Hand Surgery Source



A felon is a subcutaneous abscess of the distal pulp of a phalanx, characterized by multiple vertical and fibrous trabeculae or septa. Often, a penetrating injury precedes the felon; pain and swelling develop quickly thereafter. The most common cause of the initial cellulitis is Staphylococcus aureus. The felon must be incised and drained; post-operative management includes systemic antibiotics and splinting. If left untreated, the felon can extend toward the phalanx, causing an osteitis or osteomyelitis or toward the skin, leading to necrosis and a sinus on the palmar surface of the digital pulp. Other complications of untreated felon include sequestration of the diaphysis of the distal phalanx and pyogenic arthritis of the distal interphalangeal (DIP) joint.

Related Anatomy

  • Distal pulp of phalanx
  • Distal skin and nail bed of phalanx
  • Distal digital nerves
  • Distal digital vasculature

Incidence and Related Conditions

  • Felons and paronychias account for nearly 33% of all hand infections
  • The thumb and index fingers are the most commonly affected digits

Differential Diagnosis

  • Cellulitis
  • Fingertip injuries
  • Paronychia
  • Herpetic whitlow
ICD-10 Codes


Diagnostic Guide Name


ICD 10 Diagnosis, Single Code, Left Code, Right Code and Bilateral Code

FELON FINGER   L03.012 L03.011  

ICD-10 Reference

Reproduced from the International statistical classification of diseases and related health problems, 10th revision, Fifth edition, 2016. Geneva, World Health Organization, 2016 https://apps.who.int/iris/handle/10665/246208

Clinical Presentation Photos and Related Diagrams
  • Felon Right Thumb
    Felon Right Thumb
  • Felon Right Long Finger
    Felon Right Long Finger
  • Felon Right Left Thumb
    Felon Right Left Thumb
Throbbing pain in pulp of the finger
Fingertip swelling and redness
Pain and swelling progressive
Tense fingertip pulp
Typical History

A 43-year-old right-handed male was building a deck in his backyard 10 days ago when he punctured the tip of his left index finger with a splinter of wood.  He removed the splinter himself with his jackknife.  He thought that he had removed all the splinter fragments.  He was fine for a few days but then the fingertip began to get sore and swell.  He now presents with throbbing pain in the pulp of the left index finger.  The pulp of the finger is tense, red and very painful. The redness at the fingertip appears to be increasing and spreading onto his left hand.  He has had no treatment except for removing the splinter and soaking the finger.

Positive Tests, Exams or Signs
Work-up Options
Treatment Options
  • None if problem is a true felon. A felon is an abscess in a closed space and will not respond to antibiotics alone.
  • Presence of draining sinus: longitudinal incision with excision of necrotic skin edges
  • No sinus: unilateral longitudinal incision on ulnar side of digit dorsal and distal to DIP joint flexion crease
  • Hospitalization with observation: incision, drainage and catheter irrigation
CPT Codes for Treatment Options

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Common Procedure Name
I&D felon
CPT Description
Drainage of finger abscess; complicated (e.g. felon)
CPT Code Number
CPT Code References

The American Medical Association (AMA) and Hand Surgery Resource, LLC have entered into a royalty free agreement which allows Hand Surgery Resource to provide our users with 75 commonly used hand surgery related CPT Codes for educational promises. For procedures associated with this Diagnostic Guide the CPT Codes are provided above. Reference materials for these codes is provided below. If the CPT Codes for the for the procedures associated with this Diagnostic Guide are not listed, then Hand Surgery Resource recommends using the references below to identify the proper CPT Codes.

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 CPT 2021 Professional Edition: Spiralbound

  • Osteomyelitis, tenosynovitis, skin necrosis, fingertip deformity, septic arthritis, instability of finger pad

Early incision and drainage of a felon combined with antibiotic treatment usually provides an excellent outcome.  If the patient has complicating factors such as diabetes mellitus or if the care is delayed, then the simple felon can be complicated by distal phalanx osteomyelitis, DIP joint infection or necrosis of the pulp skin.

Key Educational Points
  • The most common cause of the initial cellulitis is Staphylococcus aureus.
  • Felons often follow after a puncture wound or a paronychia.
  • A felon is an infection of the fingertip pulp in comparison to a paronychia, which is an infection of the eponychial fold.

New Articles

  1. George P, DeJesus RA. Venous flow-through flap reconstruction following severe finger wound infection: case report. J Reconstr Microsurg 2009;25(4):267-9. PMID: 19301235
  2. Gawley B, Motykie G, Piazza RC, et al. Rapid progression of metastatic bronchogenic carcinoma after felon drainage. Orthopedics 2006;29(11):1035-6. PMID: 17134058


  1. Tannan SC, Deal DN. Diagnosis and management of the acute felon: evidence-based review. J Hand Surg Am 2012;37(12):2603-4. PMID: 23174075
  2. Watson PA, Jebson PJ. The natural history of the neglected felon. Iowa Orthop J 1996;16:164-6. PMID: 9129291


  1. Kilgore ES Jr, Brown LG, Newmeyer WL, et al. Treatment of felons. Am J Surg 1975;130(2):194-8. PMID: 1155734
  2. Weiner JJ. New incision for closed space infection (felon) involving distal phalanx of finger. Ann Surg 1940;111(1):126-34. PMID: 17857519