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Felon
From WikiSM
Contents
Other Names
- Felon
- Pulp space infection
Background
- This page describes acute infections of the fingertip pulp space, commonly referred to as a 'Felon'
History
- 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]
Epidemiology
- Represent about 15-20% of all hand infections[2]
Pathophysiology

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
Pathoanatomy
- 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
- Systemic
Differential Diagnosis
- Felon
- Paronychia
- Herpetic Whitlow
- Fungal infection
- Drug reactions
- Pemphigus Vulgaris
- Rheumatoid Arthritis
- Cellulitis
- Flexor Tenosynovitis
- Closed Fist Infection (fight bite)
- Scabies
- Sporotrichosis
Differential Diagnosis Finger Pain
- Fractures
- Dislocations
- Tendinopathies
- Ligament Injuries
- Neuropathies
- Arthropathies
- Nail Bed Injuries
- Pediatric Considerations
- Other
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
Evaluation
- Diagnosis is primarily clinical
- Note, do not confuse with Herpetic Whitlow
Radiographs
- Standard Radiographs Hand
- Typically normal
- Should be obtained to exclude foreign body, exclude osteomyelitis
Ultrasound
- Can be utilized by placing hand in bowl of water
- Use high frequency linear probe
- Findings
- Cobblestoning
- Small fluid collection
Classification
- Not applicable
Management

Felon incision and drainage approach[7]
Nonoperative
- 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
- Need to cover for staph aureus, strep
- Consider Cephalexin, TMP/SMX, Clindamycin, Dicloxacillin among other options
Operative
- Indications
- Failure of conservative management
- Technique
- Debridement of abscess cavity
Rehab and Return to Play
Rehabilitation
- No clear rehabilitation guidelines
Return to Play/ Work
- No clear return to play guidelines
Complications and Prognosis
Prognosis
- When treated appropriately, patients have good prognosis
Complications
- Rarely, if untreated/ neglected[8]
- Osteomyelitis
- Flexor Tenosynovitis
- Septic Arthritis of distal interphalangeal joint (DIPJ)
- Ischemic Necrosis of surrounding tissue
- Skin slough
- Flexor Tendon Rupture
See Also
External
- Sports Med Review Hand Pain: https://www.sportsmedreview.com/by-joint/hand/
References
- ↑ Diab M. Lexicon of orthopaedic etymology. Amsterdam (the Netherlands): Harwood Academic Publishers; 1999.
- ↑ Linscheid R, Dobyns J. Common and uncommon infections of the hand. Orthop Clin North Am 1975;6: 1063–104.
- ↑ Image courtesy of orthobullets.com, "fingertip amputations & finger flaps"
- ↑ Image courtesy of uptodate.com, Overview of hand infections
- ↑ Tannan SC, Deal DN. Diagnosis and management of the acute felon: evidence-based review. J Hand Surg Am 2012;37(12):2603–4.
- ↑ 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.
- ↑ Image courtesy of wikiem.org, "Felon"
- ↑ 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
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Last edited:
16 October 2022 00:23:44
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