What is the treatment for flexor tenosynovitis in the hand caused by a cat bite?

Treatment of Flexor Tenosynovitis in Hand from Cat Bite

Flexor tenosynovitis from a cat bite requires immediate surgical debridement combined with broad-spectrum intravenous antibiotics that cover Pasteurella multocida and other common cat bite pathogens. 1

Pathophysiology and Risk Assessment

Cat bites present a particularly high risk for deep hand infections due to:

• Cat teeth are sharp and narrow, creating puncture wounds that can directly inoculate bacteria into deep structures including tendon sheaths 1
• 30-50% of cat bites become infected, significantly higher than dog bites (5-25%) 1
• Pasteurella multocida is present in 75% of cat bite wounds, along with anaerobes (65%), staphylococci and streptococci (40%) 1
• Hand wounds are more serious than bites to other body parts due to the proximity of tendons, joints, and limited soft tissue coverage 1

Initial Management

1. Wound Assessment

   • Evaluate for Kanavel's signs of flexor tenosynovitis:
     • Fusiform finger swelling
     • Finger held in slight flexion
     • Pain with passive extension
     • Tenderness along tendon sheath

2. Immediate Surgical Intervention

   • Surgical debridement and irrigation of the tendon sheath is necessary 1, 2
   • Debridement should be thorough but cautious to avoid enlarging the wound unnecessarily 1
   • Consider continuous irrigation system with lidocaine solution to allow for pain-free movement and mechanical debridement 3

3. Antimicrobial Therapy

   • Intravenous antibiotics must be started immediately 1, 4

   • First-line IV options:

     • Ampicillin-sulbactam
     • Piperacillin-tazobactam
     • Second-generation cephalosporins (cefoxitin)
     • Carbapenems (ertapenem, imipenem, meropenem) 1

   • AVOID first-generation cephalosporins, penicillinase-resistant penicillins, macrolides, and clindamycin as they have poor activity against P. multocida 1

4. Post-Surgical Management

   • Elevation of the hand to reduce swelling 1
   • Early mobilization after a short period of immobilization to prevent adhesions 5, 3
   • Intensive hand physiotherapy is critical for good functional outcomes 5

Duration of Treatment

• For established flexor tenosynovitis: 3-4 weeks of antibiotics 1
• If osteomyelitis or septic arthritis develops: 4-6 weeks of antibiotics 1
• Transition to oral therapy when clinically improving:
  • Amoxicillin-clavulanate is the preferred oral agent 1, 6
  • Alternative oral options include doxycycline or penicillin VK plus dicloxacillin 1

Monitoring and Follow-up

• Close follow-up within 24 hours after initial treatment 1
• Daily assessment of:
  • Range of motion
  • Pain levels
  • Signs of ongoing infection
  • Need for additional surgical intervention

Complications to Monitor

• Tendon rupture (can occur even months after initial infection) 2
• Adhesions and stiffness
• Osteomyelitis
• Septic arthritis
• Compartment syndrome

Common Pitfalls to Avoid

1. Delayed treatment - Cat bites to the hand should be considered a medical emergency requiring immediate evaluation 5

2. Inadequate antibiotic coverage - First-generation cephalosporins and clindamycin alone are ineffective against Pasteurella 1

3. Insufficient debridement - Thorough but careful debridement is essential 1

4. Premature closure of wounds - Infected wounds should not be closed primarily 1

5. Inadequate follow-up - Close monitoring is essential to detect complications early 1, 5

6. Insufficient rehabilitation - Early mobilization and intensive physiotherapy are critical for good functional outcomes 5, 3

Even seemingly minor cat bites to the hand can rapidly progress to serious infections with potential for permanent disability. Early surgical intervention and appropriate antibiotic therapy are essential to prevent long-term complications and preserve hand function.