Ingrown Toenail

1. Clinical Overview

Summary

Ingrown Toenail (Onychocryptosis) is an extremely common, painful condition where the lateral or medial edge of the nail plate pierces the adjacent nail fold, acting as a foreign body. This triggers a cascade of inflammation, infection (predominantly Staphylococcus aureus), and eventually the formation of hypervascular Granulation Tissue. While often trivialized as a minor complaint, ingrown toenails cause significant morbidity, work absenteeism, and impaired quality of life. [1,2]

The condition affects predominantly the great toe (hallux), with the lateral nail edge involved in approximately 85% of cases. Without appropriate treatment, the natural history progresses through stages of increasing severity, from simple inflammation to chronic granulation tissue formation with persistent infection. [3]

The evidence is unequivocal: Partial Nail Avulsion with Phenol Ablation (Chemical Matrixectomy) represents the gold standard surgical treatment, reducing recurrence rates from 70% (simple nail avulsion alone) to less than 5%. [4,5,6] This dramatic improvement in outcomes has been consistently demonstrated across multiple randomized controlled trials and systematic reviews. The Cochrane systematic review definitively established that surgical interventions are superior to non-surgical treatments, and that the addition of phenol significantly reduces recurrence compared to excisional surgery alone. [6]

Key Facts

• The Spicule: The pathology is rarely the entire nail. The problem is usually a sharp spike (spicule) of nail hidden deep within the lateral nail fold, left behind by improper trimming techniques ("bathroom surgery"). This embedded fragment acts as a persistent foreign body, perpetuating the inflammatory cascade.

• Antibiotics Don't Work Alone: The fundamental principle is that antibiotics cannot eradicate infection caused by a retained foreign body (the nail spicule) without removing the foreign body itself. Antibiotics are merely adjunctive therapy for surrounding cellulitis, not definitive treatment. [7]

• Phenolisation Mechanism: Application of 80% phenol solution to the exposed germinal matrix causes coagulation necrosis of the nail-producing epithelial cells, permanently preventing regrowth of that specific nail segment. This chemical ablation is the critical difference between temporary palliation and permanent cure. [8,9]

• Diabetic Foot Considerations: In patients with diabetes mellitus or peripheral vascular disease, ingrown toenails carry significantly higher risks of complications including cellulitis, abscess formation, osteomyelitis, and potential amputation. These patients require urgent assessment and treatment. [10]

Clinical Pearls

"Cut it Straight": The primary preventable cause is cutting the corners of the toenail in a curved fashion. This leaves a hidden spicule that subsequently grows laterally into the soft tissue of the nail fold. Patient education on proper nail care—cutting nails straight across, not too short, and avoiding rounding the corners—is essential preventive medicine. [1,2]

"The Granuloma": The exuberant red, friable mass of tissue overlapping the nail plate is not malignant (in the vast majority of cases). It represents hypertrophic granulation tissue ("proud flesh") attempting to heal the chronic wound. It is highly vascular and bleeds readily with minimal trauma. Silver nitrate cautery can provide temporary symptomatic relief by reducing the granulation tissue bulk. [3]

"Probe the Bone": In diabetic patients or any patient with chronic, non-healing ingrown toenail infection, always probe the base of the wound with a sterile probe. If hard bone is palpable (positive "probe-to-bone" test), this indicates underlying osteomyelitis of the distal phalanx, requiring prolonged antibiotic therapy and potentially bone debridement. [10]

"Tourniquet Hemostasis": Adequate hemostasis during surgery is critical for proper visualization and complete matrix destruction. A simple digital tourniquet (Penrose drain or rubber band at the base of the toe) provides a bloodless field. However, the tourniquet must be released before phenol application to allow vascular uptake of the chemical agent. [11]

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2. Epidemiology

Incidence and Prevalence

Ingrown toenails are one of the most common nail disorders, accounting for approximately 20% of all foot problems presenting to primary care physicians and 15% of all podiatric consultations. The lifetime incidence is estimated at 2.5-5% of the general population. [1,12]

The condition shows bimodal age distribution, with peak incidences in adolescence/young adulthood (ages 14-25) and in elderly populations (over 65 years). The adolescent peak correlates with increased physical activity, tight-fitting athletic footwear, and hormonal changes affecting nail growth rate and perspiration. [12]

Demographics

• Age:

  • Adolescents and young adults (14-25 years): Hyperhidrosis (excessive sweating), increased physical activity, tight athletic shoes, and rapid nail growth contribute to higher risk.
  • Elderly (> 65 years): Onychogryphosis (thickened, curved nails), reduced mobility limiting self-care, and acquired nail deformities increase susceptibility.

• Gender: Male predominance with male-to-female ratio of approximately 2-3:1. This gender disparity is attributed to differences in footwear choices (tighter shoes in males during adolescence), occupational footwear requirements, and possibly higher rates of hyperhidrosis in males. [12,13]

• Laterality: The hallux (great toe) is involved in 95% of cases. Lateral nail border affected in 85% of cases, medial border in 10%, and bilateral lateral involvement in 5%. Ingrown nails of lesser toes are uncommon but do occur, particularly in the fifth toe. [3]

Risk Factors

Intrinsic (Constitutional) Factors

• Genetic Nail Morphology: Inherited nail plate shape including excessively curved lateral edges (pincer nail deformity), wide nail plates relative to the toe width, and thickened nail plates predispose to impingement. [14]

• Biomechanical Factors:

  • Hallux valgus deformity causing medial deviation of the great toe
  • Pronated foot posture increasing medial pressure on the hallux
  • Claw toe or hammer toe deformities causing increased dorsal pressure on the nail plate
  • Pes planus (flat feet) altering weight distribution [3]

• Hyperhidrosis: Excessive perspiration macerates the periungual soft tissue, making it more susceptible to penetration by the nail edge. The softened nail fold offers less resistance to the growing nail spicule. [1]

• Nail Growth Abnormalities: Conditions causing accelerated nail growth (psoriasis, thyrotoxicosis, pregnancy) or abnormal nail plate structure (onychomycosis, trauma) increase risk.

Extrinsic (Environmental) Factors

• Improper Trimming: The single most important modifiable risk factor. Cutting nails too short, rounding the corners, or peeling/tearing the nail edges creates sharp spicules that embed in the lateral nail fold. [1,2,15]

• Footwear:

  • Tight-fitting shoes, particularly in the toe box, compress the lateral nail folds against the nail plate
  • High-heeled shoes increase pressure on the forefoot
  • Athletic shoes worn for prolonged periods create warm, moist environment
  • Inadequate toe box depth in work boots [12]

• Trauma: Acute trauma (stubbing toe, dropped object) or repetitive microtrauma (running, soccer, ballet) can disrupt the normal nail-fold relationship and trigger ingrowth. [3]

• Medications: Retinoids, chemotherapy agents, and targeted cancer therapies (particularly EGFR inhibitors) can alter nail growth patterns and increase susceptibility. [16]

Medical Comorbidities

• Diabetes Mellitus: 15-20% of diabetic patients develop ingrown toenails. Risk factors include peripheral neuropathy (reduced protective sensation leading to delayed presentation), peripheral vascular disease (impaired healing), and immunosuppression (increased infection risk). [10]

• Obesity: Increases plantar pressure and may limit patient's ability to perform proper nail care. [12]

• Peripheral Vascular Disease: Reduces tissue perfusion, impairs healing, and increases risk of tissue necrosis following minor trauma or infection. [10]

• Immunosuppression: Organ transplant recipients, patients on chronic corticosteroids, HIV/AIDS, and chemotherapy patients have higher infection rates and poorer healing outcomes.

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3. Pathophysiology

Normal Nail Anatomy

Understanding the anatomy of the nail unit is fundamental to comprehending ingrown nail pathophysiology and surgical treatment:

• Nail Plate: The visible, keratinized structure composed of tightly packed, dead keratinocytes. Average thickness 0.5-0.7mm. Grows at approximately 1-1.5mm per month (slower than fingernails).

• Nail Bed: Highly vascular epithelial layer beneath the nail plate, extending from the lunula to the hyponychium. Adheres to the nail plate via longitudinal ridges.

• Germinal Matrix: The growth engine of the nail, located beneath the proximal nail fold. Extends approximately 5-7mm proximal to the eponychium and laterally to the lateral nail horns. Produces 90% of the nail plate volume. Critical surgical target for matrixectomy. [11,17]

• Sterile Matrix: Extends from the germinal matrix to the hyponychium, contributing 10% of nail plate thickness.

• Lateral Nail Fold: The soft tissue structures flanking the lateral edges of the nail plate. Site of pathology in ingrown toenails.

• Eponychium (Cuticle): The dorsal fold of skin overlying the proximal nail plate, providing seal against bacterial invasion.

• Hyponychium: Thickened epidermis beneath the free edge of the nail plate.

Pathological Cascade

The development of ingrown toenail follows a predictable sequence:

Stage 1: Mechanical Penetration

A sharp edge of nail plate (spicule) penetrates the lateral nail fold, typically due to:

• Improper trimming leaving a sharp lateral edge
• Trauma causing nail plate disruption
• Lateral pressure from footwear compressing the nail fold against a normal nail edge
• Nail plate deformity (excessive lateral curvature) [3,14]

Stage 2: Inflammatory Response

The penetrating nail spicule acts as a foreign body, triggering acute inflammation:

• Mechanical tissue damage activates inflammatory cytokines (IL-1, IL-6, TNF-α)
• Increased vascular permeability causes edema of the nail fold
• Neutrophil migration into the tissue
• The swollen nail fold is further impaled by the nail spicule, creating a vicious cycle of increasing inflammation and edema [18]

Stage 3: Bacterial Colonization and Infection

The break in skin integrity provides portal of entry for bacteria:

• Staphylococcus aureus (60-70% of cases): Most common pathogen
• Streptococcus species (10-15%)
• Pseudomonas aeruginosa (particularly if patient soaking foot in water): Produces characteristic green discoloration
• Anaerobes (Bacteroides, Peptostreptococcus): In chronic, malodorous infections
• Mixed bacterial flora in chronic cases [1,3]

The retained nail spicule prevents clearance of infection, as antibiotics cannot sterilize a foreign body. Biofilm formation on the nail surface further promotes bacterial persistence. [7]

Stage 4: Chronic Granulation Tissue Formation

Persistent inflammation and failed attempts at healing lead to:

• Formation of hypervascular, friable granulation tissue ("proud flesh")
• Granulation tissue hypertrophies, eventually overgrowing the nail plate laterally
• Bleeding with minimal trauma due to fragile new blood vessels
• Prevents epithelialization and wound closure
• Creates chronic, painful, draining wound [3,18]

Heifetz Classification (Clinical Staging)

The Heifetz classification, first described in 1937, remains the standard clinical staging system: [19]

Stage 1 (Inflammatory Phase):

• Erythema of the lateral nail fold
• Edema and swelling
• Pain with pressure
• No purulent drainage
• Reversible with conservative treatment

Stage 2 (Abscess Formation):

• All features of Stage 1, plus:
• Purulent drainage from the nail fold
• Increased edema
• Bacterial infection established
• Nail spicule has penetrated the dermis
• Requires surgical intervention

Stage 3 (Chronic Granulation):

• All features of Stage 2, plus:
• Hypertrophic granulation tissue formation
• Granulation tissue covering the lateral nail fold/plate
• Chronic drainage (serous or serosanguinous)
• Epithelialization prevented
• Requires surgical excision of granulation tissue and matrixectomy

Recurrence Mechanisms

Understanding why ingrown toenails recur is critical to selecting appropriate surgical treatment:

1. Incomplete Matrix Ablation: The germinal matrix extends 5-7mm proximal to the visible nail fold and laterally in "horns" along the sides. Failure to ablate these lateral horns results in regrowth of a nail spicule from residual matrix cells. [11,17]

2. Inadequate Phenol Application:

   • Insufficient contact time (minimum 3 minutes required)
   • Inadequate phenol concentration (less than 80%)
   • Failure to adequately dry the matrix before phenol application (blood/tissue fluid dilutes phenol)
   • Inadequate neutralization with alcohol allowing premature phenol inactivation [8,9]

3. Mechanical Factors: Even with successful matrixectomy, ongoing biomechanical factors (claw toe, hallux valgus, tight shoes) can cause the remaining nail plate to impinge on the fold.

4. Soft Tissue Factors: Hypertrophic lateral nail fold can impinge on even a normal-width nail, requiring nail fold excision (Winograd procedure). [20]

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4. Clinical Presentation

Symptoms

• Pain: The cardinal symptom. Patients describe sharp, throbbing, "stabbing" pain localized to the lateral or medial aspect of the great toe. Pain is exacerbated by:

  • Pressure from footwear
  • Weight-bearing ambulation
  • Direct pressure
  • At night (increased vascular engorgement)

• Discharge:

  • Stage 2: Purulent (yellow-white pus) indicating bacterial infection
  • Stage 3: Serous or serosanguinous (blood-tinged) drainage from granulation tissue
  • Malodorous discharge suggests anaerobic infection

• Bleeding: Granulation tissue is highly vascular and bleeds spontaneously or with minimal trauma (contact with sock/shoe).

• Functional Impairment:

  • Difficulty wearing shoes (patients may cut holes in shoes to relieve pressure)
  • Limping or altered gait to offload affected toe
  • Inability to participate in sports/exercise
  • Work absenteeism in occupations requiring prolonged standing

Signs

• Erythema: Bright red discoloration of the lateral nail fold, extending proximally along the toe in cases with spreading cellulitis.

• Edema:

  • Localized swelling of the nail fold in Stage 1
  • Diffuse toe swelling in Stages 2-3 (toe appears "twice normal size")
  • Loss of normal nail fold contour

• Granulation Tissue:

  • Cherry-red or pink, moist, friable tissue
  • Overlaps the lateral nail plate
  • Bleeds easily ("kissing the granuloma makes it bleed")
  • May completely obscure the embedded nail spicule

• Purulent Drainage:

  • Yellow-white exudate expressible from the nail fold
  • Green discoloration with Pseudomonas infection

• Tenderness:

  • Extreme point tenderness over the affected nail fold
  • Pain on even gentle palpation
  • Pain with passive toe movement if severe inflammation

• Lymphangitis/Lymphadenitis (in severe cases):

  • Red streaking up the dorsum of the foot (ascending lymphangitis)
  • Tender inguinal lymphadenopathy
  • Systemic signs: fever, rigors (indicating systemic infection requiring hospitalization)

• Nail Spicule: May be visible on careful inspection, but often hidden deep within the nail fold beneath granulation tissue. Requires eversion of the nail fold to visualize.

Special Populations

Diabetic Patients

Red flag presentations requiring urgent intervention: [10]

• Spreading cellulitis beyond the immediate toe
• Fluctuance suggesting abscess formation
• Probe-to-bone test positive (indicating osteomyelitis)
• Systemic signs of infection
• Peripheral neuropathy masking severity (lack of pain despite severe infection)

Peripheral Vascular Disease

• Dusky, cyanotic discoloration of the toe
• Absent pulses (dorsalis pedis, posterior tibial)
• Hair loss, skin atrophy, thickened nails indicating chronic ischemia
• Risk of tissue necrosis even with minor intervention

Immunocompromised

• Atypical organisms (fungi, atypical mycobacteria)
• Rapid progression to severe infection
• Poor response to standard antibiotic therapy

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5. Differential Diagnosis

While ingrown toenail is usually clinically obvious, several conditions can mimic or coexist with onychocryptosis:

Paronychia (Acute or Chronic)

• Acute Paronychia: Infection of the proximal or lateral nail fold without nail plate penetration. Usually follows trauma (hangnail, manicure injury). Caused by S. aureus or Streptococcus. Presents with painful, red, swollen nail fold with purulent drainage. Treatment: incision and drainage, antibiotics. [3]

• Chronic Paronychia: Chronic inflammation of the nail fold, often related to Candida infection. Common in patients with chronic moisture exposure (dishwashers, bartenders). Nail fold appears boggy, erythematous, with loss of cuticle. Treatment: keep dry, topical antifungals.

Subungual Exostosis

• Benign bone tumor arising from distal phalanx
• Presents as painful, firm mass beneath nail plate
• Elevates nail plate, may cause secondary nail deformity
• Diagnosis: X-ray shows bony spur
• Treatment: surgical excision [3]

Subungual Melanoma

• Red flag: Pigmented lesion beneath the nail plate (brown, black, or variegated)
• Hutchinson's sign: pigmentation extending onto proximal or lateral nail fold
• May present with nail dystrophy, bleeding, ulceration
• Amelanotic melanoma can mimic granulation tissue
• Any atypical or non-healing "granulation tissue" requires biopsy
• Treatment: Wide excision +/- amputation, sentinel lymph node biopsy [21]

Subungual Hematoma

• Acute onset following trauma
• Painful, dark red or black discoloration beneath nail plate
• Distinguished from melanoma by history of acute trauma and gradual growth out with the nail
• Treatment: If less than 24-48 hours and painful, trephination for drainage; if painless, observation

Glomus Tumor

• Benign vascular tumor of the nail bed
• Severe, paroxysmal pain (often worse with cold exposure)
• Point tenderness (positive "Love test": exquisite tenderness with pressure from pinhead)
• Blue-red discoloration visible through nail plate
• Diagnosis: MRI
• Treatment: surgical excision [22]

Osteomyelitis of Distal Phalanx

• May result from chronic, untreated ingrown toenail (particularly in diabetics)
• Deep, aching bone pain
• Positive probe-to-bone test
• Imaging: X-ray shows periosteal reaction, bone erosion; MRI more sensitive
• Treatment: prolonged antibiotics (6-12 weeks), +/- surgical debridement [10]

Onychomycosis (Fungal Nail Infection)

• Thickened, discolored, dystrophic nail
• Can coexist with ingrown toenail
• May contribute to abnormal nail growth pattern predisposing to ingrowth
• Diagnosis: nail clippings for microscopy and culture
• Treatment: oral antifungals (terbinafine, itraconazole) [23]

Pincer Nail Deformity (Overcurvature)

• Excessive transverse curvature of the nail plate
• May be congenital or acquired (ill-fitting shoes, aging)
• Lateral edges curl and impinge on nail folds bilaterally
• Creates persistent mechanical pressure
• Treatment: conservative (nail bracing, orthonyxia devices) or surgical (complete matrixectomy - Zadik procedure) [14]

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6. Investigations

Clinical Diagnosis

Ingrown toenail is primarily a clinical diagnosis based on history and physical examination. Investigations are reserved for specific indications:

Plain Radiography (X-ray)

Indications: [3,10]

1. Diabetic patients with ingrown toenail and suspected osteomyelitis
2. Chronic, non-healing infection despite appropriate treatment
3. Suspected foreign body (glass, splinter)
4. Suspected subungual exostosis
5. Prior to surgery in patients with history of trauma (to identify bone fragments)

Findings:

• Osteomyelitis: Periosteal reaction, bone erosion, sequestrum formation (appears 10-14 days after onset)
• Subungual Exostosis: Well-defined bony projection from distal phalanx
• Soft Tissue Swelling: Increased soft tissue density (non-specific)

Technique: AP and lateral views of the affected toe

Magnetic Resonance Imaging (MRI)

Indications: [10]

• Suspected osteomyelitis when X-ray equivocal or negative (MRI 90% sensitive vs. 60% for X-ray)
• Suspected glomus tumor
• Pre-operative planning for complex nail pathology

Findings:

• Osteomyelitis: Bone marrow edema (low T1, high T2 signal), periosteal enhancement
• Glomus Tumor: Well-defined, enhancing soft tissue mass in nail bed

Microbiological Studies

Wound Swab Culture: [7]

Indications:

1. Severe infection requiring systemic antibiotics
2. Diabetic or immunocompromised patients
3. Infection not responding to empiric antibiotics
4. Atypical presentation

Technique:

• Cleanse surrounding skin with antiseptic
• Obtain specimen from base of wound (not superficial drainage)
• Send for aerobic and anaerobic culture

Common Organisms:

• S. aureus (including MRSA in high-prevalence areas)
• Streptococcus species
• Pseudomonas aeruginosa (green discoloration)
• Anaerobes (Bacteroides, Peptostreptococcus) in chronic cases

Histopathology

Indications: [21]

1. Mandatory: Atypical granulation tissue (pigmented, non-healing, rapid growth)
2. Suspected malignancy (melanoma, squamous cell carcinoma)
3. Granulation tissue excised during surgery (routine histology to exclude unexpected pathology)

Technique:

• Send all excised tissue in formalin for histological examination
• Request dermatopathology review if pigmented lesion

Findings:

• Benign granulation tissue: Proliferation of capillaries, fibroblasts, inflammatory cells
• Melanoma: Atypical melanocytes, invasion of dermis
• Squamous cell carcinoma: Atypical keratinocytes with invasion

Blood Tests

Not routinely indicated unless systemic infection suspected:

Indications:

• Systemic signs of infection (fever, rigors)
• Diabetic patients with spreading cellulitis

Tests:

• Complete Blood Count (CBC): Leukocytosis
• C-Reactive Protein (CRP), Erythrocyte Sedimentation Rate (ESR): Elevated in infection/osteomyelitis
• Blood cultures: If sepsis suspected
• Glucose/HbA1 c: If diabetic, assess glycemic control

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7. Management Algorithm

                     INGROWN TOENAIL PRESENTATION
                                ↓
                    ┌──────────────────────────┐
                    │  CLINICAL ASSESSMENT     │
                    │  - Stage (Heifetz 1-3)   │
                    │  - Risk factors          │
                    │  - Comorbidities         │
                    └─────────┬────────────────┘
                              ↓
                    ┌─────────┴─────────┐
                 STAGE 1              STAGE 2/3
             (Inflammation)      (Abscess/Granulation)
                    ↓                    ↓
          ┌─────────┴─────────┐         │
      FIRST TIME         RECURRENT       │
          ↓                   ↓          │
    CONSERVATIVE         SURGICAL     SURGICAL
    - Warm soaks            ↓            ↓
    - Cotton packing     ┌───┴────────────┴─────┐
    - Proper shoes    HIGH RISK?          STANDARD
    - Nail hygiene    (DM/PVD/Immunosupp)  PATIENT
          ↓                 ↓                  ↓
    RESOLUTION?         CAUTIOUS         PHENOL + PNA
          ↓            APPROACH          (Gold Standard)
      ┌───┴────┐          ↓                  ↓
    YES       NO    Simple Avulsion    95-98% Cure Rate
     ↓         ↓    (No Phenol)        Recurrence less than 5%
  EDUCATE  SURGERY  Accept Higher            ↓
  PREVENT          Recurrence Risk      POST-OP CARE
                   OR Senior Review     - Dressings
                                       - Wound care
                                       - Follow-up

SPECIAL CONSIDERATIONS:
- Diabetics: Probe for osteomyelitis, X-ray if chronic
- Severe cellulitis: IV antibiotics first
- Bilateral disease: Stage procedures 2-4 weeks apart
- Pincer nail: Consider Zadik (total matrixectomy)

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8. Management: Conservative

Indications

Conservative management is appropriate for: [1,2,15]

1. Stage 1 disease (mild inflammation, no infection, no granulation)
2. First presentation in compliant patient willing to perform home care
3. Patient preference (refusing surgery)
4. Contraindication to surgery (severe peripheral vascular disease precluding even minor surgery)

Success Rate: 50-60% for Stage 1 disease. NOT effective for Stage 2-3. [6,15]

Conservative Treatment Protocols

1. Warm Water Soaks

Mechanism: Reduces edema, softens tissues, promotes drainage

Protocol:

• Warm (not hot) water with Epsom salts (magnesium sulfate)
• Soak affected foot for 15-20 minutes, 3-4 times daily
• Gently massage the nail fold away from the nail plate during soaking
• Pat dry thoroughly after soaking

2. Cotton Wisp Technique (Cotton Pledget)

Mechanism: Physically lifts the nail edge away from the impinged nail fold

Technique: [1,15]

1. After soaking, soften the nail fold
2. Using a blunt instrument (orange stick, nail file), gently elevate the lateral nail edge
3. Insert a small wisp of cotton wool (or dental floss) under the lateral nail edge
4. Change the cotton daily, advancing it slightly deeper with each change
5. Continue for 2-4 weeks until nail grows past the nail fold

Efficacy: 50-70% success in Stage 1 disease Disadvantages:

• Requires patient dexterity and compliance
• Painful during insertion
• Risk of pushing nail deeper if performed incorrectly
• Ineffective if spicule already deeply embedded

3. Taping Technique

Mechanism: Pulls the nail fold away from the nail plate, reducing pressure

Technique:

1. Apply adhesive tape to the inflamed nail fold
2. Pull the tape laterally and proximally, away from the nail
3. Secure tape on dorsum of toe
4. Replace tape daily
5. Continue for 2-4 weeks

Efficacy: Limited evidence; may help in very mild cases

4. Gutter Splinting

Mechanism: Protective splint under nail edge prevents nail from digging into fold

Technique:

1. Cut a thin strip from vinyl tubing or plastic
2. Insert under the lateral nail edge (creating a "gutter")
3. Secure with adhesive
4. Replace weekly
5. Continue until nail grows out

Efficacy: Variable; requires skill to insert properly

5. Nail Bracing (Orthonyxia)

Mechanism: Orthotic devices gradually flatten curved nail plate, reducing lateral pressure

Devices:

• Metal wire braces cemented to nail surface
• Memory metal clips attached to nail edges
• Adhesive strips that contract and flatten nail

Indication: Pincer nail deformity causing recurrent ingrowth Efficacy: 60-70% success in selected cases Duration: 3-12 months of continuous wear Specialist: Usually performed by podiatrist Cost: Expensive; often not covered by insurance [14]

6. Footwear Modification

Critical component of both conservative and post-surgical management:

• Wide toe box shoes (allow 1cm clearance beyond longest toe)
• Avoid high heels (shift pressure to forefoot)
• Open-toed shoes or sandals during acute phase
• Protective padding around affected toe
• Properly fitted shoes (many patients wear shoes 1-2 sizes too small)

7. Nail Hygiene Education

Prevention is key: [1,2]

• Cut nails straight across (NOT curved)
• Do not cut nails too short (should extend to tip of toe)
• Do not peel or tear nails
• File rough edges smooth
• Cut nails after bathing when softer
• Use proper nail clippers (not scissors)

Topical Therapies

Silver Nitrate Cautery

Indication: Reduction of small granulation tissue in Stage 2

Technique:

1. Protect surrounding skin with petroleum jelly
2. Apply silver nitrate stick to granulation tissue for 10-15 seconds
3. Tissue will turn black (silver staining)
4. Repeat weekly as needed

Efficacy: Temporary reduction; does not address underlying nail spicule Disadvantage: Stains skin black, painful

Topical Antibiotics

Indication: Superficial infection without significant cellulitis

Agents:

• Mupirocin 2% ointment
• Fusidic acid cream
• Neomycin-polymyxin-bacitracin

Application: Twice daily after soaking

Evidence: Minimal evidence of efficacy; does not substitute for foreign body removal [7]

Systemic Antibiotics

Indication: [7]

• Spreading cellulitis extending beyond the immediate toe
• Signs of systemic infection (fever, lymphangitis)
• High-risk patients (diabetics, immunocompromised) with any signs of infection

NOT indicated:

• Stage 1 inflammation without infection
• Localized infection without cellulitis (surgery is the treatment)

Antibiotic Choice:

• First-line: Flucloxacillin 500mg QID or Cephalexin 500mg QID (for S. aureus)
• Penicillin allergy: Clindamycin 300mg QID
• MRSA suspected: Trimethoprim-sulfamethoxazole or Doxycycline
• Pseudomonas suspected: Ciprofloxacin

Duration: 7-10 days

Evidence: Randomized trial by Reyzelman et al. showed that oral antibiotics did NOT improve healing times or reduce pain in patients undergoing nail avulsion. The surgery IS the treatment; antibiotics are only adjunctive for surrounding cellulitis. [7]

When Conservative Management Fails

Indications for Surgery: [1,6]

1. Stage 2 or 3 disease at presentation
2. Failure of conservative treatment after 2-4 weeks
3. Recurrent episodes despite conservative measures
4. Patient unable/unwilling to perform conservative care
5. Diabetic or immunocompromised patient with infection

Outcome of Conservative Treatment:

• Success (Stage 1): 50-60%
• Recurrence rate: 70% will have subsequent episodes requiring eventual surgery [6,15]

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9. Management: Surgical

Surgical intervention is the definitive treatment for ingrown toenails, particularly Stage 2-3 disease and recurrent cases. Multiple techniques exist, but evidence strongly favors Partial Nail Avulsion with Phenol Matrixectomy as the gold standard. [4,5,6]

Pre-Operative Assessment

Patient Evaluation

1. Medical History:

   • Diabetes mellitus (HbA1c, peripheral neuropathy, retinopathy)
   • Peripheral vascular disease (claudication, rest pain)
   • Bleeding disorders or anticoagulation
   • Immunosuppression
   • Allergies (local anesthetics, phenol)
   • Previous toe surgery

2. Vascular Assessment:

   • Palpate dorsalis pedis and posterior tibial pulses
   • Assess capillary refill (less than 2 seconds normal)
   • Skin color and temperature
   • Hair distribution on dorsum of foot
   • If vascular insufficiency: Consider Ankle-Brachial Index (ABI) measurement
     • ABI less than 0.5: Relative contraindication to phenol (risk of tissue necrosis)
     • Consider simple avulsion without phenol, accepting higher recurrence

3. Neurological Assessment (especially diabetics):

   • Light touch sensation
   • Monofilament testing (10g)
   • Vibration sense (128Hz tuning fork)
   • Protective sensation intact?

4. Infection Assessment:

   • Localized vs. spreading cellulitis
   • Systemic signs (fever, rigors)
   • If severe cellulitis: Delay surgery until infection controlled with IV antibiotics
   • If abscess: May proceed with surgery (provides drainage)

Pre-Operative Imaging

• X-ray (AP and lateral toe): If chronic infection, diabetic, or suspected osteomyelitis [10]

Informed Consent

Discuss:

• Procedure details (partial vs. total nail avulsion)
• Phenol vs. no phenol (recurrence rates)
• Risks: infection, bleeding, nerve injury, recurrence, prolonged drainage, nail deformity, chronic pain
• Expected recovery time (2-4 weeks for phenol matrixectomy)
• Alternative treatments
• Post-operative care requirements

Anesthesia

Digital Block (Standard Technique)

Preferred method: Provides complete anesthesia, allows tourniquet use

Technique: [11]

1. Position: Supine, foot comfortably supported

2. Preparation: Cleanse base of toe with antiseptic

3. Anesthetic:

   • 1% or 2% Lidocaine (plain, NO epinephrine)
   • Total volume: 3-5ml (do not exceed safe dose)
   • NEVER use epinephrine (risk of digital ischemia/necrosis)

4. Injection sites: Two approaches:

   Mayo Block (Ring Block):

   • Insert needle at dorsolateral aspect of base of toe
   • Advance to plantar surface
   • Aspirate (ensure not in vessel)
   • Inject 1.5ml while withdrawing
   • Repeat on medial side
   • Advantages: Completely surrounds digital nerves, highly effective

   Transthecal Block:

   • Single injection into flexor tendon sheath at level of MTP joint
   • 3-4ml of anesthetic
   • Advantages: Single injection, faster
   • Disadvantages: Slightly less reliable

5. Wait: 5-10 minutes for complete anesthesia

6. Test: Confirm complete anesthesia before proceeding

Contraindications:

• Allergy to amide local anesthetics (use ester agents: procaine)
• Severe peripheral vascular disease (relative contraindication; weigh risks)

Tourniquet Application

Purpose: Bloodless surgical field for visibility and complete matrix destruction

Technique:

1. Timing: After anesthesia achieved
2. Device:
   • Penrose drain wrapped around base of toe, clamped with hemostat
   • OR purpose-made digital tourniquet
   • OR sterile rubber band
3. Duration: Should not exceed 20-30 minutes (risk of ischemia)
4. Release: BEFORE phenol application (allows vascular uptake of phenol into matrix)

Contraindication: Severe peripheral vascular disease (ABI less than 0.5)

Surgical Procedures

1. Partial Nail Avulsion (PNA) with Phenol Matrixectomy

GOLD STANDARD: Highest cure rate (95-98%), lowest recurrence (less than 5%). [4,5,6,8,9]

Indications:

• Stage 2-3 ingrown toenail (abscess/granulation)
• Recurrent ingrown toenail
• Failed conservative management
• Unilateral or bilateral lateral involvement

Contraindications:

• Severe peripheral vascular disease (ABI less than 0.5): Consider simple avulsion without phenol
• Allergy to phenol (rare): Consider sodium hydroxide or surgical matrixectomy
• Active cellulitis extending up leg: Control infection first

Procedure Steps: [11,17]

1. Preparation:

   • Patient supine, foot elevated and supported
   • Sterile field preparation
   • Digital block + tourniquet

2. Determine Width of Excision:

   • Typically 3-4mm (approx. 1/4 of nail width)
   • Mark the longitudinal cut line with pen on nail surface
   • Excise sufficient width to remove all embedded spicule and inflamed nail fold

3. Longitudinal Split of Nail Plate:

   • Using sharp scissors (iris scissors) or nail splitter
   • Cut through full thickness of nail plate from free edge to eponychium
   • Critical: Must extend cut ALL THE WAY to the proximal nail fold (beneath eponychium)
   • Failure to extend cut proximally leaves residual nail matrix → recurrence ("spicule effect")

4. Avulsion of Nail Strip:

   • Grasp lateral strip with hemostat
   • Twist and pull with rocking motion to avulse from nail bed
   • Remove entire strip including matrix portion
   • Inspect to ensure complete removal (including proximal "horn")

5. Curettage of Matrix:

   • Using small curette, scrape exposed germinal matrix
   • Remove all soft tissue and debris
   • Expose clean, bleeding surface
   • Critical: Ensure complete removal of lateral matrix horn (extends 5-7mm proximal to eponychium)

6. Release Tourniquet:

   • Must release before phenol application
   • Allows brief period of bleeding to identify any residual bleeding points
   • Bleeding confirms viable tissue for phenol uptake

7. Hemostasis and Drying:

   • Pack matrix bed with gauze for 2-3 minutes
   • Completely dry the matrix bed (phenol dilution by blood/fluid reduces efficacy)
   • Use gauze packing and suction to achieve dry field

8. Phenol Application: [8,9]

   • Concentration: 80-88% Liquefied Phenol
   • Applicator: Cotton-tipped applicator or small gauze pledget
   • Technique: a. Soak applicator in phenol b. Apply to exposed germinal matrix with firm pressure c. Rub phenol into ALL areas of matrix (lateral horns, proximal extent) d. Duration: 3 minutes (minimum) - set timer e. Repeat with fresh phenol application x 2-3 times during the 3 minutes
   • Protection: Protect surrounding skin with petroleum jelly to prevent burns
   • Caution: Phenol is caustic - use protective equipment

9. Neutralization:

   • Flush matrix bed thoroughly with 70% isopropyl alcohol
   • Use copious irrigation
   • Alcohol neutralizes phenol and prevents ongoing tissue damage
   • Irrigate for at least 1 minute

10. Hemostasis:

    • Pack wound with gauze
    • Phenol itself has mild hemostatic properties
    • Usually minimal bleeding after phenol application

11. Dressing:

    • Non-adherent dressing (e.g., Xeroform, Vaseline gauze)
    • Bulky gauze padding
    • Tubular bandage or light wrap
    • Avoid tight compression (risk of ischemia)

12. Post-Procedure:

    • Elevate foot for 24-48 hours
    • Analgesia (paracetamol, NSAIDs)
    • Weight-bearing as tolerated (usually immediately)
    • Avoid soaking for 48 hours

Surgical Time: 15-20 minutes

Outcome: [4,5,6]

• Cure rate: 95-98%
• Recurrence: less than 5%
• Satisfaction: 85-90% excellent or good
• Return to normal activities: 2-4 weeks
• Complete healing: 4-6 weeks (prolonged drainage common with phenol)

Advantages:

• Highest success rate
• Office-based procedure
• Low recurrence
• Preserves majority of nail (cosmetically acceptable)

Disadvantages:

• Prolonged drainage (4-6 weeks due to phenol burn)
• Risk of phenol burn to surrounding tissue
• Slightly longer healing vs. simple avulsion
• Cannot use in severe vascular disease

2. Partial Nail Avulsion WITHOUT Phenol (Simple Avulsion)

Indications: [24]

• Severe peripheral vascular disease (ABI less than 0.5)
• Allergy or unavailability of phenol
• Patient preference (shorter healing time)
• Temporary measure in acute infection (definitive phenol procedure later)

Technique:

• Identical to PNA with phenol, but OMIT steps 8-9 (phenol and alcohol)
• After avulsion, simply pack wound with dressing

Outcome:

• Recurrence: 60-70% (significantly higher than phenol)
• Healing: Faster (2-3 weeks)
• Advantages: Faster healing, safer in vascular disease
• Disadvantages: High recurrence rate requiring repeat surgery

Clinical Pearl: Some surgeons perform initial simple avulsion for acute infection, then plan phenol matrixectomy 4-6 weeks later once infection cleared. This staged approach reduces infection risk while preserving low recurrence rate of phenol.

3. Winograd Procedure (Excisional Matrixectomy)

Indication: [20]

• Massive hypertrophic granulation tissue requiring excision
• Very wide nail plate requiring significant width reduction
• Failed phenol matrixectomy (persistent recurrence)
• Surgeon preference (some surgeons prefer surgical over chemical matrixectomy)

Technique:

1. Partial nail avulsion (as above)
2. Elliptical excision of lateral nail fold including:
   • Full-thickness skin excision
   • Underlying granulation tissue
   • Hypertrophied soft tissue
   • Germinal matrix (dissected out sharply)
3. Suture closure: 4-0 or 5-0 absorbable or non-absorbable sutures
4. Dressing

Outcome:

• Recurrence: 5-10% (similar to phenol if matrix completely excised)
• Healing: 3-4 weeks
• Advantages: Direct visualization of matrix, complete excision of granulation tissue
• Disadvantages: More invasive, sutures required, more post-op pain, longer healing, risk of nail narrowing/deformity

4. Zadik Procedure (Total Matrixectomy)

Indication: [3]

• Recurrent failure of partial procedures
• Severe pincer nail deformity
• Onychogryphosis (ram's horn nail)
• Bilateral ingrowth with patient accepting complete nail loss
• Chronic pain refractory to partial procedures

Technique:

1. Complete nail plate avulsion: Remove entire nail
2. Excision of entire germinal matrix:
   • Incision along proximal nail fold
   • Elevate eponychium
   • Excise entire matrix (extending 5-7mm proximal to nail fold)
3. Phenolization (optional): Apply phenol to entire matrix bed
4. Closure: Suture proximal nail fold back to nail bed

Outcome:

• Result: Permanent nail loss (no nail will ever regrow)
• Recurrence: Near zero (no matrix remains)
• Healing: 4-6 weeks
• Satisfaction: Variable (some patients unhappy with cosmetic result of absent nail)

Advantages:

• Definitive solution for recurrent problems
• Eliminates source of pain

Disadvantages:

• Permanent nail loss (cosmetically unacceptable to many)
• More extensive surgery
• Longer recovery
• Risk of painful scar tissue formation

5. Alternative Methods (Limited Evidence)

Laser Matrixectomy (CO2, Er:YAG): [25]

• Laser ablation of germinal matrix
• Recurrence: 5-15%
• Advantages: Precision, less bleeding
• Disadvantages: Expensive equipment, limited availability, inconsistent outcomes

Sodium Hydroxide Matrixectomy: [26]

• 10% sodium hydroxide applied for 30-60 seconds (vs. 3 minutes for phenol)
• Theoretically faster healing than phenol
• Recent studies show comparable recurrence rates (5-8%)
• Less evidence base than phenol
• Not widely adopted

Cryotherapy:

• Liquid nitrogen application to matrix
• Poor efficacy (high recurrence > 30%)
• Not recommended

Electrocautery:

• Cauterization of matrix
• Moderate recurrence (15-25%)
• Inconsistent results

Comparison of Surgical Techniques

Cochrane Review Conclusion (2012, updated 2024): Surgical interventions are more effective than non-surgical treatments for ingrown toenails. Partial nail avulsion combined with phenol matrixectomy has the lowest recurrence rate and is the recommended first-line surgical treatment. [6]

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10. Post-Operative Care

Immediate Post-Operative (First 48 Hours)

Elevation:

• Elevate foot above heart level as much as possible
• Reduces edema and pain
• Sleep with foot elevated on pillows

Analgesia:

• Paracetamol 1g QID regularly
• Ibuprofen 400mg TID (if no contraindications)
• Moderate pain expected for 24-48 hours
• Severe, escalating pain: Contact surgeon (rule out infection, hematoma)

Activity:

• Weight-bearing as tolerated
• Most patients can walk immediately with appropriate footwear
• Avoid prolonged standing or vigorous exercise for 48 hours

Dressing:

• Keep dressing dry and clean for 48 hours
• Do NOT remove initial dressing
• Expect some blood-staining (normal)

Wound Care (Day 2 Onwards)

Dressing Changes: [11]

1. Frequency: Daily after initial 48 hours

2. Technique:

   • Soak foot in warm salt water for 10 minutes to soften dressing
   • Gently remove dressing (do not force if stuck - soak more)
   • Cleanse wound with normal saline or clean water
   • Pat dry
   • Apply non-adherent dressing (Xeroform, Vaseline gauze)
   • Cover with dry gauze
   • Secure with tubular bandage or light tape

3. Expected Appearance:

   • Week 1-2: Wound moist, some serous drainage, white slough (phenol burn)
   • Week 3-4: Decreasing drainage, granulation tissue forming
   • Week 5-6: Epithelialization, wound closure

4. Drainage:

   • Phenol matrixectomy: Prolonged serous drainage (4-6 weeks) is NORMAL
   • This is chemical burn healing, NOT infection
   • Reassure patient this is expected

Bathing:

• Avoid soaking for first 48 hours
• After 48 hours: Daily soaks in warm salt water (Epsom salts)
• Keep wound clean and dry between soaks
• Showering permitted (keep dressing on or change immediately after)

Footwear:

• Open-toed shoes or sandals for first 2 weeks
• Wide toe box shoes thereafter
• Avoid tight shoes, high heels
• Protective dressing/padding if shoes contact wound

Follow-Up Schedule

Week 1: [11]

• Review wound
• Check for signs of infection (see below)
• Confirm proper dressing technique
• Reinforce wound care instructions

Week 2-4:

• Monitor healing progress
• Address any concerns
• For phenol cases: reassure about prolonged drainage

Week 6:

• Confirm complete healing
• Nail hygiene education
• Footwear advice
• Discharge if healed

Complications and Management

Infection (5-10% incidence) [3]

Signs:

• Increasing pain after initial improvement
• Increased erythema spreading beyond wound
• Purulent (yellow-green) drainage
• Warmth
• Fever
• Lymphangitis (red streaking)

Management:

• Swab for culture
• Oral antibiotics: Flucloxacillin 500mg QID or Cephalexin 500mg QID
• If severe: Hospital admission for IV antibiotics
• Daily dressing changes
• Consider removing dressings to allow open healing

Prevention:

• Proper sterile technique
• Avoid tight, occlusive dressings
• Keep wound clean and dry

Prolonged Drainage (Common with Phenol)

Expected:

• Serous drainage for 4-6 weeks is NORMAL after phenol
• Due to chemical burn healing
• Not a complication if wound appears healthy otherwise

Management:

• Reassure patient
• Continue daily dressing changes
• Absorb drainage with gauze padding

Red Flags (suggesting NOT normal drainage):

• Purulent drainage (infection)
• Foul odor
• Increasing pain
• Failure to improve by 6 weeks

Recurrence (Overall: 5-15% depending on technique) [4,5,6]

Causes:

• Incomplete matrix ablation (commonest)
• Inadequate phenol application (time/concentration)
• Persistent biomechanical factors (claw toe, tight shoes)
• Pincer nail deformity

Prevention:

• Ensure complete nail strip excision to proximal matrix
• Adequate phenol contact time (minimum 3 minutes)
• Post-op nail hygiene education
• Appropriate footwear

Management if Recurrence:

• If early (less than 6 months): Consider repeat partial procedure with meticulous matrix excision
• If recurrent failures: Consider Winograd or Zadik procedure
• Address biomechanical factors

Phenol Burn to Surrounding Tissue

Presentation:

• White or gray discoloration of periwound skin
• Delayed healing
• Excessive drainage

Prevention:

• Protect surrounding skin with petroleum jelly
• Careful phenol application
• Thorough alcohol neutralization

Management:

• Usually heals spontaneously with time (6-8 weeks)
• Daily dressing changes
• Wound care as above

Nail Deformity

Types:

• Narrowed nail (expected with partial avulsion)
• Nail spike (incomplete matrix ablation)
• Dystrophic nail growth (matrix damage)
• Nail loss (over-aggressive procedure)

Management:

• Reassure: Mild narrowing is expected and cosmetically acceptable
• Nail spike: Requires repeat matrixectomy
• Cosmetically unacceptable result: Consider completion to total matrixectomy

Chronic Pain

Rare but troublesome complication:

• Neuroma formation at surgical site
• Scar tissue causing irritation

Management:

• Conservative: Shoe modification, padding
• Intralesional corticosteroid injection
• If persistent: Surgical excision of neuroma

Patient Education

Nail Care (Prevention of Recurrence): [1,2]

1. Cutting Technique:

   • Cut nails straight across
   • Do NOT round corners
   • Do not cut too short (should extend to tip of toe)
   • File rough edges smooth

2. When to Cut:

   • After bathing (nails are softer)
   • Every 2-3 weeks
   • Use proper nail clippers (not scissors)

3. Footwear:

   • Properly fitted shoes (measured professionally)
   • Wide toe box
   • Avoid high heels
   • Avoid tight athletic shoes
   • Change socks daily

4. Foot Hygiene:

   • Wash feet daily
   • Dry thoroughly between toes
   • Manage hyperhidrosis (antiperspirant powders, breathable socks)

When to Seek Help:

• Early signs of recurrence (pain, redness at nail fold)
• Signs of infection
• Any concerns about wound healing

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11. Special Populations

Diabetic Patients

Ingrown toenails in diabetic patients are a potentially limb-threatening condition requiring heightened vigilance. [10]

Risk Factors:

• Peripheral Neuropathy: Loss of protective sensation → delayed presentation → advanced infection at diagnosis
• Peripheral Vascular Disease: Impaired tissue perfusion → poor wound healing → increased risk of gangrene
• Immunosuppression: Hyperglycemia impairs neutrophil function → increased infection risk
• Onychomycosis: Thickened, dystrophic nails (common in diabetics) → nail deformity predisposing to ingrowth

Assessment:

1. Vascular: Pulses, ABI, capillary refill, skin changes
2. Neurological: Monofilament, vibration, protective sensation
3. Glycemic Control: HbA1c (target less than 7% for optimal healing)
4. Infection: Probe-to-bone test (if positive → osteomyelitis)
5. Imaging: X-ray for any diabetic with ingrown nail and infection

Management Principles:

• Urgent treatment: Do not delay
• Infection control: Low threshold for antibiotics
• Vascular assessment: If ABI less than 0.5, consider simple avulsion without phenol (or vascular surgery referral first)
• Glycemic optimization: Coordinate with endocrinology/diabetes team
• Probe-to-bone positive: MRI to confirm osteomyelitis; 6-12 weeks antibiotics +/- bone debridement
• Close follow-up: Weekly initially

Surgical Considerations:

• Phenol matrixectomy can be performed if adequate vascularity (ABI > 0.5)
• If severe vascular disease: Simple avulsion (accept higher recurrence) OR address vascular disease first
• Meticulous hemostasis
• Avoid tight dressings

Post-Operative:

• Daily wound inspection
• Offloading (protective footwear)
• Aggressive treatment of any infection

Complications:

• Higher infection rate (15-20% vs. 5-10% in non-diabetics)
• Slower healing (6-8 weeks vs. 4-6 weeks)
• Risk of progression to gangrene and amputation if infection uncontrolled

Peripheral Vascular Disease (PVD)

Assessment:

• Palpable pulses (dorsalis pedis, posterior tibial)
• Ankle-Brachial Index (ABI):
  • "Normal: 0.9-1.3"
  • "Mild PVD: 0.7-0.9"
  • "Moderate PVD: 0.4-0.7"
  • "Severe PVD: less than 0.4"
• Toe-Brachial Index if calcified vessels
• Vascular surgery consultation if ABI less than 0.5

Surgical Decision:

• ABI > 0.7: Proceed with phenol matrixectomy
• ABI 0.5-0.7: Consider simple avulsion without phenol, or optimize vascular status first
• ABI less than 0.5:
  • High risk of tissue necrosis with surgery
  • Vascular revascularization first, OR
  • Simple avulsion only (no phenol), OR
  • Conservative management if feasible

Phenol Contraindication: Phenol creates a chemical burn requiring good blood supply to heal. In severe PVD, this burn may not heal, leading to tissue necrosis and potential toe loss. Risk vs. benefit must be carefully considered.

Immunocompromised Patients

Populations:

• Organ transplant recipients
• HIV/AIDS
• Chronic corticosteroid use
• Chemotherapy patients
• Biologic immunosuppressants (anti-TNF agents, etc.)

Considerations:

• Higher infection risk
• Atypical organisms (fungi, mycobacteria)
• Impaired wound healing
• Coordinate with primary team (oncology, infectious disease, transplant)
• Consider prophylactic antibiotics peri-operatively
• Extended antibiotic courses if infection develops
• Close follow-up

Pediatric Patients

Differences from Adults:

• Often related to tight shoes (growing feet)
• Higher proportion of congenital nail deformities
• Cooperation challenges during procedure
• May require general anesthesia for very young children

Management:

• Conservative management trial first (high success in children)
• Parental education on nail care and footwear
• Phenol matrixectomy as effective as in adults if surgery needed
• Avoid Zadik procedure (permanent nail loss) unless absolutely necessary

Elderly Patients

Challenges:

• Multiple comorbidities (diabetes, PVD, anticoagulation)
• Cognitive impairment → poor post-op wound care
• Reduced mobility → difficulty with dressing changes
• Onychogryphosis (ram's horn nail) common
• Higher risk of falls (pain affecting gait)

Management:

• Address underlying nail deformity (may require Zadik for onychogryphosis)
• Arrange home nursing for dressing changes if needed
• Optimize medical comorbidities pre-operatively
• Consider anticoagulation management (discuss with cardiologist)
• Fall risk assessment and prevention

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12. Prevention

Primary Prevention (Preventing First Episode)

Patient Education: [1,2]

1. Proper Nail Cutting:

   • Cut straight across (NOT curved)
   • Cut to level of toe tip (NOT shorter)
   • Do not round corners
   • File smooth any rough edges
   • Use proper nail clippers
   • Cut after bathing (nails softer)

2. Footwear Selection:

   • Professional shoe fitting
   • Wide toe box (1cm clearance beyond longest toe)
   • Appropriate length (thumbs-breadth beyond longest toe)
   • Avoid chronically tight shoes
   • Avoid high heels
   • Change athletic shoes regularly (worn shoes lose toe box structure)

3. Foot Hygiene:

   • Daily washing
   • Thorough drying (especially between toes)
   • Moisture control:
     • Antiperspirant foot powders if hyperhidrosis
     • Breathable socks (cotton, moisture-wicking)
     • Change socks daily (or multiple times if hyperhidrosis)
     • Alternate shoes (allow to dry between wears)

4. Activity Modification:

   • Appropriate athletic footwear for sport
   • Protective footwear in occupational settings
   • Avoid repetitive trauma (e.g., ill-fitting soccer cleats)

Secondary Prevention (Preventing Recurrence)

Post-Surgical:

• All of the above primary prevention measures
• Regular podiatry follow-up if nail deformity
• Early intervention for any signs of recurrence

High-Risk Patients:

• Diabetics: Regular podiatry screening (every 3-6 months)
• Nail bracing devices if recurrent pincer nail
• Consider prophylactic partial matrixectomy for severe congenital nail deformities

Occupational Considerations

High-Risk Occupations:

• Military (boots, prolonged marching)
• Athletes (soccer, ballet, running)
• Workers requiring steel-toed boots

Interventions:

• Proper boot fitting
• Custom orthotics if biomechanical issues
• Regular nail care protocols
• Early access to treatment

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13. Prognosis

Natural History (Untreated)

Progressive worsening through Heifetz stages:

• Stage 1 may spontaneously resolve in minority of cases (20-30%)
• Stage 2-3 invariably require intervention
• Chronic infection risk
• Risk of spread to bone (osteomyelitis) if prolonged

Treatment Outcomes

Conservative Treatment [6,15]

Success Rates:

• Stage 1: 50-60% resolution
• Stage 2-3: less than 20% resolution

Recurrence:

• 70% will eventually require surgery

Time to Resolution (if successful):

• 2-4 weeks

Surgical Treatment [4,5,6]

Partial Nail Avulsion + Phenol:

• Success: 95-98%
• Recurrence: less than 5%
• Healing: 4-6 weeks
• Satisfaction: 85-90% excellent/good
• Return to normal activity: 2-3 weeks
• Return to athletics: 4-6 weeks

Partial Nail Avulsion Alone (no phenol):

• Success: 30-40% (due to high recurrence)
• Recurrence: 60-70%
• Healing: 2-3 weeks (faster than phenol)

Winograd Procedure:

• Success: 90-95%
• Recurrence: 5-10%
• Healing: 3-4 weeks

Zadik Procedure:

• Success: > 98% (for eliminating recurrence)
• Recurrence: Near zero
• Satisfaction: Variable (cosmetic concern about absent nail)

Factors Affecting Prognosis

Better Prognosis:

• First episode
• Stage 1 disease
• Unilateral involvement
• Good vascular status
• Non-diabetic
• Compliant patient
• Proper post-op care
• Appropriate footwear
• Phenol matrixectomy

Poorer Prognosis:

• Recurrent episodes
• Diabetes mellitus
• Peripheral vascular disease
• Immunosuppression
• Pincer nail deformity
• Persistent biomechanical factors
• Poor patient compliance
• Inadequate surgical technique

Long-Term Outcomes

Phenol Matrixectomy (10-year data): [4]

• 95% remain symptom-free
• 5% develop recurrence (usually within first 2 years)
• High patient satisfaction
• Cosmetically acceptable (slightly narrower nail)
• Minimal chronic complications

Quality of Life:

• Dramatic improvement in pain scores
• Return to normal activities
• Improved footwear tolerance
• Resolution of embarrassment/social issues (odor, discharge)

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14. Evidence & Guidelines

Cochrane Systematic Review (2012, Updated 2024) [6]

"Interventions for Ingrowing Toenails" by Eekhof et al.

Key Findings:

1. Surgical vs. Non-Surgical: Surgical interventions are significantly more effective than non-surgical treatments for preventing recurrence.

2. Phenol vs. No Phenol: Partial nail avulsion combined with phenol matrixectomy has significantly lower recurrence rates compared to nail avulsion alone (RR 0.05-0.25 across multiple RCTs).

3. Phenol vs. Surgical Excision: Phenol matrixectomy has comparable or superior outcomes to surgical excisional matrixectomy (Winograd), with faster healing and fewer complications.

4. Recommendation: "Partial nail avulsion combined with chemical (phenol) ablation of the nail matrix should be the first-line surgical treatment for ingrown toenails."

Strength of Evidence: High (multiple RCTs, consistent findings)

Randomized Controlled Trials

Phenol vs. Simple Avulsion: [4,5]

• Multiple RCTs consistently demonstrate recurrence rates:
  • "Phenol matrixectomy: 2-5%"
  • "Simple avulsion: 60-73%"
  • Number Needed to Treat (NNT) = 2 (i.e., for every 2 patients treated with phenol instead of simple avulsion, 1 recurrence is prevented)

Phenol vs. Sodium Hydroxide: [26]

• Recent trials comparing 10% sodium hydroxide vs. 80% phenol
• Comparable recurrence rates (5-8% vs. 3-5%)
• Sodium hydroxide: Shorter application time (30-60 seconds vs. 3 minutes)
• Sodium hydroxide: Possibly faster healing
• Conclusion: Sodium hydroxide appears promising but requires larger trials; phenol remains gold standard

Clinical Practice Guidelines

American Family Physician (2019): [1]

• First-line: Conservative management for Stage 1
• Surgical intervention for Stage 2-3 or failed conservative management
• Recommended technique: Partial nail avulsion with phenol matrixectomy
• Evidence rating: A (consistent, good-quality patient-oriented evidence)

British Association of Dermatologists (No formal guideline, but consensus):

• Phenol matrixectomy gold standard
• Simple avulsion acceptable if phenol unavailable or contraindicated
• Zadik procedure for recalcitrant cases

Antibiotic Evidence [7]

Reyzelman et al. (2000): "Treatment of the Infected Ingrown Toenail"

• Randomized trial: Antibiotics + surgery vs. Surgery alone
• Finding: No difference in healing time, pain scores, or outcomes
• Conclusion: "Surgical removal of the offending nail border is the treatment; antibiotics are only adjunctive for cellulitis extension"

Level of Evidence Summary

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15. Patient Explanation (Layperson Summary)

What is an Ingrown Toenail?

An ingrown toenail happens when the edge of your toenail grows into the soft skin next to it. Think of it like a splinter that doesn't come out—your body treats the nail like a foreign object and tries to fight it, causing redness, swelling, pain, and sometimes infection.

The most common toe affected is your big toe. It usually starts with pain and redness at the corner of the nail, and if left untreated, it can develop pus and a red, raw lump of flesh that bleeds easily.

What Causes It?

The most common cause is cutting your toenails wrong. If you round the corners when you cut your nails (like many people do), you leave a sharp little spike of nail hidden under the skin. As the nail grows, this spike digs deeper into your flesh.

Other causes include:

• Wearing shoes that are too tight
• Sweaty feet (the soft, damp skin is easily pierced by the nail)
• Injury to your toe
• Having naturally curved nails (runs in families)

What are the Symptoms?

• Sharp, throbbing pain at the side of your toenail
• Redness and swelling
• Pus or watery discharge (sometimes blood)
• A red, raw lump growing over the side of your nail (this is called "proud flesh")
• Difficulty wearing shoes
• Limping because it hurts to walk

How is it Treated?

For Mild Cases (just starting, no infection):

• Soak your foot in warm salt water 3-4 times a day
• Gently lift the nail edge and place a tiny piece of cotton wool underneath
• Wear open-toed shoes or sandals
• Cut your nails straight across (not curved)
• This works about half the time if you catch it early

For Moderate to Severe Cases (infection, pus, or that red lump):

You will need a minor surgery called a "Partial Nail Avulsion." Don't worry—it's not as scary as it sounds!

What Happens:

1. Your doctor numbs your toe completely (you won't feel anything)
2. They remove just the thin strip of nail that's digging into your skin (not your whole nail)
3. They apply a chemical (phenol) to the root of that nail edge so it never grows back
4. They bandage it up

The whole procedure takes about 15-20 minutes, and you can walk immediately afterward.

Recovery:

• Your toe will drain clear fluid for 4-6 weeks (this is normal)
• You'll change the dressing daily at home
• You can wear open shoes and return to most activities within a week
• Full healing takes 4-6 weeks
• Your nail will look completely normal afterward, just slightly narrower

Success Rate:

• 95-98% of people are cured permanently
• Only 2-5% have the problem come back

Will it Hurt?

• The numbing injection stings for a few seconds
• After that, you feel nothing during the procedure
• For the first 1-2 days after, your toe will be sore (like a bad bruise). Regular painkillers (paracetamol, ibuprofen) control this well
• By day 3-4, most people have minimal pain

How Do I Prevent It?

The Golden Rule: Cut Your Toenails Straight Across

• Don't round the corners
• Don't cut them too short
• File any sharp edges smooth
• Cut them after a bath (when they're soft)

Other Tips:

• Wear shoes that fit properly (not too tight)
• Keep your feet clean and dry
• If your feet sweat a lot, use foot powder and change your socks daily
• Avoid repeatedly stubbing or injuring your toe

When Should I See a Doctor Urgently?

• Red streaks going up your foot or leg
• Fever or feeling unwell
• If you have diabetes (even a mild ingrown nail needs urgent treatment)
• Severe pain or pus
• Black discoloration under the nail (rare, but could be serious)

Can I Just Live With It?

It's tempting to ignore it, but ingrown toenails don't usually get better on their own once they're past the early stage. They get progressively worse and more painful. In diabetics or people with poor circulation, they can become dangerous and lead to serious infections.

The good news: The treatment is straightforward, highly effective, and gets you back to normal life quickly.

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16. Examination Focus (Viva Vault)

Clinical Viva Questions

Q1: Describe the anatomy of the nail unit relevant to surgical treatment of ingrown toenails.

A: The nail unit comprises:

• Nail Plate: Keratinized structure, thickness 0.5-0.7mm
• Nail Bed: Vascular epithelium from lunula to hyponychium
• Germinal Matrix: The growth center located beneath the proximal nail fold, extending 5-7mm proximal to the eponychium and laterally forming "horns." This produces 90% of the nail plate and is the critical surgical target. Incomplete ablation of the lateral horns is the commonest cause of recurrence.
• Sterile Matrix: Contributes remaining 10% of nail thickness
• Lateral Nail Folds: Site of pathology
• Eponychium: Dorsal seal protecting against bacterial entry

Surgical success depends on complete ablation of the lateral germinal matrix horns.

Q2: What are the stages of ingrown toenail (Heifetz classification) and how does this guide management?

A: The Heifetz classification (1937) has three stages:

• Stage 1 (Inflammatory): Erythema, edema, pain, no infection. Management: Trial of conservative treatment (soaks, cotton wisp, footwear modification). Success rate 50-60%.

• Stage 2 (Abscess): Infection with purulent drainage, nail spicule penetrated dermis. Management: Surgical intervention required—partial nail avulsion ± phenol matrixectomy.

• Stage 3 (Chronic Granulation): Hypertrophic granulation tissue, chronic drainage, failed epithelialization. Management: Surgical intervention required—often needs excision of granulation tissue (Winograd procedure) in addition to matrixectomy.

The staging system guides whether conservative or surgical treatment is appropriate and helps set realistic patient expectations.

Q3: Describe your technique for partial nail avulsion with phenol matrixectomy.

A: (Systematic surgical description)

Pre-operative: Digital block with 1% lidocaine (plain, no epinephrine), digital tourniquet

Steps:

1. Mark width of excision (typically 3-4mm)
2. Longitudinal split of nail plate with scissors from free edge to proximal nail fold (must extend beneath eponychium)
3. Grasp and avulse nail strip with hemostat using twisting motion
4. Curette exposed germinal matrix to remove all soft tissue
5. Release tourniquet (critical—allows vascular uptake of phenol)
6. Pack and dry the matrix bed completely (blood dilutes phenol)
7. Apply 80% phenol to matrix with cotton applicator for 3 minutes (timed), reapplying 2-3 times
8. Irrigate copiously with 70% isopropyl alcohol to neutralize
9. Dress with non-adherent gauze

Key Technical Points:

• Complete proximal extension of nail split (to remove lateral matrix horns)
• Adequate drying before phenol (blood inactivates phenol)
• Full 3-minute contact time (shorter time → incomplete ablation)
• Thorough alcohol neutralization (prevents ongoing tissue damage)

Q4: What is the mechanism of action of phenol, and what are the contraindications to its use?

A:

Mechanism: Phenol (carbolic acid) causes coagulation necrosis of the germinal matrix epithelium by:

• Protein denaturation
• Cell membrane disruption
• Destruction of nail matrix keratinocytes
• Prevents future nail plate production from treated area

Alcohol neutralization stops the chemical action and prevents extensive tissue damage.

Contraindications:

1. Severe peripheral vascular disease (ABI less than 0.5): Phenol creates a chemical burn requiring adequate blood supply to heal. In ischemic tissue, this may lead to tissue necrosis.
2. Allergy to phenol (rare)
3. Relative contraindication: Active severe cellulitis (some surgeons prefer to control infection first; others argue surgery provides source control)

Alternative: If PVD contraindicates phenol, perform simple avulsion (accepting 60-70% recurrence rate) OR address vascular disease first (revascularization) OR use sodium hydroxide (emerging evidence).

Q5: What are the borders of the germinal matrix and why is this anatomically important?

A: The germinal matrix extends:

• Proximal: Approximately 5-7mm proximal to the eponychium (cuticle)
• Lateral: Forms "horns" that curve around the lateral edges of the nail unit, extending to the lateral condyles of the distal phalanx
• Distal: To the lunula

Surgical Importance: The lateral horns are the critical area for ingrown toenail surgery. Failure to excise the nail strip all the way to the proximal extent of the matrix, or failure to adequately ablate these lateral horns with phenol, leaves residual nail-producing epithelium. This residual matrix regenerates a nail spicule causing recurrence—the so-called "spicule effect."

This is why the nail plate must be split beneath the eponychium (not just to the visible nail fold) and why phenol must be applied with firm pressure to all recesses of the exposed matrix bed for the full 3 minutes.

Q6: Compare and contrast partial nail avulsion with phenol vs. Winograd vs. Zadik procedures.

A:

Clinical Pearl: Phenol matrixectomy is gold standard for most cases (high cure, low recurrence, good evidence). Winograd reserved for cases requiring soft tissue debridement. Zadik for recalcitrant cases where patient accepts complete nail loss.

Q7: A 55-year-old diabetic presents with an ingrown toenail. What are your specific concerns and how would you manage them?

A:

Concerns (The Diabetic Foot Triad):

1. Peripheral Neuropathy: Loss of protective sensation → delayed presentation → advanced infection at presentation
2. Peripheral Vascular Disease: Impaired healing, risk of gangrene
3. Immunosuppression: Hyperglycemia impairs neutrophil function → increased infection risk, risk of osteomyelitis

Assessment:

• Vascular: Pulses, ABI (if less than 0.5, phenol contraindicated)
• Neurological: Monofilament, vibration (assess protective sensation)
• Infection severity: Probe-to-bone test (if positive → osteomyelitis)
• Glycemic control: HbA1c
• Imaging: X-ray mandatory (rule out osteomyelitis, gas gangrene)

Management:

• Urgent treatment (do not delay)
• If osteomyelitis: MRI confirmation, 6-12 weeks IV antibiotics ± bone debridement
• If adequate vascularity (ABI > 0.5): Phenol matrixectomy as standard
• If severe PVD: Simple avulsion without phenol OR revascularization first
• Optimize glycemic control
• Low threshold for antibiotics (cover S. aureus, consider MRSA if prevalent)
• Close follow-up: Weekly initially

Red Flags Requiring Admission:

• Spreading cellulitis
• Systemic signs (fever, rigors)
• Gangrene
• Osteomyelitis

Q8: What is the evidence for use of antibiotics in ingrown toenails?

A:

Key Study: Reyzelman et al., Randomized trial comparing antibiotics + surgery vs. surgery alone

Finding: No difference in healing time, pain, or outcomes

Conclusion: "The nail spicule is a foreign body. You cannot sterilize a foreign body with antibiotics. Surgical removal of the offending nail is the treatment; antibiotics are only adjunctive."

Current Evidence-Based Practice:

• Stage 1 (inflammation only): No antibiotics
• Stage 2-3 (infection): Surgery is the definitive treatment
• Antibiotics indicated for:
  • Spreading cellulitis beyond immediate toe
  • High-risk patients (diabetics, immunocompromised)
  • Systemic signs
  • Post-operative infection

Empiric Antibiotic Choice: Flucloxacillin or Cephalexin (for S. aureus coverage)

Q9: What is your differential diagnosis for a painful, bleeding mass at the lateral nail fold?

A:

1. Ingrown Toenail with Granulation Tissue (Commonest):

   • History of nail trauma/trimming
   • Visible embedded nail spicule (may be hidden)
   • Responds to nail avulsion

2. Subungual Melanoma (RED FLAG):

   • Pigmented lesion (brown/black) beneath nail or in nail fold
   • Hutchinson's sign (pigmentation extending onto skin)
   • ANY atypical or non-healing "granulation tissue" requires biopsy
   • Can be amelanotic (unpigmented)

3. Pyogenic Granuloma:

   • Benign vascular proliferation
   • Follows minor trauma
   • Cherry-red, pedunculated mass
   • Bleeds profusely
   • Treatment: Excision, cautery

4. Glomus Tumor:

   • Severe paroxysmal pain (worse with cold)
   • Blue-red visible through nail
   • Point tenderness (Love test)
   • MRI diagnosis
   • Treatment: Excision

5. Squamous Cell Carcinoma:

   • Chronic non-healing ulcer
   • Elderly, sun-exposed
   • Biopsy mandatory

Clinical Approach: If in any doubt about typical granulation tissue (pigmented, atypical growth pattern, non-healing), biopsy is mandatory to exclude malignancy.

Q10: A patient develops recurrence 6 months after phenol matrixectomy. What are the possible causes and how would you manage this?

A:

Possible Causes of Recurrence:

1. Incomplete Matrix Ablation (Commonest):

   • Nail strip not excised all the way to proximal matrix extent (left matrix horn)
   • Inadequate phenol application time (less than 3 minutes)
   • Inadequate phenol concentration
   • Matrix bed not adequately dried (blood diluted phenol)
   • Poor alcohol neutralization

2. Biomechanical Factors:

   • Persistent tight footwear
   • Claw toe or hammer toe deformity
   • Hallux valgus
   • Continued poor nail trimming

3. Anatomical Factors:

   • Pincer nail deformity (overcurvature)
   • Hypertrophic lateral nail fold

Management:

1. Assessment:

   • Confirm true recurrence (nail spicule) vs. hypertrophic granulation tissue
   • Examine nail morphology (pincer nail?)
   • Review biomechanical factors (footwear, toe deformity)
   • Review post-op care compliance

2. Treatment Options:

   If Early Recurrence (less than 6 months), Likely Technical:

   • Repeat partial nail avulsion with phenol
   • Meticulous technique: Ensure complete proximal excision, adequate phenol time
   • Consider slightly wider excision

   If Recurrent Failures (2+ failed phenol procedures):

   • Winograd Procedure: Surgical excision of matrix and lateral nail fold
   • Provides direct visualization of matrix (ensures complete removal)
   • OR Zadik Procedure: Total matrixectomy if patient accepts complete nail loss

   If Pincer Nail:

   • Nail bracing (orthonyxia) devices, OR
   • Zadik procedure (only definitive cure for severe pincer nail)

Prevention of Recurrence:

• Patient education on nail care
• Footwear modification
• Address biomechanical abnormalities (orthotics, toe straightening procedures if severe)

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17. Summary: Key Examination Points

High-Yield Concepts

1. Gold Standard Treatment: Partial nail avulsion + phenol matrixectomy (95-98% cure, less than 5% recurrence)

2. Phenol Mechanism: Coagulation necrosis of germinal matrix → prevents nail regrowth from treated area

3. Critical Surgical Step: Complete excision of nail strip to proximal extent of matrix (beneath eponychium) to ablate lateral matrix horns

4. Phenol Contraindication: Severe peripheral vascular disease (ABI less than 0.5)—chemical burn requires adequate blood supply to heal

5. Heifetz Stages: Guide conservative (Stage 1) vs. surgical (Stage 2-3) management

6. Antibiotics Don't Work Alone: Cannot sterilize foreign body (nail spicule); surgery is definitive treatment

7. Diabetic Red Flags: Probe-to-bone test positive → osteomyelitis; requires X-ray/MRI, prolonged antibiotics

8. Germinal Matrix Anatomy: Extends 5-7mm proximal to eponychium with lateral horns—failure to ablate horns = recurrence

9. Evidence: Cochrane review confirms surgical > non-surgical, and phenol > simple avulsion

10. Prevention: Cut nails straight across (NOT curved), avoid tight shoes

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18. References

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3. Chabchoub I, Litaiem N. Ingrown Toenails. StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan. PMID: 31536303.

4. Khan IA, Shah SF, Waqar SH, et al. Treatment of ingrown toe nail-comparison of phenolization after partial nail avulsion and partial nail avulsion alone. J Ayub Med Coll Abbottabad. 2014 Oct-Dec;26(4):478-481. PMID: 25672179.

5. Isik C, Cakici H, Cagri Kose K, Goksugur N. Comparison of partial matrixectomy and combination treatment (partial matrixectomy + phenol) in ingrown toenail. Med Glas (Zenica). 2013 Feb;10(1):177-180. PMID: 23348167.

6. Eekhof JA, Van Wijk B, Knuistingh Neven A, van der Wouden JC. Interventions for ingrowing toenails. Cochrane Database Syst Rev. 2012 Apr 18;(4):CD001541. doi: 10.1002/14651858.CD001541.pub3. PMID: 22513901.

7. Reyzelman AM, Trombello KA, Vayser DJ, Armstrong DG, Harkless LB. Are antibiotics necessary in the treatment of locally infected ingrown toenails? Arch Fam Med. 2000 Sep-Oct;9(9):930-932. doi: 10.1001/archfami.9.9.930.

8. Becerro de Bengoa Vallejo R, Losa Iglesias ME, Sanchez Gomez R, Jules KT. Gauze application of phenol for matrixectomy. J Am Podiatr Med Assoc. 2008 Sep-Oct;98(5):410-414. PMID: 18820047.

9. Burzotta JL, Turri RM, Tsouris J. Phenol and alcohol chemical matrixectomy. Clin Podiatr Med Surg. 1989 Apr;6(2):453-467. PMID: 2650853.

10. Armstrong DG, Lavery LA, Harkless LB. Validation of a diabetic wound classification system. The contribution of depth, infection, and ischemia to risk of amputation. Diabetes Care. 1998 May;21(5):855-859. [Context: Diabetic foot infection assessment]

11. Zuber TJ. Ingrown toenail removal. Am Fam Physician. 2002 Jun 15;65(12):2547-2552. PMID: 12086244.

12. Huang S, Wang J, Chen Z, Kang Y. Surgical interventions for ingrown toenail. Foot Ankle Surg. 2024 Apr;30(3):189-197. doi: 10.1016/j.fas.2023.12.003. PMID: 38177051.

13. Dąbrowski M, Litowińska A. Recurrence and satisfaction with sutured surgical treatment of an ingrown toenail. Ann Med Surg (Lond). 2020 Aug;56:229-233. doi: 10.1016/j.amsu.2020.06.029. PMID: 32637092.

14. Di Chiacchio N, Pasch MV. Nail Orthosis: A Simple and Efficient Treatment for Pincer Nails. Skin Appendage Disord. 2020;6(6):369-372. [Context: Pincer nail deformity]

15. Espensen EH, Nixon BP, Armstrong DG. Chemical matrixectomy for ingrown toenails: Is there an evidence basis to guide therapy? J Am Podiatr Med Assoc. 2002 May;92(5):287-295. PMID: 12015409.

16. Piraccini BM, Richert B, de Berker DAR, et al. Pathogenesis, Clinical Signs and Treatment Recommendations in Brittle Nails: A Review. Dermatol Ther (Heidelb). 2020;10(1):15-27. [Context: Nail disorders]

17. Caprioli R, Bilotti MA. Surgical nail procedures. Clin Podiatr Med Surg. 1989 Apr;6(2):333-355. PMID: 2650852.

18. Thornington MJ. Toenail avulsion. Can Fam Physician. 1983 May;29:1093-1095. PMID: 21283372. [Historical context]

19. Heifetz CJ. Ingrown toe-nail: a clinical study. Am J Surg. 1937;38:298-315. [Classic description of staging]

20. DeBrule MB. Operative treatment of ingrown toenail by nail fold resection without matricectomy. J Am Podiatr Med Assoc. 2015 Jul;105(4):334-338. doi: 10.7547/13-121.1. PMID: 26218152.

21. Dika E, Patrizi A, Veronesi G, et al. Dermoscopy of Subungual Melanoma: A Study of 10 Consecutive Cases. Dermatol Pract Concept. 2018;8(1):15-20. [Context: Differential diagnosis]

22. Shin DK, Kim MJ. Subungual Glomus Tumor: Clinical Manifestations and Outcome of Surgical Treatment. J Korean Med Sci. 2010;25(10):1481-1485. [Context: Differential diagnosis]

23. Gupta AK, Venkataraman M, Renaud HJ, Summerbell R, Shear NH. The increasing problem of treatment-resistant onychomycosis and fungal nail infections. Expert Rev Anti Infect Ther. 2021;19(9):1121-1135. [Context: Comorbid conditions]

24. Yang KC, Li YT. Treatment of recurrent ingrown great toenail associated with granulation tissue by partial nail avulsion followed by matricectomy with sharpulse carbon dioxide laser. Dermatol Surg. 2002 May;28(5):419-421. PMID: 12030876.

25. Li G, Tan X, Hui Y, et al. A new treatment for ingrown toenail with CO2 laser: a retrospective study. J Dermatolog Treat. 2024 Dec;35(1):2434698. doi: 10.1080/09546634.2024.2434698. PMID: 39622511.

26. Srinivas S, Wessinger JD, Nasser E, Strickland S, Udoeyo IF. Comparative Analysis of Rate of Recurrence Using Sodium Hydroxide versus Phenol for Chemical Matrixectomies of Toenails. J Am Podiatr Med Assoc. 2025 Jul-Aug;115(4):23-099. doi: 10.7547/23-099. PMID: 40875443.

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