Septic Arthritis
Septic Arthritis: Excerpt from The 5-Minute Pediatric Consult
Sujit S. Iyer, MDRakesh D. Mistry, MD, MSJoel A. Fein, MD, MPH (4th Edition)
Septic Arthritis - BASICS
Septic Arthritis - description
Microbiologic infection and inflammation of the usually sterile joint space.
Septic Arthritis - epidemiology
- Predominant age: 2–6 years, adolescent (Neisseria gonorrhoeae)
- Predominant sex: Male > Female, 2:1
- Predominantly large joints affected: Knee, hip, elbow, ankle
Septic Arthritis - pathophysiology
- Entry of bacteria into joint space:
- Hematogenous spread
- Direct inoculation (penetrating trauma)
- Extension from bone infection (mainly in children <1 year old when vessels cross from metaphysis to epiphysis)
- Influx of inflammatory cells within the joint capsule
- Rapid destruction of cartilaginous structures within the joint by bacterial and lysosomal enzymes:
- If untreated, may progress to necrosis of the intra-articular epiphysis
Septic Arthritis - etiology
- Bacteria:
- Staphylococcus aureus most common etiology outside of perinatal period (Methicillin-sensitive and Methicillin-resistant)
- Streptococci
- Kingella kingae
- Haemophilus influenzae
- Salmonella
- N. gonorrhoeae
- Neisseria meningitidis
- Borrielia burgdorfderi (Lyme)
- Aseptic arthritis:
- Rubella
- Parvovirus
- Hepatitis B or C
- Mumps
- Herpesviruses (Epstein-Barr virus, cytomegalovirus, herpes simplex virus, varicella zoster virus)
- Epstein-Barr virus
- Varicella
- Candida albicans (neonatal)
Septic Arthritis - associated conditions
- Neonatal septic arthritis may be associated with S. aureus, group B streptococcus, Escherichia coli, and Candida.
- Sickle cell disease is associated with Salmonella infection, although S. aureus is still the most common.
- Immunocompromised patients: Mycoplasma, Ureaplasma, or Aspergillus infection
Septic Arthritis - DIAGNOSIS
Septic Arthritis - signs & symptoms
Septic Arthritis - history
- Fever, rigors
- Affected joint pain, or refusal to walk or move joint in preverbal children
- History of recent trauma does not rule out septic arthritis.
- Pain of bacterial arthritis worsens over 1–3 days and does not wax and wane.
- Septic arthritis is rarely polyarticular.
- Lyme arthritis is typically more subacute, without constitutional symptoms.
Septic Arthritis - physical exam
- Fever occurs within the 1st few days of illness in 75% of patients but less commonly in infants. Only 50% of children with gonococcal arthritis have fever.
- Children with septic arthritis usually appear ill.
- The joint appears warm and swollen.
- Infants may demonsrate ”pseudoparalysis”
- Hip involvement causes the leg to be held flexed, abducted, and externally rotated.
- The child with septic arthritis usually has pain through any range of motion. In contrast, most traumatic injuries allow some painless range of motion of that joint.
- Lyme infection is characterized by painless joint that is warm, swollen, and tender
- There are usually no external findings when the hip or shoulder joints are infected.
- Consider hip involvement when the patient complains of knee or thigh pain.
- In the frightened or uncooperative child, it is possible to have the parent perform an examination for tenderness and range of motion while the physician observes from a distance.
Septic Arthritis - tests
Septic Arthritis - lab
- Synovial fluid analysis in septic arthritis:
- The WBC count is often >100,000/mm3, but may be as low as 50,000/mm3 in early infections.
- The glucose level in the synovial fluid is <50% that of the serum.
- Culture of the joint reveals an organism in 70–80% of cases (except for gonorrhea).
- Inoculation of joint fluid into blood culture bottle facilitates recovery of Kingella kingae.
- A gram stain of synovial fluid reveals pathogens in 50% of cases.
- Other supportive tests:
- ESR is elevated (>30 mm/h) in 95% of cases. Retain suspicion if >20 mm/h.
- The C-reactive protein (CRP) is increased. In one study, a CRP <1.0 mg/dL had a negative predictive value of 87% in a population in which the prevalence of septic arthritis in tested patients was 29%.
- Blood cultures are positive in 30–40% of cases.
- A high peripheral WBC count is neither sensitive nor specific for septic arthritis.
- An immunofluorescent antibody assay for Borrelia burgdorferi, when available, may be helpful in the rapid differentiation between bacterial arthritis and Lyme disease. Modest inflammation (25–50,000 WBC) is usually evident in the synovial fluid.
Septic Arthritis - imaging
- Radiography is rarely helpful in diagnosis; may show widening of joint space and/or displacement of the normal fat pads in the knee or elbow, and is less often positive in the shoulder or hip.
- Ultrasound of the affected joint usually delineates the amount of fluid within the joint capsule. Increased blood flow on color Doppler may suggest infection. However, this test cannot differentiate between an infectious and a purely inflammatory disease.
- A technetium-99 bone scan reveals increased uptake in the perimeter of the joint during the “blood pool” phase of the study.
- False-positives:
- Bone scan cannot easily differentiate septic arthritis from epiphyseal osteomyelitis.
- Evaluation of synovial fluid from patients with rheumatologic disease may mimic that of infectious arthritis; however, the clinical picture should allow differentiation of these entities.
Septic Arthritis - differencial diagnosis
- Osteomyelitis with contiguous spread
- Cellulitis causing decreased range of motion of joint secondary to inflammation
- Tuberculous arthritis
- Psoas abscess or retroperitoneal abscess with associated hip pain
- Prepatellar bursitis (knee)
- Tumors:
- Osteogenic sarcoma (long-bone pain spreading to joint space)
- Leukemia/Lymphoma
- Trauma:
- Occult fracture in proximity to growth plate
- Ligamentous injury (sprain)
- Foreign-body synovitis
- Traumatic knee effusion/Hemarthrosis
- Immunologic:
- Toxic synovitis
- Postinfectious
- Acute rheumatic fever
- Reactive arthritis
- Campylobacter, Shigella, Yersinia, Chlamydia infection
- Reiter syndrome (after gastrointestinal or chlamydial infection) arthritis, uveitis, urethritis
- Collagen vascular
- Systemic lupus erythematosus
- Juvenile rheumatoid arthritis
- Henoch-Schönlein purpura
- Behçet syndrome (iridocyclitis, genital and oral ulcerations)
- Inflammatory bowel disease (Crohn disease, ulcerative colitis)
- Serum sickness
- Erythema multiforme/Stevens-Johnson syndrome
- Miscellaneous:
- Knee
- Apophysitis (e.g., Osgood-Schlatter disease)
- Patellofemoral pain syndrome (chondromalacia patella)
- Osteochondritis desiccans
- Hip
- Slipped capital femoral epiphysis
- An algorithm using 4 or more of the following factors has been used to successfully differentiate septic arthritis and transient synovitis of the hip:
- Fever
- ESR >20 mm/h
- CRP >1.0 mg/dL
- WBC >11,000 cells/mL
- Joint space fluid apparent on plain radiograph
- The absence of all of these parameters is strongly associated with the absence of septic arthritis
- Pitfalls:
- Clinical examination in conjunction with the history of acute onset should raise the suspicion of septic arthritis, even in the face of “negative” laboratory screening tests. The most accurate determinations can be inferred from analysis of the synovial fluid.
- Realize that some children, especially neonates and young infants, will not manifest signs of systemic disease early in the course of the illness.
- Observe failure or success of therapy, especially when the extremity is immobilized.
Septic Arthritis - TREATMENT
Septic Arthritis - initial stabilization
- Drainage of infection: Should occur as soon as possible if bacterial cause is suspected
- Indications for open surgical drainage/irrigation:
- Hip involvement
- Shoulder involvement (controversial)
- Thick, purulent, or fibrinous exudate unable to pass through 18-gauge needle
- All other joints not undergoing open drainage should undergo needle aspiration.
- Antibiotic administration immediately after joint aspiration is performed
- Immobilization of extremity
- Pain management
Septic Arthritis - medication
- Choice of antibiotics depends on age of child as outlined.
- Antistaphylococcal penicillin, 1st-generation cephalosporins are usual first-line antibiotics.
- The incidence of MRSA septic arthritis is increasing in many communites. Therefore, in areas where prevalence of methicillin-resistant S. aureus is high (>15%), vancomycin or clindamycin should be considered as first-line treatment until susceptibilities identified. Addition of ceftriaxone in sickle cell patients. Duration of therapy (intravenous and by mouth) for various organisms:
- Treat for at least 2 weeks after resolution of fever and joint effusion.
- At least ≥28 days: S. aureus, gram-negative organisms, group B streptococcus, and for infections of the shoulder and hip.
- At least ≥4 days: H. influenzae, N. meningitidis, streptococci
- At least ≥7 days: N. gonorrhoeae
- Intrarticular injection of antibiotics is not recommended.
- Unproven therapies:
- Steroid therapy in the 1st 4 days has been postulated to reduce residual dysfunction, however this has yet to be proven effective
Septic Arthritis - FOLLOW UP
Septic Arthritis - prognosis
- Depends on duration of illness prior to institution of appropriate therapy
- Incidence of residual joint dysfunction increased if antibiotic therapy not instituted within 1st 4 days of illness
Septic Arthritis - complications
- Permanent limitation of range of motion owing to tissue destruction and scarring.
- Growth disturbance if the epiphysis is involved
Septic Arthritis - patient monitoring
- Involve orthopedic surgery and physical therapy services in follow-up.
- Once the patient is receiving oral therapy, serum bactericidal titers (SBTs) must be monitored on a weekly basis if possible. Oral antibiotic titers should be kept at 8 times the SBT.
- When to expect improvement: With appropriate antibacterial therapy, one should see improvement of symptoms with 2 days of initial administration.
- Signs to watch for:
- Continued pain, fever, or lack of improvement of range of motion after 3–4 days of appropriate antibiotic treatment
- Rising ESR or CRP in the face of antibiotic treatment
- Severe cases of septic arthritis may require serial drainage and debridement
Septic Arthritis - bibliography
- Caird MS, Flynn JM, Leung YL, et al. Factors distinguishing septic arthritis from transient synovitis of the hip in children. A Prospective Study. J Bone Joint Surg Am. 2006;88:1251–1257.
- DelBeccaro MA, Champoux AN, Bockers T, et al. Septic arthritis versus transient synovitis of the hip: The value of screening laboratory tests. Ann Emerg Med. 1992;21:1418–1422.
- Hopkinson N. Sexually-acquired reactive arthritis. Hosp Med. 2001;62:83–85.
- Jung ST, Rowe SM, Moon ES, et al. Significance of laboratory and radiologic findings for differentiating between septic arthritis and transient synovitis of the hip. J Pediatr Orthop. 2003;23:368–372.
- Khachatourians AG, Patzakis MJ, Roidis N, et al. Laboratory monitoring in pediatric acute osteomyelitis and septic arthritis. Clin Orthop. 2003;409:186–194.
- Kocher MS, Mandiga R, Murphy JM, et al. A clinical practice guideline for treatment of septic arthritis in children. J Bone Joint Surg. 2003;85-A:994–999.
- Levine MJ, McGuire KJ, McGowan KL, et al. Assessment of the test characteristics of C-reactive protein for septic arthritis in children. J Pediatr Orthop. 2003;23:373–377.
- Maraqa NF, Gomez MM, Rathore MH. Outpatient parenteral antimicrobial therapy in osteoarticular infections in children. J Pediatr Orthop. 2002;22:506–510.
- Martinez-Aguilar, et al. Community-acquired, methicillin-resistant and methicillin-susceptible Staphylococcus aureus musculoskeltal infections in children. Pediatr Infect Dis J. 2004;23:701–706.
- Odio et al. Double blinded, randomized, placebo-controlled study of dexamethasone therapy for hematogenous septic arthritis in children. Pediatr Infect Dis J. 2003;22;883–888.
- Shaw BA, et al. Acute septic arthritis in infancy and childhood. Clin Orthop. 1990;257:212–215.
- Vinod MB, Matussek J, Curtis N, et al. Duration of antibiotics in children with osteomyelitis and septic arthritis. J Paediatr Child Health. 2002;38:363–367.
- Wall EJ. Childhood osteomyelitis and septic arthritis. Curr Opin Pediatr. 1998;10:73–76.
- Wang CL, Wang SM, Yang YJ, et al. Septic arthritis in children: Relationship of causative pathogens, complications, and outcome. J Microbiol Immunol Infect. 2003;36:41–46.
- Willis AA, Widmann RF, Flynn JM, et al. Lyme arthritis presenting as acute septic arthritis in children. J Pediatr Orthop. 2003;23:114–118.
Septic Arthritis - CODES
Septic Arthritis - icd9
711.0 Sepsis, joint
Septic Arthritis - FAQ
- Q: How can one differentiate toxic synovitis from septic arthritis on the initial visit?
- A: Although this is sometimes a difficult diagnosis to make with certainty, patients with toxic synovitis usually exhibit certain characteristics that patients with septic arthritis do not:
Almost always involves the hip joint
History of previous viral infection
Some painless range of motion of the involved joint is possible.
The ESR is <20 mm/h.
Fever is low grade.
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Book Source Details
- Book Title: The 5-Minute Pediatric Consult
- Author(s): M. William Schwartz MD; et al.
- Year of Publication: 2008
- Copyright Details: The 5-Minute Pediatric Consult, Copyright © 2008 Lippincott Williams & Wilkins.
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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More About This Book:
Title: The 5-Minute Pediatric Consult
Authors: M. William Schwartz MD; et al.
Publisher: Lippincott Williams & Wilkins
Copyright: 2008
ISBN: 0-7817-7577-9
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