Approach Considerations
There are no randomized trials to guide the treatment of a felon.
Treatment is guided by whether or not there is an associated abscess. However, this is often a rapidly spreading infection and therefore unless presenting very early, strong consideration should be made to incision and drainage.
If there is no abscess, treatment can be with oral antibiotics for low risk patients or IV antibiotics for high risk infections. Treatment should include MRSA coverage. If MRSA is not suspected a first generation cephalosporin is appropriate. If MRSA is suspected, trimethoprim/sulfamethoxazole would be appropriate for outpatient treatment or vancomycin for inpatient treatment. [10]
Emergency Department Care
Adequate early treatment of a felon can prevent abscess formation and other serious complications.
Administer antibiotics with activity against methicillin-resistant Staphylococcus.
Decompression is almost always indicated.
Prior to incision, several steps can be performed to aid in adequate drainage.
A digital block provides adequate local anesthesia.
The limb can be exsanguinated by holding at 90º for 5 minutes and then applying a forarm tourniquet. [11, 12]
Incision and drainage:
Multiple incisions have been proposed for the incision and drainage of a felon, however no randomized trials exist. Most experts recommend either a unilateral longitudinal approach, a volar approach or a hockey stick appropach. [4]
All attempts should be made for the incision to be in the area of maximum swelling and tenderness. The incision should not cross the distal interphalangeal (DIP) joint to prevent formation of a flexion contracture at the DIP flexion crease. Probing is not carried out proximally to avoid extension of infection into the flexor tendon sheath.
A longitudinal incision in the midline is effective without serious iatrogenic complications that are observed with other traditionally recommended incisions. Incisions should ideally made on the opposite side of the pinching surface unless the point of maximal fluctuance is on the pinching surface. The incision should be made on the ulnar side of digits 2,3,4 and the radial side of digits 1 and 5.
When using the longitudinal approach, it should begin doral to and 0.5cm distal to the DIP flexion crease and extend distally. Care should be made not to violate the tendon sheath. The wound should be deepend along a plane until the abscess is entered. Using tenotomy scissors or a hemostat care should be made to break up all involved septa. [13]
A wik may be placed in the incision to allow continued drainage for 2-5 days. [14]
Daily soaks in warm soapy water or dilute povidone-iodine solution can be used.
Other approaches not discussed are associated with a variety of complications.
Consultations
An orthopedist or hand surgeon should be consulted for more complex cases, especially when there is concern for osteomyelitis or flexor tenosynovitis, or immunocompromised patients.
Because of the potential for complications, prompt follow-up should be arranged in all cases. Surgical consultation should be obtained if there is no improvement within 12-24 hours of conventional therapy. If patients are unable to follow-up they should be advised to return for a wound check within 24-48 hours.
Medical Care
If treated early, drainage, elevation, and oral antibiotics may be adequate. Appropriate follow-up should always be arranged. Severe infections and complicated cases may require hospitalization for intravenous antibiotics and surgical drainage.
The most common organism involved is S aureus, accounting for around 80% of cases. Empiric coverage for MRSA is recommended. Gram stain, if available, should be used to guide therapy.
Provide tetanus prophylaxis if appropriate.
Surgical Care
If drainage and antibiotic therapy yield no improvement within 12-24 hours, consultation with a surgeon is recommended.
Complications
Potential complications of felon include fingertip necrosis, osteomyelitis, and/or flexor tenosynovitis.
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Differential diagnosis for a felon includes herpetic whitlow.
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A paronychia can progress to a felon if left untreated.
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Drainage of pus from under perionychium in a paronychia.
