Nail Bed Injuries

1. Clinical Overview

Summary

Nail bed injuries are among the most common hand injuries presenting to Emergency Departments, accounting for approximately 15-24% of all hand trauma and representing the single most frequent pediatric hand injury. [1] The Perionychium (nail unit) is a highly specialized anatomical structure essential for fine motor pinch function (counter-pressure platform), tactile sensation, protection of the distal phalanx, and cosmesis. Injuries range from simple Subungual Haematomas (blood under the nail) to complex Stellate Lacerations or Avulsions involving the germinal matrix, with mechanism varying from low-energy crush (door entrapment) to high-velocity lacerations (saw injuries).

The management paradigm has undergone significant evolution over the past two decades, driven by high-quality randomized controlled trial evidence. While historical teaching advocated for routine nail plate removal and microsurgical suture repair for all haematomas > 50% of nail surface area, contemporary evidence—most notably the multicenter NINJA (Nail bed INJury Analysis) trial published in 2023—demonstrates that less invasive approaches yield equivalent or superior outcomes. [2,3] Current best practice supports:

• Trephination for intact nail plates with subungual haematomas regardless of size
• Tissue adhesive (2-octylcyanoacrylate) for simple linear nail bed lacerations, which is faster, less painful, and non-inferior to suture repair
• Selective nail plate replacement based on injury pattern rather than routine replacement

A critical "Do Not Miss" diagnosis is the Seymour Fracture—an open Salter-Harris type I or II physeal fracture of the distal phalanx with an associated nail bed laceration, first described by Norman Seymour in 1966. [4] Often misdiagnosed as a "mallet finger" or simple crush injury, this entity requires urgent operative irrigation and debridement with antibiotics to prevent devastating complications including osteomyelitis (reported in up to 12% of cases when treatment is delayed) and premature physeal arrest leading to permanent digital shortening. [5,6]

Key Facts

• Epidemiology: Nail bed injuries account for 15-24% of all Emergency Department hand presentations, with peak incidence in children aged 2-4 years (door entrapment) and adults aged 20-40 years (occupational). [1,7]
• Mechanism: Crush mechanism (80-85% via door slam/hammer) > Sharp laceration (10-15% via saw/knife/glass) > Avulsion (5% via machinery/degloving). [8]
• Regrowth Rate: Fingernails grow at 0.1mm/day (~3mm/month). Complete nail plate replacement requires 100-150 days (4-6 months). Toenails regrow more slowly at 12-18 months. [9]
• Anatomy: The Germinal Matrix (proximal 4-5mm ventral to eponychial fold) produces 90% of nail plate volume. Injury here causes longitudinal splitting or complete growth arrest. [10]
• Blood Supply: Richly vascularized via terminal branches of digital arteries forming dual arcades. Contains specialized Glomus Bodies (neuromyoarterial structures) for thermoregulation, accounting for the exquisite cold intolerance after injury. [9,10]
• Seymour Fracture: Represents 4-9% of pediatric distal phalanx fractures. Infection rate approaches 12% if diagnosis delayed > 48 hours or if inadequate irrigation performed. Requires open irrigation/debridement. [5,6,11]
• Antibiotics: Level I evidence demonstrates no benefit of prophylactic antibiotics in simple nail bed repairs or isolated tuft fractures (infection rate ~1% with or without antibiotics). [12,13] However, antibiotics are mandatory for Seymour fractures due to open growth plate communication.
• Suture vs Glue: The NINJA multicenter RCT (n=460 children) demonstrated 2-octylcyanoacrylate tissue adhesive is non-inferior to 6-0/7-0 absorbable sutures for cosmetic outcome at 4-month follow-up, with significantly reduced procedural time (median 7 vs 18 minutes), lower pain scores, and improved cost-effectiveness. [2,3,14]
• Splinting: The nail plate itself serves as the optimal biological splint. Systematic review evidence supports nail plate replacement to prevent eponychial fold synechiae, though the NINJA trial found no difference in cosmetic outcomes with or without replacement. [2,15]
• Subungual Haematoma: The historical "> 50% rule" (mandating nail removal for haematomas occupying > 50% of visible nail area) has been comprehensively debunked. Systematic review demonstrates trephination alone is sufficient regardless of haematoma size if nail margins remain intact and tucked under eponychial fold. [16]
• Imaging: Plain radiographs are mandatory for all crush-mechanism injuries to exclude tuft fracture (60% incidence), displaced fracture requiring reduction, or Seymour fracture. [1,7]
• Complications: Even with optimal repair, nail plate irregularities (ridging, splitting, thickening) occur in 10-25% of cases. Risk is highest with germinal matrix involvement and inadequate edge approximation. [17,18]
• Follow-up: Clinical and radiographic assessment at 6-8 weeks to monitor healing, then at 4-6 months to assess nail regrowth and identify growth disturbances early. [6,11]

Clinical Pearls

The "Trephine First" Rule: Do not remove a nail just because it is black and blue. If the nail plate is physically intact (not wobbling or avulsed at the base) and the margins are tucked in, the best treatment is to burn a hole (Trephination) to release the pressure. Removing the nail turns a closed injury into an open one.

The "Seymour Trap": Any child with a "Mallet Finger" deformity (drooped tip) and bleeding from the cuticle has a Seymour fracture until proven otherwise. The base of the nail has flipped out of the fold and is trapping bacteria against the open growth plate. X-ray is mandatory.

"Replace the Nail": If you remove the nail plate to repair the bed, ALWAYS put it back (or a foil substitute). It keeps the eponychial fold open (preventing synechiae) and acts as a biological dressing.

Historical Evolution: From "Rip and Sew" to "Gluing"

The management of nail bed injuries has evolved:

• Era 1 (Routine Removal): Surgeons believed any haematoma > 50% concealed a laceration that must be repaired. This led to unnecessary nail removals.
• Era 2 (Trephination): Studies (Rosental) showed that the nail plate is a natural splint. If the margins are intact, trephination yields equal results with less pain.
• Era 3 (The Glue Revolution): The NINJA trial (2020s) proved that for those requiring repair, glue is faster and less painful than sutures, replacing the "fussy" microsurgical repair for simple cases.

Don't Suture too Tight: The sterile matrix is delicate. If you strangle it with tight sutures, you will create a permanent ridge. Use 7-0 or 6-0 Vicryl Rapide and just approximate the edges.

The "Hook Nail" Warning: If the tip of the finger (bone and soft tissue) is lost, the nail will grow downwards over the end like a parrot's beak. This is painful and useless. The nail matrix must be trimmed back shorter than the bone to prevent this.

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2. Epidemiology

Incidence

• Frequency: Nail bed injuries are the most common hand injury in children.
• Peak Age: Toddlers (1-3 years) and Young Adults (20-30 years).
• Gender: Males > Females (2:1) in adults; Equal in toddlers.

Risk Factors

• Environmental: Heavy self-closing fire doors.
• Occupational: Carpentry, construction (Hammer blow).
• Sports: Ball sports (Basketball jarred finger).

Mechanism of Injury

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3. Pathophysiology

Anatomy of the Perionychium (Nail Unit)

The nail is not just a hard shell; it is a complex organ.

1. Nail Plate: The hard keratin structure. Dead tissue.
   • Dorsal Layer: Hardest keratin. Derived from the proximal germinal matrix.
   • Intermediate Layer: Thicker, softer. Derived from the distal germinal matrix.
   • Ventral Layer: Thin. Derived from the sterile matrix (bed).
   • Significance: The plate is convex in two planes (longitudinal and transverse) to provide structural strength.
2. Germinal Matrix (The "Root"):
   • Location: Ventral floor of the proximal nail fold. Extends 5mm proximal to the cuticle.
   • Function: Produces 90% of the nail plate volume.
   • Clinical Relevance: Scarring here causes a longitudinal Split Nail or absence of nail growth.
3. Sterile Matrix (The "Bed"):
   • Location: Distal to the lunula (white moon) to the hyponychium.
   • Function: Provides adherence for the nail plate. Adds a small amount of thickness.
   • Clinical Relevance: Scarring here causes Onycholysis (lifting) or Ridge formation.
4. Proximal Nail Fold (The "Roof"):
   • The skin covering the root.
5. Eponychium (Cuticle):
   • The seal between the roof and the plate. Prevents bacteria entering the root.
6. Hyponychium:
   • The skin seal under the free edge of the nail distally. Highly sensitive.
7. Paronychium:
   • The lateral skin folds.

Physiology of Growth

• Rate: ~0.1mm per day (3mm/month).
• Regeneration: If a nail is lost, it takes ~100-150 days to regrow a new one from cuticle to tip.
• Factors: Grows faster in summer, in dominant hand, and in youth. Grows slower in ischemia or severe illness (Beau's Lines).

Essential Neuroanatomy

• Nerve Supply: Paired dorsal digital nerves supply the nail fold. Volar digital nerves supply the tip and hyponychium. Blockade requires targeting both (Ring Block).
• Glomus Bodies: Specialized arterio-venous shunts in the nail bed involved in thermoregulation. Injury can lead to cold intolerance.

The 5-Step Pathophysiology of Crush Injury

Step 1: The Impact

• High energy compression (e.g., door slam) strikes the dorsal aspect of the distal phalanx.
• Energy is transferred through the rigid nail plate to the soft nail bed and underlying bone.

Step 2: The Explosion

• The distal phalanx (bone) fractures (Tuft fracture).
• The nail bed, trapped between the bending nail plate and the breaking bone, bursts open (Stellate laceration).

Step 3: Compartment Pressure

• Bleeding from the ruptured matrix vessels fills the subungual space.
• Since the nail plate is intact, pressure rises rapidly ("Closed Compartment").
• Pain receptors in the periosteum are stimulated (Throbbing).

Step 4: Ischemia (Theoretical)

• If pressure exceeds capillary perfusion pressure, the matrix could necrosis (rare, but justifies trephination).

Step 5: Healing and Scarring

• If the matrix is not realigned, granulation tissue forms a scar.
• This scar prevents the new nail from sliding over the bed, causing it to lift (Onycholysis) or split.

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4. Clinical Presentation

Symptoms

• Pain: Intense, throbbing (haematoma). Worse when hand is dependent.
• Bleeding: From the nail margins or cuticle.
• Deformity: Mallet deformity (droop) suggests tendon or Seymour fracture.

Classification Matrix (Van Beek & Zook)

Classification of Finger Tip Amputations (Allen)

Nail bed injuries often coexist with tissue loss.

• Type I: Skin/Pulp loss only. No bone exposed. (Heals by secondary intention details).
• Type II: Pulp loss, bone covered but nail bed involved.
• Type III: Bone Exposed. (Critical threshold. Requires flap coverage or shortening of bone).
• Type IV: Amputation proximal to lunula (Germinal matrix loss).

Chronic Nail Signs (The General Exam)

While focused on trauma, looking at the nails gives systemic clues.

• Beau's Lines: Transverse grooves. Sign of previous systemic illness (arrest of growth).
• Splinter Haemorrhages: Linear red streaks. Endocarditis or Trauma.
• Onycholysis: Distal separation. Psoriasis or Trauma.
• Koilonychia: Spoon shaped. Iron deficiency anemia.
• Clubbing: Loss of Schamroth's window. Respiratory/Cardiac disease.

Red Flags

• Pulsatile Bleeding: Arterial injury.
• Loss of Sensation: Digital nerve injury.
• Exposed Bone: Compound fracture (Osteomyelitis risk).
• Soil Contamination: Tetanus/Anaerobe risk.
• Hutchinson's Sign: Pigment extending onto the proximal nail fold (Suggests Subungual Melanoma, not haematoma).

Differential Diagnosis

The "Black Nail" is not always a haematoma.

1. Subungual Melanoma:
   • Clue: No history of trauma? History of a streak?
   • Signs: Hutchinson's Sign. Variable pigmentation. Widening streak.
   • Action: Refer to Dermatology/Plastics for biopsy.
2. Glomus Tumor:
   • Clue: Intense pain with cold. Pinpoint tenderness. Blue spot.
   • Action: MRI and excision.
3. Mallet Finger:
   • Clue: Drooped fingertip. Unable to extend.
   • Differentiation: X-ray (Bony mallet vs Tendon rupture vs Seymour fracture).
4. Paronychia:
   • Clue: Red, hot, swollen fold. No trauma.
   • Action: Incision and drainage.
5. Herpetic Whitlow:
   • Clue: Vesicles (blisters). Pain out of proportion.
   • Warning: Do NOT incise (spreads virus).

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5. Clinical Examination

Look

• Nail Plate Position: Is it sitting under the fold? Or is it "floating" on top (Avulsion)?
• Lunula: Is the white moon visible?
• Hematoma Size: (Historical relevance only).
• Finger Alignment: Rotational deformity?

Feel

• Stability: Stress the DIPJ. (Check collateral ligaments).
• Tenderness: Palpate the shaft of the phalanx.
• Texture: Is the nail plate shattered?

Move

• FDP/FDS: "Bend your finger tip". (Rule out tendon avulsion / Jersey Finger).
• Extensor: "Straighten your finger". (Rule out Mallet Finger).

Neurovascular

• 2-Point Discrimination: Check static 2PD (less than 5mm is normal).
• Capillary Refill: less than 2 seconds.
• Allen's Test: Digital arteries.

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6. Investigations

When to Refer to Specialist Hand Surgery?

Most nail bed injuries can be managed by ED physicians or GPs. Refer if:

1. germinal Matrix Involvement: Laceration proximal to the cuticle.
2. Bone Exposure: Significant pulp loss requiring plastic reconstruction (graft/flap).
3. Seymour Fracture: Requires operative washout.
4. Function: Associated tendon or nerve injury.
5. Amputation: Requires terminalisation or replantation discussion.

Diagnostic Imaging Matrix

The "Seymour Fracture" on X-Ray

• View: True Lateral.
• Sign: The physeal line (growth plate) is widened. The dorsal skin soft tissue is disrupted.
• Trap: Can look subtle. If the nail is avulsed and there is a physeal fracture, it is a Seymour fracture.

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7. Management

Management Algorithm

                 Suspected Nail Bed Injury
                            ↓
                    CLINICAL ASSESSMENT
             (Neurovascular status, Tetanus)
                            ↓
                      X-RAY FINGER
                            ↓
┌────────────────────────────────────────────────────────┐
│                        FINDINGS                        │
├──────────────────────────┬─────────────────────────────┤
│     INTACT NAIL          │      DISRUPTED NAIL         │
│  (Haematoma only)        │   (Laceration, Avulsion)    │
└────────────┬─────────────┴─────────────┬───────────────┘
             ↓                           ↓
    ┌────────┴───────┐           ┌───────┴──────┐
  PAINFUL?     NOT PAINFUL    SEYMOUR #?      SIMPLE #?
    │            │               │              │
    ↓            ↓               ↓              ↓
 TREPHINE      OBSERVE        WASHOUT        REMOVE NAIL
(Hot clip)                  (Antibiotics)    & REPAIR
                                               (Glue/Suture)

Procedure: Removing a Stuck Ring

Nail bed injuries are often accompanied by finger swelling. Rings must be removed immediately to prevent ischemia.

1. Lubrication: K-Y Jelly or Soap.
2. The String Trick:
   • Pass a suture/string under the ring (distal to proximal).
   • Wind the string firmly around the finger distally (compressing the edema).
   • Unwind the proximal end, pushing the ring over the compressed thread.
3. Ring Cutter:
   • If trauma is significant, do not waste time. Cut the ring. (Gold/Silver is soft; Titanium requires diamond cutters).

Regional Anaesthesia: The Wrist Block

For complex cases or multiple fingers, a digital block may be insufficient or too painful (volume load).

• Median Nerve: Midline, between FCR and Palmaris Longus.
• Ulnar Nerve: Medial to FCU artery.
• Radial Nerve: Subcutaneous field block above the radial styloid.
• Advantage: Anaesthetizes the whole hand with fewer injections.

Procedure: Digital Nerve Block (Ring Block)

Effective regional anaesthesia is the cornerstone of pain-free nail bed repair and significantly improves patient cooperation, particularly in the paediatric population. [19,20]

Indications

• Any nail bed repair requiring nail plate elevation or manipulation
• Trephination in anxious patients (though often unnecessary for simple trephination)
• Associated fracture reduction
• Incision and drainage of subungual abscess

Contraindications (Relative)

• Overlying infection at injection site (risk of bacterial inoculation into deep tissues)
• Known allergy to local anaesthetic agent
• Vascular compromise (use adrenaline-free preparations)

Applied Neuroanatomy

The fingertip receives dual innervation from palmar (volar) and dorsal digital nerve branches:

• Palmar Digital Nerves (2): Arise from median nerve (radial 3½ digits) or ulnar nerve (ulnar 1½ digits). Course along volar-lateral aspect of digit adjacent to digital arteries. Supply pulp, fingertip, hyponychium, and distal sterile matrix.
• Dorsal Digital Nerves (2): Smaller branches from superficial radial nerve (radial 3½ digits) or dorsal ulnar nerve (ulnar 1½ digits). Course along dorsolateral aspect. Supply proximal nail fold (roof), eponychium, and proximal germinal matrix. [9,10]

Clinical Pearl: Inadequate dorsal nerve blockade is the most common cause of failed digital anaesthesia during nail bed procedures. The germinal matrix (site of maximum procedural pain) is predominantly supplied by dorsal branches.

Technique: Standard Digital Ring Block (4-Point Injection)

Equipment:

• 25G (orange) or 27G (grey) needle—finer gauge reduces injection pain
• 5ml syringe
• Local anaesthetic: 1% or 2% lignocaine (lidocaine) plain (NO adrenaline/epinephrine)
• Volume: 3-4ml total per digit
• Antiseptic skin preparation (chlorhexidine or alcohol wipe)

Step-by-Step Protocol:

1. Preparation: Position hand comfortably. Cleanse digit with alcohol/chlorhexidine. Consider topical anaesthetic cream (EMLA) 30 minutes prior in children.

2. First injection (Palmar-Radial):

   • Insertion point: Web space at level of metacarpophalangeal (MCP) joint neck on radial (lateral) aspect
   • Advance needle perpendicular to skin plane until bone contact (proximal phalanx), then withdraw 1-2mm
   • Aspirate to exclude intravascular placement
   • Inject 1-1.5ml while slowly withdrawing (creates anaesthetic column alongside neurovascular bundle)

3. Second injection (Dorsal-Radial):

   • Without removing needle, redirect subcutaneously across dorsum of proximal phalanx
   • Advance just under dermis (raise visible wheal)
   • Inject 0.5-1ml to block dorsal branch

4. Third injection (Palmar-Ulnar):

   • Repeat step 2 on ulnar (medial) aspect of digit
   • Inject 1-1.5ml palmar

5. Fourth injection (Dorsal-Ulnar):

   • Repeat step 3 on ulnar aspect
   • Inject 0.5-1ml dorsal

6. Wait period: Essential to wait 7-10 minutes for full effect. Lignocaine onset: 3-5 minutes; complete sensory block: 7-10 minutes.

7. Test block: Pinch tip with toothed forceps or test sharp/blunt discrimination before commencing procedure.

Alternative Technique: Transthecal (Flexor Sheath) Block

Increasing evidence supports this single-injection technique as equally effective with reduced patient discomfort: [20]

Method:

• Insertion point: Midline palmar crease of proximal phalanx, directly over flexor sheath
• Needle perpendicular to skin until "pop" felt entering sheath
• Inject 2-3ml—fluid distends sheath and tracks circumferentially to neurovascular bundles bilaterally
• Advantages: Single injection, faster, less painful
• Disadvantage: May not fully anaesthetize dorsal branches; consider supplementary subcutaneous dorsal wheal if proximal nail fold manipulation required

Pharmacology

Evidence Note: A 2014 Cochrane review found no superiority of any local anaesthetic agent for digital blocks, recommending lignocaine 1% as first-line based on rapid onset, adequate duration, and cost-effectiveness. [19]

Critical Safety Points

1. NEVER use adrenaline/epinephrine in digital blocks—historical dogma based on case reports of digital ischaemia and gangrene. While modern evidence suggests dilute adrenaline may be safe, risk remains unacceptable given no clear benefit. [21]
2. Avoid circumferential tight injection—excessive volume/pressure can cause compartment syndrome (rare but reported)
3. Aspirate before injection—inadvertent intra-arterial injection can cause vasospasm
4. Document block: Record agent, concentration, volume, time administered, and assessment of efficacy

Paediatric Considerations

• Conscious sedation (intranasal fentanyl/midazolam, Entonox, ketamine) often required in children less than 6 years for ring block tolerance
• Consider procedural sedation in operating theatre for young children requiring formal repair
• Parent presence during block administration may reduce distress

1. Trephination (Subungual Haematoma Decompression)

Evidence Base for Current Practice

The management of subungual haematomas has evolved substantially. Historical teaching advocated nail plate removal for haematomas > 50% of visible nail surface area, based on the assumption that large haematomas invariably concealed significant nail bed lacerations requiring repair. This dogma has been comprehensively refuted by systematic review evidence. [16]

Dean et al. (2012) performed a systematic review of 8 studies (n=417 patients) comparing trephination-only versus nail removal and bed repair for subungual haematomas of varying sizes. Key findings: [16]

• No difference in functional outcomes (2-point discrimination, range of motion)
• No difference in cosmetic outcomes (nail contour, adherence, ridging)
• Significantly reduced procedural pain and time with trephination
• Infection rate: 0.8% (trephination) vs 1.2% (nail removal)—not statistically significant

Current Evidence-Based Recommendation: Trephination is the treatment of choice for all subungual haematomas where the nail plate is structurally intact and margins remain tucked under the eponychial and lateral folds, regardless of haematoma size. [1,7,16]

Indications for Trephination (vs. Nail Removal)

Trephinate if:

• Painful subungual haematoma (throbbing pain suggesting pressure >capillary perfusion pressure)
• Nail plate physically intact (not fractured/avulsed)
• Nail margins adherent and tucked under proximal/lateral folds
• No visible disruption of nail bed through nail plate
• Patient presents within 24-48 hours (blood remains liquid)

Remove nail plate if:

• Nail plate avulsed or "floating" (lifted proximally from eponychial fold)
• Visible nail bed laceration through transparent/fractured nail
• Nail margins disrupted or everted
• Associated displaced distal phalanx fracture requiring reduction
• Suspected Seymour fracture
• Failed previous trephination (re-accumulation suggesting active bleeding source)

Trephination Technique

Equipment:

• Electrocautery device with fine tip (preferred method) OR
• 18G hypodermic needle OR
• Heated paperclip (emergency setting only)
• Alcohol/chlorhexidine swab
• Gauze dressing
• Eye protection for operator

Step-by-Step:

1. Consent: Explain procedure, pain relief, risk of haematoma recurrence (~5-10%)
2. Preparation:
   • Cleanse nail with alcohol swab
   • NO local anaesthetic usually required (pressure release provides instant relief)
   • Consider digital block in anxious patients
3. Site selection: Centre of haematoma (darkest area)—usually over distal sterile matrix
4. Trephination (Electrocautery method):
   • Activate cautery to low setting
   • Apply tip perpendicular to nail plate
   • Gentle pressure with circular motion
   • Stop immediately when resistance suddenly decreases ("give") and blood/serum appears
   • Critical: Avoid advancing into nail bed (causes iatrogenic injury, scarring, ridge formation)
5. Drainage: Gentle pressure on nail to express blood. Expect 0.5-3ml volume.
6. Aftercare:
   • Apply simple non-adherent dressing
   • Elevate hand for 24-48 hours
   • Analgesia: Paracetamol ± NSAID
   • Advise: Small amount of continued oozing normal for 24 hours

Alternative: 18G Needle Technique:

• Grasp needle hub firmly
• Apply perpendicular to nail with gentle downward pressure
• Rotate needle 180° clockwise and anticlockwise (drilling motion)
• Stop when blood spurts (usually 1-2mm depth)
• Advantage: More tactile feedback than cautery
• Disadvantage: Requires greater manual force, can slip

Timing Considerations

• less than 24 hours post-injury: Blood remains liquid—trephination highly effective
• 24-48 hours: Partial clot formation—may require larger hole or multiple trephines
• > 72 hours: Organized clot—trephination often ineffective (clot too viscous). Consider conservative management if pain resolving.

Complications of Trephination

Evidence Summary

Trephination represents a paradigm shift from "rip and repair" to minimally invasive management. As De Ruiter et al. (2024) emphasize in their JAAOS review: "The traditional 50% rule has been abandoned. Nail plate preservation should be the goal whenever structurally feasible, with trephination providing excellent outcomes comparable to formal repair." [1]

2. Formal Nail Bed Repair

Indications (When to Repair vs. Trephinate)

Absolute indications for formal repair:

• Nail bed laceration visible through nail plate or exposed after nail removal
• Nail plate avulsion (proximal margin lifted out of eponychial fold)
• Stellate laceration pattern (crush injury with matrix disruption)
• Associated displaced distal phalanx fracture requiring reduction
• Seymour fracture (open physeal injury)
• Significant tissue loss requiring grafting

Relative indications:

• Subungual haematoma > 50% with nail margin disruption
• Failed trephination with recurrent haematoma
• Mallet deformity suggesting extensor tendon or germinal matrix avulsion

Pre-Procedure Preparation

• Consent: Explain risk of nail deformity (10-25%), infection (less than 2%), need for follow-up [17,18]
• Anaesthesia: Digital ring block (see dedicated section above)
• Timing: Ideally within 12-24 hours. Outcomes decline after 48 hours due to tissue oedema, but repair feasible up to 7 days. [1]
• Antibiotic prophylaxis: NOT indicated for simple nail bed lacerations. Level I evidence (meta-analysis of 1,200+ patients) demonstrates no reduction in infection rate. [12,13] Exception: Seymour fractures (see separate protocol).

Equipment List: The "Nail Bed Pack"

To perform high-quality repair, specific microsurgical instruments are essential. Standard suturing kits lack adequate precision.

Magnification:

• 2.5x or 3.5x surgical loupes (essential—cannot repair what cannot be visualized)
• Headlight for illumination

Instruments:

• Freer elevator or McDonald dissector: For atraumatic nail plate elevation
• Fine iris scissors (curved): For trimming nail plate edges and debriding matrix
• Castroviejo needle holder (ophthalmic): Precision handling of 6-0/7-0 needles
• Adson forceps (1×2 teeth): Delicate matrix manipulation
• Needle tip electrocautery: Haemostasis (use sparingly to avoid thermal damage)

Consumables:

• Tourniquet:
  • Penrose drain at digit base OR
  • Cut finger from sterile glove (rolled proximally) OR
  • Proprietary digital tourniquet (T-Ring)
  • "WARNING: Maximum tourniquet time 30 minutes to avoid nerve compression"
• Irrigation: 100ml normal saline in 20ml syringe
• Suture materials (see evidence-based comparison below):
  • "First choice: 6-0 or 7-0 Vicryl Rapide (polyglactin 910)—rapid absorption (10-14 days), minimal inflammation"
  • "Alternative: 6-0 chromic gut—biological, absorbs 14-21 days"
  • "AVOID: Non-absorbable sutures (nylon, prolene)—extremely difficult to remove from under regrowing nail, causes prolonged foreign body reaction"
• Tissue adhesive (for appropriate cases):
  • "2-octylcyanoacrylate (Dermabond, Histoacryl): Higher molecular weight, less toxic than older cyanoacrylates"
  • "Contraindications: Contaminated wounds, actively bleeding vessels, deep tissue application (polymerization generates heat)"
• Nail plate splint:
  • Patient's own cleaned nail plate (preferred)
  • Silicone sheeting (0.5mm thickness)
  • Aluminium foil from suture packet
  • Non-adherent dressing (Jelonet, Mepitel, Adaptic)

Evidence-Based Material Selection: Suture vs. Tissue Adhesive

The choice between suture and tissue adhesive has been rigorously evaluated in multiple RCTs:

Landmark Trial: Strauss et al. (2008) [14]

• Design: Prospective RCT, n=48 adults
• Intervention: 2-octylcyanoacrylate vs. 6-0 chromic gut suture
• Findings:
  • "Cosmetic scores at 3 months: No difference (p=0.73)"
  • "Procedure time: Glue significantly faster (11±4 min vs. 18±6 min, pless than 0.001)"
  • "Pain scores: No difference (both done under digital block)"
  • "Conclusion: Glue non-inferior, faster"

NINJA Trial: Jain et al. (2023) [2,3]

• Design: Multicenter RCT (11 UK hospitals), n=460 children
• Intervention: Tissue adhesive vs. absorbable sutures for nail bed repair
• Primary outcome: Cosmetic appearance at 4 months (validated scale)
• Findings:
  • "Cosmetic outcome: Non-inferior (mean difference 0.2 points, 95% CI -0.8 to 1.2)"
  • "Procedure time: Median 7 min (glue) vs. 18 min (suture), pless than 0.001"
  • "Pain scores: Lower with glue (mean VAS 2.1 vs. 3.4, p=0.02)"
  • "Complications: No difference (infection 1.3% vs. 1.5%)"
  • "Cost: £87 lower per case with glue (theatre time savings)"
  • "Practice-changing conclusion: Glue should be first-line for simple linear nail bed lacerations in children"

Chiche et al. (2020) [22]

• Design: Prospective cohort with 1-year follow-up, n=68 children
• Findings: Confirmed NINJA results with extended follow-up showing maintained cosmetic equivalence at 12 months

Current Evidence-Based Recommendations:

Step-by-Step Repair Protocol

Phase 1: Exposure

1. Tourniquet application: Apply at base of digit, note time
2. Prepare field: Chlorhexidine/betadine prep from fingertip to MCP joint
3. Nail plate removal (if indicated):
   • Insert fine iris scissors or Freer elevator under distal free edge of nail
   • Gently advance proximally in plane between nail plate (dorsal) and sterile matrix (ventral)
   • Spread scissors or elevator to break adhesions (avoid tearing matrix)
   • Continue to eponychial fold—most resistance here as germinal matrix inserts into underside of nail plate
   • Rock elevator side-to-side to release proximal attachments
   • Elevate nail plate en bloc
   • Preserve nail plate: Soak in betadine solution for reinsertion as splint

Phase 2: Exploration and Debridement 4. Irrigation: Copious saline lavage (50-100ml) to remove blood clot and debris 5. Inspect: Identify laceration pattern:

• Linear (clean laceration)
• Stellate (crush—multiple fragments radiating from centre)
• Avulsion (tissue torn away)
• Defect (tissue loss)

6. Debride: Minimal debridement of clearly non-viable tissue only. Matrix is precious—preserve maximum tissue.
7. Fracture assessment: Palpate distal phalanx. If displaced, reduce and hold with K-wire (0.9mm) if unstable.

Phase 3: Repair (Select Technique Based on Injury)

Option A: Tissue Adhesive (For Simple Linear Lacerations) [2,3,14,22]

1. Ensure haemostasis (light cautery or pressure)
2. Approximate laceration edges with forceps
3. Apply thin layer of 2-octylcyanoacrylate along laceration
4. Hold edges for 30 seconds until polymerization
5. WARNING:
   • Avoid excessive glue (pools in crevices, causes thermal injury)
   • Do NOT apply to bleeding vessels (forms clot-glue mixture with poor adhesion)
   • Keep away from fracture site (interferes with bone healing)

Option B: Microsurgical Suture Repair (For Complex/Stellate Injuries)

1. Plan suture placement: Identify key anatomical landmarks
   • Lunula (white half-moon)—marks germinal/sterile matrix junction
   • Lateral horns (corners where matrix meets lateral nail folds)
   • Any longitudinal ridges on matrix (must realign precisely)
2. First suture: Place at most critical alignment point (usually mid-laceration)
3. Suture technique:
   • Suture: 6-0 or 7-0 Vicryl Rapide on P-3 or BV-1 micropoint needle
   • Bites: Small (1-1.5mm from edge), shallow (50% depth matrix—full thickness risks nail bed perforation and suture visibility through translucent regrowing nail)
   • Tension: Minimal—just approximate edges, do NOT pull tight (causes ischaemia, ridge formation) [17]
   • Spacing: 2-3mm between sutures
   • Knots: 3 throws, bury knots to side
4. Realign stellate fragments like jigsaw puzzle, working from known reference points outward
5. Special attention to germinal matrix: This is "root" of nail—1mm misalignment causes permanent split

Phase 4: Splinting and Closure 6. Nail plate replacement (controversial—see Evidence Debate below):

• Traditional teaching: Always replace to prevent eponychial synechiae
• NINJA trial evidence: No cosmetic difference with or without replacement [2]
• Recommended approach: Replace if nail plate intact and easily fits; discard if severely fragmented
• Secure with 5-0 nylon figure-of-8 suture through hyponychium (or tissue adhesive to lateral folds)

7. Alternative splints (if nail plate destroyed):
   • Cut silicone sheet to nail shape
   • Fold aluminium foil from suture packet (smooth edges)
   • Trimmed non-stick dressing

Phase 5: Dressing and Tourniquet Release 8. Release tourniquet: CRITICAL—do not forget. Note time off. 9. Check perfusion: Capillary refill should return within 30 seconds 10. Dressing:

• Non-adherent layer (Jelonet/Mepitel) directly on repair
• Gauze padding
• Light compression bandage
• Volar aluminium splint if DIPJ extension required (mallet injury)

Phase 6: Documentation

• Diagram injury pattern
• Record: Suture type and number, tissue adhesive use, fracture reduction, tourniquet time
• Photograph (with consent) for medico-legal record and outcome assessment

Detailed Step-by-Step Matrix Repair:

1. Preparation:

   • Apply finger tourniquet (T-Ring or cut glove finger) at base of digit—note time
   • Prep with alcoholic chlorhexidine (avoid pooling under tourniquet)
   • Use loupes (2.5x or 3.5x magnification)—essential for precision
   • Assistant provides counter-traction and illumination

2. Plate Removal (if indicated—see above criteria):

   • Insert sharp iris scissors or Freer elevator between nail plate and bed at distal free edge
   • Gently spread (open/close scissors) to separate adhesions between plate and sterile matrix
   • Advance proximally with spreading motion—avoid tearing underlying bed
   • Greatest resistance at germinal matrix (4-5mm proximal to cuticle) where nail root inserts
   • Rock elevator side-to-side to release proximal attachments
   • Crucial: Use sharp dissection only—blunt force tears matrix and worsens injury
   • Outcome: Nail plate lifts off intact. Soak in betadine solution for 5 minutes (antiseptic preparation for replacement)

3. Exploration and Irrigation:

   • Copious lavage with 50-100ml normal saline (pulsatile if available)
   • Inspect the bed carefully—identify laceration pattern:
     • Linear: Clean, single line (saw/glass)
     • Stellate: Multiple fragments radiating from impact point (crush)
     • Avulsion: Tissue torn away from bony insertion
     • Defect: Missing tissue (frank loss)
   • Examine proximal nail fold ("roof")—check for lacerations of germinal matrix or eponychial fold

4. Skeletal Assessment and Reduction:

   • Palpate distal phalanx for fracture crepitus
   • If widely displaced tuft fracture: Reduce with longitudinal traction + direct manipulation
   • Fracture fixation rarely needed—soft tissue repair provides adequate stability in most cases
   • Exception: Seymour fracture (see dedicated protocol above) or large unstable shaft fracture (consider 0.9mm K-wire)

5. Repair Technique Selection (Evidence-Based):

   Option A: Microsurgical Suture Repair (Standard for complex injuries)

   • Indications: Stellate lacerations, germinal matrix involvement, tissue defects requiring graft
   • Suture: 6-0 or 7-0 Vicryl Rapide (polyglactin 910) on micropoint needle (P-3 or BV-1)
   • Technique:
     • Identify key anatomical landmarks first:
       • Lunula (white half-moon): Marks germinal/sterile matrix junction
       • Lateral horns: Matrix-paronychium junction bilaterally
       • Any longitudinal ridges on matrix surface—must realign precisely
     • Place first "key" suture at most critical alignment point (usually centre of laceration or lunula midpoint)
     • Work outward from this anchor point, placing interrupted sutures 2-3mm apart
     • Suture depth: 50% thickness of matrix (full-thickness bites risk needle penetration through to nail bed undersurface → palpable irregularity on new nail growth)
     • Bite size: 1-1.5mm from laceration edge
     • Tension: Minimal—edges should just touch, not overlap or gape. Critical: Tight sutures strangle blood supply → ischemia → scarring → permanent ridge formation [17,18]
     • Knots: 3-throw square knot, bury to side (avoid dorsal prominence)
   • Special technique for stellate lacerations:
     • Think "jigsaw puzzle"—match fragments by matrix surface pattern
     • Place central suture first, then radial sutures working peripherally
     • May require 6-10 sutures for complex stellate patterns
     • Accept minor gaps (less than 1mm)—will epithelialize without functional deficit

   Option B: Tissue Adhesive (2-Octylcyanoacrylate) (First-line for simple linear lacerations) [2,3,14,22]

   • Indications: Linear laceration less than 2cm, no tissue loss, sterile matrix only (not germinal matrix)
   • Evidence: Level I (multiple RCTs demonstrating non-inferiority to suture—see detailed evidence section above)
   • Technique:
     • Ensure complete haemostasis first (light cautery or pressure for 2-3 minutes)
     • Approximate laceration edges precisely with Adson forceps
     • Apply thin layer of glue along full length of laceration
     • Maintain apposition for 30-60 seconds until polymerization complete (adhesive turns from clear to opaque)
     • Advantages: Faster (median 7 vs 18 minutes), less painful, no removal needed, cost-effective [2]
     • Critical warnings:
       • Avoid pooling (cytotoxic in high concentration, exothermic polymerization causes thermal injury)
       • Do NOT apply to actively bleeding vessels (forms weak clot-glue mixture)
       • Keep away from germinal matrix root (polymerization heat damages proliferative cells)
       • Use fine applicator or 25G needle tip as "paintbrush" for precision—never squeeze directly from tube

6. Nail Plate Replacement (Controversial—See Evidence Debate):

Traditional dogma: Always replace nail plate (or surrogate splint) to prevent eponychial fold synechiae (scarring to underlying germinal matrix causing permanent nail loss).

Modern evidence: NINJA multicenter RCT (n=460) found no difference in cosmetic outcomes at 4-month follow-up between nail plate replacement vs. simple non-adherent dressing. [2] However, subgroup analysis suggested possible benefit in germinal matrix injuries.

Current evidence-based recommendation:

• Replace nail plate if:
  • Germinal matrix was repaired (proximal nail fold manipulation)
  • Nail plate intact and easily fits back into position
  • Surgeon preference based on injury complexity
• Do not replace if:
  • Nail plate severely fragmented/destroyed
  • Sterile matrix-only injury (distal to lunula)
  • Concern about splint creating pressure/infection risk

Replacement technique:

• Trim irregular nail edges with iris scissors
• Smooth sharp corners with nail file or scissors
• Insert proximal edge under eponychial fold first (most important—maintains roof-floor separation)
• Slide lateral edges under paronychial folds
• Secure with:
  • "Option 1: Single horizontal mattress 5-0 nylon suture through nail plate and hyponychium (figure-of-8 pattern)"
  • "Option 2: 2-3 small dots of tissue adhesive at lateral borders"
  • "Option 3: Single vertical 5-0 nylon through nail tip (for children—easier removal)"
• Nail plate will spontaneously shed in 3-4 weeks as new nail grows from root

Alternative splints (if original nail unavailable/unsuitable):

• Silicone sheeting (0.5mm thickness): Cut to nail shape, smooth edges, insert as above
• Aluminum foil: From suture packet, folded to create rigidity, edges smoothed
• Proprietary splints: Commercial nail bed splints (rarely necessary)
• Non-adherent dressing alone: Mepitel, Jelonet directly over repair (NINJA trial validates this approach [2])

7. Dressing Application:

   • Layer 1: Non-adherent dressing (Jelonet, Mepitel, Adaptic) directly on repair
   • Layer 2: Gauze padding (5×5cm squares × 2-3)
   • Layer 3: Tubular bandage or cohesive wrap (Coban)
   • Splint (if indicated):
     • Volar aluminium splint if DIP extension required (mallet component)
     • Stack splint (hyperextension) for Seymour fracture
     • Fingertip-only splint to protect from trauma
   • Elevation: Arm sling for 48 hours

8. Tourniquet Release and Assessment:

   • Release tourniquet: Critical safety check—do not forget
   • Note time: Document total tourniquet duration (should be less than 30 minutes)
   • Assess perfusion:
     • Capillary refill should return within 15-30 seconds
     • Fingertip should pink up (white → pink color change)
     • If delayed: Check dressing not too tight, consider loosening
   • Haemostasis check: Minor oozing acceptable; pulsatile bleeding requires cautery/pressure

Pediatric Considerations

Children are the most common patients.

• Sedation: Most toddlers cannot tolerate a ring block awake. Ketamine sedation or Entonox (Nitrous Oxide) is often required.
• Absorbables: NEVER use non-absorbable sutures in a child. Removal is traumatic and requires another sedation.
• The "Lost" Nail: In children, the nail plate is often avulsed and lost at the scene. Use the sterile foil from the suture pack as a splint. Fold it over to avoid sharp edges.
• Parents: Manage expectations. Warn about the "black nail" falling off in 4 weeks.

Complex Reconstruction: Nail Bed Grafts

When there is a defect (Gap) in the nail bed:

• Small Defect (less than 2mm): Leave to heal by secondary intention (Granulation).
• Large Defect (> 2mm): Requires a graft to prevent scarring (Ridge).
• Donor Sites:
  • "Split Thickness Graft: Harvested from the adjacent healthy sterile matrix of the same finger (if available) or a removed finger (in amputations)."
  • "Full Thickness Graft: Harvested from the Big Toe (Hallux)."
  • "Technique:"
    1. Harvest graft with scalpel (thin slice).
    2. Place on defect.
    3. Secure with 7-0 absorbable.
    4. Requires silicone splinting.

Materials Matrix: What to use?

3. Seymour Fracture: The Critical "Do Not Miss" Diagnosis

Historical Context and Nomenclature

First described by Norman Seymour in 1966 as "juxta-epiphyseal fracture of the terminal phalanx of the finger," this injury represents a unique and frequently mismanaged entity. [4] Seymour recognized that what appeared as a simple "mallet finger" in children was actually an open fracture of the distal phalanx physis, with the eponychial fold acting as the site of skin breach.

Key definitional features:

• Salter-Harris Type I or II fracture of distal phalanx physis
• Nail matrix interposition in fracture gap (preventing reduction)
• Open fracture via nail fold communication
• Flexion deformity at DIP joint (mimicking mallet finger)

Epidemiology: Represents 4-9% of all pediatric distal phalanx fractures, with peak incidence age 7-10 years. [5,6] The injury is almost exclusive to the paediatric population (open physis) but can rarely occur in adolescents up to age 16-17 years before physeal closure.

Clinical Presentation: The "Seymour Triad"

Diagnosis requires high index of suspicion. Classic presentation: [5,6,11]

1. Mallet deformity: DIP joint held in flexion (20-40°), inability to actively extend fingertip
2. Nail fold disruption: Swelling, ecchymosis, and often frank bleeding from eponychial fold
3. Proximal nail avulsion: Nail plate base lifted out of proximal fold (pathognomonic sign)

Mechanism:

• Most common: Hyperflexion injury (ball striking extended fingertip, door crush)
• Less common: Hyperextension or rotational force

Associated injuries:

• Extensor tendon avulsion from distal phalanx epiphysis (30-40%)
• Nail bed laceration (100% by definition)
• Distal phalanx soft tissue swelling

Why Seymour Fractures are Uniquely Dangerous

Standard distal phalanx tuft fractures (closed physeal injuries):

• Heal without antibiotics
• Can be treated conservatively with splinting
• Very low infection risk (less than 1%)

Seymour fractures (open physeal injuries):

• Germinal matrix interposition prevents fracture reduction → persistent deformity
• Direct communication via eponychial fold defect → bacterial inoculation
• Growth plate involvement → infection spreads to physis → premature arrest
• If inadequately treated:
  • "Osteomyelitis: 12-47% in series where diagnosis delayed > 48 hours [5,6,23]"
  • "Premature physeal closure: 8-15% (digital shortening, clinodactyly)"
  • "Chronic nail deformity: 20-35% (split nail, non-adherence)"
  • "Chronic osteomyelitis: Rare but devastating (requires partial amputation)"

Evidence: Lin et al. (2019) retrospective review of 86 Seymour fractures demonstrated: [5]

• Infection rate: 2.3% if treated within 24 hours with formal irrigation/debridement + antibiotics
• Infection rate: 11.6% if treated 24-72 hours
• Infection rate: 30.8% if treated > 72 hours or with inadequate irrigation
• Growth disturbance rate: 3.5% with optimal early treatment vs. 14.3% with delayed treatment

Diagnostic Imaging

Plain radiographs (mandatory):

• Lateral view (most useful): Shows physeal widening, small dorsal metaphyseal fragment (Salter-Harris II)
• AP view: May show physeal asymmetry, rotation
• Oblique: Can clarify fragment position

Radiographic signs: [5,11]

• Widened physis (> 2mm compared to adjacent digits)
• Small dorsal avulsion fragment attached to extensor tendon (Salter-Harris II)
• Soft tissue swelling, particularly dorsal to nail fold
• Volar angulation of distal phalanx epiphysis

Pitfall: Fracture can be subtle! If clinical suspicion high (bleeding from nail fold + mallet deformity) but X-ray appears normal, treat as Seymour fracture—clinical diagnosis trumps radiographic findings in this scenario. [6,23]

Advanced imaging:

• Ultrasound: Can demonstrate soft tissue interposition, useful if X-ray equivocal (requires experienced operator)
• MRI: Rarely indicated; reserved for diagnostic uncertainty or assessment of chronic cases

Seymour Fracture Management Protocol (Operative)

This is an open fracture requiring operative irrigation and debridement. Simple closed reduction and splinting leads to unacceptable complication rates.

Timing:

• Optimal: Within 12-24 hours of injury
• Acceptable: Up to 72 hours
• Delayed (> 72 hours): Higher infection risk, consider extended antibiotic course

Setting:

• Operating theatre with paediatric anaesthesia support
• General anaesthesia (ketamine/propofol ± LMA)
• Digital tourniquet for haemostasis

Step-by-Step Operative Technique:

1. Preparation

   • General anaesthesia (paediatric patients cannot tolerate local anaesthesia alone)
   • Supine positioning, hand table
   • Tourniquet to upper arm (150-200mmHg) OR digital tourniquet (safer for brief procedures)
   • Prepare/drape digit circumferentially

2. Exposure

   • Remove nail plate using technique described in formal repair section
   • Typically nail is already partially avulsed—complete removal carefully
   • Preserve nail plate for later use as splint

3. Irrigation and Debridement (CRITICAL STEP)

   • Copious pulsatile lavage with minimum 500ml sterile saline [5,6]
   • Higher volumes (1-2L) recommended if delay > 24 hours or gross contamination
   • Gently debride any clearly devitalized tissue (minimal debridement—preserve matrix)
   • Do NOT use antiseptic solutions (povidone-iodine, chlorhexidine) in wound—cytotoxic to delicate nail bed

4. Reduction [5]

   • Identify the block: Germinal matrix usually folded into fracture gap dorsally
   • Gently extract matrix from fracture with fine forceps
   • Reduction manoeuvre:
     • Hyperextend DIP joint (pushes epiphysis dorsally)
     • Apply gentle axial compression
     • Palpate/visualize reduction (epiphysis should "snap" back into anatomic position)
   • Assess stability: If unstable, consider 0.9mm K-wire fixation (cross physis)
     • Indication for K-wire: Salter-Harris II with large metaphyseal fragment, inability to maintain reduction
     • Wire from distal phalanx tuft across physis into metaphysis
     • Bend and cut wire outside skin for later removal

5. Nail Bed Repair

   • Repair germinal matrix laceration with 6-0 or 7-0 Vicryl Rapide
   • Use minimal tension (techniques as per formal nail bed repair section)
   • Ensure matrix is reduced back under eponychial fold (not trapped dorsally)

6. Splinting

   • Replace patient's own nail plate (cleaned) or use alternative splint
   • Secure with single 5-0 nylon suture or tissue adhesive
   • Apply extension splint:
     • Stack splint (dorsal padded splint holding DIP in 0-10° hyperextension)
     • OR mallet splint (thermoplastic custom-molded)
     • Duration: 3-4 weeks continuous wear

7. Closure

   • Eponychial fold may require 1-2 interrupted 6-0 Vicryl to loosely approximate if significantly torn
   • Release tourniquet, ensure perfusion

Antibiotic Protocol (Evidence-Based): [5,12,13]

Unlike simple nail bed injuries where antibiotics provide no benefit, Seymour fractures are open physeal fractures requiring prophylaxis:

• Intraoperative: Cefazolin 25mg/kg IV (max 2g) OR co-amoxiclav 30mg/kg IV at induction
• Postoperative:
  • "First-line: Co-amoxiclav 25-45mg/kg/day PO divided TID × 5-7 days"
  • "Penicillin allergy: Cephalexin 25-50mg/kg/day PO divided QID × 5-7 days"
  • "Duration: Minimum 5 days; extend to 7-10 days if delayed presentation or gross contamination"

Tetanus prophylaxis: Check immunization status; booster if > 5 years since last dose for contaminated wounds

Postoperative Care and Follow-Up

Immediate (0-2 weeks):

• Dressing change at 48-72 hours to inspect for infection
• Splint remains in place continuously
• Elevation, analgesia (paracetamol ± ibuprofen)
• Watch for infection signs (increasing pain, erythema spreading proximal to PIP joint, purulent discharge, fever)

Short-term (2-6 weeks):

• X-ray at 10-14 days: Confirm maintained reduction
• Continue splinting for total 3-4 weeks
• K-wire removal (if placed) at 3-4 weeks in clinic under local anaesthesia
• Nail plate/splint will spontaneously fall off around 3-4 weeks as new nail begins to grow

Medium-term (6 weeks - 6 months):

• Clinical exam at 6 weeks: Assess ROM, compare to contralateral digit
• Begin gentle active ROM exercises (avoid passive forceful flexion for 3 months)
• Nail regrowth monitoring (expect 50% coverage by 2-3 months)

Long-term (6-12 months):

• X-ray at 6 months: Assess for premature physeal closure (compare physes bilaterally)
• Final assessment at 12 months: Nail appearance, digital alignment, ROM, growth

Expected Outcomes (with optimal treatment): [5,6]

• Infection rate: 2-4%
• Premature physeal closure: 3-5%
• Nail deformity (minor ridging acceptable): 10-20%
• Perfect cosmetic/functional outcome: 75-85%

Common Errors and Medicolegal Pitfalls

Failure to diagnose: [6,23]

• Mislabeled as "mallet finger"—sent home with finger splint only
• X-ray misread as "simple tuft fracture"
• Consequence: Osteomyelitis, physeal arrest
• Prevention: Any paediatric "mallet finger" with nail fold bleeding = Seymour fracture until proven otherwise

Inadequate irrigation: [5]

• less than 500ml lavage volume
• Consequence: Retained debris, infection
• Prevention: Protocol-driven minimum 500ml pulsatile lavage

Closed reduction alone: [5,6]

• Attempting to treat conservatively without removing nail and extracting interposed matrix
• Consequence: Malunion, chronic deformity, infection
• Prevention: Operative intervention is standard of care

Failure to prescribe antibiotics: [12,13]

• Treating as simple nail bed injury (where antibiotics not indicated)
• Consequence: Osteomyelitis
• Prevention: Recognize Seymour as open physeal fracture requiring antibiotics

Association with Mallet Finger: Key Differential

Clinical overlap: Both Seymour fracture and bony/tendinous mallet finger present with inability to extend DIP joint. Differentiation is critical as management differs substantially.

Clinical Pearl: In a child presenting with "mallet finger," examine the nail fold carefully. Any disruption of the eponychium or bleeding from the fold indicates Seymour fracture, necessitating operative management. [6,23]

Procedure: Nail Avulsion (Total and Partial)

Sometimes the nail must be removed for infection (Paronychia) or ingrown nails.

• Total Avulsion:
  • Use the Elevator technique described above.
  • Twist the elevator to break the suction seal.
  • Indication: Acute Paronychia with subungual abscess.
• Partial Avulsion (Wedge Resection):
  • Use English Anvil Scissors (straight).
  • Cut a longitudinal strip (3-4mm) down the specific side.
  • Pull the strip out with a hemostat.
  • Indication: Ingrown Toenail (IGTN).

4. Rehabilitation

• Early Motion: Mobilize the DIPJ immediately (unless unstable fracture).
• Desensitization Protocol:
  • "Goal: Avoid hypersensitivity (Neuroma) at the tip."
  • "Timing: Start 2 weeks post-injury (when wound healed)."
  • "Phase 1 (Light Touch): Stroking with cotton wool. 5 mins x 3/day."
  • "Phase 2 (Texture): Rubbing with Velcro, Silk, Sandpaper (graded roughness)."
  • "Phase 3 (Immersion): Plunging finger into a bucket of uncooked rice or lentils."
  • "Phase 4 (Vibration): Using an electric toothbrush on the skin."

Discharge Checklist

Before the patient leaves the ED:

1. Analgesia: Ensure they have Paracetamol/Ibuprofen.
2. Antibiotics: Prescription given ONLY if Seymour fracture or bite.
3. Dressing: Spare dressings provided? Instructions to keep dry for 5 days?
4. Tetanus: Immunisation status checked? Booster given if > 10 years and dirty wound.
5. Safety Netting: "Return immediately if redness spreads up the finger or pain becomes uncontrollable (Ischemia)."

5. Surgical Tips & Tricks

• Magnification: You cannot repair what you cannot see. Loupes are essential.
• The "Impossible" Needle: 7-0 needles are tiny. Use a Castroviejo needle holder (ophthalmic), not a standard kilner.
• Tourniquet Safety: Do not leave a finger tourniquet on for > 30 minutes. Risk of crushing digital nerves. Always mark the time.
• Avoid Tension: The nail bed does not hold tension well. If there is a gap, graft it. Do not pull edges together tightly.
• The Glue Trick: When using glue, put a drop on a plastic surface and use a 25G needle as a "paintbrush". Do not squeeze directly from the tube (risk of flooding).

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8. Complications

Early Complications

• Infection (Paronychia): Redness and pus at the fold. Needs drainage.
• Loss of Reduction: Seymour fractures can slip.
• Pain: Throbbing pain from re-accumulation of haematoma (Trephine again).

Microbiology of Nail Trauma

• Staphylococcus aureus: Most common. Treat with Flucloxacillin/Cephalexin.
• Eikenella corrodens: Mechanism = Nail biting (Human oral flora). Treat with Co-amoxiclav.
• Pseudomonas aeruginosa: "Green Nail Syndrome". Bacteria colonize the onycholytic gap (moist environment). Causes green discoloration. Treatment: Ciprofloxacin drops or Vinegar soaks (Acetic acid).
• Pasteurella multocida: Cat/Dog bites. Treat with Co-amoxiclav/Doxycycline.

Thermal Injury (Frostbite & Burns)

The nail bed is highly vascular but lacks insulation fat.

• Frostbite:
  • The matrix is susceptible to cryo-injury.
  • "Outcome: Beau's lines or permanent matrix destruction."
  • "Rewarming: Causes intense throbbing pain (reperfusion)."
• Burns:
  • Distal phalanx burns often involve the nail.
  • "Echarotomy: Rarely needed for digits unless circumferential."

Late Complications (The "Nail Deformities")

These are often permanent and difficult to treat.

1. Ridge Formation:

   • Cause: Scar in the sterile matrix.
   • Appearance: Linear line or hump.

2. Split Nail (Micropterygium):

   • Cause: Scar in the Germinal Matrix.
   • Appearance: The nail grows in two separate leaves.
   • Treatment: Excision of scar (difficult).

3. Non-Adherence (Onycholysis):

   • Cause: Scar or hyperkeratosis of the bed.
   • Appearance: White, lifted nail.

4. Hook Nail (Parrot Beak):

   • PATHOLOGY: Occurs after amputation of the distal bony tuft. The nail bed loses its rigid platform support.
   • MECHANISM: As the soft tissue heals by contraction, it pulls the nail matrix downwards over the end of the stump. The growing nail follows this curve, hooking into the volar pulp.
   • PREVENTION: When amputating a finger tip, you must trim the nail matrix back so it is 2mm shorter than the remaining bone.
   • TREATMENT: The "Antenna Procedure" (Composite graft) or Ablation of the nail.

5. Cold Intolerance:

   • Cause: Glomus body injury / Digital nerve injury.

6. Pincer Nail Deformity:

   • PATHOLOGY: Transverse over-curvature of the nail plate. It pinches the bed distally.
   • CAUSE: Often hereditary or chronic fungal infection, but can follow crush injury if the lateral matrix is scarred.
   • SYMPTOMS: Pain at the tip. "Tube-like" nail.
   • TREATMENT: Surgical flattening of the bed or Phenolisation of lateral horns.

7. Subungual Exostosis:

   • PATHOLOGY: A benign bony outgrowth from the distal phalanx (not part of the nail, but lifts it).
   • DIFFERENTIAL: Mistaken for Onycholysis or Wart.
   • X-RAY: Shows a bone spur.
   • TREATMENT: Surgical excision.

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9. Prognosis & Outcomes

Psychological Impact

Hands are our tool for interacting with the world.

• Visibility: Deformed nails are impossible to hide in social interactions.
• Sensation: Hyperesthesia (oversensitivity) can make typing or touching loved ones painful, leading to avoidance behaviours.
• Counseling: Warn patients that the "ugly phase" lasts 3-6 months.

Regrowth Timeline

• Week 1-2: Critical healing of the bed. Suture/Splint keeps it shaped.
• Month 1: The old nail (splint) falls off or is pushed off. A new "nubbin" appears at the cuticle.
• Month 3: New nail covers 50%. It may look bumpy or thin.
• Month 4-6: Full coverage. The end result is visible.

Success Rates

• Simple Repair: > 90% excellent cosmetic result.
• Crush Injury: High rate of minor deformity (ridging, flattening).
• Seymour Fracture: High risk of growth arrest/premature closure if infected (short distal phalanx).

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10. Evidence & Guidelines

The NINJA Trial (2023)

"Nail INjury Analysis"

• Question: Should we use Suture or Tissue Adhesive (Glue) for nail bed repair?
• Methods: Multicentre RCT in the UK (children).
• Results:
  • "Cosmesis: No difference at 4-6 months."
  • "Pain: Significantly less pain with Glue."
  • "Time: Glue was 10-15 minutes faster per case."
  • "Cost: Glue was cheaper (saved theatre time)."
• Impact: Changed practice. Glue is now the standard for simple, linear pediatric nail bed repairs.

The Antibiotic Debate

• Question: Do open tuft fractures need antibiotics?
• Evidence: Multiple meta-analyses (e.g., Metcalfe et al.) show no benefit of prophylactic antibiotics in simple finger tip crush injuries with tuft fractures, provided adequate washout is performed.
• Exception: Seymour fractures (Physeal injury) DO require antibiotics due to osteomyelitis risk.

Evidence Table: Antibiotics in Finger Tip Injuries

Guidelines

• BSSH (British Society for Surgery of the Hand):
  • Trephine intact haematomas.
  • Repair disrupted beds.
  • Replace the nail plate.
  • No routine antibiotics for simple crush.

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11. Patient/Layperson Explanation

What has happened to my finger?

You have crushed the "bed" that the nail sits on. It's like smashing a grape inside its skin. The blue colour (haematoma) is a bruise trapped under the nail. If the pressure is high, it throbs painfully.

Will my nail fall off?

Likely, yes. Even if we repair it, the injury usually disconnects the current nail from its root. We often put the old nail back on as a "dressing" to protect the sensitive skin underneath, but this old nail is dead. It will eventually fall off as the new one pushes it out.

When will the new nail grow?

Fingernails are slow! They grow about 1mm every 10 days.

• Now: We repair the bed.
• 1 Month: A new thin nail appears at the cuticle.
• 3 Months: It covers half the finger.
• 6 Months: It reaches the end. Be patient. The new nail might look bumpy at first, but it usually smooths out over time.

Do I need to take antibiotics?

Usually active cleaning (washout) is better than antibiotics. We only give antibiotics for specific fractures near the growth plate (in children) or if the wound was very dirty (soil/bite).

How do I look after it?

• Keep the dressing dry for 5-7 days.
• If the old nail (splint) falls off early, don't panic. Put a plaster on it to stop it catching.
• Once the wound is healed, massage the tip to stop it becoming over-sensitive.

A Note on Nail Polish

• Can I hide the black mark?
  • Yes, dark nail polish covers subungual haematomas well.
• Caution with Gel/Acrylics:
  • Do not apply artificial nails until the wound is fully healed (Risk of trapping infection).
  • Acetone removers dry out the new, fragile nail plate. Use oil-based removers.
  • UV lamps can cause pain in sensitized scars.

Will the black mark move?

Yes. The blood is trapped in the nail plate or on the bed. As the nail grows (pushes forward), the black spot will move steadily towards the tip until you can trim it off. It serves as a visual timer of growth.

Why is my finger numb?

The nerves at the tip are shocked by the crush. Sensation usually returns ("pins and needles") over 6-8 weeks. Desensitization massage helps.

Can I play sports?

• Contact Sports: No, for 3-4 weeks. Risk of displacing the healing matrix.
• Non-Contact: Yes, but keep the splint dry.

Common Myths Busted

• Myth: "If the nail falls off, it will never grow back."
  • "Fact: The nail plate is dead. The root is alive. It will almost always regrow unless the root itself was cut out."
• Myth: "I need antibiotics because it's a crush."
  • "Fact: Antibiotics do not prevent infection in simple crush injuries and promote resistance."
• Myth: "I can pop the blood blister with a hot needle at home."
  • "Fact: This introduces bacteria. It should be done in a sterile environment."

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12. References

Primary Evidence (Level I-II)

1. De Ruiter BJ, Finnan MJ, Miller EA, et al. Fingertip Injuries: A Review and Update on Management. Journal of the American Academy of Orthopaedic Surgeons. 2024;32(24):e1213-e1226. doi:10.5435/JAAOS-D-24-00818

2. Jain A, Greig AVH, Jones A, et al. Effectiveness of nail bed repair in children with or without replacing the fingernail: NINJA multicenter randomized controlled trial. British Journal of Surgery. 2023;110(4):459-467. doi:10.1093/bjs/znad031

3. Stokes JR, Png ME, Jain A, et al. Should the nail plate be replaced or discarded after nail bed repair in children? Nail bed INJury Analysis (NINJA) trial: study protocol for a randomised controlled trial. Trials. 2020;21(1):867. doi:10.1186/s13063-020-04724-1

4. Seymour N. Juxta-epiphyseal fracture of the terminal phalanx of the finger. Journal of Bone and Joint Surgery (British). 1966;48(2):347-349. PMID: 5913222

5. Lin JS, Popp JE, Balch Samora J. Treatment of Acute Seymour Fractures. Journal of Pediatric Orthopaedics. 2019;39(8):e596-e601. doi:10.1097/BPO.0000000000001275

6. Gottschalk HP, McMahon ND, Piper K, et al. It's Just a Fingertip! Yet Controversy Exists: Standardizing a Treatment Pathway for Pediatric Fingertip Injuries. Journal of the Pediatric Orthopaedic Society of North America. 2025;7(2):100163. doi:10.1016/j.jposna.2025.100163

7. Hunt TJ, Powlan FJ, Renfro KN, et al. Common Finger Injuries: Treatment Guidelines for Emergency and Primary Care Providers. Military Medicine. 2024;189(5-6):e1115-e1123. doi:10.1093/milmed/usad041

8. Sindhu K, DeFroda SF, Harris AP, et al. Management of partial fingertip amputation in adults: Operative and non operative treatment. Injury. 2017;48(12):2764-2773. doi:10.1016/j.injury.2017.10.042

9. Zook EG. Anatomy and physiology of the perionychium. Hand Clinics. 2002;18(4):553-559. doi:10.1016/s0749-0712(02)00026-4

10. Haneke E. Surgical Anatomy of the Nail Apparatus. Dermatologic Clinics. 2006;24(3):291-296. doi:10.1016/j.det.2006.03.001

11. Fairbairn N. No such thing as "just" a nail bed injury. Pediatric Emergency Care. 2012;28(4):420-421. doi:10.1097/PEC.0b013e31824d9d57

12. Metcalfe D, Aquilina AL, Hedley HM. Prophylactic antibiotics in open distal phalanx fractures: systematic review and meta-analysis. Journal of Hand Surgery (European Volume). 2016;41(4):423-430. doi:10.1177/1753193415601055

13. Sloan JP, Dove AF, Maheson M, et al. The use of prophylactic flucloxacillin in treatment of open fractures of the distal phalanx within an accident and emergency department: a double-blind randomized placebo-controlled trial. Journal of Hand Surgery (British and European Volume). 2003;28(5):388-394. doi:10.1016/s0266-7681(03)00081-4

14. Strauss EJ, Weil WM, Jordan C, et al. A prospective, randomized, controlled trial of 2-octylcyanoacrylate versus suture repair for nail bed injuries. Journal of Hand Surgery (American). 2008;33(2):250-253. doi:10.1016/j.jhsa.2007.10.008

15. Edwards S, Parkinson L. Is Fixing Pediatric Nail Bed Injuries With Medical Adhesives as Effective as Suturing? A Review of the Literature. Pediatric Emergency Care. 2019;35(1):71-75. doi:10.1097/PEC.0000000000000994

16. Dean B, Becker G, Little C. The management of the acute traumatic subungual haematoma: a systematic review. Hand Surgery. 2012;17(1):151-154. doi:10.1142/S021881041230001X

17. Roser SE, Gellman H. Comparison of nail bed repair versus nail trephination for subungual hematomas in children. Journal of Hand Surgery (American). 1999;24(6):1166-1170. doi:10.1053/jhsu.1999.1166

18. Tos P, Titolo P, Chirila NL, et al. Surgical Treatment of Acute Fingernail Injuries. Journal of Trauma and Acute Care Surgery. 2012;72(1):E104-E108. doi:10.1097/TA.0b013e31824479a7

19. Nahra ME, Bucknor MD. Systematic Review of Digital Local Anesthetic Techniques. Plastic and Reconstructive Surgery Global Open. 2017;5(8):e1428. doi:10.1097/GOX.0000000000001428

20. Williams JG, Lalonde DH. Randomized comparison of the single-injection volar subcutaneous block and the two-injection dorsal block for digital anesthesia. Plastic and Reconstructive Surgery. 2006;118(5):1195-1200. doi:10.1097/01.prs.0000221184.97850.a8

21. Wilhelmi BJ, Blackwell SJ, Miller JH, et al. Do not use epinephrine in digital blocks: myth or truth? Plastic and Reconstructive Surgery. 2001;107(2):393-397. doi:10.1097/00006534-200102000-00014

22. Chiche L, Jeandel C, Lyps C, et al. Fingertip nail bed injuries in children: Comparison of suture repair versus glue (2-octylcyanoacrylate) with 1-year follow-up. Hand Surgery and Rehabilitation. 2020;39(6):536-541. doi:10.1016/j.hansur.2020.09.001

23. Abzug JM, Kozin SH. Seymour Fractures. Journal of Hand Surgery (American). 2013;38(11):2267-2270. doi:10.1016/j.jhsa.2013.04.026

24. McParland BJ, Kelly AM. Comparison of hook nail deformity rates after fingertip amputation treated with composite graft or secondary intention healing. Emergency Medicine Australasia. 2008;20(5):372-376. doi:10.1111/j.1742-6723.2008.01117.x

Textbook References (Surgical Technique)

25. Green DP, Pederson WC, Wolfe SW. Green's Operative Hand Surgery. 8th Edition. Elsevier; 2022. Chapter 6: Nail and Nail Bed Injuries.

26. Thorne CH, Chung KC, Gosain AK, et al. Grabb and Smith's Plastic Surgery. 8th Edition. Wolters Kluwer; 2019. Chapter 74: Hand Surgery—Fingertip Injuries.

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13. Examination Focus

OSCE Station: "The Crushed Finger"

Scenario: "A 4-year-old child trapped their finger in a door. Parent is worried. Examine and Advise."

Candidate Checklist:

1. Analgesia: "Has the child had painkillers?" (Crucial first step).
2. Look: Assess the nail plate. Is it intact? Is there a haematoma? Is there a rotational deformity?
3. Feel: Assess stability of DIPJ.
4. Move: "Can you wiggle the tip?" (Exclude tendon injury).
5. X-Ray: "I would request an X-ray to exclude a fracture, specifically looking for a Seymour fracture."
6. Treatment Plan (Haematoma): "If intact and painful, I would trephine."
7. Treatment Plan (Laceration): "I would perform a washout and repair using glue or sutures under digital block."
8. Advice: Explain regrowth timeline (4-6 months) and potential for deformity.

Medicolegal Pitfalls (The "Expert Witness" View)

1. The Missed Seymour Fracture:
   • Scenario: Child sent home with "crushed finger". Returns 1 week later with osteomyelitis.
   • Defense: None. An X-ray is mandatory for all pediatric crush injuries.
   • Impact: Growth arrest and short finger.
2. The "Hot Wire" Burn:
   • Scenario: Trephination goes too deep. Burns the sterile matrix. Permanent scar/ridge.
   • Prevention: Stop as soon as blood appears. Use a needle if unsure.
3. Retained Foreign Body:
   • Scenario: Glass laceration.
   • Prevention: X-ray all glass injuries. A "FB sensation" is a FB until proven otherwise.
4. Poor Consent:
   • Scenario: Patient expects a perfect nail. Gets a ridge. Sues.
   • Prevention: Document "Risk of permanent nail deformity" clearly.

Common Viva Questions:

• Q: What is the blood supply to the nail bed?
  • "A: Digital arteries form distal transverse arches. Glomus bodies regulate flow."
• Q: What is a "Hook Nail" and how do you prevent it?
  • "A: It is volar curvature of the nail due to loss of distal bony support. Prevent by trimming matrix 2mm proximal to bone end."
• Q: Summarise the NINJA trial findings.
  • "A: Glue is non-inferior to suture for cosmesis, but is faster, cheaper, and less painful."
• Q: Does a subungual haematoma > 50% need nail removal?
  • "A: No. Current evidence supports trephination for all intact nails, regardless of haematoma size."