Felon

By admin Last updated Dec 8, 2023

Ovid: 5-Minute Sports Medicine Consult, The

Felon

Michael M. Linder

Andrew Harcourt

Basics

Description

Infection of the palmar pulp space of the distal finger or thumb (1)
Progresses rapidly to a severe throbbing pain and swelling in the distal pulp space
If left untreated, swelling may lead to ischemia and distal nerve damage.

Epidemiology

Usual cause is penetrating trauma with a subsequent bacterial infection
The most common pathogen is Staphylococcus aureus, but it may be caused by Streptococcus or gram-negative organisms (1).

Risk Factors

Penetrating trauma

Etiology

Small vertical septa divide the volar pulp space into small fascial compartments (2).
These compartments provide a closed space for infection but help to prevent spread to the flexor tendons, distal phalanx, or joint capsule.

Diagnosis

Physical Exam

Physical examination:
- Complete neurovascular exam of distal digit
- Examination of function of affected digit
- Examination for evidence of flexor tenosynovitis
Signs and symptoms:
- Commonly present with affected hand overhead in an effort to reduce pain
- Erythematous and swollen distal pulp space
- Exquisite tenderness over distal pulp space
- Loss of sensation indicates advanced state and likely tissue necrosis.

Diagnostic Tests & Interpretation

Lab

Wound cultures should be obtained to help direct antibiotic coverage because osteomyelitis can develop quickly.

Imaging

Anteroposterior (AP) and lateral radiographs assist in the assessment of a retained foreign body or if osteomyelitis is suspected.

Differential Diagnosis

Herpetic whitlow
Flexor tenosynovitis

Treatment

ED Treatment

The hallmark of treatment is early and complete incision and drainage of the affected pulp space.
Lateral approach (3):
- Digital nerve block with long-acting anesthetic agent
- Tourniquet with Penrose drain to promote a bloodless field
- Simple longitudinal incision is preferred to minimize long-term complications.
- Begin incision 3–5 mm distal to distal interphalangeal (DIP) joint to avoid injury to flexor tendon sheath or joint capsule.
- Incision should be made dorsal to the neurovascular bundle and extend just distal to the free edge of nail.
- The incision should be made on the ulnar aspects of digits 2–4 and on the radial aspect of digits 1 and 5.
- A blunt probe or hemostat is used to dissect the fibrous septa.
- Care is used to irrigate and remove all necrotic and purulent material.
- The wound tis hen packed with sterile gauze for 24–48 hr.
- The finger then is splinted for protection.

P.157

Alternatively, a simple vertical volar incision may be made for felons that appear to point at the whirl of the fingertip.
Incisions carried all the way across the fingertip may result in an unstable fingertip and are now discouraged (2).

Medication

Increasing prevalence of community-acquired methicillin-resistant S. aureus (MRSA) requires knowledge of local patterns and susceptibilities.
Treatment should include coverage for MRSA until culture results are available.
Adults:
- Trimethoprim-sulfamethoxazole DS 1 pill PO b.i.d. × 7–10 days
- Clindamycin 300 mg PO q6h × 7–10 days
Children:
- Trimethoprim-sulfamethoxazole 20 mg/kg/day PO divided b.i.d. × 7–10 days
- Clindamycin 25 mg/kg/day PO q6–8h × 7–10 days

Surgery/Other Procedures

Complicated felons, those where osteomyelitis or tenosynovitis is suspected or where incision and drainage needs operating room débridement, necessitate orthopedic consultation.

Ongoing Care

Follow-Up Recommendations

Most patients can be treated and followed as outpatients.
Examination in 24–48 hr for repacking is indicated.
Adjustment of antibiotic coverage is dictated by culture results.
Complications can include frank disruption of the digital nerve and subsequent loss of sensation in distal digit, painful neuromas, and an unstable finger pad (4).
Incorrectly placed incisions can leave scars that interfere with sensation and pincer grasp function.

References

1. Clark DC. Common acute hand infections. Am Fam Physician. 2003;68:2167–2176.

2. Hauck RM, Camp L, Ehrlich HP, et al. Pulp nonfiction: microscopic anatomy of the digital pulp space. Plast Reconstr Surg. 2004;113:536–539.

3. Roberts, et al. Clinical procedures in emergency medicine, 4th ed.; Chapter 38, (2004).

4. Marx, et al. Rosen's emergency medicine: concepts and clinical practice, 6th ed.; Chapter 47, (2005).

Codes

ICD9

681.01 Felon