Hand Infections

Areas that may become infected:

• Superficial
  • Finger tip (Paronychia)
  • Pulp space (Felon)
  • Web Space (Collar stud abscess)
  • Subdermal
• Deep
  • Flexor sheaths → Radial & Ulnar bursae
  • Parona’s space
  • Mid palmar space
  • Thenar space
  • Hypothenar space
  • Joint Spaces
• Most common pathogen: Staphylococcus aureus

Paronychia

• Nail fold infection
• Treatment: Incision & drainage (I&D) with incision at edge of nail
• May require partial or complete nail removal
• Resistant cases: Consider Candida albicans

Felon

• Infection of pulp space
• Treatment: I&D with mid-lateral incision in pulp space
  • Ulnar side except for thumb and little finger
• Main concern: Multiple loculations requiring breakdown
  • Peel off volar aspect of distal phalanx

Collar Stud Abscess

• Characteristics: Two separate abscesses in web space
  • Hourglass-shaped appearance
  • Larger on dorsal surface, can extend proximally
  • Fingers appear slightly spread apart
• Treatment:
  • Avoid incision through web space (prevents bad scarring)

Flexor Sheath Infections

Kanavel’s Signs:

1. Flexed posture
2. Pain along flexor sheath
3. Fusiform swelling
4. Pain on passive stretch

Management:

• Early cases: Antibiotics if short-duration presentation
• Unclear diagnosis: Consider further evaluation
• Incision & Drainage (I&D) in case of soft tissue infection:
  • Two transverse incisions over A1 and A5 pulleys
  • Dissect flexor sheath proximal & distal to pulley
  • Longitudinal incision & pus culture
  • Insert umbilical catheter to irrigate sheath proximally to distally (prevents infection spread)
  • Consider leaving catheter for irrigation or relook at 48 hours
  • Severe infections: May require full sheath exploration via mid-lateral incisions (avoids exposing flexor tendons)

Radial & Ulnar Bursae

• Anatomy:
  • Continuations of flexor sheaths of little and thumb digits
  • Meet just proximal to flexor retinaculum
• Horseshoe Abscess: Infection tracking down from thumb/little finger

Palmar Spaces

• Lie deep to flexor tendons but superficial to metacarpals
• Rare but difficult to diagnose
• Three spaces:
  1. Mid-palmar space (Over middle and ring MC, contains 2nd–4th lumbricals)
  2. Thenar space (Overlies 2nd MC, contains 1st lumbrical)
  3. Hypothenar space (Overlies little finger MC, contains hypothenar muscles)
• Mid-palmar & thenar spaces separated by a fibrous septum from 3rd MC
• Signs of infection:
  • Severe pain
  • High fever
  • Absence of fusiform swelling (unlike flexor sheath infections)
  • Does not involve fingers

Parona’s Space

• Potential space at wrist level (deep to radial & ulnar bursa confluence)
• Bound by: FCU, PQ, FPL, flexor tendons
• Concern: Pus can compromise median nerve

Bites & Infections

Common Organisms by Bite Type:

• Cat: Pasteurella multocida
• Dog: Streptococcus viridans, Pasteurella multocida
• Human: Eikenella corrodens
• Other anaerobes possible but above are most common

Dog & Cat Bites (Order of Frequency):

1. Streptococcus viridans
2. Pasteurella multocida
3. Staphylococcus aureus

Fight Bites (Clenched Fist Injuries)

• Exploration of underlying joint is essential, even if not obviously involved
• Puncture wound in joint capsule is distal to skin wound (due to flexion at time of injury)
• Common organisms:
  1. Group A Streptococcus
  2. Staphylococcus aureus
  3. Eikenella corrodens
  4. Other anaerobes

Other Infections

Herpetic Whitlow

• Herpes simplex virus
• Vesicular lesions on children's fingers
• History of herpes
• Treatment: Acyclovir

Necrotizing Fasciitis

• Rare but high mortality
• Mixed aggressive pathogens:
  • Group A Streptococcus ± Staphylococcus
  • Anaerobes ± Staphylococcus
• Intra-operative findings:
  • Dishwater pus
  • Fat liquefaction
  • Muscle necrosis

Fungal Infections

• Consider fungal causes (Candida albicans) in chronic, non-responsive cases

Onychomycosis

• Fungal nail bed infection
• Common, chronic
• Signs:
  • Yellow/brown discoloration
  • Purulent discharge in severe cases
• Organism: Trichophyton rubrum

Subcutaneous Fungal Infections

• Typical Organism: Sporothrix schenckii
• Source: Inoculation from soil/plants (e.g., rose thorn)
• Presentation: Starts as papule at inoculation site
• Treatment: Topical potassium iodine solution

Mycobacterial Infections

• Most common chronic infection of the hand
• Tend to attack synovium → Can mimic inflammatory arthropathy
• Diagnosis:
  • Culture on Lownstein-Jensen medium (for mycobacteria)
  • Ziehl-Neelsen stain (for acid-fast bacilli)
  • CXR (to rule out hematogenous spread)

Typical Mycobacterial Organisms:

• Mycobacterium marinum → Fresh/saltwater exposure
• Mycobacterium kansasii → Soil exposure
• M. avium-intracellulare → Soil, poultry (most common in HIV)

Leprosy

• Mycobacterium leprae
• Primarily a nerve disease, skin lesions on hands are secondary

Syphilis

• Treponema pallidum
• Signs: Ulcers on fingers (chancre)