Hand Infections

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Basics & Bugs - Setting the Stage

  • Anatomy: Pathways of Spread
    • Hand's fascial planes (thenar, midpalmar) & tendon sheaths allow rapid infection spread.
    • Flexor tendon sheaths: Synovial fluid aids bacterial growth; risk of proximal spread to Parona's space.
    • Hand Tendon Sheaths and Fascial Spaces
  • Common Bugs & Considerations:
    • Staphylococcus aureus: Most common. MRSA strains prevalent.

      Staphylococcus aureus is the most common pathogen in hand infections.

    • Streptococcus pyogenes: Aggressive, can cause necrotizing fasciitis.
    • Polymicrobial: Frequent in bites (human: Eikenella corrodens; animal: Pasteurella multocida).
  • Key Risk Factors:
    • Penetrating trauma (thorns, bites).
    • Diabetes Mellitus (impaired healing/immunity).
    • IV Drug Use (direct inoculation). 📌 IVDU.
    • Immunocompromise (steroids, HIV).

Surface Skirmishes - Skin & Nail Invaders

  • Paronychia: Periungual tissue infection.
    • Acute: S. aureus, Streptococci. Tx: Warm soaks, antibiotics. I&D (lift eponychial fold / incise with No. 11 blade).
    • Chronic (>6 wks): Candida albicans, GNBs. Tx: Avoid irritants, antifungals/steroids. Marsupialization. Paronychia Drainage Techniques
  • Felon: Digital pulp infection (closed septal compartments).
    • Clinical: Throbbing pain, tense swelling.
    • Complications: Osteomyelitis, flexor tenosynovitis, necrosis.
    • Tx: I&D. Incisions: Unilateral longitudinal, hockey-stick.

    ⭐ Transverse incisions for felon drainage are generally contraindicated due to risk of neurovascular injury or flexion contracture.

  • Erysipeloid: Caused by Erysipelothrix rhusiopathiae.
    • Source: Occupational: butchers, fish handlers.
    • Clinical: Violaceous, demarcated lesion (fingers/hand).
    • Tx: Penicillin.

Deeper Dangers - Tendons & Spaces

Flexor Tenosynovitis (FTS): Infection of flexor tendon sheath.

  • 📌 Kanavel's Signs (FLEX):
    • Finger held in slight Flexion
    • Length of tendon sheath tender (palpation)
    • Enlarged finger (fusiform/symmetrical swelling)
    • Xtension (passive) of finger causes pain
  • Pathogens: S. aureus (common), Strep.
  • Tx: Urgent IV Abx & surgical drainage (Brunner/mid-axial incisions).

⭐ Kanavel's signs are pathognomonic for flexor tenosynovitis.

Kanavel's signs of flexor tenosynovitis diagram

Deep Space Infections: Serious; require prompt drainage.

  • Thenar Space:
    • Signs: Thumb abducted, swollen & painful thenar eminence.
    • Drainage: Dorsal (1st web) or volar (thenar crease) incision.
  • Midpalmar Space:
    • Signs: Loss of palmar concavity, dorsal swelling often present.
    • Drainage: Transverse palmar or longitudinal dorsal incisions.
  • Hypothenar Space:
    • Signs: Swelling & tenderness over hypothenar eminence.
    • Drainage: Ulnar border incision (mid-axial).
  • Web Space (Collar-Button Abscess):
    • Signs: "Dumbbell" swelling (dorsal & volar), abducted fingers.
    • Drainage: Dorsal & volar longitudinal/zigzag incisions.

Special Ops - Unique Foes & Joints

  • Herpetic Whitlow:
    • Viral (HSV). Painful vesicles, digits. Pain out of proportion.
    • Dx: Tzanck smear (multinucleated giant cells).
    • Rx: Acyclovir. AVOID incision & drainage.

    ⭐ Herpetic whitlow should not be surgically incised; can worsen infection or cause secondary bacterial infection.

  • Atypical Mycobacterial Infections (e.g., M. marinum):
    • "Fish tank granuloma". Hx: aquatic exposure.
    • Chronic, indolent course; papules, nodules, ulcers.
    • Dx: Biopsy, culture (Löwenstein-Jensen at 30-32°C).
    • Rx: Prolonged multi-drug therapy (e.g., clarithromycin + rifampicin/ethambutol). Fish tank granuloma on finger
  • Septic Arthritis (Hand Joints):
    • Causes: Direct inoculation, hematogenous.
    • Dx: Joint aspiration (WBC >50,000/µL, Gram stain, culture).
    • Rx: IV antibiotics, urgent surgical arthrotomy/washout.
  • Bite Wounds:
    • Human: Eikenella corrodens.
    • Animal (cat/dog): Pasteurella multocida.
    • Rx: Thorough debridement, irrigation, prophylactic antibiotics (e.g., amoxicillin-clavulanate).

High‑Yield Points - ⚡ Biggest Takeaways

  • Kanavel's four cardinal signs are diagnostic for flexor tenosynovitis.
  • Staphylococcus aureus is the most common causative organism in most hand infections.
  • Paronychia involves the nail fold; felon affects the digital pulp.
  • Herpetic whitlow is a viral infection (HSV); avoid incision and drainage.
  • Human bites (fight bites) are high-risk for polymicrobial infections including Eikenella corrodens; require aggressive treatment.
  • Deep space infections (e.g., thenar, midpalmar) necessitate prompt surgical drainage.

Practice Questions: Hand Infections

Test your understanding with these related questions

Which of the following is true about tenosynovitis of the finger?

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Flashcards: Hand Infections

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This is the _____ test, used for diagnosis of De Quervain's tenosynovitis

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This is the _____ test, used for diagnosis of De Quervain's tenosynovitis

Eichoff's

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