- See: Infections of the Hand / Human Bite Wounds
- Discussion:
- MP joint and the adjacent tissues and spaces are most commonly involved because teeth of the opponent are struck with knuckle of the clenched fist;
- when the hand is unclenched, the skin wound retracts proximally covering deeper part of the wound within which the bacteria have been deposited;
- this airless, traumatized area forms an ideal site for anearobic growth;
- up to 75% of patients will have injuries to bone, joint, tendon, or cartilage;
- depending on the severity, a human bite may result in periarticular fibrosis sufficient to cause joint arthrodesis or even amputation of a digit;
- in neglected cases, once the volar plate and the collateral ligaments are damaged and the flexor tendons are adherent, the chances for obtaining a functioning finger are minimal;
- Anatomy of Extensor Mechanism
- Offending Organisms:
- see: bacteriology of hand infections;
- viridans strep, grp a strep, staph aureus, eikenella corrodens, bacteriodes, fusobacterium, actinomycetes, spirochetes;
- alpha-hemolytic streptococci are the most frequent isolates from human bite wounds;
- anaerobic bacteria are commonly found in all types of infected bites;
- borrelia vincentii is a spirochete that may appear in association w/ w/ bacteroides;
- in bites inflicted by hospitalized patients, consider enterobacteriaceae;
- Eikenella corrodens in hand infections.
- Treatment:
- tetanus prophylaxis if indicated;
- debridement:
- cleaning, irrigation and debridement most important;
- to adequately visualize deep structures around the wound, incise both proximally and distally;
- excise traumatized tissue;
- soft tissues including the capsule and extensor hood, are allowed to seek their own position over the joint;
- partial or even complete lacerations are seldom if ever assoc w/ significant retraction at this level;
- see: extensor tendon lacerations:
- if needed lacterated tendons are repair secondarily, at one week;
- incised skin can be closed but bite wound needs to be left open;
- antibiotics
- initially patients should be maintained on IV antibiotics (consider unasyn);
- once, it is clear that the wound is clean and well debrided, oral agents may be used;
- amoxicillin clavulante perfered
- advantage is that it treats, gram positive, gram negative, as well as anaerobic organisms;
- if patient is allergic to penicillins, then consider treating w/ combination of clindamycin and cipro;
- alternative try cefoxitin or erythromycin
Infections following clenched-fist injury: a new perspective.
Osteomyelitis of the hand after a human bite.