Who let the dogs out? - Pyogenic Flexor Tenosynovitis

HPI:
Pre-teen male with no PMH presents to the ED after a dog bite the night before. Patient was bit on the palm of his left hand by a relative’s pit bull known to be fully vaccinated. Wound had been becoming more painful and 3rd digit is more swollen, painful, and difficult to range. No other injuries or complaints.

Physical Exam:
Two sub-centimeter puncture wounds to the center of the palm of the left hand, hemostatic with small amount of surrounding erythema present. 3rd digit with fusiform soft tissue swelling, increased warmth, and significant tenderness to palpation. Finger in slightly flexed positioning. Decreased ROM of the 3rd digit with flexion and significant pain with passive extension. Sensation intact to light touch throughout digits and hand. No other erythema, swelling, or significant tenderness present over LUE.  2+ palpable radial and ulnar pulses present.

Radiology:
No fracture or acute changes. No foreign body present.

Management:
Patient was admitted and was started on IV antibiotics for suspected pyogenic flexor tenosynovitis. Wound was rechecked in the morning with minimal improvement in symptoms and patient underwent I&D of digit and hand with continued IV antibiotics.

Discussion:
Pyogenic flexor tenosynovitis = infection of synovial sheath surrounding the flexor tendon

• Staph aureus = most common
  
• Eikenella = human bites
  
• Pasteurella multocida = animal bites
  

Pain/swelling usually delayed 24-48 hours, usually localized to the palmar aspect of one digit of the hand

Kanavel signs – key physical exam findings for diagnosis

• Flexed posturing of the digit
  
• Tenderness to palpation over tendon sheath
  
• Significant pain with passive extension of digit
  
• Fusiform swelling of the digit
  

Obtain x-rays to rule out bony involvement or foreign body

MRI can help diagnose but is expensive and generally unnecessary since clinical exam usually is sufficient

Treatment:
If early presentation:   

• Admission
• IV abx
• Immobilization
• Observation
  

If late presentation or if no improvement after 24 hours of conservative treatment:

• Operative I&D with IV antibiotics
  

Empiric Abx to consider:
Otherwise healthy individuals--

• Cefazolin 1-2 g IV q6-8h
• Clindamycin 600 mg IV q8h 
  
• Erythromycin 500-1000 mg IV q6h 
  

Immunocompromised individuals or bite involvement:

• Ampicillin-sulbactam 1.5-3 g IV q6h
  
• Cefoxitin 2 g IV q6-8h
  
• Clindamycin 600 mg IV q8h PLUS levofloxacin 500 mg IV q24h 
  

 Consider with dog bites-- most are polymicrobial:

• Staph
  
• Strep
  
• Pasteurella multocida
• Anerobes

Key Points:
History and physical examination is key to diagnosis
Start antibiotics early 
Consider surgical intervention when there is:

• crushed tissue
  
• bite to pulp space
  
• involvement of:
  

                o   nail bed 
                o   flexor tendon sheath
                o   deep spaces of the palm
                o   joint spaces

Kanavel signs may not be seen if patient has:

• Early presentation
  
• Antibiotics recently administered
  
• Immunocompromised state/Chronic infection/Diabetes