Felon

1. See Also
   1. Paronychia
   2. Hand Infection
2. Definitions
   1. Felon (Finger Pulp Abscess, Whitlow)
      1. Infection of closed space of distal phalanx pulp
3. Pathophysiology
   1. Infection contained within compartment walled by the fibrous septae of the finger pulp
4. Causes
   1. Staphyococcus aureus
   2. Streptococcus species
5. Mechanism: Local finger tip Puncture Wound
   1. Splinter
   2. Glass fragment
   3. Punctures (e.g. Finger-stick Blood Sugar testing)
6. Symptoms
   1. Rapidly increasing pressure and pain at finger tip
   2. Thumb and index finger most commonly affected
7. Signs
   1. Tense, swollen and erythematous of the finger pad (pulp)
8. Differential Diagnosis
   1. Paronychia
   2. Herpetic Whitlow
   3. Cellulitis
   4. Tuft Fracture
9. Imaging: Bedside Ultrasound
   1. May demonstrate fluid collection within pulp
10. Complications
    1. Osteomyelitis of distal phalanx
    2. Tissue necrosis of finger pulp
    3. Contiguous spread
       1. Pyogenic Flexor Tenosynovitis
       2. Does not typically spread to adjacent DIP joint (infection typically contained within fibrous septae)
11. Management: Conservative measures
    1. Tetanus Prophylaxis
    2. Warm soaks
    3. Elevate the hand
    4. Antibiotics for 7 to 10 days (not typically needed for isolated abscess AFTER Incision and Drainage)
       1. Cephalexin (Keflex)
       2. Dicloxacillin
       3. Trimethoprim-Sulfamethoxazole
       4. Amoxicillin-Clavulanate (Augmentin)
       5. Clindamycin
12. Management: Early Incision and Drainage
    1. Indications
       1. Clear abscess pocket identified
       2. No improvement after 24 hours conservative therapy
    2. Contraindications
       1. Herpetic Whitlow
    3. Anesthesia
       1. Digital Block (Metacarpal Block)
    4. Technique
       1. Apply Tourniquet at base of finger
       2. Identify point of maximal tenderness and swelling
          1. Make 5-10 mm incision using method below
       3. No specific point of tenderness
          1. Make straight single volar (superficial abscess) or high lateral incision (deep abscess)
             1. Start incision 3-5 mm distal to DIP joint
             2. Keep lateral incision within 5 mm of nail border
             3. Continue incision distally to distal phalanx tip
             4. Thumb and pinky finger: Incise radial side
             5. Index, long and ring fingers: Incise ulnar side
          2. Avoid incision methods with higher risk of scar
             1. Transverse palmar incision
             2. J-shaped incision
             3. Fish mouth incision
       4. Wound exploration
          1. Gently open subcutaneous tissue with hemostat
          2. Irrigate wound
          3. Pack with sterile gauze for 48 hours
    5. Complications
       1. Painful neuroma
       2. Finger pad instability
       3. Scarring
13. Follow-up care
    1. Splint and elevate for 48 hours
    2. Saline soaks twice daily
    3. Maintain range of motion
    4. Anticipate healing in 2 weeks
14. References
    1. Clark (2003) Am Fam Physician 68:2167-76 [PubMed]