Physical Examination

If the bite results in a puncture wound that is swollen, red, and painful, the wound is likely to be infected. Patients with infection may have an elevated temperature, swollen glands, or a history of fever. Any loss of motion or sensation in the fingers suggests that a tendon or nerve has been severed. If a flexor tendon has been severed, the patient will be unable to extend or flex some portion of the finger. When a nerve has been lacerated, there is a loss of sensation over the tip of the finger.

Closed fist injuries often result in injury to the extensor tendon and its sheath. When a closed fist injury occurs to someone with a clenched fist, the bacterial load is often carried back into the hand as the tendon slides back to its relaxed state (Fig. 10—1). This means that the problem of contamination cannot be easily resolved using normal methods of irrigating and cleaning a wound.

Patients who present with dog or cat bites have a wounded area that is painful, red, and swollen. Abscess formation may develop.

Diagnostic Studies

Wound cultures are used to diagnose the infecting organisms. Aerobic and anaerobic cultures should be included. For human bites, the most common infecting organisms include Staphylococcus aureus, streptococci, and Eikenella corrodens. For cat bites, cultures should be examined for Pasteurella multocida. For dog bites, Straphlococcus aureus, Streptococcus viridans, Bacteroides spp., and P. multocida may be cultured. All patients with lacerations over the metacarpophalangeal joint should be x-rayed for retained teeth fragments, regardless of patient-reported history.

Radiographs are used to exclude fractures or foreign bodies (e.g., teeth). Radiographs can be used to determine if osteomyelitis is present, which has been frequently reported in cat bites.

Differential Diagnosis

Puncture wound Insect bite Other animal bite Marine animal bite


Human Bite to the Hand

There are two major mechanisms of human bites to the hand. An example of penetrating trauma is a closed fist injury, in which one person strikes another in the mouth, causing a fight bite to the hand. If the hand is clenched in a fist, laceration of the skin over the knuckle may damage a tendon sheath or tendon, as well as surrounding tissue or underlying bones of the joint. Wounds over the fingers or other surfaces of the hand are the result of a direct and deliberate ("chomping') human

Essentials of Human Physiology

Essentials of Human Physiology

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