Hand Infections

1. Clinical Overview

Summary

Hand infections represent a unique surgical challenge due to the hand's complex anatomy, characterized by multiple closed, non-distensible compartments including pulp spaces, tendon sheaths, and deep palmar fascial spaces. [1,2] The unyielding fascial boundaries and septal structures create high-pressure compartments where bacterial proliferation leads to rapid pressure elevation, vascular compromise, tissue necrosis, and irreversible functional loss. [3,4]

Unlike infections elsewhere in the body, hand infections carry an exceptionally high risk of permanent disability if not recognized and treated urgently. The tendon nutrition depends on synovial fluid circulation and vascular vincula; infection destroys both mechanisms within 24-48 hours, leading to tendon necrosis, adhesion formation, and permanent stiffness. [5,6] Prompt diagnosis and often urgent surgical intervention are required to preserve hand function.

Incidence and Impact

Hand infections account for approximately 5-10% of emergency department hand presentations and represent 30-35% of emergency hand surgery cases in tertiary centers. [7] The socioeconomic impact is substantial, with average time off work ranging from 2-8 weeks depending on infection type and occupation. [8] Diabetic patients have 3-4 fold higher complication rates and amputation risk. [9]

Key Facts

• Paronychia: Infection of the nail fold. Most common hand infection (35-40% of cases), usually following minor trauma or nail manipulation. [10]
• Felon: Infection of the pulp space of the fingertip. The pulp contains vertical fibrous septae that anchor the skin to the periosteum; swelling here causes vascular tamponade and osteomyelitis of the distal phalanx if untreated. [4]
• Pyogenic Flexor Tenosynovitis (PFT): Infection within the synovial sheath of the flexor tendon. It destroys the gliding mechanism and tendon blood supply (vincula) within hours to days, representing a true hand surgery emergency. [1,5]
• Deep Space Infections: Infection of thenar, midpalmar, or hypothenar spaces. Can result in "horseshoe abscess" tracking through the space of Parona at the wrist. [11]
• Bite Wounds: Human and animal bites carry high infection risk (15-20% for human bites, 30-50% for cat bites) with specific polymicrobial flora requiring targeted antibiotic therapy. [12,13]

Clinical Pearls

Kanavel's Cardinal Signs: Used to diagnose Pyogenic Flexor Tenosynovitis. [1,14]

1. Tenderness along the flexor tendon sheath (not just the joint).
2. Fusiform swelling ("Sausage finger"

• uniform swelling along the digit).

3. Finger held in semi-flexion (to maximize sheath volume and minimize pain).
4. Pain on passive extension: The earliest and most sensitive sign. Extending the finger stretches the inflamed sheath causing excruciating pain.

Presence of all 4 signs: 97% sensitivity, 95% specificity for PFT. [14] Presence of 3/4 signs: Still warrants urgent surgical exploration. [5]

The "Fight Bite": A laceration over the metacarpophalangeal (MCP) joint must be assumed to be a human bite (tooth injury from punching a mouth) until proven otherwise. [12,15] Eikenella corrodens is the pathognomonic organism, part of polymicrobial flora including anaerobes. [13] Treat with Co-amoxiclav. Never close these wounds primarily - high risk of deep infection and septic arthritis.

The "Little Finger & Thumb Connection": The flexor tendon sheath of the little finger communicates with the ulnar bursa. The thumb sheath communicates with the radial bursa. These two bursae connect proximally at the wrist (Space of Parona). [11] Therefore, an infection in the little finger can spread rapidly to the thumb and forearm, creating a "Horseshoe Abscess." The index, middle, and ring fingers usually have isolated sheaths that terminate at the level of the MCP joints.

Delayed Presentation = Worse Outcome: For PFT, delay > 48 hours increases risk of tendon necrosis from 8% to 35%, and permanent stiffness from 15% to 45%. [6] Early surgical drainage (less than 24h) achieves 85-90% good functional outcomes vs less than 60% with delayed treatment. [5,16]

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2. Epidemiology

Incidence by Infection Type

Risk Factors

Patient Factors:

• Diabetes mellitus: 3-4 fold increased risk, worse outcomes, higher amputation rate. [9]
• Immunosuppression: Chemotherapy, HIV, chronic steroids, biologic agents.
• Peripheral vascular disease: Impaired healing, higher surgical failure rate.
• Chronic kidney disease: Altered immune response, impaired wound healing.
• Occupational: Manual laborers, butchers, fishermen, healthcare workers.
• Nail biting/picking: Chronic paronychia.

Mechanism Factors:

• Penetrating trauma: Splinters, needles, rose thorns, fish bones.
• Bite wounds: Human (fight bite), dog, cat.
• Intravenous drug use: Direct inoculation, often polymicrobial/atypical organisms.
• Prior hand surgery: Scarring, altered anatomy.

Microbiology

Common Organisms

• Staphylococcus aureus: 60-80% of hand infections. Increasing MRSA prevalence (10-30% in many regions). [7,17]
• Streptococcus species: β-hemolytic streptococci cause spreading cellulitis and lymphangitis.
• Coagulase-negative Staphylococci: Less virulent, often indolent course.

Organism-Specific Infections

Special Populations

Diabetics: Higher rates of MRSA, Gram-negative organisms, and polymicrobial infections. [9]

Immunocompromised: Atypical organisms (mycobacteria, fungi, opportunistic), indolent presentation despite severe underlying infection.

IVDU: Staphylococcus aureus (including MRSA), Gram-negatives, anaerobes, polymicrobial.

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3. Pathophysiology

Anatomical Foundations

Understanding hand infection pathophysiology requires appreciation of the hand's unique anatomical compartments:

Pulp Space

The fingertip pulp is divided into 15-20 small compartments by vertical fibrous septae that extend from the periosteum of the distal phalanx to the overlying skin. [4] These septae serve to:

• Anchor the skin to bone for stable pinch and grasp
• Create a stable cushion for tactile sensation
• Subdivide the pulp into small, non-distensible compartments

Infection Consequences: Bacterial proliferation within this closed space causes:

1. Rapid pressure elevation (compartment syndrome)
2. Vascular tamponade of terminal digital arteries
3. Ischemic necrosis of pulp soft tissue
4. Osteomyelitis of distal phalanx (occurs in 15-20% of untreated felons) [4]
5. Permanent pulp loss, unstable fingertip, sensory deficit

Flexor Tendon Sheaths

The flexor tendons glide within synovial sheaths that extend from the metacarpal neck (A1 pulley) to the distal phalanx insertion. [5,11]

Thumb and Little Finger: Sheaths continue proximally as the radial and ulnar bursae, respectively, extending into the distal forearm and communicating at the Space of Parona.

Index, Middle, Ring Fingers: Isolated sheaths terminate at the MCP joint level (though anatomical variations exist in 15-20% of individuals). [11]

Synovial Sheath Function:

• Produces synovial fluid that nourishes tendon (avascular within sheath)
• Permits low-friction gliding (excursion up to 8cm)
• Maintained by vincular blood supply at specific zones

Infection Consequences: Bacterial infection within this closed synovial space causes: [1,5,6]

1. Pressure-induced tendon ischemia: Intra-sheath pressure can exceed capillary perfusion pressure (30-40 mmHg) within hours
2. Vincula thrombosis: Small vascular pedicles are highly susceptible to inflammatory thrombosis
3. Synovial destruction: Purulent exudate destroys the smooth synovial lining
4. Adhesion formation: Inflammatory cascade produces fibrinous adhesions between tendon and sheath
5. Tendon necrosis: Combination of ischemia and bacterial proteases causes tendon substance destruction
6. Sheath rupture: Infection can rupture into adjacent spaces (web spaces, deep palmar spaces)

Timeline: Irreversible damage begins within 24-48 hours; delay > 48h increases permanent functional loss from 15% to 45%. [6,16]

Deep Palmar Spaces

The hand contains several potential spaces bounded by fascial layers: [11]

Thenar Space: Between adductor pollicis and index metacarpal. Infections here cause thenar eminence swelling, thumb abduction posture.

Midpalmar Space: Between flexor tendons and palmar interosseous fascia. Contains lumbrical muscles and digital neurovascular bundles. Largest space, can accommodate significant pus.

Hypothenar Space: Deep to hypothenar muscles, least commonly infected.

Space of Parona: Potential space in distal forearm between pronator quadratus and deep flexor tendons. Connects radial and ulnar bursae ("horseshoe abscess"). [11]

Web Spaces: Between fingers. "Collar-stud abscess" has volar and dorsal components connected through narrow lumbrical canal.

Compartment Syndrome Pathophysiology

Hand infections create compartment syndrome through:

1. Bacterial proliferation and exudate formation
2. Inflammatory vasodilation and capillary leak
3. Pressure elevation in non-distensible fascial compartments
4. Venous compression → further edema
5. Arterial compression → ischemia
6. Tissue necrosis → further inflammation
7. Progressive cycle until surgical decompression

Critical Pressure: Compartment pressures > 30 mmHg compromise perfusion; > 40 mmHg cause ischemia.

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4. Clinical Presentation

Symptoms

Universal Features

• Throbbing pain: Constant, severe, progressive. Classically described as "throbbing at night preventing sleep"
• indicates pus under pressure requiring drainage. [2]
• Swelling: Localized to specific anatomical compartment initially, may spread.
• Erythema: Overlying skin redness, may have ascending lymphangitis (red streaks).
• Warmth: Inflammatory heat localized to infected area.
• Functional impairment: Inability to use hand, inability to tolerate dependent position.

Systemic Features

• Fever: Present in 40-60% of deep infections, higher with necrotizing fasciitis.
• Malaise: Constitutional symptoms suggest deeper/spreading infection.
• Lymphadenopathy: Epitrochlear and axillary nodes.

Infection-Specific Presentations

Paronychia

Acute Paronychia: [10]

• Painful, red, swollen nail fold (usually lateral nail fold)
• May have visible purulent collection through skin
• Recent history of nail manipulation, manicure, hangnail trauma
• Localized to nail fold, does not extend to pulp
• Examination: Fluctuance at nail fold, pus may be expressible

Chronic Paronychia:

• Indolent, recurrent inflammation of proximal nail fold
• Often multiple fingers
• Associated with wet work, diabetes, Candida infection
• Nail plate dystrophy, loss of cuticle seal
• Examination: Boggy, thickened nail fold, no acute fluctuance

Felon

• Severe throbbing pain in fingertip pulp [4]
• Tense, exquisitely tender pulp
• Unable to sleep due to pain
• History of penetrating injury (splinter, needle stick) 3-7 days prior
• Examination:
  • Pulp is tense, erythematous, exquisitely tender to palpation
  • No fluctuance (due to septal compartmentalization)
  • May have area of maximum tenderness/pointing
  • "Assess for osteomyelitis: bony tenderness, exposure, radiographic changes"

Pyogenic Flexor Tenosynovitis (PFT)

Classic Presentation: [1,5,14]

• Kanavel's four cardinal signs (see Clinical Pearls)
• Uniform swelling along entire digit ("sausage finger")
• Severe pain on attempting passive extension
• Patient cradles hand, keeps affected finger flexed
• History of penetrating trauma to palm/digit (may be minor: rose thorn, fish bone)

Atypical Presentations:

• Diabetics may have blunted inflammatory response
• Incomplete Kanavel's signs in early infection (less than 24h) or chronic infection
• Post-operative PFT (rare): after trigger finger release, tendon repair

Complications at Presentation:

• Sheath rupture into web space or deep palmar space (20% if > 48h delay) [6]
• Septic flexor digitorum profundus (FDP) tenosynovitis extending to forearm
• Systemic sepsis (rare, but higher in diabetics)

Deep Space Infections

Thenar Space: [11]

• Thenar eminence swelling and tenderness
• Thumb held in abduction and opposition
• Obliteration of first web space contour
• May follow radial bursa infection or penetrating trauma to thenar area

Midpalmar Space:

• Loss of palmar concavity ("palmar fullness")
• Dorsal hand swelling (dorsal edema is often more impressive than volar)
• Fingers held in flexion
• Pain with passive extension of middle/ring fingers
• May follow ulnar bursa rupture or penetrating palmar trauma

"Horseshoe Abscess":

• Infection tracking from thumb (radial bursa) → Space of Parona → ulnar bursa → little finger
• Simultaneous swelling of thumb and little finger
• Forearm swelling and tenderness
• Systemic toxicity common
• Requires extensive surgical drainage

Bite Wounds

"Fight Bite" (Human Bite over MCP): [12,13,15]

• Laceration/puncture over MCP joint ("knuckle")
• History: punched someone in the mouth (often concealed/denied)
• High risk of:
  • Extensor tendon injury (EDC laceration)
  • MCP joint capsule penetration → septic arthritis
  • Deep inoculation of oral flora
  • Eikenella corrodens, anaerobes, S. aureus, Streptococcus
• Examination: Small wound belies deep injury; assess with MCP extended AND flexed (wound position may shift with MCP flexion)

Cat Bite: [12]

• Deep puncture wounds (long, sharp canine teeth)
• Rapid onset infection (less than 24h in 50% of cases)
• Pasteurella multocida - aggressive, necrotizing
• High risk of PFT, septic arthritis, osteomyelitis
• Examination: Small puncture, significant deep swelling and pain

Dog Bite:

• More tissue destruction (tearing injury)
• Pasteurella, Streptococcus, Staphylococcus, anaerobes
• Lower infection rate than cat (15-20%) but more tissue damage
• Examination: Irregular laceration, crush injury, potential degloving

Herpetic Whitlow

• Vesicular eruption on fingertip [18]
• Intense pain, burning sensation
• Healthcare workers, dental workers (oral contact)
• HSV-1 > HSV-2
• Key: Vesicles on erythematous base, NOT purulent (unlike felon)
• DO NOT INCISE - will spread virus and cause bacterial superinfection
• Self-limiting (2-3 weeks)
• Examination: Clear vesicles, may coalesce into bullae; no pus

Necrotizing Fasciitis of the Hand

• Rare but devastating (mortality 10-30%) [19,20]
• Severe pain out of proportion to physical findings
• Rapid progression despite antibiotics
• Skin changes: dusky, bullae, crepitus
• Systemic toxicity: fever, tachycardia, hypotension, altered mental status
• Risk factors: Diabetes, IVDU, immunosuppression, recent surgery
• Examination:
  • Skin discoloration (purple, gray, black)
  • Bullae containing dark/hemorrhagic fluid
  • Crepitus (gas in tissues from Clostridium or polymicrobial)
  • Hypoesthesia (nerve necrosis)
  • Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) score > 6 suggests necrotizing infection [19]

History

Essential Questions

1. Timing: When did symptoms start? How rapidly progressing?
2. Trauma: Any penetrating injury? Bite? Splinter? Needle stick? Rose thorn? Fish bone?
3. Occupation: Manual labor? Healthcare? Animal exposure?
4. Hobbies: Gardening? Fishing? Pet ownership?
5. Bite history: Animal bite? Human bite? "Fight bite"?
6. Previous treatment: Antibiotics already tried? Prior drainage?
7. Comorbidities: Diabetes? Immunosuppression? Peripheral vascular disease?
8. Medications: Immunosuppressants? Biologics? Steroids?
9. Hand dominance: Impact on function.
10. Tetanus status: Especially for penetrating trauma.

Red Flag History

• Rapid progression (less than 24h): Necrotizing infection, Pasteurella.
• "Fight bite": Human oral flora, Eikenella, high risk deep infection.
• Systemic symptoms: Fever, rigors, malaise suggest deep/spreading infection.
• Diabetic patient: Higher complication risk, may need admission.
• Immunosuppressed: Consider atypical organisms.

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5. Clinical Examination

General Approach

Examine the hand systematically using "Look, Feel, Move" framework in a well-lit room with patient comfortable. Always compare to contralateral hand.

Look

• Position: Does patient cradle the hand? Which finger(s) affected? Posture of fingers?
• Swelling: Localized or diffuse? Dorsal edema? Loss of skin creases?
• Erythema: Distribution, margins, tracking lymphangitis?
• Skin changes: Vesicles (herpetic whitlow)? Bullae (necrotizing)? Necrosis?
• Wounds: Lacerations, punctures, bite marks, previous surgical scars.
• Deformity: Alignment, previous injury.

Feel

• Temperature: Warmth suggests active infection.
• Tenderness: Localize to specific anatomical structure (nail fold, pulp, tendon sheath, joint, deep space).
• Fluctuance: Presence suggests pus amenable to drainage (may be absent in multiloculated/compartmentalized infections like felon).
• Crepitus: Gas in tissues (necrotizing fasciitis, gas-forming organisms).
• Pulses: Radial, ulnar arteries; digital artery perfusion.
• Sensation: Digital nerves (test 2-point discrimination if possible; normal less than 6mm).

Move

• Active ROM: Can patient move finger? What movements avoided?
• Passive ROM:
  • "Pain on passive extension of affected finger: Kanavel's sign for PFT"
  • Joint stiffness
  • Crepitus with movement
• Tendon integrity: Test FDP (DIP flexion), FDS (PIP flexion), extensor (digit extension).

Infection-Specific Examination Findings

Paronychia

• Erythema and swelling of lateral or proximal nail fold
• Fluctuance at nail fold
• Pus may be expressed with gentle pressure
• Nail plate may be lifted by underlying pus (subungual abscess)

Felon

• Tense, erythematous fingertip pulp
• Exquisite tenderness to palpation
• No fluctuance (due to septal compartmentalization)
• Point of maximum tenderness may indicate area most likely to "point"

Pyogenic Flexor Tenosynovitis

• All 4 Kanavel's signs: 97% sensitivity, 95% specificity [14]
• Fusiform swelling of entire digit
• Tenderness along flexor sheath (not just at joints)
• Finger held in flexion
• Key test: Pain with passive extension (most sensitive sign)

Deep Space Infections

• Thenar space: Thenar swelling, thumb abduction, loss of first web contour
• Midpalmar space: Loss of palmar concavity, dorsal edema, fingers flexed
• Hypothenar: Rare, hypothenar tenderness and swelling

Bite Wounds

• Assess wound with MCP in extension AND flexion (injury occurs in flexion, examination often in extension)
• Look for extensor tendon injury (loss of active extension)
• Check for joint capsule violation (visible capsule, fat in wound)
• Assess neurovascular status distal to wound

Lymphatic Examination

• Lymphangitis: Red streaks tracking proximally (spreading infection)
• Epitrochlear nodes: Medial elbow
• Axillary nodes: Axilla

Systemic Examination

• Temperature: Fever suggests deep/systemic infection
• Heart rate: Tachycardia
• Blood pressure: Hypotension in severe sepsis/necrotizing fasciitis
• Mental status: Confusion in systemic sepsis

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6. Investigations

Imaging

Plain Radiographs (X-ray)

Indications: [2,17]

• ALL bite wounds (human or animal)
• ALL penetrating trauma
• Suspected foreign body
• Suspected osteomyelitis
• Suspected necrotizing infection (gas in tissues)
• Suspected fracture
• Diabetic patients (higher risk osteomyelitis)

Views: Minimum two orthogonal views (PA and lateral). Consider oblique views for foreign body detection.

Radiographic Findings:

• Foreign bodies: Glass (radiopaque), wood (radiolucent, may see soft tissue swelling/gas), metal, tooth fragments
• Gas in soft tissues: Air-fluid levels, tissue emphysema (necrotizing fasciitis, gas-forming organisms, traumatic air introduction)
• Osteomyelitis: Periosteal reaction (earliest, 10-14 days), cortical destruction, sequestrum, involucrum (late findings, > 2-3 weeks)
• Joint effusion: Widened joint space, soft tissue swelling around joint (septic arthritis)
• Fracture: Especially in bite wounds (tooth impact)

Limitations: Early osteomyelitis (first 10-14 days) may have normal X-ray. Consider MRI if high suspicion.

Ultrasound

Utility:

• Identify fluid collections (abscess)
• Guide aspiration/drainage
• Assess tendon integrity
• Real-time dynamic assessment

Limitations: Operator-dependent, limited by soft tissue swelling/edema.

MRI

Indications:

• Suspected osteomyelitis with normal X-ray
• Extent of deep space infection pre-operative planning
• Tendon integrity assessment in complex presentations
• Septic arthritis evaluation

MRI Findings:

• Osteomyelitis: Bone marrow edema (T1 low signal, T2/STIR high signal), cortical destruction, periosteal reaction, abscess
• Septic arthritis: Joint effusion, synovial enhancement, erosions
• Tenosynovitis: Fluid in tendon sheath, synovial enhancement
• Abscess: Rim-enhancing fluid collection
• Necrotizing fasciitis: Fascial thickening, edema, enhancement, gas

Limitations: Expensive, time-consuming, often unnecessary for acute presentations (clinical diagnosis). Do not delay surgery for MRI.

CT Scan

Indications:

• Suspected necrotizing fasciitis (assess gas extent)
• Foreign body localization (especially radiolucent on X-ray)
• Complex anatomy planning

Laboratory Investigations

Routine Labs

Full Blood Count (FBC):

• White cell count: Elevated in infection (> 11,000/μL); markedly elevated (> 15,000) or low (less than 4,000) in severe sepsis/necrotizing fasciitis
• Neutrophilia: Left shift suggests bacterial infection
• Thrombocytopenia: Severe sepsis, DIC in necrotizing fasciitis

Inflammatory Markers:

• C-reactive protein (CRP): Elevated (> 50 mg/L suggests significant infection); trending useful for monitoring response to treatment
• Erythrocyte sedimentation rate (ESR): Less useful acutely, better for chronic osteomyelitis

Metabolic Panel:

• Glucose: Identify undiagnosed diabetes; diabetics may have elevated glucose during infection
• Renal function: Baseline before nephrotoxic antibiotics (vancomycin, gentamicin); elevated creatinine in severe sepsis
• Electrolytes: Abnormal in systemic sepsis

Lactate:

• Elevated in severe sepsis, necrotizing fasciitis
• Marker of tissue hypoperfusion

LRINEC Score (Necrotizing Fasciitis)

Laboratory Risk Indicator for Necrotizing Fasciitis score: [19]

Interpretation:

• ≤5: Low risk (less than 50% probability necrotizing fasciitis)
• 6-7: Intermediate risk
• ≥8: High risk (> 75% probability necrotizing fasciitis)

Limitation: Do not rely solely on LRINEC - clinical suspicion supersedes score. Necrotizing fasciitis is a surgical diagnosis.

Microbiological Investigations

Wound Swabs:

• Indications: Open wound with discharge
• Technique: Deep swab of wound base (not superficial skin); send for aerobic and anaerobic culture
• Limitation: Surface swab may not represent deep organism; contamination with skin flora

Aspiration:

• Needle aspiration of fluctuant collection under sterile technique
• Send for Gram stain (immediate), culture (aerobic + anaerobic)

Intraoperative Cultures:

• Gold standard: Deep tissue sample, pus, bone (if osteomyelitis)
• Send for:
  • Gram stain (rapid, guides initial antibiotic choice)
  • Aerobic culture
  • Anaerobic culture
  • Fungal culture (if chronic, immunosuppressed, atypical)
  • Mycobacterial culture (if chronic granulomatous, fish tank exposure)
  • Antibiotic sensitivity testing

Blood Cultures:

• Indications: Systemic sepsis, fever, immunosuppressed, diabetic
• Two sets from different sites

Special Tests

Viral PCR: Herpetic whitlow (HSV-1/HSV-2) - swab vesicle fluid

Mycobacterial/Fungal Culture: Chronic, indolent infections; Mycobacterium marinum (fish tank), Sporothrix schenckii (rose thorn)

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7. Management

General Principles

1. High index of suspicion: Hand infections are emergencies; early recognition and treatment crucial. [2,5,6]
2. Elevation: "Hand above heart at all times" - reduces edema, improves venous/lymphatic drainage. Bradford sling or foam wedge elevation. [2]
3. Splinting: Immobilize in position of safety (Edinburgh position): wrist 20-30° extension, MCP joints 70-90° flexion, interphalangeal (IP) joints full extension, thumb abducted. Prevents stiffness.
4. Antibiotics: Start empiric IV antibiotics early, refine based on cultures. [17]
5. Surgery: Surgical drainage for: abscess, PFT, deep space infection, failed conservative management, diabetic/immunosuppressed. [5,16]
6. Tetanus: Ensure prophylaxis up-to-date (especially penetrating trauma, bites).
7. Early hand therapy: Once infection controlled, aggressive hand therapy to prevent stiffness. [6]

Management Algorithm

                    HAND INFECTION PRESENTATION
                                ↓
                    ┌──── INITIAL ASSESSMENT ────┐
                    │   • Kanavel's signs?        │
                    │   • Deep space involvement? │
                    │   • Systemic sepsis?        │
                    │   • Comorbidities?          │
                    └──────────┬──────────────────┘
                               ↓
        ┌──────────────────────┴─────────────────────┐
        │                                             │
    SUPERFICIAL                               DEEP / SEVERE
  (Cellulitis, early                    (PFT, Deep space, Felon,
   paronychia without                   Necrotizing, Systemic sepsis,
   abscess)                              Diabetic/immunosuppressed)
        │                                             │
        ↓                                             ↓
   OUTPATIENT Rx                              ADMIT TO HOSPITAL
   • Oral antibiotics                         • NBM (for surgery)
   • Elevation (sling)                        • IV antibiotics
   • Splint (position of safety)              • Elevation (Bradford sling)
   • Review 24-48h                            • Bloods (FBC, CRP, glucose)
   • Clear safety-netting:                    • X-ray (all bites, trauma)
     Return immediately if:                   • Consent for surgery
     - Worsening despite Abx                  • Tetanus prophylaxis
     - Systemic symptoms                            │
     - Spreading infection                          ↓
        │                                    SURGICAL DRAINAGE
        ↓                                    (Urgent less than 24h for PFT)
   RESPONSE?                                        │
    ↙     ↘                                         ↓
  YES      NO                              • Intraoperative cultures
   ↓        ↓                              • Adequate drainage/washout
Continue   ADMIT                           • Leave wound open (delayed closure)
Abx      + CONSIDER                        • Soft dressing, splint
Complete  SURGERY                          • IV antibiotics 48-72h
Course                                     • Transition to oral once improving
                                          • Hand therapy (early mobilization)
                                                     ↓
                                            FOLLOW-UP & REHABILITATION

Conservative (Non-Surgical) Management

Indications: [2,17]

• Early cellulitis without abscess
• Paronychia without significant purulent collection
• Mild infections in non-diabetic, immunocompetent patients
• Herpetic whitlow (DO NOT INCISE)

Treatment:

1. Elevation: High arm sling (Bradford sling), hand above heart
2. Splinting: Position of safety
3. Oral antibiotics:
   • First-line: Flucloxacillin 500mg QID (covers S. aureus, Streptococcus)
   • Penicillin allergy: Clarithromycin 500mg BD OR Clindamycin 300mg QID
   • Bites: Co-amoxiclav 625mg TDS (covers Pasteurella, Eikenella, anaerobes)
   • Suspected MRSA: Add Doxycycline 100mg BD OR change to Linezolid
4. Analgesia: NSAIDs (ibuprofen) + paracetamol; avoid opioids unless severe
5. Review: Mandatory review at 24-48 hours
6. Safety-netting: Clear written/verbal instructions to return immediately if worsening, systemic symptoms, spreading infection

Duration: Typically 5-7 days; longer if slow response.

Failure indicators: Worsening pain, spreading erythema, fever, systemic symptoms → ADMIT + SURGERY

Surgical Management

Indications for Surgery

Absolute: [5,16]

• Pyogenic flexor tenosynovitis (PFT)
• Deep space abscess
• Felon
• Paronychia with abscess
• Necrotizing fasciitis (true surgical emergency)
• Septic arthritis
• Osteomyelitis requiring debridement
• Bite wounds (formal exploration, washout; delayed closure)

Relative:

• Failed conservative management (48h)
• Diabetic with any deep infection
• Immunosuppressed
• Significant pain despite analgesia
• Neurovascular compromise

Timing

• PFT: Urgent surgery within 24 hours (delay > 48h significantly worsens outcomes) [6,16]
• Necrotizing fasciitis: True emergency, surgery within 6 hours [19,20]
• Felon, deep space abscess: Urgent, ideally within 24 hours
• Paronychia with abscess: Can be done in ED or clinic; theatre if extensive
• Bite wounds: Urgent washout within 24 hours

Surgical Principles

1. Adequate drainage: Create wounds that allow dependent drainage; avoid "blind poking"
2. Preserve anatomy: Minimize damage to neurovascular structures, pulleys, tendons
3. Leave open: Do NOT primarily close infected wounds (exception: selected clean animal bites after extensive washout, but high risk)
4. Delayed closure: 3-5 days when infection controlled, or heal by secondary intention
5. Intraoperative cultures: Deep tissue, pus, bone if applicable
6. Postoperative splinting: Position of safety
7. Early mobilization: Once infection controlled (usually 48-72h), start gentle active ROM to prevent stiffness

Procedure-Specific Techniques

Paronychia Drainage

Technique: [10]

• Simple drainage: Incise along lateral nail fold, elevate skin to drain pus
• Partial nail removal: If pus extends under nail plate, remove lateral 1/3 to 1/2 of nail plate to allow drainage
• Complete nail removal: Rarely needed; for extensive subungual abscess
• Leave wound open, pack lightly with iodoform gauze
• Soak in warm water TDS after 48h

Felon Drainage

Technique: [4]

• Unilateral longitudinal incision: Along non-contact surface (ulnar side of thumb, index, middle; radial side of ring, little finger)
• Incision extends from just proximal to DIP flexion crease to 3-4mm proximal to fingertip
• Bluntly break down septae with curved mosquito forceps
• Send pus for culture
• Irrigate thoroughly
• Leave wound open, pack lightly
• Avoid: "Fish-mouth" incisions (across fingertip) - cause unstable scar, sensory loss
• Avoid: Bilateral incisions - risk digital nerve/artery injury

Pyogenic Flexor Tenosynovitis (PFT) Drainage

Technique: [1,5,14,16]

Option 1: Continuous Catheter Irrigation (Preferred for early/mild PFT)

• Two small incisions:
  • "Proximal: Over A1 pulley (distal palmar crease)"
  • "Distal: Over distal sheath (just proximal to DIP flexion crease)"
• Introduce blunt instrument (e.g., small feeding tube, infant feeding tube) into sheath
• Irrigate with sterile saline (500ml-1L)
• Continuous irrigation: Leave catheter in situ, infuse saline 30-50 ml/h × 24-48h OR intermittent irrigation 50ml Q4-6h
• Remove catheter when:
  • Effluent clear
  • Pain/swelling improving
  • Afebrile
  • Usually 24-72 hours

Option 2: Open Drainage and Washout (For delayed presentation, severe infection, failed catheter irrigation)

• Incisions: As above, may extend
• Open sheath widely
• Remove all purulent material, fibrinous exudate
• Inspect tendon: assess viability (may be necrotic, grayish)
• Copious irrigation (> 1L saline)
• Leave wound open OR loose closure over drain
• Early passive ROM (48-72h) to prevent adhesions

Postoperative:

• IV antibiotics 48-72h
• Splint in position of safety initially
• Early mobilization: Controlled passive ROM once infection controlled (critical to prevent adhesions/stiffness) [6]

Deep Space Abscess Drainage

Thenar Space: [11]

• Dorsal incision over first web space OR
• Volar thenar incision (preserving recurrent motor branch of median nerve)
• Blunt dissection to thenar space
• Drain abscess, break down loculations
• Irrigate thoroughly
• Leave wound open with drain

Midpalmar Space:

• Longitudinal incision over point of maximal tenderness (usually over 3rd or 4th metacarpal)
• Deepen between flexor tendons, avoiding neurovascular bundles
• Enter midpalmar space
• Drain abscess, irrigate
• May need counter-incision dorsally if "collar-stud" component

Web Space:

• "Collar-stud abscess": Volar AND dorsal components connected through lumbrical canal
• Must drain BOTH sides:
  • Volar incision at distal palmar crease
  • Dorsal incision over web space (longitudinal, avoiding extensor tendons)
  • Connect incisions through lumbrical canal
  • Drain, irrigate, leave open

Bite Wound Exploration

Technique: [12,13,15]

• Extend wound for full visualization (preserve neurovascular structures)
• Assess with MCP in flexion AND extension (wound position changes)
• Identify ALL injured structures:
  • Extensor tendon (EDC)
  • MCP joint capsule
  • Bone/cartilage
• Copious high-pressure irrigation (> 1L, pulsatile lavage if available)
• Debride devitalized tissue, foreign material
• Repair tendon if clean, recent (less than 12h); otherwise delayed repair
• DO NOT close wound (high infection risk; leave open for delayed primary closure in 3-5 days OR secondary intention healing)
• Splint in position of safety
• IV antibiotics

Antibiotic Therapy

Empiric Antibiotics (Before Culture Results)

Adjustments:

• Culture results available: Narrow spectrum to target organism and sensitivities
• MRSA isolated: Vancomycin OR Linezolid OR Daptomycin
• Gram-negatives: Ciprofloxacin, Cephalosporins, or Carbapenems based on sensitivity
• Anaerobes: Metronidazole (but covered by Co-amoxiclav, Pip-tazo)
• Pseudomonas (nail infections): Ciprofloxacin 500mg BD PO

Special Situations:

• Herpetic whitlow: Acyclovir 400mg 5× daily PO × 7-10 days (if severe or immunocompromised: Acyclovir 5-10mg/kg TDS IV) [18]
• Mycobacterium marinum: Clarithromycin + Ethambutol OR Doxycycline + Rifampicin (prolonged treatment, 3-6 months)
• Sporotrichosis: Itraconazole 200mg BD × 3-6 months

Adjunctive Measures

Tetanus Prophylaxis:

• If less than 3 doses ever, or > 10 years since last booster (> 5 years for contaminated wounds): Give tetanus toxoid booster
• If never vaccinated or uncertain: Tetanus immunoglobulin + vaccine course

Analgesia:

• Multimodal: Paracetamol 1g QID + Ibuprofen 400mg TDS
• Avoid opioids unless severe pain (impairs hand therapy compliance)

Glycemic Control (Diabetics):

• Optimize glucose control (target less than 10 mmol/L, ideally less than 8 mmol/L)
• May need insulin sliding scale
• Infection worsens hyperglycemia; hyperglycemia worsens infection outcomes [9]

Rehabilitation and Hand Therapy

Timing: Start as soon as infection controlled (usually 48-72h post-surgery) [6]

Goals:

• Prevent adhesions (especially PFT)
• Restore ROM
• Restore strength and function
• Minimize stiffness (the "enemy" of hand surgery)

Phases:

1. Acute (0-7 days): Elevation, splinting, gentle active ROM
2. Subacute (1-3 weeks): Progressive active ROM, light functional activities
3. Rehabilitation (3-12 weeks): Strengthening, scar massage, full functional restoration

Specific to PFT: Early controlled passive ROM is CRITICAL to prevent tendon adhesions to sheath. [6]

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8. Complications

Early Complications (less than 2 weeks)

Persistent Infection:

• Inadequate drainage
• Resistant organism (MRSA)
• Undrained deep collection
• Foreign body retention
• Osteomyelitis
• Management: Repeat imaging, re-exploration, prolonged antibiotics, bone biopsy/culture

Spread of Infection:

• Sheath rupture into adjacent spaces (PFT → web space, deep palmar space)
• Lymphangitis, lymphadenitis
• Systemic sepsis, septic shock
• Management: Aggressive surgical drainage, IV antibiotics, ICU support if septic shock

Tendon Necrosis: [5,6]

• PFT: Tendon becomes gray, non-viable
• Leads to tendon rupture (immediate or delayed)
• Management: Debride necrotic tendon; staged tendon grafting/reconstruction (months later, after infection fully resolved)

Neurovascular Injury:

• Surgical complication (nerve/artery injury during drainage)
• Compression from swelling
• Ischemia from compartment syndrome
• Management: Exploration, repair if needed, compartment release

Stiffness: [6]

• Most common complication of hand infections
• Inflammatory adhesions between tendon and sheath
• Joint capsule contracture
• Edema-induced fibrosis
• Prevention: Early hand therapy, aggressive ROM exercises
• Management: Hand therapy, splinting; if severe and chronic: tenolysis, capsulotomy (delayed, 6-12 months post-infection)

Late Complications (> 2 weeks)

Chronic Osteomyelitis:

• 10-15% of felons if treatment delayed
• Requires prolonged antibiotics (6-12 weeks), often surgical debridement/sequestrectomy
• May lead to amputation if refractory

Septic Arthritis:

• DIP/PIP/MCP joint involvement
• Cartilage destruction leads to arthritis
• Management: Urgent washout, IV antibiotics, may need arthrodesis if severe

Tendon Rupture:

• Delayed rupture weeks to months after PFT
• Sudden loss of function (e.g., unable to flex DIP joint)
• Management: Staged tendon reconstruction (cannot do in presence of infection)

Amputation:

• 2-5% of severe hand infections (higher in diabetics: 8-12%) [9]
• Indications: Unreconstructable tissue loss, refractory osteomyelitis, necrotizing fasciitis with tissue necrosis
• Functional impact depends on digit(s) lost

Permanent Stiffness/Disability:

• Common in PFT (10-20% have significant permanent stiffness even with optimal treatment) [6,16]
• Higher if delayed treatment > 48h (45% significant stiffness) [6]
• Impact: Loss of grip strength, fine motor impairment, inability to return to previous occupation (especially manual laborers)

Complex Regional Pain Syndrome (CRPS):

• Rare but devastating
• Disproportionate pain, allodynia, trophic changes
• Management: Pain clinic referral, multimodal pain management, aggressive hand therapy

Psychological Impact:

• Anxiety, depression (especially if permanent disability, amputation)
• Fear of using hand
• Management: Psychological support, occupational therapy

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9. Prognosis and Outcomes

Overall Outcomes by Infection Type

Prognostic Factors

Favorable:

• Early presentation (less than 24h)
• Non-diabetic
• Immunocompetent
• Compliant with treatment
• No comorbidities
• Appropriate antibiotics
• Timely surgical drainage
• Early hand therapy

Unfavorable: [6,9,16]

• Delayed presentation (> 48h)
• Diabetes mellitus (3-4 fold worse outcomes, higher amputation rate)
• Immunosuppression
• Peripheral vascular disease
• IVDU
• MRSA infection
• Necrotizing fasciitis
• Tendon necrosis at surgery
• Poor compliance with rehabilitation

Return to Function

Timeline:

• Paronychia: 1-2 weeks
• Felon: 2-4 weeks
• PFT: 4-12 weeks (depends on severity, adherence to hand therapy)
• Deep space: 6-12 weeks
• Necrotizing fasciitis: 3-12 months (if survival)

Return to Work:

• Sedentary work: 2-4 weeks
• Manual labor: 6-12 weeks (may require permanent job modification if significant stiffness)

Long-Term Follow-Up

Hand therapy: Critical for optimal outcomes; duration 3-6 months for severe infections. [6]

Functional assessment: Grip strength, pinch strength, ROM measurements.

Reconstruction: Delayed tendon reconstruction/tenolysis if severe stiffness/tendon rupture (typically 6-12 months after infection fully resolved).

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10. Evidence and Guidelines

Key Guidelines

Landmark Evidence

1. Kanavel AB. (1912). Infections of the Hand

• Seminal textbook describing hand infection anatomy, fascial spaces, and cardinal signs of flexor tenosynovitis
• Kanavel's four cardinal signs remain the gold standard diagnostic criteria 100+ years later [1,14]

2. Kennedy CD, et al. (2016). Kanavel's Signs and Pyogenic Flexor Tenosynovitis

• Systematic review validating Kanavel's signs: 97% sensitivity, 95% specificity when all 4 present [14]
• Reinforced importance of early surgical drainage less than 24h for optimal outcomes
• PMID: 26022113

3. Hyatt BT, et al. (2017). Flexor Tenosynovitis

• Comprehensive review of PFT management
• Delay > 48h increases poor outcomes from 15% to 45% [6,16]
• Continuous catheter irrigation effective for early cases; open drainage for delayed/severe
• PMID: 28336044

4. Kennedy SA, et al. (2015). Human and Other Mammalian Bite Injuries of the Hand

• Systematic review of bite wound management
• Human bites: 15-20% infection rate; Eikenella corrodens pathognomonic [12,13,15]
• Cat bites: 30-50% infection rate; Pasteurella multocida, rapid onset less than 24h [12]
• Primary closure contraindicated; formal exploration and washout essential
• PMID: 25538130

5. Christopoulos G, et al. (2024). Necrotizing Fasciitis Originating in the Hand

• Systematic review and meta-analysis of hand necrotizing fasciitis
• Mortality 10-30%; higher in diabetics, IVDU [19,20]
• Urgent surgery less than 6h improves survival
• LRINEC score ≥6 suggests necrotizing infection
• PMID: 36544252

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11. Patient and Layperson Explanation

Why is a hand infection so serious?

Your hand is an incredibly complex and delicate structure - like a precision machine with many moving parts packed tightly together. The tendons that move your fingers run through tight tunnels (like cables in a sheath), and there are many small closed spaces in your hand.

When bacteria get into these spaces, they multiply and cause swelling. But because these spaces are surrounded by tough, non-stretchy tissue, the pressure builds up rapidly - like blowing up a balloon inside a rigid box. This pressure squeezes the blood vessels that supply the tendons and other structures, cutting off their blood supply. Without blood, the tendons can die within 24-48 hours, leading to permanent loss of function.

That's why hand infections are surgical emergencies - time is critical.

What are the symptoms I should watch for?

See a doctor urgently if you have:

• Severe, throbbing pain in your hand or finger that keeps you awake at night
• Swelling and redness
• A finger that looks like a "sausage" and is very tender
• Inability to straighten your finger, or severe pain when someone tries to straighten it for you
• Fever or feeling unwell
• Red streaks tracking up your arm
• Any bite wound to your hand (human or animal)

What is the treatment?

Elevation: You must keep your hand elevated above the level of your heart at all times - even when sleeping. This helps drain the swelling and improves healing. Use a high arm sling.

Antibiotics: Strong antibiotics, usually given directly into a vein (IV) for the first few days, then tablets to complete the course.

Surgery: Many hand infections require surgery to drain the pus and wash out the infection. This is done under anesthetic. The surgeon will make a small cut to release the pressure and drain the infection. The wound is usually left open (not stitched) to allow continued drainage and prevent the infection from being trapped inside. The wound will heal from the bottom up over the next few weeks.

Hand therapy: Once the infection is controlled (usually after a few days), you'll start exercises with a hand therapist. This is crucial to prevent stiffness - the biggest long-term problem after hand infections.

Why can't you stitch my bite wound closed?

Animal and human mouths contain millions of bacteria. When you get bitten, these bacteria are injected deep into your hand. If we stitch the wound closed, we trap the bacteria inside, creating a perfect environment for them to multiply - like sealing them in a warm, dark incubator. This leads to a severe deep infection that can spread to joints, tendons, and bones.

Instead, we clean the wound thoroughly, give you antibiotics, and leave it open to drain. The wound will heal on its own from the inside out over 2-3 weeks, or we may stitch it closed after 3-5 days once we're sure there's no infection.

What are the long-term outcomes?

Best case: If the infection is caught early and treated promptly, most people make a full recovery with normal hand function. You'll need hand therapy for several weeks to regain movement and strength.

Stiffness: The most common long-term problem is some degree of finger stiffness. This happens because the infection causes scar tissue to form between the moving parts. Aggressive hand therapy can minimize this, but some people have permanent stiffness affecting grip strength and fine movements.

Severe cases: If treatment is delayed, or in severe infections, you may have permanent loss of function, or rarely, amputation of a finger or part of the hand.

Key message: Hand infections are serious but treatable. The earlier you get treatment, the better your outcome.

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12. References

Primary Sources

1. Hermena S, et al. Pyogenic Flexor Tenosynovitis. StatPearls. 2025. PMID: 35015439
2. Clark DC. Common acute hand infections. Am Fam Physician. 2003;68(11):2167-2176. PMID: 14677662
3. Barger J, et al. Fingertip Infections. StatPearls. 2020. PMID: 32586457
4. Nardi NM, et al. Felon. StatPearls. 2025. PMID: 28613683
5. Hyatt BT, et al. Flexor Tenosynovitis. Orthop Clin North Am. 2017;48(2):217-227. PMID: 28336044
6. Langer MF, et al. Pyogenic Flexor Tenosynovitis. Dtsch Arztebl Int. 2021;118(27-28):467-472. PMID: 34134159
7. King V, et al. Infection Management for the Hand Surgeon. Plast Reconstr Surg Glob Open. 2023;11(7):e5096. PMID: 37453773
8. Koshy JC, et al. Hand Infections. J Hand Surg Am. 2019;44(1):46-54. PMID: 30017648
9. Gonzalez MH, et al. The diabetic hand: a retrospective study. J Hand Surg Br. 1999;24(5):608-611. [Referenced for diabetic complication rates]
10. Dulski A, et al. Paronychia. StatPearls. 2025. PMID: 31335027
11. Crosswell S, et al. The anatomy of deep hand space infections: the deep thenar space. J Hand Surg Eur Vol. 2014;39(7):743-748. PMID: 25459963
12. Kennedy SA, et al. Human and other mammalian bite injuries of the hand: evaluation and management. J Am Acad Orthop Surg. 2015;23(1):47-57. PMID: 25538130
13. Schmidt DR, et al. Eikenella corrodens in human bite infections of the hand. J Trauma. 1983;23(6):478-482. PMID: 6345799
14. Kennedy CD, et al. In Brief: Kanavel's Signs and Pyogenic Flexor Tenosynovitis. Clin Orthop Relat Res. 2016;474(1):280-284. PMID: 26022113
15. Weinberg A, et al. Eikenella corrodens infection of the hand--a case report and literature review. Orthopedics. 1987;10(10):1417-1419. PMID: 3331197
16. Pang HN, et al. Pyogenic flexor tenosynovitis: early operative treatment. Hand Surg. 2007;12(3):157-161. [Referenced for delay outcomes]
17. Stevens DL, et al. Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the Infectious Diseases Society of America. Clin Infect Dis. 2014;59(2):e10-e52. [Referenced for antibiotic recommendations]
18. Betz D, et al. Herpetic Whitlow. StatPearls. 2025. PMID: 29494001
19. Christopoulos G, et al. Necrotizing Fasciitis Originating in the Hand: A Systematic Review and Meta-Analysis. J Hand Surg Am. 2024;49(1):92.e1-92.e13. PMID: 36544252
20. Delavari S, et al. Necrotizing Fasciitis of the Hand: Management with Literature Review. Arch Bone Jt Surg. 2024;12(8):543-551. PMID: 39036596

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13. Examination Focus

Common FRCS/MRCS Exam Questions

1. Clinical Diagnosis

• Question: "What are Kanavel's four cardinal signs of flexor tenosynovitis?"
• Answer:
  1. Tenderness along the flexor tendon sheath
  2. Fusiform swelling of the digit
  3. Finger held in semi-flexion
  4. Pain on passive extension (most sensitive)

2. Microbiology

• Question: "A patient presents with an infected laceration over the MCP joint after punching someone in the mouth. What is the pathognomonic organism?"
• Answer: Eikenella corrodens (part of polymicrobial oral flora including anaerobes and S. aureus). Treat with Co-amoxiclav. Do NOT close wound primarily.

3. Treatment

• Question: "What antibiotic would you use for a cat bite to the hand?"
• Answer: Co-amoxiclav (covers Pasteurella multocida, which is resistant to flucloxacillin). Cat bites have 30-50% infection rate with rapid onset (less than 24h) and high risk of deep infection/PFT.

4. Anatomy

• Question: "A patient has flexor tenosynovitis of the little finger. Where else might the infection spread?"
• Answer: The little finger flexor sheath communicates with the ulnar bursa, which connects to the radial bursa (thumb) via the Space of Parona at the wrist. This can create a "horseshoe abscess" affecting thumb, little finger, and forearm.

5. Surgical Technique

• Question: "What incision would you use to drain a felon, and which incision must you avoid?"
• Answer:
  • "Use: Unilateral longitudinal incision along non-contact surface (ulnar side for thumb/index/middle; radial side for ring/little)"
  • Avoid: "Fish-mouth" incision (across fingertip) - causes unstable scar, sensory loss, fingertip instability

6. Complications

• Question: "What is the most common long-term complication of pyogenic flexor tenosynovitis?"
• Answer: Stiffness (occurs in 10-20% even with optimal treatment; 30-45% if treatment delayed > 48h). Caused by adhesions between tendon and sheath. Prevention: early surgical drainage + aggressive hand therapy.

Viva Points

Herpetic Whitlow:

• Warning: DO NOT incise this!
• Why: It is a viral infection (HSV-1/HSV-2), not bacterial
• Diagnosis: Clinical (painful vesicles on erythematous base on fingertip) + viral swab/PCR
• Risk group: Healthcare workers, dental workers (oral contact)
• Treatment: Acyclovir 400mg 5× daily PO × 7-10 days; keep covered to prevent autoinoculation
• If incised: Spreads virus, causes bacterial superinfection, prolongs healing

Collar-Stud Abscess:

• Definition: Web space abscess with two components (volar and dorsal) connected by a narrow tract through the lumbrical canal (like a collar stud)
• Surgical pearl: You MUST drain BOTH sides (volar AND dorsal) - draining only one side will fail
• Technique: Volar incision at distal palmar crease + dorsal incision over web space (longitudinal, avoiding extensor tendons)

Necrotizing Fasciitis Red Flags:

• Pain out of proportion to clinical findings
• Rapid progression despite antibiotics
• Skin changes: dusky, gray, bullae (especially hemorrhagic bullae)
• Crepitus (gas in tissues)
• Systemic toxicity: fever, tachycardia, hypotension, confusion
• LRINEC score ≥6 (but do NOT delay surgery for scoring)
• Management: TRUE SURGICAL EMERGENCY - urgent extensive debridement less than 6h, broad-spectrum antibiotics (Pip-tazo + Clindamycin), ICU support

Position of Safety (Edinburgh Position):

• Purpose: Prevent hand stiffness during immobilization
• Position:
  • "Wrist: 20-30° extension"
  • "MCP joints: 70-90° flexion"
  • "PIP and DIP joints: Full extension (0°)"
  • "Thumb: Abducted and opposed"
• Rationale: This position keeps collateral ligaments at maximum length, preventing contracture

Early Mobilization:

• Critical for PFT: Early passive ROM (48-72h post-surgery once infection controlled) prevents tendon-sheath adhesions
• Enemy of hand surgery: Stiffness
• Balance: Infection control vs. mobilization - too early risks spreading infection; too late risks permanent stiffness

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Medical Disclaimer: MedVellum content is for educational purposes and clinical reference. Clinical decisions should account for individual patient circumstances. Always consult appropriate specialists for urgent hand infections - these are surgical emergencies requiring specialist hand surgeon input.