Review Article Human and Other Mammalian Bite Injuries of the Hand: Evaluation and Management

Abstract Stephen A. Kennedy, MD The hand is the most common site for bite injuries. Because of specific Laura E. Stoll, MD characteristics of hand anatomy, bite mechanics, and organisms found in human and animal saliva, even small wounds can lead to aggressive Alexander S. Lauder, MD infections. Failure to recognize and treat hand bites can result in significant morbidity. Human and animal bites most commonly lead to polymicrobial bacterial infections with a mixture of aerobic and anaerobic organisms. Pasteurella species are commonly found in dog and cat bite wounds, and Eikenella is characteristic of human wounds. Staphylococcus, Streptococcus, and anaerobic bacterial species are common to all mammals. Although public health measures in developed countries have been highly effective at reducing rabies transmission, dog bites remain the most common source of rabies infection worldwide. Human bites can transmit HIV, hepatitis B, or hepatitis C, especially when contaminated blood is exposed to an open wound. Appropriate management of any mammal bite requires recognition, early wound cleansing, evaluation of injured structures, and infection prophylaxis. Structural repair is performed as indicated by the severity and contamination of the injury, and wounds may require delayed closure. Wound infections typically require débridement, empiric antibiotics, and delayed repair or reconstruction.

uman and animal bites are account the costs to the patient in Hcommon hand injuries.1,2 Most terms of time off work, rehabilitation, bites are from dogs, cats, and hu- and permanent impairment.6 From the Department of Orthopaedics 2,3 and Sports Medicine, University of mans. These injuries prompt as Washington, Seattle, WA. many as 330,000 emergency depart- ment visits in the United States None of the following authors or any Epidemiology 4 immediate family member has annually. However, thetrueinci- received anything of value from or has dence is difficult to ascertain In a lifetime, approximately .50% stock or stock options held in because minor injuries are often self- of the population will sustain an a commercial company or institution treated without the advice of 1 . related directly or indirectly to the animal bite. Of these bites, 90% 5 subject of this article: Dr. Kennedy, a healthcare provider. Population are from domestic animals, and most Dr. Stoll, and Dr. Lauder. studies suggest that, in the United will occur during childhood.1,6 Dogs J Am Acad Orthop Surg 2015;23: States, approximately 4.5 million are responsible for 80% to 90% of 47-57 people (1.5% of the population) are bites.7 Whether specific breeds are 3 http://dx.doi.org/10.5435/ bitten annually by dogs alone. The more dangerous than others is 5,8-11 JAAOS-23-01-47 estimated healthcare cost associated a subject of controversy. The with management of cat and dog bites American Veterinary Medical Asso- Copyright 2014 by the American . Academy of Orthopaedic Surgeons. in the United States is $850 million ciation and US Centers for Disease annually and does not take into Control and Prevention have argued

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Figure 1 Figure 2

Clinical photograph of the hand A, Illustration demonstrating the typical position of the hand at the time of impact demonstrating an acute fight bite at against the teeth, which results in a fight bite or reverse bite injury. B, Illustration the metacarpophalangeal joint of the demonstrating the position of the disrupted skin (yellow line), tendon (red line), first finger. (Copyright Ohio State and joint capsule (blue line) when the hand returns to a relaxed position. Note University Department of Emergency that the tendon disruption is not immediately visible within the skin wound, and Medicine, Columbus, OH.) the capsular tear is covered with tendon, creating a closed space that can lead to infection.

against breed-specific legislation and whereas bites to the shoulders, arms, Clenched Fist Injuries advocate instead for community and hands are most often seen in Clenched fist injuries, which are also 14 measures for bite prevention.9,10 In men. Human bites can result from known as fight bites or reverse bite most cases, the patient is familiar altercations, assault, abuse, sexual injuries, are the most common form with the animal responsible for the activities, or self-defense. The true of human hand bites (Figure 1). bite injury.3,11 Cat bites are the sec- incidence of human bites is likely These injuries result from the impact ond most common domestic animal underestimated because patients of a clenched fist against the teeth of bite, constituting 5% to 15% of may not seek medical attention. another person. The MCP joint is all bites.2,7,8 Dog bites are more most frequently involved because of common in boys and men, and cat its prominence when a fist is bites are most common in adult Anatomy and Mechanism clenched. The overlying skin is taut women.2,7 of Injury at the time of impact, leaving little Human bites are less common than soft-tissue protection. In a study of domestic animal bites, accounting for Anatomy 191 patients with clenched fist in- 2% to 3% of hand bites.12 These Because of the unique anatomy of juries, the authors found that the bites can be categorized as (1) the hand, bite wounds may appear teeth often penetrated the extensor clenched fist injuries (“fight bites”), small. However, tendons, bones, mechanism and joint capsule (67%), which result from the impact of the nerves, blood vessels, and joint leading to injury of the articular hand against the teeth during a fight, structures are superficial and at cartilage and bone.13 When the hand or (2) occlusive bite injuries, which risk of injury. The skin of the hand subsequently returns to a relaxed are caused by the teeth closing is generally well perfused, but inoc- position, retraction of the extensor directly on tissue. Patients with ulation with polymicrobial oral tendon removes the injured tendon clenched fist injuries are typically flora leads to infectious spread from view in the skin wound and male, the dominant hand is usually along structures with relatively seals the capsular tear, creating involved, and the bite most often low vascularity such as tendons, a closed environment ideal for bac- occurs at the metacarpophalangeal ligaments, bones, and cartilage. terial growth and the development of (MCP) joints of the hand.13 Occlu- Following a bite injury, cellulitis, septic arthritis16 (Figure 2). Infection sive bites occur more often in women abscess, infectious tenosynovitis, may also spread to the subcutaneous than in men and are more frequently septic arthritis, osteomyelitis, space, subaponeurotic space, and inflicted by men.14 Occlusive bites and even sepsis can develop, pre- along the lumbrical muscle, leading to the breasts, arms, genitals, or legs disposing the hand to long-term to infection in the palm and flexor are most often seen in women, morbidity.15 tendon sheaths.

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Occlusive Human Bites Figure 3 Occlusive bite wounds are caused by direct closure of the teeth on tissue. If the fingers are involved, bites often penetrate the dorsal and volar skin to inoculate the tendon or joint capsule with oral flora. Severe bites may result in traumatic amputation of the finger through the distal phalanx or distal interphalangeal joint. In more proximal bites, a semicircular imprint of the teeth is often seen at the location of the bite, with variable depth of penetration and injury to the underlying structures. Infections are less common in proximal occlusive bites than in bites to the hand and wrist.6

Dog Bites The severity of a dog bite is corre- lated with dog size, breed, training, and circumstances of the bite.3,9-11 Large breeds, particularly those trained as attack, guard, and police dogs, tend to inflict more damage. Adult canine jaws are capable of exerting bite forces of .300 lbs.17 The teeth vary in shape from long sharp canine teeth to more rounded incisors, premolars, and molars with grinding surfaces (Figure 3, A). This variety of shapes has evolved to A, Photograph demonstrating typical dog dental anatomy. (Copyright iStock. clamp and hold, tear, and crush com/chalabala) B, Clinical photograph of the hand demonstrating soft-tissue tearing and avulsion injuries resulting from a dog bite. C, Photograph food. Crush wounds, devasculari- demonstrating typical cat dental anatomy. (Copyright iStock.com/rblake80) zation, and soft-tissue avulsion D, Clinical photograph of the hand and forearm demonstrating ascending result from high pressures and lymphangitis following a cat bite to the hand. (Copyright Amanda Roof, MD, shearing (Figure 3, B). The injury is Seattle, WA.) further compromised by direct inoculation with oral flora. In severe bites, soft-tissue coverage piercing deeply to enter the joint capsule or inoculate the periosteum Disease Transmission may be required following wound and Bacteriology débridement. and bone with oral flora (Figure 3, D). An estimated 30% to 50% of cat bites are complicated by infection, Human Bites Cat Bites whereas infections associated with Human bites have a reputation for Although cats do not have the jaw dog bites typically occur at less than causing severe hand infections. In strength of dogs, they do have sharp, half that rate.7 Cat bites result in human saliva, .600 bacterial species narrow teeth that have evolved to a higher rate of infectious sequelae have been identified.18 Cultures of pierce and tear the tissue of small and invasive treatment among bite wounds are frequently poly- prey (Figure 3, C). This dental anat- patients who present for medical microbial, typically with four iso- omy causes puncture-type wounds, treatment.8 lates per culture.19,20 The common

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Table 1 Bacteria Typically Isolated From Infected Bite Wounds19-21 Source Aerobic Bacteria Anaerobic Bacteria

Human Streptococcus species, Staphylococcus species, Prevotella species, Fusobacterium species, Eikenella corrodens, Haemophilus species, Eubacterium species, Veillonella species, Enterobacteriaceae, Gemella morbillorum, Peptostreptococcus species, other organisms Neisseria species, other organisms Dog Pasteurella species, Streptococcus species, Fusobacterium species, Porphyromonas Staphylococcus species, Neisseria species, species, Prevotella species, Propionibacterium Corynebacterium species, Moraxella species, species, Bacteroides species, Enterococcus species, other organisms Peptostreptococcus species, other organisms Cat Pasteurella species, Streptococcus species, Fusobacterium species, Porphyromonas Staphylococcus species, Neisseria species, species, Prevotella species, Propionibacterium Corynebacterium species, Moraxella species, species, Bacteroides species, other organisms Enterococcus species, other organisms

for HCV does not include medica- Table 2 tion but does include a baseline anti- Viral Infections Transmitted by Human and Animal Bites HCV test with retesting performed at Bite Source Viruses 4 and 6 months.22,23 When a bite occurs during an altercation, testing Human HIV, hepatitis B, hepatitis C, herpes simplex of both parties is recommended a Dogs, bats, raccoons, skunks, Rhabdoviridae (rabies) because blood-borne illness can be and other rodents transmitted from the patient to the Rats and mice Hantavirus biter.22,23 Monkeys (especially macaques) Simian B

a In areas where rabies is endemic Dog and Cat Bites Like infections associated with human bites, most infections result- aerobic and anaerobic bacteria iso- the time of injury, the CDC recom- ing from dog and cat bites are poly- lated from human bite infections are mends postexposure prophylaxis microbial, regardless of wound type listed in Table 1.19,21 Eikenella cor- with highly active antiretroviral ther- or clinical presentation.21 In a study rodens was isolated in 17% to 30% apy.22 This is a combination of anti- of 107 patients with infections of cases in several studies.19-21 The retroviral medications used to treat caused by dog or cat bites, mixed high level of infectivity associated AIDS; a 28-day prophylactic course is aerobes and anaerobes constituted with human bites may be attributed recommended after exposure.22 The .50% of wound cultures, with an to the combination of virulence patient should also have a baseline average number of five bacterial factors from multiple bacteria. blood test to determine preexposure isolates per sample.24 Aerobic and Pure gram-negative or anaerobic HIV status, with retesting performed anaerobic bacterial species com- infections are uncommon.19,20 at3and6months.22 monly isolated from dog and cat HIV, hepatitis B (HBV), and hepa- HBV can be transmitted via saliva bites are listed in Table 1. In several titis C (HCV) can be transmitted by only if the skin is pierced. The use of studies, Pasteurella species were the human bites, but this rarely occurs22 postexposure prophylaxis is consid- most frequently found isolates in (Table 2). Salivary inhibitors usually ered if the exposure results in bleed- cultures of dog (50%) and cat (75%) inactivate the infectious potential of ing.22,23 An HBV surface antigen bites.7,24,25 the HIV virus, making the risk of titer should be obtained regardless of Pasteurella is a gram-negative, transmission from saliva alone vaccination status.22,23 If the HBV facultative, anaerobic, pleomorphic essentially negligible.22,23 Risk is sig- status of the biter is unknown, and coccobacillus that causes an early nificantly increased when blood is HBV antibodies are insufficient or and severe inflammatory response.24 present, however (0.1% to 0.3%).22 If absent, then the accelerated course of P canis is most commonly found in HIV infection is known or suspected the HBV vaccine may be adminis- dogs, whereas P multocida and P and there was visible blood present at tered.22,23 Postexposure follow-up septica are most commonly found in

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cats.24 The laboratory should be countries with a high population timing and location of injury, patient informed of the bite type and the of stray dogs. In countries where factors (eg, immunocompromised potential for Pasteurella iso- rabies is endemic, patients who are status, age), immunization history, lates.7,24,26 Cultures require appro- bitten should be treated based on and recent history of antibiotic ther- priate growth media and may take the assumption that the dog was apy should be considered when up to 1 week to grow. infected. determining treatment (Figure 4). In Capnocytophaga canimorsus infec- In the United States, rabies infec- patients with prosthetic joints, there tion after a dog bite is rare but de- tion is rare and is most commonly is a risk of blood-borne seeding if serves mention because it can lead to transmitted by bats.30 Bats, rac- bacteremia develops. In cases of cellulitis, sepsis, meningitis, endo- coons, skunks, and foxes are the clenched fist injuries, it may be dif- carditis, disseminated intravascular most common carriers of rabies in ficult to obtain an adequate history coagulation, acute respiratory dis- the United States.30 In patients with because of the patient’s reluctance to tress syndrome, organ damage, and a bite from one of these animals, the disclose the circumstances sur- death.15 Virulence is low in healthy clinician must maintain a high index rounding the injury, but this is persons, but this infection can result of suspicion for rabies exposure essential in counseling the patient in significant morbidity in elderly or because of the severity of the illness regarding transmission of blood immunocompromised patients. In the and the need to institute prophylaxis. borne illnesses. setting of sepsis, reported rates of The animal should be captured and mortality ranging from 30% to 60% tested. Postexposure prophylaxis is have been reported.15 After an incu- initiated until the disease can be Physical Examination bation period of up to 1 week, clinical ruled out in the offending animal.29 The size and depth of the wound and manifestations include fever, chills, the amount of devitalized tissue myalgia, vomiting, malaise, petechial Tetanus should be assessed along with rash, and purpuric lesions. Manage- potential damage to neurovascular ment includes hospital admission and Clostridium tetani is not commonly structures and tendons, underlying immediate antimicrobial therapy.15 found in wounds associated with fractures, the presence of exposed human, dog, or cat bites, but bone, the integrity of the joint, and Clostridium spores are ubiquitous, the presence of infection. A bite Bites From Other Mammals 31 and tetanus is potentially fatal. In wound located over a joint or tendon Other mammalian species such as patients who have been bitten, is a risk factor for more severe infec- bats, raccoons, skunks, rats, and administration of tetanus toxoid is tion, which could require hospitali- other nondomestic animals are recommended for those who have zation.32 Fight bites may be infrequent sources of hand bites. Bites not received a booster within 5 years, overlooked by the patient and from these animals have the potential and immunoglobulin should be healthcare provider because of the to transmit rabies as well as uncom- administered to those who have small lacerations that characterize monly encountered diseases such as had two or fewer previous tetanus these injuries. In addition, the patient rat-bite fever, hantavirus, and other 31 immunizations. may be intoxicated and/or the illnesses.27 Whenever possible, the healthcare provider may be focused animal involved should be captured on the potential for other fractures, and tested. Urgent infectious disease Diagnosis and Evaluation lacerations, and injuries. consultation is recommended for During the examination, particular unusual bites. For example, bites History attention should be paid to the func- from laboratory macaque monkeys Symptoms of infection can occur tion of the extensor mechanism. The may transmit simian B virus, within 12 hours of injury.24,25 In- intrinsic muscle attachments to the which is fatal in 80% of untreated fections related to cat bites develop lateral bands can allow proximal humans.28 as early as 3 hours after the incident interphalangeal (PIP) joint extension in approximately 50% of cases. The despite complete disruption of the Rabies most prominent symptoms include central slip over the PIP joint or the Dog bites are the most common erythema, edema, progressive pain, extensor tendon more proximally.33 source of rabies worldwide.29,30 and fever. Extension at the MCP joint should More than 55,000 deaths are Obtaining a pertinent medical his- be evaluated, and the Elson test attributed to rabies annually. Most tory is essential to evaluate the patient should be performed to evaluate for of these fatalities occur in developing for an increased risk of infection. The disruption of the extensor

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Figure 4 graphed to document possible assault or abuse.

Diagnostic Imaging Plain radiographs are used to evaluate for underlying fractures, joint pathol- ogy, and foreign bodies. Although often unremarkable, radiography may demonstrate fracture, impaction in- juries of bone, tooth fragments, or air in the joint or soft tissues. Radiography is also useful for detecting osteomyeli- tis. A puncture wound with associated fracture is at high risk for osteomyelitis. In patients with advanced infection, radiographic findings that indicate osteomyelitis include periarticular osteoporosis, joint space narrowing, bony erosion, and periostitis. Ultraso- nography can demonstrate fluid col- lection and vascular injury.7

Laboratory Tests Although laboratory studies are not routinely ordered after an acute hand bite, they may be useful for detecting possible infection. Erythrocyte sedi- mentation rate, C-reactive protein level, and white-blood cell count can help to evaluate the patient for sys- temic inflammation and can be used as a baseline for treatment. However, Algorithm for initial evaluation and management of an acute hand bite. CRP = these studies may be normal even in C-reactive protein, ESR = erythrocyte sedimentation rate, HBV = hepatitis B virus, the presence of infection, or the re- HCV = hepatitis C virus, Tdap = tetanus, diphtheria, and pertussis, WBC = white sults may be elevated in patients with blood cell count other sources of inflammation or infection; therefore, these studies should not be used alone to diagnose mechanism.33 During the Elson test, whereas passive extension centralizes or rule out infection.7,35,36 resisted PIP joint extension is as- the tendon and allows for mainte- In patients with infection, cultures sessed with the PIP joint flexed to 90° nance of an extended position. should be obtained (preferably from over the edge of a table. If PIP joint In children with human occlusion intraoperative wound tissue samples) extension is weak and the distal bites, the intercanine distance can to detect aerobic and anaerobic bac- interphalangeal joint hyperextends, be used to evaluate whether a child teria. The bite source and potential rupture of the central slip is likely. or an abusive adult inflicted the presence of organisms should be Sagittal band rupture should be bite.34 Adults have an intercanine communicated to the laboratory evaluated by performing an extensor distance of 3.0 to 4.5 cm, whereas because Eikenella, Pasteurella,and lag examination at the MCP joint. thedistanceis2.5to3.0cmin other organisms may be difficult to Sagittal band disruption may allow children.34 This method lacks some isolate.24,26 In patients with acute extensor tendon subluxation between specificity because adult dentition bites without infection, swabs for the metacarpal heads, preventing is present by age 12 years; there- culture are unreliable and are typi- active extension of the MCP joint, fore, the bite should be photo- cally not recommended.

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Management Table 3 Empiric Antibiotic Prophylaxis for Human, Dog, and Cat Bitesa,36,37 Prophylaxis Route Agents of Choice Alternate Regimens Although routine antibiotic pro- Oral Amoxicillin-clavulanate One of the following:b phylaxis is not necessarily recom- Doxycycline, trimethoprim- mended for all bite wounds, it is sulfamethoxazole, penicillin VK, recommended for hand bites.6 In cefuroxime, fluoroquinolones a review of eight randomized con- (ciprofloxacin or moxifloxacin) trolled trials, Medeiros and Saconato6 Intravenous Ampicillin-sulbactam, Fluoroquinolones (eg, piperacillin-tazobactam, ciprofloxacin) plus showed that hand and wrist bites are ticarcillin-clavulanate, metronidazole, carbapenem an independent risk factor for ceftriaxone plus metronidazole monotherapy (eg, imipenem, infection, and antibiotic prophylaxis meropenem, ertapenem) reduces infection from 28% to 2% a Same for all three types of bites (number needed to treat = 4). Even b Plus clindamycin or metronidazole in patients who present early (,24 hours) and are free of infection, tendon injury, or joint injury, bed- side débridement and wound care 90%.29 Rabies vaccine and immu- vascular injury, and deep tissue alone are insufficient.6 High-risk noglobulin are given in high-risk infection.5,7 populations and patients with punc- situations. Immunoglobulin pro- In patients with acute clenched fist ture wounds, crush injuries with vides immediate virus-neutralizing injuries (fight bites), the wound can devitalized tissue, or deep wounds antibodies while the vaccine in- be extended to provide adequate that cannot be cleansed easily par- duces host-immune production of exposure for inspection. Arthrotomy ticularly benefit from antibiotic antibodies within 7 to 10 days.29 and inspection of the joint surface prophylaxis. Multiple doses of rabies vaccination may be beneficial even if the capsule Broad antibiotic coverage is recom- can be discontinued once testing of appears to be intact because puncture mended to address the polymicrobial the source animal has excluded rabies. wounds can quickly seal off. Part of nature of common oral flora and bite the penetrating tooth is occasionally infections. For example, E corrodens retained and should be removed at and Pasteurella species are generally Wound Management the time of exploration.13 Insufficient susceptible to penicillin and ampicil- Management of the wound partially evidence exists to determine whether lin,26 but staphylococci and anaerobic depends on its size, character, and the exploration in the operating room is species often produce b-lactamase, presence or absence of infection. necessary for all acute fight bites.39 which provides resistance to these When multiple tiny punctures asso- These injuries are often treated with antibiotics.22 The addition of ciated with a bite from a cat or small irrigation and débridement in the a b-lactamase inhibitor significantly dog are treated with antibiotics, emergency department and an increases the effectiveness of these an- lancing of the punctures is not intravenous dose of antibiotic. The tibiotics, and amoxicillin-clavulanate is typically required unless infection patient is discharged with oral the oral antibiotic of choice for human, develops. Open wounds, however, amoxicillin-clavulinic acid, and close dog, and cat bites.26,37,38 Oral and should be irrigated and débrided. follow-up is recommended. intravenous antibiotic options and The goals of initial wound man- The time from injury to treatment is alternative medications are listed in agement include hemostasis, copious important. Basadre and Parry40 ret- Table 3. Cephalexin, dicloxacillin, and irrigation, removal of foreign bodies, rospectively reviewed 124 patients erythromycin should not be used and excisional débridement of devi- with human bite injuries to the hand. because they demonstrate poor activity talized tissue. The use of local anes- Forty-seven patients were seen against Eikenella and Pasteurella. thesia for evaluation of the wound within 24 hours of injury, 51 pre- In cases in which rabies trans- provides the opportunity for a more sented 1 to 7 days after injury, and mission is possible, irrigation and thorough assessment, irrigation, and 26 presented $7 days after débridement, the use of soap, and the débridement. During wound explo- injury.39,40 Of the patients who application of alcohol or povidone- ration, the hand is assessed for ten- presented within 24 hours, 78% iodine to the wound can reduce don disruption, bone or joint received wound care only and 22% the likelihood of transmission by penetration, open fracture, neuro- underwent surgical débridement, but

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all had excellent functional out- at the same institution in the same lished infection may benefit from comes.39,40 Among the patients who time frame); however, this rate may hospitalization and repeat débride- presented between 1 and 7 days after be an acceptable trade-off for ment as needed. injury, those without infection also improved cosmetic appearance. Scant data are available to guide the had good outcomes independent of Other studies also included bites to healthcare provider with regard to the initial treatment, but patients all body regions and found no dif- the appropriate duration of antibiotic with infection lost motion and grip ference between patients who treatment. In general, the duration of strength if surgical débridement was underwent suture closure and those therapy is based on the severity of the not performed.39,40 Complications who did not.43,44 However, these infection. For example, antibiotic included septic arthritis, osteomyeli- studies are underpowered to draw treatment for cellulitis is typically tis, and tenosynovitis. For patients conclusions from on the effect of 10 to 14 days, whereas treatment for who presented $7 days after injury, suture closure for hand bites in tenosynovitis, septic arthritis, and 93% were treated surgically and had particular. Studies consistently osteomyelitis is 3 weeks, 4 weeks, good outcomes.39,40 confirm that bites to the hand are and 6 weeks, respectively.7,8,35 The a subset of injuries that have C-reactive protein level and other a higher risk of infection than do markers of infection (eg, erythrocyte Surgical Repair bites to other areas of the body.42,43 sedimentation rate, white blood Tendon repair, tendon transfer, os- Leaving a wound open is not cell count) may decrease in response teosynthesis, vascular repair, revi- a substitute for antibiotic therapy or to treatment, but clinical observation sion amputation, and/or soft-tissue irrigation and débridement. Heavy remains the best measure of man- coverage can be performed if the contamination or uncertain adequacy agement of infection.7,35 Once the tissues are adequately débrided.5 of débridement remains a contraindi- infection is controlled, delayed Successful results have been achieved cation to primary closure. reconstructive efforts may be with primary flexor tendon and Postoperative management of bite considered.35,36 extensor tendon repairs after human wounds should include elevation, bites.41 Whether exploration and wound care, and antibiotics. Careful surgical repair is performed in the follow-up is required to monitor the Functional Outcomes emergency department or in the progression of healing. The patient The heterogeneity of types of bites, operating room depends on injury should be counseled to return imme- time from injury to presentation, factors, patient factors, and local diately if symptoms worsen. and the presence of injured struc- resources. However, patients with tures makes the prediction of func- flexor tendon lacerations, bone pen- tional outcomes challenging. Early etration, and extensive devitalization Infection assessment of bite injuries, irriga- or contamination will likely benefit Following a diagnosis of infection, tion and débridement, and modern from treatment in the operating expeditious treatment is required to antimicrobial therapy have signifi- room. prevent progression. Tissue cultures cantly improved outcomes of bites Suture closure of acute bite wounds are preferred over culture swabs to the hand from humans, dogs, on the hand is a controversial topic. because of the improved accuracy and cats. Patients who present Leaving these wounds open for bacte- in diagnosing bacterial pathogens. early and are treated may have rial egress has been recommended.42-45 Most infections are treated with irri- few sequelae. Delayed presentation However, recent studies of emergency gation, excisional débridement, and or inadequate initial management, management of these injuries show delayed closure. All necrotic tissue however, may lead to persistent substantial improvement in cosmetic should be débrided (Figure 5). infection, advanced joint destruction, appearance with primary closure Infected bone should be excised and and osteomyelitis.36 Untreated (particularly for facial wounds), with loose fragments of articular cartilage septic arthritis has a profound little or no increased risk of infec- should be removed. In severe cases, effect on functional outcome, par- tion.42-44 In a study of 145 patients significant bone excision is required, ticularly if there is evidence of joint with bite wounds treated with primary and patients should be advised space narrowing or bony changes.46 closure, Chen et al45 acknowledged early of the potential risk for later Once osteomyelitis develops, defini- that infection rates may have been amputation.35,36 After débridement, tive treatment may require amputa- slightly higher in their study pop- leaving wounds open to heal by tion.36 Other complications include ulation (6% versus 3.4% for the secondary intention facilitates bac- erosion of the flexor tendon standard sutured wound infection rate terial egress. Patients with estab- and volar plate, tendon rupture,

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Copyright Ó the American Academy of Orthopaedic Surgeons. Unauthorized reproduction of this article is prohibited. Stephen A. Kennedy, MD, et al

Figure 5

A through F, Clinical photographs and radiographic imaging of the hand in a 59-year-old man who presented with right hand pain and swelling for 6 days. He had a 2-month-old healed puncture wound over the third metacarpal caused by a bite from the family German shepherd. A, Moderate swelling is visible over the third metacarpal, with mild erythema around the healed puncture. B, PA radiograph of the right the hand demonstrating lucency in the metacarpal neck and a periosteal reaction on the ulnar aspect of the metacarpal diaphysis. C, Three-dimensional CT scan reconstruction demonstrating an osteolytic metaphyseal lesion and a fistulous tract through the third metacarpal to the mid diaphysis. D, Intraoperative photograph of the hand demonstrating surgical drainage, which was followed by curettage and excision of bone for culture. Swabs were negative for organisms, but the tissue culture showed multiple anaerobic species, including Fusobacterium, Bacteroides, and Prevotella species. E, PA fluoroscopic image of the hand following the curettage and excision of the infected area back to healthy bleeding bone. F, PA fluoroscopic image of the hand after insertion of antibiotic-loaded cement spacers into the dead space. These spacers were later removed.

and the development of tendon juries can lead to severe infection and of infection in select cases, and pri- adhesions. functional impairment. Antimicro- mary surgical repair and closure may bial treatment is indicated for all bites be considered in select patients. Early to the hand regardless whether they assessment of bite injuries, irrigation Summary are acute or severe and has signifi- and débridement, and modern anti- cantly reduced the morbidity and microbial therapy have been success- Because of the unique anatomy of the mortality associated with these in- ful in reducing the morbidity, hand and the bacteriology of human juries. Surgical débridement can duration of treatment, and costs and mammalian oral flora, bite in- effectively decrease the development associated with hand bite injuries.

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11. Sacks JJ, Sinclair L, Gilchrist J, Golab GC, algorithm. J Natl Med Assoc 2013;105(1): References Lockwood R: Breeds of dogs involved in 92-95. fatal human attacks in the United States between 1979 and 1998. J Am Vet Med 24. Talan DA, Citron DM, Abrahamian FM, Evidence-based Medicine: Levels of Assoc 2000;217(6):836-840. Moran GJ, Goldstein EJ; Emergency evidence are described in the table of Medicine Animal Bite Infection Study 12. Endom EE: Initial management of animal Group: Bacteriologic analysis of infected contents. In this article, references and human bites, in Post TW, ed: dog and cat bites. N Engl J Med 1999;340 17, 19, and 44 are level I studies. UpToDate. http://www.uptodate.com/ (2):85-92. contents/initial-management-of-animal- References 3, 4, 6, 21, 23, 42, 43, 25. Westling K, Farra A, Cars B, et al: Cat bite and-human-bites. Accessed October 5, wound infections: A prospective clinical and 45 are level II studies. 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