Kwok Chuen Wong, MBChB, FRCSEd(Orth)1 and Kwok Sui Leung, MD, FRCSEd1
1 Department of Orthopaedics and Traumatology, Chinese University of
Hong Kong, 5/F, Clinical Science Building, Prince of Wales Hospital,
Hong Kong Special Administrative Region, China. E-mail address for K.C.
Investigation performed at the Department of Orthopaedics and
Traumatology, Chinese University of Hong Kong, Prince of Wales Hospital,
Hong Kong, China
The authors did not receive grants or outside funding in support of
their research or preparation of this manuscript. They did not receive
payments or other benefits or a commitment or agreement to provide such
benefits from a commercial entity. No commercial entity paid or
directed, or agreed to pay or direct, any benefits to any research fund,
foundation, educational institution, or other charitable or nonprofit
organization with which the authors are affiliated or associated.
Microorganisms are transmitted in hospitals mainly by contact,
droplet, and airborne routes.
Orthopaedic surgeons have a substantial occupational risk of
contracting a blood-borne infection because of frequent handling of
sharp instruments and objects during operative procedures.
Aerosolization means the formation of aerosols and droplets when
blood or other body fluids are mechanically disturbed. Smaller particles
(<5 µm) will remain suspended in air. Pathogens that can survive in
these small airborne particles may cause infection if they are inhaled.
Aerosol-generating procedures in patients with tuberculosis or severe
acute respiratory syndrome (SARS) may facilitate airborne transmission.
The Hospital Infection Control Practices Advisory Committee and the
Centers for Disease Control and Prevention have established guidelines
for isolation precautions in hospitals.
Surgeons and health-care workers have always had a high risk of
exposure to blood-borne diseases as a result of their occupation.
Orthopaedic surgeons have substantial occupational exposure to blood and
the risk of blood-borne infection because of frequent handling of sharp
instruments, metal objects (e.g., wire), and bone fragments during
The purpose of this review is to discuss the risk of occupational
blood-borne infection and the means of disease transmission by contact,
droplet, and airborne routes in orthopaedic surgery. The role of
aerosolization in the facilitation of disease transmission will be
analyzed. Severe acute respiratory syndrome (SARS), the recently
recognized and highly contagious respiratory infection, will be
discussed in detail. Finally, precautionary measures to protect against
occupational infection will be reviewed.
Means of Transmission of Microorganisms
Understanding the means of transmission of infectious diseases is
very important in the prevention of occupational transmission of
pathogens. Microorganisms are transmitted in hospitals mainly by
contact, droplet, and airborne routes.
This is the most important and frequent mode of transmission of
nosocomial infection. There are two types of contact transmission:
direct and indirect. Direct-contact transmission involves direct
body-to-body contact with the transfer of microorganisms during routine
care of patients. Indirect-contact transmission is the transmission of
pathogens by contact with contaminated objects such as dressings,
needles, and instruments.
Droplets are primarily generated by patients during coughing,
sneezing, and talking and during the performance of certain procedures
such as suctioning and bronchoscopy. Transmission occurs when droplets
containing microorganisms generated from the infected patient are
propelled a short distance through the air and deposited on the skin or
mucosal surface of the health-care worker. Severe acute respiratory
syndrome (SARS) is one of the illnesses transmitted by droplets, and it
has spread worldwide and raised global concern.
Aerosolization means the formation of aerosols and droplets when
blood or another body fluid is mechanically disturbed. Small particles
(<5 µm) can remain suspended in air and can be dispersed widely by air
currents. Airborne transmission can occur by dissemination of these
small particles if they contain pathogens, and inhalation of these
particles may result in infection. Mycobacterium tuberculosis is an
example of a typical microorganism transmitted by this airborne route.
Health-care workers and particularly surgeons are at risk for
occupational transmission of blood-borne pathogens, such as hepatitis-B
virus, hepatitis-C virus, and human immunodeficiency virus (HIV).
Infection with blood-borne pathogens occurs mainly by contact
transmission—i.e., percutaneous or mucocutaneous exposure to blood-borne
pathogens. Percutaneous exposure is due to needlesticks or cuts from
other sharp instruments, implanted materials, or bone fragments
contaminated with the blood of infected patients. Mucocutaneous exposure
occurs through contact of the mucous membrane of the eyes, nose, or
mouth or contact of the skin with the blood of infected patients.
Percutaneous injuries are a substantial risk for health care workers,
with 5520 percutaneous injuries reported by fifteen hospitals
participating in the Centers for Disease Control and Prevention National
Surveillance System for Hospital Health Care Workers (NaSH) between June
1995 and July 19995. Of 4569 percutaneous injuries, 2826 (62%) were
associated with hollow-bore needles5. Of 3057 percutaneous injuries,
approximately 38% occurred during use of needles and 42% occurred after
use and before disposal of needles5.
The risk of percutaneous and mucocutaneous exposure for orthopaedic
surgeons and operating room personnel has also been investigated.
Gerberding et al.3 discussed the risk of exposure to blood at San
Francisco General Hospital after analyzing data on 1307 consecutive
operations. They found that percutaneous injury occurred in twenty-two
operations (1.7%) and mucocutaneous exposure occurred in sixty-two
(4.7%). The risk of exposure was higher when procedures lasted more than
three hours and blood loss exceeded 300 mL.
Quebbeman et al.4 studied the prevalence of percutaneous injuries and
mucocutaneous exposure during 234 operations involving 1763 operating
room personnel. They found that percutaneous injuries occurred in
thirty-five operations (15%) and mucocutaneous exposure, in 118 (50%).
In addition, orthopaedic surgeons had increased face and neck
contamination due to splattering of blood from power tools and the use
of irrigation fluids.
In a study in which a mail survey was sent to 1200 orthopaedic
surgeons in the United Kingdom and 800 (67%) responded, 511 surgeons
reported that they had sustained needlestick injuries or contamination
of the eyes with patients' body fluid within the past month6.
In another investigation, orthopaedic surgeons attending the annual
meeting of the American Academy of Orthopaedic Surgeons in 1991 were
surveyed about occupational blood contact and HIV infection2. Of 7147
orthopaedic surgeons at the meeting, 3420 (47.9%) participated in the
survey; 2989 (87.4%) reported cutaneous contact with blood and 1340
(39.2%) reported percutaneous contact with blood in the previous month.
One hundred and nine surgeons (3.2%) reported percutaneous contact with
the blood of a patient known to have HIV infection or acquired
immunodeficiency syndrome (AIDS) in their career. Among 108 participants
with nonoccupational HIV risk factors, only two were positive for the
HIV antibody. Among 3267 participants without nonoccupational HIV risk
factors, none was positive for the HIV antibody.
Surgeons sustain most percutaneous injuries when they are suturing.
The index finger of the nondominant hand is often injured because of the
surgeon's use of his or her fingers to hold tissue while suturing or
during blind suturing7,8.
The occupational risk of infection with blood-borne pathogens depends
on a variety of factors9 as presented in Table I.
TABLE I Factors That Affect the Risk of Occupational Infection with
Prevalence of pathogens in the patient population
Amount of pathogens in the blood of the patient at the time of
Type of pathogens
Incidence of percutaneous or mucocutaneous exposure
Type and severity of percutaneous injuries; i.e., whether the
injuries were caused by a solid-bore needle, a hollow-bore needle, a
scalpel, or another instrument. (A laboratory experiment demonstrated
that more blood is transferred by deeper injuries and hollow-bore
needles97. Therefore, the risk is higher with hollow-bore needles and
deeper injuries than it is with solid-bore needles and superficial
Availability and use of preexposure vaccination and postexposure
prophylaxis (i.e., treatment for prevention of disease once exposure has
The risk of transmission of hepatitis-B virus during a single
percutaneous exposure of an unvaccinated person to blood infected with
the virus ranges from 6% to 30%10,11. The risk associated with
mucocutaneous exposure has not been quantified but may be higher than
the risk with other blood-borne pathogens. Hepatitis-B virus can survive
in dried blood at room temperature on environmental surfaces for at
least one week12. The potential for transmission of hepatitis-B virus
through contact with environmental surfaces has been demonstrated in
investigations of outbreaks of infections with hepatitis-B virus among
patients and staff of hemodialysis units13,14. Hepatitis-B virus has
been found in saliva but is usually undetectable in urine and feces15.
Transmission of the virus by human bites is therefore possible and has
been documented16. The risk of infection after exposure depends on the
status of the hepatitis-Be antigen of the source individual. The
presence of hepatitis-Be antigen in the serum is associated with higher
levels of circulating virus in the blood and therefore with greater
infectivity of an individual who is positive for the antigen11.
Vaccination against hepatitis B is a safe and effective way to
prevent hepatitis-B infection. It is strongly recommended that all
surgeons receive the vaccine. Testing for antibody response should be
completed one to two months after the third vaccine dose. A protective
antibody response is 10 mIU/mL. Vaccine-induced hepatitis-B surface
antibodies decline gradually over time17. However, immune memory remains
intact indefinitely following immunization, and people with declining
levels of hepatitis-B surface antibodies are still protected against the
disease18. Therefore, neither booster doses of hepatitis-B vaccine nor
periodic testing for hepatitis-B surface antibodies is necessary for
previously immunized surgeons19. The hepatitis-B vaccination status and
the vaccine-response status of the exposed surgeon will aid in
determining appropriate postexposure prophylaxis. The mainstay of
postexposure prophylaxis is hepatitis-B vaccine, but in some settings
the addition of hepatitis-B immunoglobulin provides better protection.
Table II summarizes the recommendations of the Centers for Disease
Control and Prevention for postexposure prophylaxis after parenteral
exposure to hepatitis-B virus.
TABLE II Recommended Postexposure Prophylaxis Following Parenteral
Exposure to Hepatitis B Virus
A nonresponder is a person with an inadequate antibody response to
hepatitis-B virus vaccine (hepatitis-B surface antibodies < 10 mIU/mL).
The option of giving one dose of hepatitis-B immunoglobulin and
reinitiating the vaccine series is preferred for nonresponders who have
not completed a second three-dose vaccine series. The option of two
doses of hepatitis-B immunoglobulin is preferred for persons who
previously completed a second vaccine series but did not respond to it.
A responder is a person with an adequate protective antibody response to
hepatitis-B virus vaccine (hepatitis-B surface antibodies 10 mIU/mL).
The prevalence of anti-hepatitis-C virus seroconversion (an
indication of infection) after an accidental percutaneous exposure to
blood infected with the virus averages 1.8% and ranges from 0% to 7%20.
The prevalence is lower than that associated with exposure to
hepatitis-B virus. Transmission rarely occurs from exposure of the
mucous membrane to blood. We are aware of only two case reports
demonstrating transmission of hepatitis-C virus following occupational
conjunctival exposure to blood21,22. To our knowledge, transmission of
hepatitis-C virus during exposure of intact or nonintact skin to the
blood of patients with hepatitis-C virus infection has never been
documented. In addition, hepatitis-C virus RNA has not been detected in
the urine, feces, or saliva from patients with chronic hepatitis-C virus
infection23. The risk of transmission of hepatitis-C virus during
exposure to the above secretions has not been quantified but is expected
to be low. Currently, neither vaccines nor medications for postexposure
treatment are available to prevent hepatitis-C virus infection.
Human Immunodeficiency Virus (HIV)
The risk of HIV infection due to a single percutaneous injury is
estimated to be 0.3% (95% confidence interval = 0.2% to 0.5%)24,25. It
is higher than the estimated risk of infection after exposure of a
mucosal membrane (0.09%) (95% confidence interval = 0.006% to 0.5%)26.
Transmission of HIV due to exposure involving small amounts of blood on
intact skin has not been documented, to our knowledge. In one
prospective study of 2712 cases of exposure of intact skin to HIV, no
infections were found27. Therefore, a small amount of HIV on intact skin
probably poses no risk. In one case-control study of health-care workers
who had percutaneous exposure to HIV, the risk of HIV infection was
shown to increase with exposure to a larger amount of HIV-infected
blood28. Four factors were also found to be associated with an increased
risk of HIV transmission in that study: (1) deep injury, (2) visible
blood on the device that caused the injury, (3) a procedure that
involved a large-gauge hollow-bore needle directly placed in a vein or
artery, and (4) exposure to a patient with acquired immunodeficiency
syndrome or a high plasma viral burden28.
HIV has been found in the saliva from some AIDS patients, although in
lower quantities than in the plasma29. HIV has not been recovered from
the sweat of HIV-infected persons. The risk of transmission through
exposure to these fluids is probably considerably lower than the risk
with exposure to HIV-infected blood27. The relative infectivity of HIV
varies among individuals and over time for a single individual30. Unlike
the case for hepatitis-B virus infection, there is currently no readily
available laboratory test with which to assess increased HIV
Although medications for postexposure prophylaxis against HIV
infection are available, data regarding their efficacy are limited.
Zidovudine (azidothymidine [AZT]), a nucleoside analogue reverse
transcriptase inhibitor, is the only drug that has been studied and
shown to reduce the risk of HIV transmission following occupational
exposure. A retrospective case-control study on health-care workers
revealed an 81% (95% confidence interval = 48% to 94%) reduction in the
risk of infection with the use of AZT after percutaneous exposure28.
However, a combination of antiviral medications, rather than a one-drug
AZT regimen, is now recommended (based on data derived from treatment of
HIV-infected patients) for its theoretical advantage of more effective
prevention of HIV transmission31. The Centers for Disease Control and
Prevention (CDC) recommended a basic two-drug regimen of AZT and
lamivudine when there is a risk of infection. A three-drug regimen, with
the addition of a protease inhibitor such as indinavir, is recommended
when there is a higher risk of transmission31. All of these antiviral
drugs are potentially toxic and have been associated with side effects.
As most instances of occupational exposure to HIV do not result in HIV
transmission, the risks and benefits of prescribing postexposure
prophylaxis must be carefully considered.
Droplet and Airborne Transmission
Tuberculosis is a respiratory infection caused by Mycobacterium
tuberculosis and is spread by airborne transmission. The SARS virus is
predominantly spread by droplets shed from respiratory secretions of
infected individuals. Although airborne transmission does not seem to be
a major route for the spread of the SARS virus, there have been
anecdotal reports that aerosol-generating procedures might facilitate
transmission of the virus in some cases32. As a result, it is crucial to
understand the role of aerosolization of body fluids in facilitating
Aerosols are defined as fine particles with a diameter of 10 µm that
are suspended in a gas. Droplets are much larger particles that have a
definite trajectory pathway away from the site of production33. Aerosols
and droplets can be formed when blood or another body fluid is
mechanically disturbed. They are thus generated by some patients during
coughing and sneezing; they can also be generated by the use of pulsed
irrigation or power tools during operative procedures. The more violent
the disturbance, the more likely is the formation of aerosols and
smaller droplets. Larger particles (5 µm in diameter) settle rapidly
under gravity, whereas smaller particles (<5 µm in diameter) settle
slowly and remain in the air.
If a suspension of microorganisms is aerosolized, the liquid
component will dry up rapidly, leaving the microbial contents as droplet
nuclei suspended in air. These droplet nuclei containing microorganisms,
usually referred to as infected airborne particles, can be dispersed by
air currents generated by ventilation or movement of people and can
reach a long distance from an infected source. Particles of <5 µm in
diameter are more likely to reach the alveoli of the lung than are
larger particles, which tend to be trapped in the upper respiratory
tract. Therefore, airborne transmission can occur by dissemination of
these infected airborne particles if a susceptible host inhales them.
Contact transmission of infection may also occur if these aerosols come
into contact with mucous membranes or small wounds34. Thus, special air
handling and ventilation are required to prevent this airborne
Droplets generated from infected persons do not travel far, usually 3
ft (0.9 m) in air, and are deposited on environmental surfaces or on the
skin or mucous membranes of individuals. Any pathogens that can survive
in these droplets pose a risk of infection.
Mucocutaneous exposure due to droplet transmission should not be
confused with airborne transmission by aerosols35 because droplets do
not remain suspended in air. Special air handling or ventilation is thus
not required to prevent droplet transmission.
Particles of various sizes are produced during coughing and sneezing.
Pathogens capable of surviving in small droplet nuclei (<5 µm in
diameter) then become airborne. To be capable of surviving in small
droplet nuclei, the pathogen must be durable and resistant to drying.
Therefore, when a patient with tuberculosis coughs, he or she spreads
the disease by the airborne route. When a patient with influenza coughs,
he or she spreads the disease by droplet transmission. SARS is thought
to spread predominantly by droplet transmission.
Although it is known that blood-borne pathogens can be transmitted
through mucous membrane exposure, there is a lack of evidence suggesting
that blood-borne pathogens can be transmitted by inhalation of
aerosolized blood. Hepatitis-B virus infection is not transmitted by
inhalation of aerosolized blood36,37. However, studies have shown that
common orthopaedic power tools are capable of generating respirable
blood containing aerosols38-40. These aerosols can be spread all over
the operating room, contaminating the animate and inanimate
environmental surfaces39. A study in which cascade impactors were
mounted in the breathing zones of primary and assistant surgeons
demonstrated that the surgeons were exposed to respirable blood
containing aerosols in the operating rooms41. An experimental study
demonstrated that HIV can remain viable in cool aerosols generated by
power tools42. This may cause HIV transmission to surgeons exposed to
aerosols generated during operations on HIV-infected patients.
Therefore, aerosolized blood-borne pathogens may lead to airborne
infection if the aerosols containing the pathogens are inhaled.
Additional work is required to determine whether this aerosol amounts to
a significant occupational risk in operating theaters.
Precautionary measures against contact with infectious aerosols and
droplets have to be mandatory during procedures in which high-speed
orthopaedic power tools are used. Every person present during the
surgery should wear personal protective apparel, including surgical
gloves, a water-resistant surgical gown with long sleeves, a surgical
mask, and full-face protection with a face-shield. Additional
respiratory protective equipment should be used when surgeons operate on
patients with tuberculosis or SARS. It is recommended that the surgery
be performed by experienced surgeons and anesthetists and sufficiently
trained personnel to reduce operative time and the duration of exposure
to infectious aerosols. Use of diathermy and power tools should be kept
to a minimum. Wound irrigation with bulb syringes is preferred to pulsed
irrigation. It is critical to remove and dispose of protective apparel
and respiratory devices without contaminating oneself at the conclusion
of the procedure. It is essential to wash the hands prior to touching
the face, eyes, or nose after removal of protective apparel. Most
operating rooms undergo up to twenty room-air exchanges per hour.
Therefore, any infectious aerosol particles should be removed quickly.
However, the entire operating theater must be properly decontaminated
between cases, as pathogens within droplets can survive for hours
outside the body on inanimate environmental surfaces.
Tuberculosis is the prototype disease for the study of airborne
infection because it is transmitted effectively through the air when
people in close contact with a person with active disease inhale droplet
nuclei containing tubercle bacilli (1 to 5 µm in diameter).
Investigations of outbreaks of tuberculosis can illustrate several
important principles of disease transmission. One study showed that
inadequate ventilation resulted in recirculation of contaminated air and
positive tuberculin conversion in 35% of sixty employees43. Tuberculosis
may also spread through inhalation of aerosols generated during the care
of a tuberculous skin lesion44 or during procedures such as irrigation
of tuberculous abscesses of the hip and thigh with saline solution45.
These cases demonstrated that nonpulmonary tuberculosis could also be
contagious in certain settings. Other aerosol-generating procedures such
as nasotracheal suctioning can amplify the risk of transmission, as
shown by an outbreak in an emergency room, where an intubated man was
present for only four hours and spread infection to at least sixteen of
the 112 emergency room staff46. Managing unsuspected cases of
tuberculosis also results in a higher risk of tuberculin conversion47.
Early identification and a high index of suspicion of the disease are
essential for preventing the disease.
Severe Acute Respiratory Syndrome (SARS)
SARS is a newly recognized, severe febrile respiratory illness caused
by a previously unknown coronavirus, SARS-associated coronavirus (SARS-CoV).
The condition primarily affects people who come into close contact with
infected patients as well as health-care workers who look after the
patients. This highly contagious respiratory infection can affect
healthy people and can frequently result in rapid deterioration and
progress to respiratory failure. It is also a potentially fatal disease.
In an epidemiological study of 1425 patients with SARS, the mortality
rate was reported to range from 13.2% for patients younger than sixty
years of age to 43.3% for those older than sixty years of age48. SARS
was spread worldwide to thirty countries by travelers in 2003, prompting
the World Health Organization to issue a global alert for the first time
in more than a decade.
The primary mode of spread is by droplet transmission. It occurs when
individuals come into close contact with contaminated respiratory
droplets that were shed from secretions of an infected person during
coughing or sneezing49. SARS-CoV can be found in urine and feces from
infected individuals50. New evidence suggests that the virus survives in
feces and urine at room temperature for at least one to two days.
Heating to 56°C kills the virus, as does exposure to many commonly used
disinfectants51. SARS-CoV can thus be transmitted if people touch their
own mucous membrane with their contaminated hands. Blood can also
contain SARS-CoV, and viremia has been detected up to ten days after the
onset of symptoms in patients with SARS52. There is a theoretical risk
that SARS-CoV can behave like other blood-borne pathogens and spread the
disease by contact transmission. However, we are not aware of any study
in which this possibility was investigated. More work is required to
determine whether this means of transmission of SARS actually exists.
Originally, SARS was not thought to spread by the airborne route.
However, the outbreak in Hong Kong that originated at the Metropole
Hotel53 and the Amoy Gardens54 indicates that airborne transmission is
possible in special settings. Aerosolization of body fluids of an
infected person may facilitate the transmission. However, there is a
lack of evidence suggesting that SARS can be transmitted secondarily by
aerosolization of blood.
It has been shown that the viral load in the nasopharyngeal aspirates
of SARS patients does not peak until ten days after the onset of
symptoms. At fifteen days, it decreases to the levels measured during
the initial presentation to the hospital (mean, 3.2 days after the onset
of symptoms). In the stool, the viral load appears to peak at fourteen
days after the onset of symptoms50. The infectivity of SARS-CoV might be
variable over time, even during the symptomatic phase of the disease,
and transmission may be more likely during the later stages of the
The World Health Organization categorizes SARS into suspected and
probable cases according to the case definition55. In brief, the case
definition of SARS includes a fever of 38°C during the two days before
presentation; coughing, shortness of breath, malaise, or headache; new
pulmonary infiltrates on chest radiographs or high-resolution computed
tomography scans; a history of contact with an infected person; absence
of an alternative diagnosis to explain the clinical presentation; and
laboratory evidence of SARS-CoV infection. Therefore, SARS is diagnosed
according to clinical and radiographic features, contact history, and
laboratory tests. However, existing reverse transcriptase-polymerase
chain reaction (RT-PCR) tests for SARS-CoV are not very accurate,
especially during the early phase of the disease when the viral load is
low. The positivity of the test thus depends on the timing of the
collection of the specimens. Interpretation of these assays must be
performed carefully because of the possibility of false-negative
results, which are frequent early in the course of the infection, and
false-positive results, which are especially important concerns.
Existing antibody tests of seroconversion are generally useful only
after three weeks have elapsed following the disease onset, which is far
too late to be of much practical use. Therefore, in the absence of a
reliable and rapid laboratory test, the diagnosis of SARS is based
purely on clinical and radiographic features and a positive contact
This may cause some difficulties in identifying SARS, particularly in
geriatric patients. Early symptoms of SARS such as fever, malaise, and
headache are nonspecific and are associated with other, more common
illnesses. Frail elderly patients with multiple coexisting chronic
diseases might have no fever at presentation56,57, leading to a delay in
diagnosis. Therefore, the initial diagnosis depends largely on a history
of exposure risk. However, geriatric patients may not be able to provide
a precise contact history. Also, some patients may be reluctant to
reveal a true contact history because of a fear of social stigma or
quarantine of their families or friends58.
In the presence of infection, frail geriatric patients tend to have a
history of falls, confusion, incontinence, and poor feeding at
presentation. Focus on the management of injuries or fractures resulting
from falls by geriatric patients may distract orthopaedic surgeons from
investigating the medical cause of the injury, such as SARS59.
Identification of SARS in this group thus requires a high index of
suspicion. Unrecognized cases of SARS may lead to future outbreaks60.
No vaccines have yet been developed and no antiviral treatment has
been shown to be effective against SARS. Success in controlling disease
transmission relies on early identification of suspected cases, proper
isolation, and implementation of and adherence to infection control
Prevention of Occupational Infection Among Orthopaedic Surgeons
The Hospital Infection Control Practices Advisory Committee (HICPAC)
and the Centers for Disease Control and Prevention have established
guidelines for isolation precautions in hospitals62. Because pathogens
and host factors are sometimes more difficult to eliminate, a more
feasible way of controlling the spread of disease is by taking isolation
precautions to interrupt the spread directly at the level of
There are two tiers of HICPAC Isolation Precautions. The first tier
is Standard Precautions. They are designed for the care of all
inpatients, irrespective of their underlying diseases or presumed
infection status. Blood and all other body fluids of patients are
considered to be potentially infectious. The second tier is
Transmission-Based Precautions. They are used for patients known or
suspected to be infected or colonized with transmissible or
epidemiologically important pathogens for which additional precautions
beyond Standard Precautions are required to prevent nosocomial
transmission. Transmission-Based Precautions are based on the knowledge
of routes of transmission. They are classified as Contact Precautions,
Droplet Precautions, and Airborne Precautions. The precautions may be
combined for diseases that have multiple modes of transmission such as
SARS. They are also expected to be used in addition to Standard
While it is impossible to apply Transmission-Based Precautions to all
patients, early identification of certain infectious diseases that
warrant the additional use of these enhanced precautions is crucial. The
risk of transmission of infection will certainly be minimized if
precautions based on the diagnosis of infectious diseases can be
As a result, Standard Precautions should be applied whenever there is
a risk of exposure to blood or other body fluids of any patient. Contact
Precautions should also be taken when health-care workers are caring for
patients with blood-borne pathogens, and Droplet or Airborne Precautions
should be added when they are dealing with patients with a disease such
as SARS or tuberculosis.
A summary of Standard Precautions is provided in Table III. The
reader is referred to the Centers for Disease Control and Prevention for
complete recommendations with regard to both Standard and
TABLE III Summary of Standard Precautions
Take care to prevent injuries when handling sharp instruments and
needles; carefully dispose of all sharp devices; do not recap needles or
use one-handed scoop technique; use mouthpieces, resuscitation bags, or
other ventilation devices as an alternative to mouth-to-mouth
Place patients who contaminate the environment or who do not assist
in maintaining appropriate hygiene in a private room
The following sections will address the important issues pertinent to
dealing with infectious diseases in orthopaedic practice. Only salient
features of the Standard Precautions and Transmission-Based Precautions
will be highlighted.
Hand-washing is the single most important and simplest step taken by
surgeons to prevent disease transmission. It must be actively
reinforced. Hand antisepsis reduces the incidence of nosocomial
infection63-65. A recent study showed that increased hand-washing by
hospital personnel reduced the acquisition of various
health-care-associated pathogens65. Both this study and another66 showed
that the prevalence of infection decreased as adherence to hand hygiene
Studies have also indicated that scrubbing for five minutes reduces
bacterial counts as effectively as does scrubbing for ten minutes67,68.
Scrubbing for two to three minutes could reduce bacterial counts to
acceptable levels as well69,70.
Protocols for hand antisepsis for surgical personnel have required
scrubbing with a brush. However, the use of a brush may cause skin
damage and lead to shedding of bacteria from the hands. Studies have
also demonstrated that a brush is not necessary to reduce bacterial
counts on the hands of surgical personnel to acceptable levels71-73.
Therefore, brushes may do more harm than they contribute to cleaning.
Their use should be restricted to cleaning the fingernails only.
Clinical trials have compared the effect of hand-washing with plain
soap and water with the effect of some form of hand antisepsis on
infection rates. Nosocomial infection rates were lower when antiseptic
hand-washing was performed by hospital personnel74,75.
An alcohol-based surgical hand-rub is effective for hand
antisepsis76-78. In one prospective, randomized trial of 4387
consecutive operations, hand rubbing with aqueous alcoholic solution
preceded by a one-minute nonantiseptic hand wash was shown to be as
effective as a traditional surgical hand-scrub with antiseptic soap (4%
povidone iodine or 4% chlorhexidine gluconate) in preventing surgical
site infection76. The authors concluded that hand rubbing with liquid
aqueous alcoholic solution can be used safely as an alternative to the
traditional surgical hand scrub. In another study, alcohol preparations
were even more effective than povidone-iodine or chlorhexidine for the
surgical scrub77. As a result, the presurgical scrub has been replaced
in many European countries by the alcoholic rub. Table IV summarizes the
characteristics of common hand antiseptic agents.
TABLE IV Summary of the Characteristics of Common Antiseptic
* A score of +++ = excellent, ++ =
good, + = fair, and - = poor. All agents are effective against enveloped
viruses, which include hepatitis-B virus, hepatitis-C virus, HIV, and
coronavirus. Residual activity increases with addition of a low
concentration (0.5% to 1%) of chlorhexidine.
The Healthcare Infection Control Practices Advisory Committee and the
Hand Hygiene Task Force of the Centers for Disease Control and
Prevention have given the following recommendations for surgical hand
Remove debris from underneath the fingernails with use of a nail
cleaner under running water.
Perform hand antisepsis with use of either an antimicrobial soap or
an alcohol-based hand-rub that has persistent activity before performing
Scrub hands and forearms for the length of time recommended by the
manufacturer of the hand cleaner, usually two to six minutes. Long scrub
times (e.g., ten minutes) are not necessary.
Before applying an alcohol-based surgical hand-scrub product with
persistent activity, prewash hands and forearms with a non-antimicrobial
soap and dry hands and forearms completely. After applying the
alcohol-based product as recommended, allow hands and forearms to dry
thoroughly before donning sterile gloves.
Wearing gloves is fundamental to both Standard and Transmission-Based
Precautions. Gloves provide barrier protection to surgeons and reduce
the risk of exposure to blood-borne pathogens as recommended by the
Occupational Safety and Health Administration (OSHA)80. In the 2002
Cochrane Database Systematic Review of double gloving, the findings from
eighteen randomized, controlled trials showed that double gloving
reduces surgical cross infection. Wearing a glove liner between two
pairs of latex gloves or wearing cloth outer gloves to perform joint
replacement surgery decreases perforations to the innermost gloves more
than does the use of double latex gloves81. One biomechanical study
comparing double latex gloves with single latex orthopaedic gloves
indicated that double gloves might be a desirable alternative to single
orthopaedic gloves82. The most common concern that surgeons have about
wearing double gloves is loss of touch sensitivity. Watts et al. found a
significant difference (p < 0.05) in tactile sensation when similar
pressure was applied by surgeons wearing single or double gloves83.
However, the authors of the study concluded that this difference could
be minimized by applying firmer pressure when wearing double gloves.
Masks, Protective Eyewear, and Face-Shields
Masks, eye protection, and face-shields are essential Contact and
Droplet Precautions. They form an effective barrier that protects
surgeons from exposure to infectious droplets and splashes. Eye
protection is critical for orthopaedic surgeons because of the frequent
use of power tools, which spray body fluid. In a prospective study of
conjunctival contamination during common orthopaedic operations,
forty-three (65%) of sixty-six goggles worn by surgeons were
contaminated. The contamination rate of the protective flaps at the
sides of the goggles was relatively low (5%), suggesting that ordinary
spectacles, which are more convenient and comfortable than standard
goggles, provide adequate protection during routine use84. Therefore,
orthopaedic surgeons working in a high-risk environment must protect
themselves against possible conjunctival contamination by wearing a mask
with eye protection, goggles, or a face-shield or by minimizing the
spraying of body fluid in the operating theater during the use of power
Sterile surgical gowns are used to create a barrier between the
surgical field and potential sources of bacteria. They reduce wound
contamination and clinical infection rates in clean surgery85. It has
been estimated that, in joint replacement operations, 98% of bacteria
found in patients' wounds come directly or indirectly from the air in
the operating theater86. Studies have compared the effectiveness of
occlusive clothing with that of body exhaust suits in reducing airborne
bacterial contamination during joint replacement operations87-89. Body
exhaust suits did not reduce the airborne bacterial contamination in the
operating theater significantly more than did occlusive clothing (p >
Different types of surgical occlusive clothing can offer different
degrees of barrier protection to surgeons. Surgical gown fabrics with
higher water and oil repellency and smaller pore sizes generally provide
greater barrier protection90. In one comparative study, the amount of
blood strike-through and bacterial penetration was lower with
polypropylene disposable surgical gowns than it was with polyester-wood
pulp disposable gowns or reusable, cotton gowns91.
Body exhaust suits or air exhaust systems with portable
high-efficiency particulate filters are designed to protect patients
from contamination by surgical teams. They can protect surgeons only
against pathogens spread by contact or droplet transmission, not against
those spread by airborne transmission. Additional respiratory protective
equipment should be worn if there is a risk of airborne infection.
Strategies to Prevent Airborne Infection with Tuberculosis
The concept of reducing the risk of occupational exposure to airborne
transmission of tuberculosis has evolved into three levels of control:
administrative, engineering, and personal respiratory protection92.
The most important component is administrative control, which affects
the largest number of persons. This involves implementation of
administrative measures, such as maintaining a high index of suspicion,
rapid identification, isolation, diagnostic evaluation, and treatment of
The second level of control is the use of environmental or
engineering procedures, which eliminate the risk of exposure to
health-care workers without reliance on their efforts. Examples include
negative-pressure isolation rooms with more than twelve air exchanges
per hour to remove potentially infected air from the environment, air
cleaning with use of high-efficiency particulate air filters, or
ultraviolet germicidal irradiation.
The last level is the use of personal respiratory protection
equipment. On a hospital-wide basis, it is less effective than
administrative and engineering control because respiratory protection
can only reduce, not eliminate, the risk in the few areas where exposure
to tuberculosis can still occur (e.g., rooms in which patients with
known or suspected tuberculosis are being isolated and treatment rooms
in which cough-inducing or aerosol-generating procedures are performed
on such patients). These strategies also provide guidelines for dealing
with other diseases with possible airborne transmission, such as SARS.
Personal Respiratory Protective Equipment
Surgical masks (Fig. 1) are generally worn by health-care workers to
provide protection against pathogens spread by droplet transmission.
However, they provide inadequate respiratory protection against
pathogens with airborne transmission or during high-risk procedures that
generate aerosols. They may have up to 50% filter leakage and are not
sufficiently tight-fitting to prevent inhalation of aerosols. Therefore,
they can provide protection only against larger droplets93,94.
Fig. 1 Surgical mask
An N95 respirator (Fig. 2) or an equivalent or higher-standard
respirator should be worn for all contact with patients with
tuberculosis or SARS. N95 respirators are air-purifying respirators,
which protect against pathogens with droplet or airborne transmission.
They fulfill the filtering efficiency criteria of the National Institute
for Occupational Safety and Health (NIOSH) N95 standard. They are
capable of filtering with at least 95% efficiency both larger droplets
and most penetrating aerosols of 0.3 µm in diameter95. Air-purifying
respirators require the user to generate negative pressure to "suck air
through" the filtering material of the respirators. Facial hair prevents
a good seal as will use of the wrong size of respirator. Before one of
these respirators is used, it should be fit-tested according to the
manufacturer's recommendations. Users should also check the fit of the
respirator every time they wear them by placing both hands over the
respirator and exhaling vigorously to determine if the respirator seals
tightly to the face. Users should replace the respirator immediately if
breathing becomes difficult, the respirator becomes damaged, or a proper
face fit cannot be maintained. Respirators can be worn for six to eight
hours continuously before being replaced. The outer surface should not
be touched, and it must be replaced if it becomes grossly contaminated
or wet. Models with exhalation valves should not be used in areas where
a clean or sterile field is required.
Fig. 2 N95 respirator
Powered Air-Purifying Respirators
Nonoperative contact with patients with tuberculosis or SARS can be
made with use of an N95 respirator, but an invasive procedure or an
aerosol-generating procedure on such patients requires use of a highly
protective respirator such as a powered air-purifying respirator (Fig.
3). It has been shown that, when a patient with tuberculous infection
underwent a procedure that generated respiratory aerosols, operating
personnel had to wear a powered air-purifying respirator in order to
provide sufficient respiratory protection96. The Centers for Disease
Control and Prevention recommended that the same principle be applied to
patients with SARS32. At this time, there is inadequate information to
determine whether this enhanced respiratory protection will reduce the
transmission of SARS.
Fig. 3 Power air-purifying respirator. The respirator has a
motor-driven fan that draws contaminated room air into a high-efficiency
particulate air (HEPA) filter with a 99.97% filtering efficiency. The
purified air is then delivered under positive pressure to the hood by
means of a snap-in hose connector that is secured into the back of the
hood. An N95 respirator is worn underneath the powered air-purifying
respirator to provide maximum protection and protect the sterile
surgical field from the respiratory secretions of the user.
In view of the possible airborne transmission of infectious aerosols
from patients with tuberculosis or SARS, all operating room personnel
should wear a powered air-purifying respirator with a hood that covers
the head, neck, and shoulder regions during high-risk aerosol-generating
procedures. The powered air-purifying respirator has a motor-driven fan
that draws contaminated room air into a high-efficiency particulate air
(HEPA) filter with a 99.97% filtering efficiency. The purified air is
then delivered under positive pressure to the hood by means of a snap-in
hose connector that is secured into the back of the hood. The exhaled
air of the user escapes at the lower end of the hood, which is covered
by an overlying waterproof gown. An N95 respirator is worn underneath
the powered air-purifying respirator to provide maximum protection and
protect the sterile surgical field from the respiratory secretions of
Operating personnel should be trained and rehearsed on how to use the
respiratory protective devices correctly because improper use will lead
to a false sense of security. Dizziness or claustrophobia may be
experienced when wearing a powered air-purifying respirator.
Orthopaedic surgeons are frequently exposed to blood and are at a
high risk for blood-borne infection. The SARS outbreak has alerted us to
the need for reviewing our current practices of infection control.
Understanding the means of transmission of infectious diseases is very
important in preventing occupational transmission of pathogens. There is
a concern about secondary infection by aerosolization of blood or other
body fluids during the use of power tools. Epidemiological studies on
the risk of this means of transmission will be very difficult because of
the need to control all risk factors in order to establish the relative
infectivity of the patients compared with that of a control group not
generating aerosols. Because of this current uncertainty, extra
precautions should be adopted during aerosol-generating procedures.
NOTE: The authors acknowledge the help of Dr. Henry Ho for his work
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