June 15, 2006
DENTAL PREMEDICATION PROTOCOLS for Patients With Knee and Hip Prostheses: A REVIEW OF CURRENT RECOMMENDATIONS
By Portnof, Jason E; Israel, Howard A; Brause, Barry D; Behrman, David A
In 1997, the American Dental Association (ADA) and the American Academy of Orthopaedic Surgeons (AAOS) published an advisory statement regarding antibiotic prophylaxis for patients with total joint replacements undergoing dental treatment. The first periodic update of these guidelines was published in 2003. Nevertheless, confusion exists among dentists and physicians as to the clinical indications for premedication in this patient population. This article serves as an overview of current recommendations for use of chemoprophylaxis in the dental treatment of patients with prosthetic joints.
AS THE POPULATION AGES, dentists are encountering increasing numbers of patients who have undergone total joint replacement. In the United States, approximately 450,000 total joint arthroplasties are performed annually.1,2,9 Joint surgery is most common in patients 50 years of age or older.9 The majority of replacement procedures involve the joints of the lower extremities, such as the knee or hip.7
Joint replacement surgery provides a patient with improved function and quality of life. However, infection of an artificial joint prosthesis is a serious complication that causes significant morbidity. Pain, loss of function, wound breakdown, wound discharge and implant failure are severe problems for the patient and physician.17
Long-term antibiotics and extensive revision surgery are often necessary when severe infection results in failure of the implanted prosthesis. Such failures can affect a patient beyond simple quality- of-life issues. In approximately 10% to 15% of cases, attempts at curing the infection fail.17 The afflicted patient is compelled to undergo multiple cycles of treatment and experiences progressively deteriorating joint function.17 These patients may undergo chronic antibiotic therapy, arthroscopic joint drainage, surgical arthrodesis (joint fusion), surgical debridement, surgical removal of infected hardware, one- or two-stage surgical reimplantation of a new prosthetic joint, and, possibly, limb amputation.21,22 Mortality associated with prosthetic joint infections has been estimated to be as high as 2.5%.19
In order to reduce the probability of late infection of artificial joints, the dental practitioner must use current concepts in preventative medicine and chemoprophylaxis. However, antibiotic use is associated with severe risks. These risks include antibiotic- induced anaphylaxis and toxicity, increased incidence of superinfection and selection of antibiotic-resistant bacterial species.1,3,10,13 An inherent risk-benefit relationship exists that precludes indiscriminate premedication of all patients with prosthetic joints. Antibiotic prophylaxis should be reserved for patients determined to be at high risk.1,2,6,9,27
Systemic risk factors for prosthetic joint infection have been proposed to include rheumatoid arthritis, diabetes mellitus, psoriasis, steroid therapy, malignancy, poor nutritional status, advanced age and obesity.17,19,21 Local risk factors for failure of an implanted prosthesis include prior joint surgery, prolonged operating room time, postoperative surgical site infection and a slow-to-heal operative wound.17,19
Pelvic X-ray of patient with bilateral total hip prostheses. The patient's left prosthesis (right side of image as you view it) is infected with large lucencies present around prosthesis. Right hip prosthesis is not infected.
The most recent ADA/AAOS advisory statement on antibiotic prophylaxis for dental patients with total joint replacements concludes that "antibiotic prophylaxis is not indicated for dental patients with pins, plates or screws, nor is it routinely indicated for most dental patients with total joint replacements."2 The advisory statement further explains that "it is advisable to consider premedication in a small number of patients who may be at potential increased risk of experiencing hematogenous total joint infection."2 Patients with potential increased risk include all patients during the first two years following joint replacement, immunocompromised/immunosuppressed patients (that is, inflammatory arthropathies, such as rheumatoid arthritis, systemic lupus erythematosus), and patients with comorbidities (that is, previous prosthetic joint infections, malnourishment, hemophilia, HIV infection, insulin-dependent diabetes, malignancy).2
The large number of patients who suffer from systemic conditions placing them at increased risk for prosthetic joint infection compels dental practitioners to realize that a real and prevalent risk exists. Each patient presenting to the dentist with a prosthetic joint should be screened carefully for potential risk through a meticulous medical history. Ideally, all patients undergo a pre-prosthetic surgery assessment by a dentist, at which time, appropriate dental care is administered.
Postoperative infection of prosthetic joints is categorized on a continuum. Early infections are those that occur within two months of surgery, and delayed infections occur between two months and one year.4,14 Late infections are those that present more than one year after implantation.4,14 These infection categories are arbitrary, as there can be long latency periods between the onset of infection and the onset of symptoms and diagnosis.30
Incidence of early infection can be attributed to bacterial contamination during the surgical procedure or the immediate postoperative period (prior to incisional healing). This incidence has been markedly reduced by the use of preoperative antibiotic prophylaxis and modernized surgical methods and aseptic technique.2,4,14,27 Technological advances include antibiotic- impregnated methylmethacrylate cements during placement of the implant prosthesis, operating rooms with controlled laminar air- flow systems, and body exhaust suits that reduce the risk of contamination intraoperatively. 17,18,19 With these advances, the prevalence of early postoperative infection is now approximately 1% of cases.4,18,19
Early infections commonly present with features of obvious wound infection, including localized pain (exacerbated by movement), loss of range of motion, induration, edema, warmth, tenderness and wound drainage.17,19
Delayed and late infections commonly present with pain, a loose prosthesis and occasional sinus track formation.17 The patient may provide a history that includes the statement that the prosthesis "never felt right" and that the surgical wound healed slowly despite antibiotic treatment.17 The major determinants of clinical presentation are the characteristics of the host tissue in which the organism grows, the virulence of the infecting pathogen and the route of infection.29 Table 1 lists the frequencies of common presenting symptoms of prosthetic joint infections.29
Presenting Symptoms of Prosthetic Joint Infections
Patients experiencing late infection may present to their primary care physician, orthopedist or rheumatologist with reports of pain localized to the site of a previously asymptomatic total joint replacement.14 A patient suspected of having the late complication of septic arthritis in a prosthetic joint will often require arthrocentesis.14 Evaluation of the synovial fluid from the affected joint, including gram staining, culture and sensitivity testing of isolated organisms, is standard.14,18 Radiological and nuclear medicine imaging of infected prosthetic joints is also available, offering a debatable benefit to diagnosis or outcome.19,23 A discussion of the treatment of prosthetic joint infections is beyond the scope of this review.
Delayed and late infection of prosthetic joints can be the result of hematogenous seeding or direct wound contamination. Hematogenous spread is the process by which bacteria from distant sites of infection travel through the bloodstream to seed new loci of infection. It is estimated that approximately 20% to 40% of prosthetic joint infections develop from hematogenous spread.29 The two years immediately following prosthetic joint placement are considered to be the most hazardous periods in terms of potential hematogenous seeding of the implant site.2,12 It has been hypothesized that enhanced vascularity of the implant site during these two years of postsurgical wound healing facilitates hematogenous seeding of bacteria.18
Hematogenous infection of successfully placed prosthetic joints has rarely been linked with dental-induced bacteremia.4,7 Most joint infections are caused by staphylococci (that is, Staphylococcus aureus, Staphylococcus epidermidis and other coagulase-negative staphylococci ).23,27 Viridans streptococci, the predominant oral bacterial species, have been isolated less frequently. 3,4,12,13 Pallasch and Slots combined the microbiological data from six clinical studies to determine that approximately 66% of 281 microbial isolates from prosthetic joint infections were typed as staphylococci, while only 4.9% were categorized as viridans streptococci.13
Steckelberg and Osmon studied 1,033 cases of total hip and knee prosthetic joint infections at the Mayo Clinic between 1969 and 1991. They found that the majority (61%) of infections were caused by aerobic gram-positive cocci.30 The most commonly isolated organisms in this study were S. aureus, coagu\lase-negative staphylococci, beta hemolytic streptococci, viridans group streptococci and enterococci.30
Viridans streptococci, such as Streptococcus mitis, Streptococcus sanguis and Streptococcus mutans, are classified in the laboratory as α-hemolytic, gram-stain-positive organisms. Viridans streptococci are normal flora of the oropharynx, but are potentially pathogenic in the bloodstream. They are the microorganisms of primary concern to the dentist in preventing hematogenous seeding of prosthetic joint implants (and abnormal cardiac valves as well).
Viridans streptococci and other bacteria have virulence factors that enhance their ability to promote infection in a susceptible host. Pathogenic bacteria are noted to express adhesions on their cell surfaces that allow them to attach to host cells and implanted biomedical devices.17,23 These adherent bacteria are capable of forming a complex biofilm with an extracellular polysaccharide matrix that facilitates bacterial colonization and attachment to the prosthetic joint surface. Staphylococci expressing fibronectin- binding proteins have been specifically implemented in prosthetic joint infections.23
In addition, the glycocalyx of the biofilm aids in bacterial resistance to antibiotics and evasion of the host immune response.17,23 The glycocalyx acts as a poorly permeable barrier, preventing antimicrobials and immune cells from reaching bacteria deeper within the biofilm. Some bacteria, including staphylococci, may evade the immune response by invading host cells and surviving intracellularly.23 The M protein found on the cell surface of group A streptococci is antiphagocytic and facilitates immunoavoidance. Motility of certain bacteria (that is, gram-negative bacilli) through flagella and fimbriae also contribute to their virulence.17
It is hypothesized that certain bacterial products stimulate bone resorption by directly affecting the balance between osteoblast and osteoclast function.17 Several bacteria produce tissue toxins and enzymes, such as leukotoxins and hemolysins, that facilitate destruction of host tissue.23 Some authors propose that the presence of infection at the implant site may cause the local production and release of inflammatory cytokines and host enzymes.17,23 These cytokines can result in an inflammatory response and bone loss at the prosthesis cement-bone interface.
The implanted prosthesis is foreign material within the human body. As such, some researchers believe the implanted prosthesis is surrounded by an immuno-incompetent fibro-inflammatory zone that makes the region susceptible to infection.3,7,12,15 Fewer organisms are required to initiate infection, and once an infection is established, it cannot be eradicated easily with antibiotics.
The Dentist's Role
It is important to focus efforts on preventing infection rather than to engage later on in exhaustive efforts at fighting a tenacious, destructive disease process. Through careful management of the patient's oral health, the dentist plays a pivotal role in this endeavor.
It is probable that oral bacteremia spontaneously induced by daily events such as mastication and toothbrushing/flossing occur more commonly than bacteremia arising from periodontal treatment. 2,13 Dental treatment-induced bacteremia is considered to be of low- grade intensity and of short duration.13 Procedures thought to be traumatic to the oral tissues (that is, tooth extraction, periodontal surgery, scaling and root planing) cause higher rates of bacteremia than less invasive therapy (restorative dentistry, endodontic treatment). 2,13 Table 2 illustrates incidence stratification of bacteremic dental procedures. Acute dental infections are more strongly linked to bacteremia than dental manipulation in a healthy dentition.4
It is recommended that patients planning to undergo total joint arthroplasty be in good dental health. Maintenance of good oral health should be a major motivation of patients who are candidates for total joint replacement, because it has been shown that as the severity of gingival inflammation increases, the incidence and magnitude of bacteremia also increases.13,16 It is advisable that potential joint replacement patients be assessed by a dentist and determined "dentally fit" prior to surgery.4
Incidence Stratification of Bacteremic Dental Procedures
Patients who have poor oral health should be evaluated by a dentist, and proper oral care should be administered. Effective daily oral hygiene practices need to be stressed prior to and after joint replacement surgery. Anti-infectives such as chlorhexidine and other antiseptic mouthwashes, administered immediately prior to dental procedures, should be part of the dentist's armamentarium.4,13,16 The oral health of the prosthetic joint patient should be monitored regularly through routine dental visits. A goal of reducing baseline oral inflammation manifesting as gingivitis and periodontal disease is paramount. Efficient caries control is also vital.
The ADA/AAOS recommendations for antibiotic prophylactic therapy are based on an empiric regimen targeting the microbes most frequently responsible for late prosthetic joint infections. Models theorizing that late prosthetic joint infections are analogous to infective endocarditis are inaccurate. The blood supply, anatomy, microorganisms, host defenses and mechanism of infection are different in the two disease processes.2,13
Dental clinicians must choose prophylactic antibiotic regimens that target pathogenic species more likely involved with dental bacteremia, such as gram-positive streptococci (that is, Viridans streptococci, peptostreptococci). Table 3 provides a list of ADA/ AAOS recommended antibiotic prophylactic treatments. These regimens are single-dose schedules administered one hour prior to the procedure. No second doses are recommended for any of the suggested regimens.
The antimicrobial agents of choice for prophylactic treatment of dental patients with total joint replacements are the β-lactam antibiotics. This class of antimicrobial generates their bactericidal effect as inhibitors of bacterial cell wall synthesis. The extended spectrum penicillin antibiotics, such as amoxicillin (oral administration) and ampicillin (intramuscular or intravenous administration), provide activity against both gram-negative and gram-positive organisms. Because intramuscular injections are painful and unpleasant for the patient, alternative routes of administration should be considered first. Amoxicillin is quickly absorbed through the GI tract and obtains high serum levels, making it ideal for prophylaxis prior to dental procedures.
ADA/AAOS Suggested Antibiotic Prophylaxis Regimens
First-generation cephalosporins are generally most effective against aerobic gram-positive cocci. Cephalexin and cephradine are first-generation cephalosporins that can be given orally, while cefazolin can be administered intramuscularly or intravenously. There is potential cross-hypersensitivity between penicillins and cephalosporins. If this is a concern, it is best to consult with the patient's internist or allergist to determine the most appropriate antibiotic coverage.
Clindamycin is a bacteriostatic antibiotic that acts to inhibit bacterial protein synthesis. It targets the 50S bacterial ribosomal subunit and is effective against anaerobes and gram-positive aerobic bacteria. It is provided in either oral or intravenous preparations. Both amoxicillin and clindamycin are highly effective against oral anaerobes. As it is not a β-lactam antibiotic, clindamycin is available for use in patients who are allergic to penicillin.
In order to prevent deleterious sequela, dentists are obliged to be knowledgeable about the protocols for dental treatment of patients with artificial joint implants. With a careful review of the patient's medical history, dentists must use competent clinical judgment to determine which patients are appropriate candidates for prophylactic antibiotic therapy.
The dentist, primary care physician and orthopedic surgeon should work together in the treatment of the patient with total joint replacement. Open lines of cooperative communication among the specialties provide for optimal patient care.
If a patient who does not meet the ADA/AAOS guidelines for prophylactic antibiotic treatment presents with physician recommendations for chemoprophylaxis, the dentist is obligated to meticulously investigate the risk versus benefits of antibiotic prophylaxis. A consultation with the physician will clarify his or her concerns for the patient. It is possible that the physician's recommendation is based on a change in the patient's medical history that is not known to the dentist.
An interdisciplinary approach combining the efforts of physician and dentist allows for the best possible treatment of patients. Clinical decisions regarding prophylactic antibiotics for expectant dental bacteremia should be made on an individual basis.
The ADA Division of Legal Affairs reminds us that "each independent professional is ultimately responsible for his or her own treatment decisions."1, 2, 10 A dentist should never blindly follow a physician's recommendations for treatment when those recommendations conflict with the dentist's professional judgement.1, 10 Rather than prescribing an antibiotic regimen that is inconsistent with the dentist's clinical judgment, the dentist should discuss the treatment decisions with the patient and his or her physician.
Dentists are encouraged to educate health care providers unfamiliar with the ADA/AAOS guidelines for antibiotic prophylaxis in patients with total joint replacement.1, 2, 6, 11 If no consensus can be reached among the health care providers, the physician may then choose to prescribe antibiotic premedication for the patient. The dentist is not required to write prescriptions for an antibiotic regi\men that conflicts with his or her medical opinion.11 Dentists are obligated to explain all risks, benefits, alternatives and complications of treatment (including antibiotic treatment) to their patients to ensure that the patient makes all treatment decisions with proper informed consent.1, 10
There is a need for scientific studies to determine appropriate candidates for antimicrobial prophylaxis in dentistry.8 In the modern era of evidence-based medicine, a double-blind, randomized controlled clinical research trial is considered a gold standard model for clinical decision making. However, no such clinical trial has been published to determine the efficacy of prophylactic antibiotic treatment on the incidence of late prosthetic joint infection due to hematogenous spread of oral organisms.4, 8, 27 Ethical and logistical issues prevent such a trial from being performed.
As clinical science advances, polymerase chain reaction (PCR) and DNA fingerprinting of organisms isolated from the affected patient's oral cavity, blood stream and synovial fluid may help us revise our protocol for chemoprophylaxis.4, 25, 26 Until that time, dentists must use clinical judgment to determine whether chemoprophylaxis is indicated for each patient's specific situation.
The authors acknowledge the assistance of Ms. Kimberly J. Mason, B. A., in the preparation of this manuscript.
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26. Canvin JM, Goutcher SC, Hagig M, et al. Persistence of Staphylococcus aureus as detected by polymerase chain reaction in the synovial fluid of a patient with septic arthritis. Br J Rheumatol 1997 Feb;36(2):203-6.
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28. Culver DH, Horan TC, Gaynes RP, et al. Surgical wound infections rates by wound class, operative procedure, and patient risk index. Am J Med 1991; 91 (Suppl 3B): S152-7.
29. Brause BD. Infections with Prostheses in Bones and Joints. Principles and Practices of Infectious Diseases. 6th Edition. Mandell GL, Bennett JE, Dolin R, editors. Philadelphia, PA: Elsevier Churchill Livingston. 2005;Chapter 100:1332-1337.
30. Steckelberg JM, Osmond DR. Infections Associated with Indwelling Medical Devices. 2nd Edition. Bisno AL, Waldvogel FA, editors. Washington, DC:ASM Press.1994;Chapter 11:259-290.
Jason E. Portnof, D. M. D., M. D.; Howard A. Israel, D. D. S.;
Barry D. Brause, M. D.; David A. Behrman, D. M. D.
Copyright Dental Society of the State of New York Apr/May 2006
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