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Other Names

  • Felon
  • Pulp space infection


  • This page describes acute infections of the fingertip pulp space, commonly referred to as a 'Felon'


  • The term felon is french
  • Root prefix fel refers to bile
  • Thus, a fingertip felon refers to collection of poisonous bile just as a criminal felon refers to a person containing this evil humor[1]


  • Represent about 15-20% of all hand infections[2]


Anatomy of the fingertip[3]
Cross section of a felon[4]
  • General
    • Defined as a subcutaneous pyogenic infection of the pulp space compartments of the distal finger
    • Abscess forms in the small compartments of the fingertip pulp, separated by vertical fibrous septa
    • Most commonly involves the thumb and index finger
  • Etiology
    • Penetrating trauma is the most common cause (e.g. foreign body such as splinter, glucometer finger stick)
    • Can occur from untreated paronychia
  • Microbiology
    • Staph. aureus is most common
    • Likely to be polymicrobial in some patients (IVDU, DM, farmers, bites)
    • Eikenella can be seen in nail biters

Associated Conditions


  • Digital pulp
    • Is a fleshy mass at the digital tips
    • Divided into compartments by fibrous septate which provide structural support
  • Nail tip anatomy
    • Perinychium: includes the nail, the nailbed, and the surrounding tissue
    • Paronychia: lateral nail folds
    • Hyponychium: palmar surface skin distal to the nail
    • Lunula: white semi-moon shaped proximal portion of the nail
    • Sterile matrix: deep to the nail, adheres to it and is distal to the lunule
    • Germinal matrix: proximal to the sterile matrix, responsible for nail growth

Risk Factors

Differential Diagnosis

Differential Diagnosis Finger Pain

Clinical Features

Clinical example of a felon[6]
  • History
    • Pain which is severe, throbbing, worse with dependent position
    • Trouble sleeping due to pain
    • Swelling
    • Tenderness
  • Physical Exam: Physical Exam Hand
    • Firm and tense distal pulp space
    • Swelling is limited to distal soft tissue around the phalanx
    • Area of imminent rupture or pointing may be obvious
    • May see necrotic appearing tissue due to pressure




  • Can be utilized by placing hand in bowl of water
    • Use high frequency linear probe
  • Findings
    • Cobblestoning
    • Small fluid collection


  • Not applicable


Felon incision and drainage approach[7]


  • Indication
    • Virtually all cases
  • Early/ mild cases without fluctuance
    • Warm soaks
    • Rest
    • Elevation
    • Oral antibiotics
  • Felon Incision and Drainage
    • Can be performed at bedside
    • Perform digital block
    • Incise along ulnar aspect (index, middle and ring) or radial aspect (thumb, pinky)
    • Start incision 5 mm distal to DIP crease, end 5 mm proximal to nail plate border
    • Blunt dissection until abscess is decompressed
    • Do not pack
  • Antibiotics


  • Indications
    • Failure of conservative management
  • Technique
    • Debridement of abscess cavity

Rehab and Return to Play


  • No clear rehabilitation guidelines

Return to Play/ Work

  • No clear return to play guidelines

Complications and Prognosis


  • When treated appropriately, patients have good prognosis


See Also



  1. Diab M. Lexicon of orthopaedic etymology. Amsterdam (the Netherlands): Harwood Academic Publishers; 1999.
  2. Linscheid R, Dobyns J. Common and uncommon infections of the hand. Orthop Clin North Am 1975;6: 1063–104.
  3. Image courtesy of orthobullets.com, "fingertip amputations & finger flaps"
  4. Image courtesy of uptodate.com, Overview of hand infections
  5. Tannan SC, Deal DN. Diagnosis and management of the acute felon: evidence-based review. J Hand Surg Am 2012;37(12):2603–4.
  6. Sferopoulos, Nikolaos K. "Three Distinct Episodes of Thumb Felon in a Fur Industry Worker." British Journal of Medicine and Medical Research 3.4 (2013): 1766.
  7. Image courtesy of wikiem.org, "Felon"
  8. Watson PA, Jebson PJ. The natural history of the neglected felon. Iowa Orthop J 1996;16:164–6.
Created by:
John Kiel on 13 May 2022 08:35:06
Last edited:
16 October 2022 00:23:44