Human Bite

1. Mechanism: Hand is often injured in fist fight
   1. Known as Clenched-fist Injury or Fight Bite
   2. Index or Long finger MCP joint strikes tooth
      1. Site of injury obscured in extension
      2. High risk for infection spread
      3. Often associated with 5 mm Laceration over MCP
   3. Associated injuries (in 75% of cases)
      1. Penetrated tendon
      2. MCP joint capsule
      3. Metacarpal head
      4. Extensor Tendon Injury
2. Etiologies
   1. Mixed Anaerobes and aerobes
   2. Staphylococcus aureus
   3. Streptococcus
   4. Eikenella corrodens (anaerobic Gram Negative Rod)
3. Signs
   1. Thorough inspection
      1. Neurovascular evaluation
      2. Extensor tendon function
   2. Cleansing and debridement is critical
   3. Extend Laceration as needed for full visualize
4. Labs
   1. Anaerobic and aerobic cultures from wound
   2. Wound Gram Stain
5. Radiology: XRay affected finger
   1. Fracture
   2. Osteomyelitis
   3. Foreign body
6. Management
   1. Hand surgeon consultation
   2. Tetanus prophylaxis
   3. Wound left open, and no structures are repaired
   4. Extend Puncture Wounds in distal to proximal plane
      1. Explore, irrigate, and debride wound
   5. Wick placed in wound, and removed the next day
   6. Apply Soft Bulky Dressing
   7. Antibiotics
      1. Oral agents
         1. Amoxicillin-clavulanate (Augmentin) or
         2. Dicloxacillin with Penicillin (covers E. corrodens)
         3. Cephalexin (Keflex) with Penicillin or
         4. Clindamycin with Fluoroquinolone or
         5. Clindamycin with Trimethoprim-sulfamethoxazole
      2. Parenteral agents
         1. Indications
            1. Consider 1 parenteral dose and then oral
            2. Diabetes Mellitus
            3. Peripheral Vascular Disease
            4. Immunocompromised patient
            5. Wound older then 24 hours
            6. Signs of extensor tendon, capsule, or bone injury
            7. Systemic symptoms
            8. Concurrent Cellulitis
         2. Agents
            1. Ampicillin-sulbactam (Unasyn)
            2. Ticarcillin-clavulanate (Timentin)
            3. Cefoxitin (Mefoxin)
   8. Daily Wound Cleansing and dressing changes
      1. if satisfactory healing:
         1. Antibiotics for 2-3 weeks
      2. if not improving then:
         1. Additional surgical debridement
         2. Consider IV antibiotics
      3. Complete Extensor Tendon Laceration
         1. Requires secondary repair
         2. Otherwise Secondary wound closure is not necessary
   9. Inpatient Management
      1. Indicated for wound older than a few hours
7. References
   1. Clark (2003) Am Fam Physician 68:2167-76
   2. Presutti (1997) Postgrad Med 101(4): 243-54