You are in: eMedicine Specialties > Orthopedic Surgery > SYSTEMIC DISEASES Septic ArthritisArticle Last Updated: Jun 21, 2006AUTHOR AND EDITOR INFORMATIONSection 1 of 10
  Author: Gabriel Munoz, MD, Consulting Staff, Department of Emergency Medicine, Decatur Memorial Hospital Gabriel Munoz is a member of the following medical societies: American College of Emergency Physicians and American Medical Association Coauthor(s): Edmund W Raycraft, MD, Consulting Staff, Raycraft & Jones Orthopedics Editors: Jegan Krishnan, MBBS, FRACS, PhD, Chair, Senior Clinical Director, Department of Orthopedic Surgery, Flinders Medical Centre and Repatriation General Hospital, Flinders University of South Australia; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; Jerome D Wiedel, MD, Chair, Professor, Department of Orthopedics, University of Colorado Health Sciences Center; Dinesh Patel, MD, FACS, Associate Clinical Professor of Orthopedic Surgery, Harvard Medical School; Chief of Arthroscopic Surgery, Department of Orthopedic Surgery, Massachusetts General Hospital; Harris Gellman, MD, Consulting Surgeon, Broward Hand Center, Voluntary Clinical Professor of Orthopedic Surgery and Plastic Surgery, Departments of Orthopedic Surgery and Surgery, University of Miami School of Medicine Author and Editor Disclosure Synonyms and related keywords: bacterial arthritis, suppurative arthritis, purulent arthritis, infectious arthritis INTRODUCTIONSection 2 of 10
  Septic arthritis is inflammation of a synovial membrane with purulent effusion into the joint capsule, usually due to bacterial infection. This disease entity also is referred to in the literature as bacterial, suppurative, purulent, or infectious arthritis. Septic arthritis is a rather rare but important disease that typically affects monoarticular joints. The age range of those affected is broad, from the neonatal period to advanced age. Treatment consists of a combined medical and surgical approach. Septic arthritis usually is divided into gonococcal and nongonococcal arthritis, as clinical and treatment regimens differ. In adults, septic arthritis most commonly affects the knee; in children, infection into the hip joint predominates. Despite advances in diagnostic studies, powerful antibiotics, and early drainage, significant joint destruction commonly occurs. ProblemSeptic arthritis can quickly destroy a joint and can cause many complications, including osteomyelitis, bony erosions, fibrous ankylosis, sepsis, and even death. Barriers to successful management include lack of clinical suspicion in the early phase of presentation, delay in definitive diagnostic needle aspiration, and failure to provide adequate drainage of the joint. In addition, septic arthritis in neonates and infants can be especially treacherous as a result of blunted inflammatory signals and/or confounding infection at a distant site (eg, ear, umbilical catheter site). FrequencyOf all the forms of arthritis, septic arthritis is the most aggressive at quickly destroying a joint. The frequency of septic arthritis is approximately 2-10 cases per 100,000 in the general population. In patients with immunologic disorders (eg, rheumatoid arthritis, systemic lupus erythematosus), the occurrence is approximately 30-70 cases per 100,000. The incidence in patients with joint prosthesis is similar to that of patients with immunologic disorders. In gonococcal arthritis, women are approximately 3 times as likely as men to develop this disease. EtiologyMost septic arthritis cases are caused by Staphylococcus aureus and streptococci. In all age groups, 80% of cases are caused by gram-positive aerobes (60% S aureus; 15% beta-hemolytic streptococci; 5% Streptococcus pneumoniae), and approximately 20% of cases are caused by gram-negative anaerobes. In neonates and infants younger than 6 months, S aureus and gram-negative anaerobes comprise the majority of infections. The incidence of Haemophilus influenzae has dramatically decreased due to widespread use of the vaccine. In children aged 6 months to 2 years, S aureus and, to a lesser degree, H influenzae are the major organisms of infection. In patients older than 2 years, S aureus becomes the principle culprit. As sexual activity begins in the teen years, Neisseria gonorrhoeae should be suspected. PathophysiologyVarious sources of infection exist for the joint space. Bacteria may enter the joint directly as with trauma. Infection may enter hematogenously (eg, intravenous [IV] drug injection). Infection may enter from osteomyelitis that is adjacent to the capsule. Infection also may enter from soft tissue infections (eg, cellulitis, abscess, bursitis, tenosynovitis). According to Orthopaedic Pathology, the knee accounts for approximately 40-50% of infections, and the hip accounts for 20-25% of infections. However, in infants and very young children, hip involvement is the most common joint infection. Shoulders, ankles, and elbows account for approximately 10-15% of infections. Finally, septic arthritis of the wrist occurs in 10% of cases. ClinicalSeptic arthritis can be difficult to diagnose in the early stages of progression. Once purulence has developed and a bulging effusion is noted, diagnosis is made easily. Typically, the patient presents with fever and a joint that is hot, red, painful, distended, and has a markedly decreased range of motion. Restriction of movement occurs to active and passive attempts. In young sexually active patients with fever, tenosynovitis, migratory polyarthralgia, and dermatitis, suspect N gonorrhoeae. The rash may appear as papules over the trunk and extensor surfaces of distal extremities that eventually can turn into hemorrhagic pustules. Women are more likely to develop gonococcal arthritis than are men. In patients with a history of intravenous drug use (IVDU), suspect Pseudomonas. In infants and children, diagnosis can be very difficult. Neonates and infants often have blunted inflammatory signals. Symptoms such as fever, decreased appetite, and irritability without obvious joint involvement can easily lead to an incorrect diagnosis. Aside from obvious open fractures, foreign object, and trauma, searching for distant infections is very important. Clinical presentation in the older child will be similar to that in the adult. However, the child may not allow the affected joint to be touched and, sometimes, may not even allow the affected joint to be seen. Additional confounding symptoms may be present, including nausea, vomiting, headache, sore throat, and abdominal pain. Ear infections are the most common source of bacteria leading to septic arthritis in children. Distinguishing transient synovitis from septic arthritis is an area of particular concern. In one study of children, 4 independent variables have been found useful as clinical predictors for septic arthritis, including the following:
INDICATIONSSection 3 of 10
If rapid improvement is not achieved with needle aspiration, open drainage and lavage (arthroscopically or via arthrotomy) is strongly recommended. CONTRAINDICATIONSSection 4 of 10
Generally, few contraindications to arthrocentesis exist. One caveat to consider is to avoid aspirating from an area that has an established overlying soft tissue infection. This may introduce bacteria into an otherwise noninfected joint. Patients with bleeding disorders and those who are on anticoagulatory medications pose a difficult challenge, and risks must be weighed against benefits on an individual basis. WORKUPSection 5 of 10
Lab Studies
Imaging Studies
Diagnostic Procedures
TREATMENTSection 6 of 10
Medical therapyIn addition to drainage of the septic joint, rapid administration of IV antibiotics is paramount. It is important to obtain the synovial sample and blood cultures prior to commencement of IV antibiotic treatment. Certitude of final gram stain and/or culture should not preclude treatment. With this in mind, most patients respond to IV oxacillin or nafcillin in combination with IV ceftriaxone, cefotaxime, or ceftizoxime. Special situations warrant modification of this antibiotic treatment. For example, in patients who are hospitalized with suspected methicillin-resistant S aureus (MRSA), IV Vancomycin would be an appropriate regimen. In patients with suspected Pseudomonas (eg, IV drug users), an IV aminoglycoside in combination with an antipseudomonal cephalosporin (eg, IV ceftazidime, cefepime, cefoperazone) will adequately treat this organism. Patients with prosthetic joints or intraarticular injected and subsequently infected joints are highly susceptible to MRSA and methicillin-resistant Staphylococcus epidermidis (MRSE), as well as Enterobacteriaceae and Pseudomonas. In this case, IV vancomycin and IV ciprofloxacin are appropriate choices. In young sexually active patients with suspected gonococcal arthritis, IV ceftriaxone (1 g q24h) is recommended almost universally in most studies. In neonates and children, IV nafcillin or oxacillin in combination with a third-generation cephalosporin will properly treat most cases. The duration of treatment varies depending on organism and patient response to medical and surgical drainage. Management of prosthetic infected joints is varied, depending largely on whether or not the prosthesis is removed. Conservative treatment warrants removal of the prosthesis and treatment for approximately 6 weeks with antibiotics. For stable prosthetic joints, several regimens have shown very high success rates, including initial IV antibiotics with oxacillin/nafcillin or vancomycin followed by oral ciprofloxacin and oral rifampin for 6 months for knees and 3 months for hips. Joints infected with S aureus generally are treated with 4 weeks of antibiotics. Pseudomonal infections are treated for at least 3 weeks, whereas streptococcal infections and H influenzae are treated for approximately 2 weeks. Joints infected with N gonorrhoeae respond well to 1 week of IV Rocephin. If the patient responds quickly, a full 7-day regimen can be completed with oral antibiotics, such as ciprofloxacin 500 mg twice a day. Surgical therapyAdequate drainage of a septic joint is the cornerstone of successful treatment. As S aureus is the most prevalent and most virulent organism involved, rapid destruction of the joint proceeds quickly without drainage. Needle aspiration can serve as the initial diagnostic and therapeutic intervention in many cases. However, if rapid improvement is not achieved, open drainage and lavage (arthroscopically or via arthrotomy) is strongly recommended. Head-to-head comparisons on the benefits of one surgical modality over another remain unanswered. Arthroscopic drainage and lavage can be used as an initial procedure or after needle decompression fails to provide relief of infection. It is a good procedure for decompression of elbows, knees, and ankles. Arthrotomy is the best procedure for bacteria deeply embedded in a joint and for loculations. It is especially helpful for drainage of shoulders and hips. Postoperative detailsGenerally, nonweightbearing status should be maintained postoperatively, with splinting in a position of function. Once signs of infection diminish, frequent passive range of motion exercises should commence. Follow-upAs soon as infection clears, patients should gradually advance from functional splinting to isometric muscle strengthening and, finally, to active range of motion exercises. For excellent patient education resources, visit eMedicine's Arthritis Center. Also, see eMedicine's patient education article Knee Pain. COMPLICATIONSSection 7 of 10
Irreversible destruction of the joint occurs in a large percentage of patients despite proper treatment. Major complications of septic arthritis include degenerative joint disease, soft tissue injury, osteomyelitis, fibrous plus bony ankylosis, sepsis, and death. OUTCOME AND PROGNOSISSection 8 of 10
Despite proper and quick treatment of septic arthritis, prognosis remains poor. In a prospective 2-year study by Kaandorp et al with 154 patients (adults and children), 21% of cases resulted in poor patient outcome (death or severe functional deterioration), and 33% of cases resulted in poor joint outcome (amputation, arthrodesis, prosthetic surgery, or sever functional deterioration). In retrospective review assessments of nongonococcal arthritis by Pioro et al, loss of joint function occurred in 34-50% of the general population without comorbidities. Mortality in this same population ranged from 2-14%. Mortality figures in patients with polyarticular sepsis and rheumatoid arthritis ranged from 23-32% and 16-49%, respectively. FUTURE AND CONTROVERSIESSection 9 of 10
Future research will focus on targeting bacterial factors and immunological factors that worsen infection. For example, aside from the excessive amount of pus (and pressure) created by Staphylococcus, the organism also produces staphylokinase that helps to further destroy cartilage. Targeting this enzyme may prove to be beneficial. In addition, targeting host cell cytokine responses also may prove to be beneficial. For example, interleukin-1 is known to inhibit glycosaminoglycan production, in addition to producing collagenases and metalloproteinases that overwhelmingly destroy cartilage. On a macroscopic level, controversy still abounds as to which surgical drainage procedure serves the patient best. REFERENCESSection 10 of 10
Article Last Updated: Jun 21, 2006 |
