Nail Bed & Fingertip Injury Repair

Indications and Evidence Base

When to Operate — Nail Bed Injuries

Indications for Nail Plate Removal and Repair:

• Any disruption of the proximal nail fold (nail plate avulsed or displaced from the fold)
• Visible nail bed laceration or avulsion
• Seymour fracture (child with physeal fracture and nail fold disruption)
• Nail plate avulsed from its bed entirely
• (Classic teaching adds "subungual haematoma greater than 50%" — but with an intact nail and nail margin the evidence supports trephination alone irrespective of haematoma size; explore on nail-fold integrity, not haematoma size)

Trephination Only (Conservative):

• Nail plate and nail margin structurally intact (haematoma size is NOT a contraindication to trephination if the nail is intact)
• No displaced or open distal phalanx fracture
• Performed within 48 hours (haematoma liquefied); later, clot may be too organised to drain

Fingertip Reconstruction Indications:

• Allen Zone II or greater: exposed bone requires flap coverage
• Zone I may be conservative (particularly in children — remarkable healing)
• Composite graft (replaced amputated tip) if available within 6 hours, patient cooperative

Key Evidence

Allen 1980 (Hand journal): Original description of the Allen classification of fingertip amputations (Zones I-IV) with treatment recommendations by zone. Landmark paper establishing conservative treatment for Zone I injuries and the principle of matching reconstruction complexity to zone of injury. (This historical paper predates routine PubMed indexing and is cited for completeness without a verified PMID.)

Evidence nuance candidates must know: the most-quoted comparative data actually challenge the dogma of routine nail removal. Roser & Gellman found NO outcome advantage of formal nail bed repair over simple decompression when the nail and nail margin are intact, and the Cochrane review found no proven infection benefit from prophylactic antibiotics after simple repair. The teaching position is therefore: an intact nail plate with an intact nail fold can be decompressed; nail removal is reserved for a disrupted nail fold, an avulsed/displaced plate, or a frank nail-bed laceration where direct repair (suture or tissue adhesive) is needed.

Decision Algorithm

Nail Unit Anatomy

Components of the Nail Unit

Nail Plate:

• Hard keratinised structure produced by the nail matrix
• Grows continuously at approximately 3mm per month (fingernail)
• Attached to nail bed on its undersurface
• Enclosed proximally by nail fold

Germinal Matrix:

• Located under the proximal nail fold — NOT visible without nail plate removal
• Produces approximately 90% of the nail plate
• The lunula (white crescent at base of visible nail) marks its distal extent
• Injury = permanent nail deformity. Even a 1-2mm defect causes split nail or ridging.

Sterile Matrix:

• Extends from distal lunula to hyponychium
• Produces approximately 10% of nail plate
• Anchors the nail plate to the nail bed — provides adhesion
• Injury causes onycholysis (nail fails to adhere) if not repaired

Nail Fold (Eponychium):

• Proximal skin fold overlying the germinal matrix
• Maintains the nail fold space (critical for nail regrowth direction)
• Must be preserved or reconstructed after nail injuries
• Avulsion of nail fold disrupts germinal matrix — Seymour fracture equivalent in children

Hyponychium:

• Thickened epidermis at junction of nail bed and fingertip pulp
• Seal between nail plate and skin — protective barrier
• Can become infected (paronychia pattern) if disrupted

Lateral Nail Folds:

• Skin on each side of nail plate
• Important surgical landmarks for mid-lateral incisions

Allen Classification of Fingertip Amputations

Zone I — Distal to Bone (Subcutaneous Tissue Level):

• Skin and pulp loss only
• No bone exposure
• Best zone for conservative treatment
• Children: remarkable wound contraction and healing — dressings alone
• Adults: semi-occlusive dressings, composite graft if tip available

Zone II — Distal Phalanx Exposed (Bone Level):

• Bone exposed at tip but proximal nail bed preserved
• Requires soft tissue coverage
• Options: V-Y advancement, homodigital island flap, shortening and primary closure
• Goal: sensate, durable, appropriate length fingertip

Zone III — Loss to DIP Joint Level:

• Extensive tissue loss
• Cross-finger flap from adjacent digit (2-stage procedure)
• Thenar flap (for index or middle fingers, younger patients with flexible DIP)
• Pollicisation or microsurgical option for thumb

Zone IV — Proximal to DIP Joint:

• Extensive soft tissue and skeletal loss
• Consider replantation if digit available
• If not: formal amputation, revision to suitable level, or complex reconstruction

Flap Options for Fingertip Reconstruction

V-Y Advancement Flap (Atasoy — Volar):

• V-shaped incision in volar pulp skin, apex proximal
• Mobilise pulp on neurovascular pedicle
• Advance distally to cover tip
• Close donor site as Y-shape
• Suitable for: dorsal oblique and transverse amputation zones
• Limitation: limited advancement (5-8mm), cannot cover large volar losses

Bilateral V-Y (Kutler — Lateral):

• Two V-Y flaps from lateral aspects of fingertip
• More suited to volar oblique amputations
• Provides bilateral sensate skin coverage
• Donor site closed primarily

Homodigital Island Flap:

• Based on proper digital artery (single pedicle)
• Greater advancement possible (10-15mm) compared to standard V-Y
• Provides excellent sensation (nerve included in pedicle)
• Technically more demanding — requires identification of proper digital artery

Cross-Finger Flap:

• 2-stage procedure
• Skin flap raised from dorsum of adjacent digit (typically middle provides to index)
• Sutured to fingertip defect
• Divided at 3 weeks when revascularised
• Donor site skin-grafted
• Provides glabrous skin, but sensate only after re-innervation (months)
• Risk: PIP stiffness from finger immobilisation during first 3 weeks

Thenar Flap:

• Based on thenar skin (glabrous, cosmetically excellent)
• Used for index and middle finger Zone III-IV injuries
• 2-stage: attach finger to thenar region, divide at 3 weeks
• Risk: PIP flexion contracture (especially elderly patients)
• Avoid in patients older than 50 years (poor flexibility, stiffness risk)

Operative Techniques

Subungual Haematoma — Trephination

Setup:

• Digital block (2% lignocaine, or ropivacaine for longer duration)
• No tourniquet required
• Clean and prep finger

Technique:

1. Confirm haematoma on examination (blue-black discoloration under nail plate)
2. Use heated paper clip (traditional), electrocautery tip, or 18-gauge needle rotated gently
3. Apply pressure over thinnest area of haematoma (usually at centre of discoloration)
4. Allow spontaneous decompression — do NOT force instrument through
5. Gently express haematoma
6. No sutures required — wound self-seals
7. Non-adherent dressing, finger tip protection

When Trephination is NOT Sufficient:

• Remove the nail plate if the nail fold is disrupted, the plate is displaced/avulsed, or a nail-bed laceration is suspected — not on haematoma size alone (an intact nail with a large haematoma can still be simply trephined)

Nail Plate Removal and Nail Bed Repair

Setup:

• Digital block
• Tourniquet (penrose drain at base of finger, or ring tourniquet)
• Loupe magnification (essential — minimum 2.5×, ideally 3.5-4.5×)
• 6-0 chromic or 6-0 Vicryl suture (7-0 for germinal matrix)
• Needle driver, fine iris scissors, fine forceps

Step 1 — Nail Plate Removal:

1. Gently advance a flat periosteal elevator or Freer elevator between nail plate and nail bed
2. Begin distally — slide elevator from distal edge under nail plate
3. Advance proximally, separating nail bed adhesions gently
4. Once plate mobile, advance elevator into proximal nail fold to free germinal matrix attachments
5. Extract nail plate intact — preserve for later replacement
6. Clean nail plate with saline, preserve in saline-soaked gauze

Step 2 — Nail Bed Inspection:

1. Visualise entire nail bed under loupe magnification
2. Identify all lacerations — proximal germinal matrix, lunula, sterile matrix
3. Note any missing tissue (avulsion), comminution, or contamination
4. Irrigate wound thoroughly with saline

Step 3 — Nail Bed Repair:

1. Approximate germinal matrix first — highest priority. Use 7-0 absorbable suture (chromic or Vicryl).
2. Repair sterile matrix with 6-0 absorbable suture
3. Interrupted sutures — place as many as needed for full approximation
4. Do NOT use braided non-absorbable suture — knots trap debris, cause granuloma, nail deformity
5. Ensure no gap remains — even 1mm sterile matrix gap may cause nonadherence
6. Tissue adhesive alternative: 2-octylcyanoacrylate (Dermabond) is an evidence-based alternative for nail-bed lacerations — a randomised trial (Strauss 2008) showed equivalent cosmesis and function with roughly one-third of the operative time. Useful in children and clean lacerations; suture remains preferred for complex/comminuted matrix injuries.

Step 4 — Nail Plate Replacement:

1. Fenestrate (create two small drainage holes in) the cleaned nail plate
2. Trim nail plate to fit if needed
3. Slide nail plate under proximal nail fold gently
4. Suture in place with 4-0 nylon through the fenestrations into the lateral nail folds
5. The nail plate acts as: biological dressing, splint for nail fold, template for regrowth
6. Leave for 6-8 weeks until new nail begins to emerge

Alternative if Nail Plate Destroyed:

• Cut sterile foil from suture packet to size
• Silicone sheet or non-adherent dressing (Mepitel)
• Petroleum-impregnated gauze rolled into nail fold space

Seymour Fracture — Specific Protocol

Recognition:

• Child (typically 10-14 years), crush mechanism
• Apparent mallet deformity of fingertip — DIP joint extended to 10-20° or in slight flexion
• Nail plate avulsed from or lodged under nail fold
• Radiograph: physeal fracture (Salter-Harris I or II) of distal phalanx
• Critical recognition point: This is an open fracture through the nail bed

Treatment Protocol:

1. Consent for formal operative treatment (NOT simple outpatient trephination)
2. Digital block and tourniquet
3. Remove nail plate to expose fracture and nail bed
4. Formal irrigation with normal saline (minimum 500mL)
5. Debride contaminated tissue gently — avoid aggressive debridement of viable tissue
6. Reduce physeal fracture — usually reduces anatomically with nail bed repair
7. Repair nail bed with 6-0 chromic
8. Replace nail plate as splint
9. Close soft tissue
10. Systemic antibiotics (oral co-amoxiclav or cephalosporin for 5 days)
11. Radiographic follow-up at 2 weeks to confirm fracture reduction

Why Missed Seymour Fractures Cause Osteomyelitis:

• The nail fold acts as an antibiotic-resistant biofilm barrier
• The fracture communicates with outside through nail bed — open fracture biology
• Without irrigation and debridement, Staphylococcus aureus and mixed oral flora colonise the physeal fracture
• Growth arrest and digital shortening can result

V-Y Advancement Flap (Atasoy)

Indications:

• Zone II fingertip amputation with dorsal oblique or transverse pattern
• Bone exposed at tip, less than 1cm of pulp loss

Technique:

1. Design V-shaped incision on volar pulp: apex proximally at DIP flexion crease, arms extending to each side of fingertip
2. Incise through skin and subcutaneous tissue — preserve the neurovascular bundles on each side within the flap
3. Dissect flap off flexor tendon sheath — stay just superficial to the sheath
4. Test advancement: flap should move distally 5-8mm without tension
5. Place stay suture at flap apex to fingertip level
6. Close donor V as a Y with interrupted absorbable sutures
7. Non-adherent dressing, finger splint in slight flexion for comfort

Complications of Nail Bed Repair

Post-operative Protocol

Immediate Post-operative Care

Dressing:

• Non-adherent primary layer (Mepitel, paraffin gauze) directly on nail bed repair
• Absorptive secondary layer (gauze rolls)
• Light compressive bandage — not tight (digital vascular compromise)
• Finger tip protector or aluminium splint for comfort

Elevation:

• Elevate hand above heart level for first 48 hours — reduces oedema and pain
• Sling during activity for first week

Antibiotics:

• Contaminated wounds: 5 days oral antibiotics (co-amoxiclav or cephalexin)
• Clean lacerations: no antibiotics required
• Seymour fracture (open physeal): 5 days oral antibiotics mandatory

Nail Plate Management Post-operatively

• Leave replaced nail plate in situ for 6-8 weeks
• Dress with non-adherent dressing until nail fold sealed
• New nail begins to emerge from under proximal nail fold at 6-8 weeks
• Old nail plate will be shed as new nail advances
• Full nail regrowth: 3-4 months (fingernail grows 3mm per month)

Follow-up Schedule

Week 1: Wound check — assess for infection, haematoma, nail plate position

Week 2-3: Suture removal (4-0 nylon securing nail plate)

Week 6-8: Assess for new nail emergence, wound healing, early signs of nail deformity

Month 3-4: Final nail appearance assessment — full regrowth expected

Rehabilitation After Flap Reconstruction

V-Y Advancement and Homodigital Island Flap:

• Finger splint in slight flexion for 7-10 days while flap heals
• Active ROM at 10-14 days
• Scar management from 3-4 weeks (silicone gel, massage)
• Return to light work: 3-4 weeks
• Manual labour: 6-8 weeks

Cross-Finger Flap (2-stage):

• First stage: finger sutured to adjacent digit for 3 weeks — limited hand use
• Flap division at 3 weeks under local anaesthesia
• Active ROM immediately after division
• Expect PIP stiffness — hand therapy from division onwards
• Full recovery 8-12 weeks

Counselling Key Points

• Nail deformity (ridging, split) may occur even with perfect repair — inform patient pre-operatively
• Full nail regrowth takes 3-4 months — nail will look abnormal until then
• Fingertip sensitivity returns slowly over 6-18 months for flap reconstructions
• Cold intolerance at fingertip is common for 6-12 months — gradually improves
• Children have superior healing and sensory recovery compared to adults