable fixation. Deliberately over-shorten 5-10 mm — tension is the enemy of microvascular surgery.
- Typical shortening: 5-10 mm in clean amputations, up to 20-30 mm in crush injuries.
- For a transverse amputation, use two crossed 0.9-1.2 mm K-wires, or a single longitudinal intramedullary K-wire plus an oblique wire for rotational control. For an oblique cut, use the obliquity itself (step-cut or oblique osteotomy) to preserve length. Bend the distal K-wire ends over to prevent migration and soft-tissue irritation.
- Confirm rotational alignment (the nail-plate orientation matches the proximal stump — a malrotated replant is functionally useless) and confirm stability under fluoroscopy before any microvascular work.
- Repair the extensor tendon over the dorsum of the now-stable bone, before the flexor tendons, so the tendon balance is set on a fixed skeleton.
- Zones V-VI (over the MCP and proximal phalanx): the extensor mechanism is broad — use 4-0 non-absorbable (Prolene or Ticron) with a modified Kessler or core suture.
- Zones I-III (over the PIP, DIP and middle phalanx): the tendon is thin — use a meticulous running or figure-of-eight repair with 5-0 nylon.
- Set tension so the digit rests in a functional position — not hyperextended or flexed.
- Zone I (distal to the FDS insertion): repair the FDP only (there is no FDS here) with a 4-strand core suture and a running 6-0 epitendinous suture.
- Zone II (FDS to the FDS insertion): the most controversial step. The FDS and FDP share a narrow fibro-osseous canal bounded by the A2, A3 and A4 pulleys, and repairing both risks profound adhesion and stiffness. The preferred approach of many experienced replant surgeons is to repair the FDP only and trim the FDS stump flush — bone shortening has effectively widened the canal, and removing the FDS creates room for the FDP to glide. The alternative is to repair both and plan a secondary tenolysis at 3-4 months.
- Zones III-V (palm): repair both FDS and FDP — the broader canal accommodates both with less adhesion risk.
- Preserve or reconstruct the A2 and A4 pulleys (a slip of FDS or an extensor retinaculum graft if they were sacrificed) to prevent bowstringing. The A1 may be released if needed, but never A2 or A4.
- Test that the repair glides freely through the pulleys without catching before moving to the vascular repair.
- DEFLATE the tourniquet before starting any anastomosis. Arteries and veins must be distended with blood so the intima is visible, the lumen is open, and the vessel ends can be properly coapted — repairing collapsed, empty vessels under tourniquet is harder and less reliable.
- Achieve a bloodless field at the anastomosis site with a proximal rubber dam (Penrose drain) or vessel loops, and confirm haemostasis with bipolar diathermy.
- Set up the operating microscope at 16-25x magnification for digital vessel anastomosis.
- Repair the digital arteries before the veins — establish inflow first. Choose the artery with the best intima and the most favourable orientation (usually the ulnar digital artery for the index and long fingers; both arteries for the thumb, where the princeps pollicis is the target).
- Apply microvascular clamps with the lightest pressure that achieves haemostasis — excessive pressure crushes the intima and negates a well-placed anastomosis.
- Strip adventitia 1-2 mm from each cut end (loose adventitial fibres entering the lumen cause thrombosis) and irrigate the lumen with heparinised saline (100 units/mL).
- If there is a gap, harvest an interpositional vein graft from the volar forearm (cephalic vein branches) or the dorsal foot, REVERSE it so the valves point distally, and interpose it.
- Place the back wall first: 10-0 nylon, simple interrupted sutures, 8-12 sutures total for a 1-2 mm digital artery, ensuring intima-to-intima apposition. Check the lumen after each back-wall suture so the posterior intima is not caught.
- Release the clamps and confirm inflow — brisk bleeding from the distal cut ends of the veins confirms arterial flow through the capillary bed. Repair any anastomotic leaks with additional sutures.
- Identify at least two dorsal veins (the dorsal veins are larger and more numerous than the volar veins — typically two to four, 1-2 mm in diameter at the proximal phalanx). Use the veins tagged during Step 1.
- Use the same microvascular technique: adventitial stripping, heparinised saline irrigation, back wall first, 10-0 or 11-0 nylon.
- Aim for at least two patent venous anastomoses per artery. If veins are too short, use interpositional vein grafts from the same donor sites (volar forearm, dorsal foot).
- After releasing the venous clamps the digit should pink up, warm, and develop capillary refill within 2-3 minutes. If it stays dark, swollen and congested with slow refill, you are not finished — go back and find another vein.
- Repair both digital nerves with epineurial repair under the operating microscope: 9-0 or 10-0 nylon, simple interrupted sutures, 4-6 sutures per nerve, approximated without tension.
- If a gap remains, use an interpositional nerve graft — the median or ulnar dorsal cutaneous branch for smaller gaps, or a sural nerve graft for larger ones.
- In zones II and III the nerves lie alongside the arteries and are identified during the vascular dissection. Two-point discrimination of 5-10 mm is a reasonable expectation after a successful replant.
- Close the skin loosely over the repaired structures — 4-0 or 5-0 nylon simple interrupted if it closes without tension.
- If there is tension, do NOT close under tension: use a full-thickness skin graft from the hypothenar eminence, groin, or volar forearm.
- If bone, vessel or tendon is exposed and grafting is not possible, use a local flap (cross-finger or thenar) or a distant pedicle flap (groin flap).
- Loose closure accommodates post-operative swelling — a tight closure will compress the venous anastomoses.
- Zone I (distal to the DIP joint): veins are too small for anastomosis. Repair the single digital artery and rely on controlled bleed-through for venous drainage. No flexor tendon repair is needed (the FDP insertion is distal to the level), and a single longitudinal K-wire suffices. Survival is greater than 90% because the tissue volume is small and metabolic demand is low.
- Apply heparin-soaked gauze around the nail fold; the part will ooze blood for 3-5 days — this is the intended venous drainage pathway.
- Transfer to a monitored bed: warm the patient and hand (room 24-26 degrees Celsius, warming blanket or heat lamp), elevate the hand above heart level, and begin monitoring every 30 minutes for the first 48 hours.
Bone shortening and rigid fixation must be complete before the microscope comes in; any movement of the bony fragments will tear the anastomosis and cause immediate thrombosis. Deliberately over-shorten so vessel and nerve repairs sit without tension — you can always add bone graft later, but you cannot undo a failed replant caused by a tense arterial anastomosis.
Arteries and veins must be distended with blood so the intima is visible and the lumen is open. Keep total tourniquet time documented and under 90 minutes per inflation, and use a rubber dam or vessel loop for a bloodless field at the anastomosis site.
Place 3-4 back-wall sutures, flip the vessel, then place the front wall. Use a microvascular approximator clamp to hold the ends steady and pick up adventitia and media only — a back-wall suture that catches the posterior intima will thrombose the repair. Check the lumen after each back-wall suture, and if there is a gap of more than a few millimetres, take a vein graft immediately rather than over-mobilising.
After the arterial repair, check for bleeding from the distal cut vein ends — that confirms flow through the capillary bed. If inflow is good but the digit stays pale, mottled and pulseless with no distal bleeding, the distal microcirculation is dead (the no-reflow phenomenon). It is irreversible — proceed to revision amputation rather than repeatedly revising a patent anastomosis.
Aftercare & Complications
Post-operative monitoring (first 48 hours) All replant patients are admitted to a monitored bed, ideally a specialist hand unit. Check the replanted digit every 30 minutes for the first 48 hours, then hourly for the next 24 hours: - Colour: pink (normal), pale (arterial insufficiency), blue-purple (venous congestion), mottled (no-reflow).
- Temperature: warm (normal), cool (vascular compromise).
- Capillary refill: less than 2 seconds (normal), 2-3 seconds (concern), greater than 3 seconds (venous congestion).
- Swelling: mild (expected), severe with tense skin (urgent — venous congestion).
- Doppler signal: a triphasic signal confirms arterial patency; loss of signal requires urgent return to theatre.
- Needle prick test: if colour is equivocal, prick the digit with a 25G needle — bright red bleeding confirms arterial inflow, dark bleeding suggests venous congestion, and no bleeding suggests arterial thrombosis or no-reflow.
- Haematocrit: leech therapy and zone I controlled oozing can cause significant blood loss — check haemoglobin every 12 hours. Anticoagulation - Aspirin 150-300 mg daily for 3-6 weeks is the baseline at most centres.
- Therapeutic low-molecular-weight heparin (enoxaparin 1 mg/kg twice daily) for the first 5-7 days is used by some centres, particularly for high-risk replants (crush, avulsion, single-vein repair).
- Dextran-40 infusion (500 mL over 6-8 hours) for the first 24-48 hours is used by some centres but is less common now because of renal and bleeding risks.
- Heparin-soaked gauze is applied locally around the wound and nail fold, particularly in zone I artery-only replants.
- There is no high-level evidence for an optimal anticoagulation protocol — practice varies between centres. Rehabilitation timeline | Phase | Timing | Key activities | |-------|--------|----------------| | Protected | Week 0-3 | Passive ROM only; no active flexion of repaired tendons; dorsal blocking splint for zone II; gentle place-and-hold | | Early active | Week 3-6 | Graduated active ROM; tendon glide and blocking exercises; scar management begins | | Active strengthening | Week 6-12 | Progressive grip and pinch strengthening; resistive exercises; functional occupational therapy | | Advanced | Month 3-6 | Light duties; progressive resistance; desensitisation; sensory re-education | | Final | Month 6-12 | Full duties; maximal medical improvement by 9-12 months; secondary procedures (tenolysis, nerve graft, aesthetic revision) planned at 3-6 months | Complications
- Incidence
- 15-30%; about 60% of failures
- Recognition
- Dark purple-blue, swollen, tense digit; capillary refill greater than 3 seconds; brisk dark bleeding on needle prick
- Prevention and management
- Prevention: repair at least 2 veins per artery; use vein grafts if short. Management: release dressings and sutures; medicinal leeches with prophylactic ciprofloxacin; heparin-soaked gauze; return to theatre if no improvement in 2-3 hours
- Incidence
- 10-15%
- Recognition
- Pale, white, cold digit; absent capillary refill; no Doppler signal; needle prick yields no blood or only dark venous blood
- Prevention and management
- Prevention: intima-to-intima anastomosis; no tension; adequate debridement; postoperative aspirin. Management: urgent return to theatre; thrombectomy and revision anastomosis; vein graft if ends are damaged
- Incidence
- 5-10% (higher with prolonged warm ischaemia and crush)
- Recognition
- Good arterial inflow but the digit stays pale, mottled and cold with no capillary refill and no bleeding from distal veins
- Prevention and management
- Prevention: minimise warm ischaemia; cool the part immediately. Management: IRREVERSIBLE — recognise early and convert to revision amputation rather than persisting with futile revisions
- Incidence
- 5-15% (higher in crush and farmyard injuries)
- Recognition
- Increasing pain, erythema, warmth, swelling, purulent discharge; fever; raised inflammatory markers; wound dehiscence
- Prevention and management
- Prevention: thorough debridement; prophylactic cephalosporin (add an aminoglycoside or metronidazole for farmyard contamination). Management: wound and tissue cultures; targeted IV antibiotics; urgent washout; the replant may need removal if the anastomosis is involved
- Incidence
- 50-80% (long-term)
- Recognition
- Persistent pain, stiffness, colour change and numbness in the replanted digit in cold environments; the most common long-term complaint
- Prevention and management
- Prevention: none proven — near-universal. Management: education and expectation setting; keep the hand warm; sympathetic blocks may give temporary relief
- Incidence
- 30-50% (highest in zone II flexor repairs)
- Recognition
- Reduced active ROM with preserved passive ROM; flexor catching; grip weakness; PIP and DIP flexion contractures
- Prevention and management
- Prevention: repair FDP only in zone II; adequate bone shortening to widen the canal; early protected mobilisation. Management: hand therapy and serial splinting; tenolysis at 3-4 months if no improvement
- Incidence
- 10-20%
- Recognition
- Persistent pain at the osteotomy; instability on stress testing; visible deformity or rotation; no callus on X-ray by 3 months
- Prevention and management
- Prevention: debride to bleeding bone; stable fixation (2 crossed K-wires minimum); confirm alignment under fluoroscopy. Management: bone graft and revision fixation at 6 months; osteotomy and refixation for malunion
- Incidence
- 2-5% of leech-treated patients
- Recognition
- Cellulitis at the leech site; wound dehiscence; systemic signs 24-72 hours after leech therapy; Aeromonas hydrophila cultured
- Prevention and management
- Prevention: prophylactic ciprofloxacin 500 mg twice daily for the duration of leech therapy plus 3 days after the last leech. Management: stop leeches; cultures; IV ciprofloxacin (covers Aeromonas); washout if deep infection
Viva & Exam Focus
S.H.O.R.T.E.S.TSHORTEST — operative sequence in digit replantation
- The trap
- Transporting the part uncooled — burning the warm ischaemia budget before reaching theatre
- The fix
- Saline-gauze, sealed bag, on ice (never direct ice — frostbite damages the microvasculature). Finger: about 12 h warm, 24-30 h cold. Thumb and major parts: about 6 h warm, 12-18 h cold
- The trap
- Starting microvascular anastomosis before the bone is stable — fragment movement tears the anastomosis
- The fix
- Complete bone shortening and rigid fixation FIRST. Order: bone, extensor, flexor, artery, vein, nerve, skin
- The trap
- Accepting a single venous anastomosis — the leading cause of early failure (about 60% of failures)
- The fix
- Aim for at least 2 veins per artery; tag all veins at debridement; use reversed vein grafts if short; leeches if congestion persists despite an adequate repair
- The trap
- Repairing both FDS and FDP in the narrow canal — adhesions cause profound stiffness
- The fix
- Repair FDP only and excise the FDS stump, OR repair both and plan a tenolysis at 3-4 months
- The trap
- Performing microsurgery under tourniquet — collapsed, empty vessels are harder to repair
- The fix
- Tourniquet for debridement, bone and tendon only; DEFLATE before vascular anastomosis; use a rubber dam or vessel loop for a bloodless field; keep each inflation under 90 minutes
- The trap
- Repeatedly revising the artery when the distal capillary bed is dead — wasting time and tissue
- The fix
- After arterial repair, check for bleeding from the distal veins. Good inflow but a pale, pulseless digit with no distal bleeding is no-reflow — irreversible; convert to revision amputation
Clinical Decision Scenarios
Practise clinical reasoning and management decisions out loud
“A 32-year-old carpenter amputates his non-dominant index finger through the proximal phalanx (zone II) with a circular saw. He arrives 3 hours after injury with the amputated part cooled, and asks you to replant it. How do you counsel him and what is your management plan?”
“A 45-year-old machine operator has a complete amputation of his right (dominant) thumb at the IP joint level (zone I) in a guillotine injury. He arrives 2 hours after injury with the part properly cooled. Walk me through your replantation plan.”
“A 28-year-old woman presents after a ring avulsion injury to her left ring finger (class III by Urbaniak classification). The finger is completely degloved with the neurovascular bundles avulsed from the palm. She is desperate to keep her finger. How do you approach this?”
Indications
- Absolute: thumb at any level, multiple digits, palm/wrist/forearm amputations, any amputation in a child
- Relative: single digit proximal to FDS insertion, sharp mechanism, young motivated patient, dominant-hand manual worker
- Relative contraindications: single zone II digit distal to FDS, severe crush/avulsion, warm ischaemia over limit, multilevel injury, major comorbidity, self-inflicted with psychiatric concern
- Tamai zones: I distal to DIP, II DIP to PIP, III at PIP, IV proximal to PIP, V through palm
Transport and ischaemia
- Saline-soaked gauze, sealed plastic bag, on ice — never direct contact with ice
- Warm ischaemia: about 12 hours for a finger, 6 hours for a thumb
- Cold ischaemia: up to 24-30 hours for digits
- Document time of amputation and time cooled; transfer immediately
Operative sequence (SHORTEST)
- Shorten bone and stabilise (K-wires, plate or wiring)
- Heal the extensor mechanism
- Only then repair flexor tendons (FDP only in zone II; excise FDS)
- Revascularise: arterial anastomosis first — deflate the tourniquet before this step
- Two or more venous anastomoses (aim for 2:1 vein to artery)
- Epineurial nerve repair of both digital nerves
- Skin coverage (loose closure; graft or flap if tension)
- Transport to recovery with warming, elevation and 30-minute monitoring
Microvascular principles, zone I and zone II
- Trim vessel ends to healthy intima under the microscope; back wall first; 8-12 interrupted 10-0 nylon sutures
- Flush with heparinised saline; no tension; reverse any vein graft
- Zone I: artery-only repair with bleed-through; single longitudinal K-wire; survival greater than 90%
- Zone II flexor: repair FDP only and excise FDS to reduce adhesions; preserve A2 and A4 pulleys
- 10-0 for digital arteries, 11-0 for veins and smaller vessels
Post-operative monitoring and venous congestion
- Every 30 minutes for 48 hours: colour, temperature, capillary refill, Doppler, swelling
- Normal: pink, warm, capillary refill less than 2 seconds, triphasic Doppler
- Venous congestion: dark purple-blue, swollen, tense, capillary refill greater than 3 seconds — leading cause of failure (about 60%)
- Arterial thrombosis: pale, white, cold, no refill, no Doppler — urgent return to theatre
- No-reflow: patent anastomosis but pale, mottled digit — irreversible; convert to revision amputation
- Venous congestion management: release dressings, leeches (Hirudo medicinalis) with prophylactic ciprofloxacin, heparin gauze, theatre if no improvement in 2-3 hours
Complications
- Venous congestion: 15-30%; leeches and urgent revision
- Arterial thrombosis: 10-15%; urgent thrombectomy and revision
- No-reflow: 5-10%; irreversible — revision amputation
- Infection: 5-15%; debridement and prophylactic antibiotics
- Cold intolerance: 50-80% — near-universal long-term complaint
- Tendon adhesion: 30-50% in zone II; tenolysis at 3-4 months
- Non-union: 10-20%; bone graft and revision fixation by 6 months
Special cases
- Paediatric: replant all amputations — superior outcomes, neural plasticity, lower adhesion rates
- Ring avulsion (Urbaniak): class I good, class II moderate, class III poor (30-50% survival); vein grafts almost always needed
- Multiple digits: replant thumb first, then index and long; ring and little may serve as parts donors
- Leech therapy: prophylactic ciprofloxacin mandatory; monitor haemoglobin for cumulative blood loss
Background & Evidence
Epidemiology. Digit amputation is predominantly a disease of working-age adults — industrial and machinery accidents dominate in adults, while doors and household equipment predominate in children. Mechanism is the chief determinant of outcome: sharp guillotine injuries survive best (up to 90% or higher), limited crush 70-85%, severe crush 40-60%, and avulsion 30-50%. Digital neurovascular anatomy — a replantation perspective. - Arteries: each finger receives a radial and an ulnar proper digital artery running alongside the digital nerves. At the mid-proximal phalanx they are about 1-2 mm in diameter — suitable for anastomosis with 10-0 nylon. In the palm the common digital arteries are larger (2-3 mm). In the thumb the princeps pollicis artery (a terminal branch of the radial artery) is the primary target, with two to three dorsal veins. Arterial vasa nervorum supply the digital nerves, so preserving arterial flow also supports nerve recovery.
- Veins: the dorsal digital veins are larger and more numerous than the volar veins — typically two to four, 1-2 mm at the proximal phalanx. Volar veins are smaller and deeper, used as a supplement. Distal to the DIP joint (zone I) veins are usually too small for anastomosis, which is why artery-only repair with bleed-through is accepted there.
- Nerves: the median nerve supplies the volar thumb, index, long and radial half of the ring finger; the ulnar nerve supplies the ulnar half of the ring and the little finger. Each digital nerve is about 1.5-2 mm at the proximal phalanx — suitable for epineurial repair with 9-0 or 10-0 nylon. Recovery after replantation is slower and less complete than after isolated nerve repair because of ischaemia, scarring and adhesions; two-point discrimination of 5-10 mm is a reasonable expectation, with protective sensation returning earlier. Bone and fixation. Bone shortening serves two purposes — removing non-viable or contaminated bone, and reducing tension on the vessel, nerve and tendon repairs (5-10 mm in clean amputations, up to 20-30 mm in crush). Fixation options: two crossed 0.9-1.2 mm K-wires (commonest — quick and cheap but no early mobilisation), intraosseous wiring (good compression, technically demanding in a small fragment), mini-fragment plates and screws (allow earlier mobilisation but need more soft-tissue stripping), and rarely external fixation for multiple or proximal amputations. The zone II (no-man's-land) flexor dilemma. Zone II extends from the distal palmar crease to the FDS insertion, where the FDS and FDP share a narrow fibro-osseous canal bounded by the A2, A3 and A4 pulleys. In a zone II amputation both tendons are divided and the canal is disrupted. Bone shortening effectively shortens and widens the canal, which is why many experienced replant surgeons repair the FDP only and excise the FDS stump — accepting the loss of FDS function in exchange for FDP glide and a lower adhesion rate.
- Level
- Distal to the DIP joint (distal phalanx)
- Replantation considerations
- Excellent survival; minimal bone shortening; no flexor repair; artery-only acceptable with venous drainage by bleed-through
- Level
- DIP to the PIP joint (middle phalanx)
- Replantation considerations
- Good survival; FDP repair needed; limited room for vessel repair; venous repair preferred but artery-only can succeed
- Level
- At the PIP joint
- Replantation considerations
- Moderate survival; the joint may be fixed or fused; consider PIP arthrodesis in crush
- Level
- Proximal to the PIP (proximal phalanx)
- Replantation considerations
- Survival depends on mechanism; zone II flexor considerations apply if proximal to the FDS insertion; bone shortening eases tension
- Level
- Through the palm
- Replantation considerations
- Good survival; larger digital vessels in the palm; robust neurovascular bundles; better function than distal replants
- Description
- Circumferential laceration with intact neurovascular bundles
- Prognosis and management
- Good prognosis; standard repair or replantation
- Description
- Degloving with arterial injury but intact veins
- Prognosis and management
- Moderate prognosis; arterial repair with vein grafts; venous repair may be possible
- Description
- Complete degloving with arterial and venous injury
- Prognosis and management
- Poor prognosis (30-50% survival); bundles avulsed over a long segment; multiple vein and nerve grafts needed; tendon may be avulsed proximally
Special situations. Paediatric replantation is indicated for virtually all amputations regardless of mechanism or level — children have superior neural plasticity, lower adhesion rates, and growing bone that remodels; use smaller suture (11-0 for vessels, 10-0 for nerves) and smaller K-wires (0.7-0.9 mm), and monitor for growth disturbance at the replant site. In multiple digit amputation, replant the thumb first (the most functionally important digit), then the index and long (key pinch and grip); the ring and little fingers are less critical and may serve as composite-tissue or graft donors for the more important digits when vessel length is insufficient — expect 8-16 hours of operating and use two teams. In class III ring avulsion, trace the neurovascular bundles proximally to healthy ends, shorten 15-25 mm, plan for around four reversed vein grafts and sural or antebrachial nerve grafts, and discard the degloved (devascularised) skin, covering with a graft or flap. Key evidence. Survival of single-digit replants proximal to the FDS insertion is about 70-85%, but functional outcomes are variable and often modest, and thumb and multiple-digit replants consistently outperform single non-thumb finger replants (Wong 2023). Venous congestion is the leading cause of early failure (Sears and Chung 2011). Ring avulsion injuries require vein grafting and have lower survival than other mechanisms (Urbaniak 1981). Paediatric replantation outcomes are superior to adult outcomes and all paediatric amputations should be replanted when feasible (Berlin 2014). Medicinal leech therapy salvages venous-congested digits but mandates prophylactic ciprofloxacin against Aeromonas (Pickrell 2020).
References
Single digit replantation proximal to the FDS insertion — systematic review with meta-analysis
Systematic review with meta-analysis of single-digit replantation for amputations proximal to the FDS insertion. Overall digit survival was about 70-85%; functional outcomes (range of motion, grip strength, sensory recovery) were variable and often modest. Thumb and multiple-digit replants consistently outperformed single non-thumb finger replants — a single zone II replant may give comparable or worse function than revision amputation.
Replantation of finger avulsion injuries — systematic review of survival and functional outcomes
Systematic review of finger avulsion replantation. Survival was 50-80% depending on severity; venous congestion was the leading cause of early failure (about 60% of failures). Functional outcomes were poorest for class III ring avulsions, and cold intolerance affected 50-80% and was the most common long-term complaint. Adequate venous anastomoses and vein grafting are critical.
Microvascular management of ring avulsion injuries
The landmark series defining the spectrum of ring avulsion injuries and their microvascular management, graded into three classes by neurovascular and soft-tissue damage. Vein grafting was essential in most replantations because of the long segment of vessel destruction, and complete degloving (class III) had the poorest outcomes regardless of technique.
Digit replantation in children — nationwide analysis of 455 pediatric patients
Nationwide analysis of 455 paediatric digit replantations — the largest paediatric series at the time. Paediatric survival was superior to adult outcomes, and younger age correlated with better sensory recovery and range of motion (neural plasticity and tendon adaptability). All amputated parts in children should be replanted whenever technically feasible.
Leech therapy following digital replantation and revascularization
Clinical series of medicinal leech therapy (Hirudo medicinalis) for venous congestion after digital replantation and revascularization. Leeching salvaged digits in the majority of congested cases; Aeromonas infection occurred, mandating prophylactic ciprofloxacin. Each leech extracts about 5-10 mL of blood per application over a course of several days.