Pediatric Septic Arthritis Surgery Workup

  • Author: Edwards P Schwentker, MD; Chief Editor: Dennis P Grogan, MD   more...
 
Updated: Jan 21, 2009
 

Laboratory Studies

  • White blood cell (WBC) count
    • The WBC count is usually elevated, but it may be within the normal range early in the clinical course. Infants may also have a normal WBC count.
    • A normal WBC count does not rule out septic arthritis.
  • Erythrocyte sedimentation rate (ESR)
    • The ESR is elevated in septic arthritis; it returns to normal levels with resolution of the infection.
    • The initial elevation and the return to normal lag behind the clinical status.
  • C-reactive protein (CRP)
    • The CRP level is elevated in septic arthritis; it returns to normal with resolution of the infection.
    • CRP is a more valuable diagnostic tool and a better indicator of response to treatment than ESR because CRP is generally more sensitive and more responsive. Blood cultures are frequently positive for the causative organism in septic arthritis and should be obtained. The joint aspirate may not yield a viable culture.
    • Other cultures and Gram stains may be useful.
    • If gonococcal arthritis is suspected, cultures and Gram stain material should be obtained from the cervix in postpubertal girls, from the vagina of prepubertal girls, and from any urethral discharge in a male.
    • If sexual abuse is suspected—and it should be suspected in any prepubertal child with gonococcal arthritis—obtain additional cultures with samples from the pharynx and rectum.
    • If child abuse is suspected, clinicians have a legal obligation to report the suspicions and to preserve all records and laboratory results as possible future legal evidence.
    • Gram stains of joint aspirates should always be performed because a positive Gram stain is valuable information. The Gram stain is positive in a minority of the cases of septic arthritis; however, a negative result should never be interpreted as evidence that infection is not present.
    • Fluid from joint aspirates from children younger than 3 years should be inoculated directly into blood culture bottles to enhance the isolation of K kingae, a fastidious pathogen increasingly common in this age group.
  • Lyme titers should be obtained in regions where this disease is endemic. If a rapid test that can provide results within hours is not available, it may be necessary to initially assume that the diagnosis is septic arthritis and treat accordingly.
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Imaging Studies

  • Plain radiography
    • Obtain radiographs to rule out other conditions in the differential diagnosis, such as trauma or Legg-Calvé-Perthes disease. Radiographs are not helpful in diagnosing acute septic arthritis.
    • Even if the infection developed from an adjacent metaphyseal osteomyelitis, no initial bony findings are likely to be apparent until 7-10 days after onset. Signs of soft-tissue swelling and edematous infiltration into fatty tissue planes may be observed.
  • Radionuclide scanning
    • Radionuclide scanning is generally not helpful, and it is contraindicated if it delays more appropriate diagnostic or treatment measures.
    • Scanning may be helpful in locating or ruling out other sites of involvement, particularly in very sick children and in neonates.
  • Ultrasonography
    • Ultrasonography is useful in confirming a joint effusion in a deeply placed joint such as the hip.
    • This modality can also be used to guide joint aspiration.
  • Magnetic resonance imaging (MRI)
    • MRI has no role in the initial workup.
    • The use of this expensive and time-consuming modality should be reserved for situations in which simpler measures, such as joint aspiration, fail to provide a diagnosis.
    • In such cases, the diagnosis is probably something other than septic arthritis.
  • Computed tomography (CT)
    • A CT scan is indicated in patients with a suspected psoas abscess; in such patients, the clinical signs are suggestive of septic arthritis of the hip but the joint aspiration culture is negative.
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Diagnostic Procedures

  • Joint aspiration
    • Joint aspiration is the single most important diagnostic procedure.
    • Aspirate the joint with a large-bore needle before administering antibiotics.
    • Peripheral joints are readily tapped in a clinic or office setting.
    • Aspirate deep joints, such as the hip, under image-intensifier control or ultrasound guidance and with the patient appropriately sedated or anesthetized.
    • Of vital importance is ensuring that the joint was penetrated before the aspiration results are declared negative. If no fluid is obtained, perform an arthrogram by injecting contrast material through the needle.
    • A positive joint aspirate typically yields opaque yellow or white-gray pus.
    • The WBC count is usually in excess of 50,000 per milliliter, with more than 80% neutrophils.
    • A positive Gram stain is diagnostic for infection, but false-negative results are common. The failure to visualize organisms on the Gram stain does not rule out infection.
    • If gonococcal arthritis is suspected, obtain the culture in a manner approved by the clinical laboratory for this organism.
    • N gonorrhoeae is a difficult organism to grow, and special handling and special culture media are required to maximize recovery.
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Contributor Information and Disclosures
Author

Edwards P Schwentker, MD  Professor, Departments of Orthopedics and Rehabilitation and Pediatrics, Pennsylvania State College of Medicine

Disclosure: Nothing to disclose.

Specialty Editor Board

Charles T Mehlman, DO, MPH  Professor of Pediatrics and Pediatric Orthopedic Surgery, Division of Pediatric Orthopedic Surgery, Director, Musculoskeletal Outcomes Research, Cincinnati Children's Hospital Medical Center

Charles T Mehlman, DO, MPH is a member of the following medical societies: American Academy of Pediatrics, American Fracture Association, American Medical Association, American Orthopaedic Foot and Ankle Society, American Osteopathic Association, Arthroscopy Association of North America, North American Spine Society, Ohio State Medical Association, Pediatric Orthopaedic Society of North America, and Scoliosis Research Society

Disclosure: Nothing to disclose.

Francisco Talavera, PharmD, PhD  Senior Pharmacy Editor, eMedicine

Disclosure: eMedicine Salary Employment

George H Thompson, MD  Director, Pediatric Orthopedics, Rainbow Babies and Children's Hospital

George H Thompson, MD is a member of the following medical societies: American Academy of Orthopaedic Surgeons, American Orthopaedic Association, Pediatric Orthopaedic Society of North America, and Scoliosis Research Society

Disclosure: OrthoPediatrics None Consulting; Journal of Pediatric Orthopaedics Salary Management position

Dinesh Patel, MD, FACS  Associate Clinical Professor of Orthopedic Surgery, Harvard Medical School; Chief of Arthroscopic Surgery, Department of Orthopedic Surgery, Massachusetts General Hospital

Dinesh Patel, MD, FACS is a member of the following medical societies: American Academy of Orthopaedic Surgeons

Disclosure: Nothing to disclose.

Chief Editor

Dennis P Grogan, MD  Clinical Professor, Department of Orthopedic Surgery, University of South Florida College of Medicine; Chief of Staff, Department of Orthopedic Surgery, Shriners Hospital for Children of Tampa

Dennis P Grogan, MD is a member of the following medical societies: American Academy of Orthopaedic Surgeons, American Medical Association, American Orthopaedic Association, American Orthopaedic Foot and Ankle Society, Eastern Orthopaedic Association, Irish American Orthopaedic Society, Pediatric Orthopaedic Society of North America, and Scoliosis Research Society

Disclosure: Nothing to disclose.

References

  1. Rice PA. Gonococcal arthritis (disseminated gonococcal infection). Infect Dis Clin North Am. Dec 2005;19(4):853-61. [Medline].

  2. Frank G, Mahoney HM, Eppes SC. Musculoskeletal infections in children. Pediatr Clin North Am. Aug 2005;52(4):1083-106, ix. [Medline].

  3. Peltola H, Kallio MJ, Unkila-Kallio L. Reduced incidence of septic arthritis in children by Haemophilus influenzae type-b vaccination. Implications for treatment. J Bone Joint Surg Br. May 1998;80(3):471-3. [Medline].

  4. Moylett EH, Rossmann SN, Epps HR, Demmler GJ. Importance of Kingella kingae as a pediatric pathogen in the United States. Pediatr Infect Dis J. Mar 2000;19(3):263-5. [Medline].

  5. Kehl-Fie TE, Miller SE, St Geme JW 3rd. Kingella kingae expresses type IV pili that mediate adherence to respiratory epithelial and synovial cells. J Bacteriol. Aug 29 2008;[Medline].

  6. Yagupsky P, Bar-Ziv Y, Howard CB, Dagan R. Epidemiology, etiology, and clinical features of septic arthritis in children younger than 24 months. Arch Pediatr Adolesc Med. May 1995;149(5):537-40. [Medline].

  7. Mataika R, Carapetis JR, Kado J, Steer AC. Acute rheumatic fever: an important differential diagnosis of septic arthritis. J Trop Pediatr. Jun 2008;54(3):205-7. [Medline].

  8. Willis AA, Widmann RF, Flynn JM, Green DW, Onel KB. Lyme arthritis presenting as acute septic arthritis in children. J Pediatr Orthop. Jan-Feb 2003;23(1):114-8. [Medline].

  9. Song J, Letts M, Monson R. Differentiation of psoas muscle abscess from septic arthritis of the hip in children. Clin Orthop Relat Res. Oct 2001;(391):258-65. [Medline].

  10. Korakaki E, Aligizakis A, Manoura A, Hatzidaki E, Saitakis E, Anatoliotaki M, et al. Methicillin-resistant Staphylococcus aureus osteomyelitis and septic arthritis in neonates: diagnosis and management. Jpn J Infect Dis. May 2007;60(2-3):129-31. [Medline].

  11. Arnold SR, Elias D, Buckingham SC, Thomas ED, Novais E, Arkader A, et al. Changing patterns of acute hematogenous osteomyelitis and septic arthritis: emergence of community-associated methicillin-resistant Staphylococcus aureus. J Pediatr Orthop. Nov-Dec 2006;26(6):703-8. [Medline].

  12. Kocher MS, Zurakowski D, Kasser JR. Differentiating between septic arthritis and transient synovitis of the hip in children: an evidence-based clinical prediction algorithm. J Bone Joint Surg Am. Dec 1999;81(12):1662-70. [Medline].

  13. Caird MS, Flynn JM, Leung YL, Millman JE, D'Italia JG, Dormans JP. Factors distinguishing septic arthritis from transient synovitis of the hip in children. A prospective study. J Bone Joint Surg Am. Jun 2006;88(6):1251-7. [Medline].

  14. Arnold SR, Elias D, Buckingham SC, Thomas ED, Novais E, Arkader A, et al. Changing patterns of acute hematogenous osteomyelitis and septic arthritis: emergence of community-associated methicillin-resistant Staphylococcus aureus. J Pediatr Orthop. Nov-Dec 2006;26(6):703-8. [Medline].

 
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Emergency room photograph of an infant with septic arthritis of the left hip. The child holds his hip rigidly in the classic position of flexion, abduction, and external rotation, a position that maximizes capsular volume. The patient is relatively comfortable as long as the hip joint remains immobile in this position.
This is the first radiograph in a series of 6 (see Images below) that document the natural history and complications of an inadequately treated septic arthritis of the left hip. The child is aged 22 months and had been symptomatic for a week before this radiograph was obtained. No bone changes are seen, but the left hip is laterally subluxated.
Second radiograph in the series of a septic left hip. Three days after presentation and 10 days after the onset of symptoms, there is still no change in the bone's appearance, but the hip joint is further subluxated.
Third radiograph in the series of a septic left hip. Three weeks after presentation, the left hip is dislocated, and new periosteal bone formation is noted. This last finding is characteristic of an associated osteomyelitis of the left femur.
Fourth radiograph in the series of a septic left hip. Seven weeks after onset, increased opacity is noted in the central portion of the proximal femoral metaphysis and in the proximal femoral epiphysis. The findings are consistent with avascular necrosis of these structures.
Fifth radiograph in the series of a septic left hip. Five months after onset, the femoral head has been completely resorbed, and the femoral shaft has regenerated.
Sixth radiograph in the series of a septic left hip. At age 11, or 9 years after onset of the infection, the hip joint and the proximal femoral growth plate are destroyed. A profound limb-length discrepancy is noted, in addition to severely impaired hip function.
 
 
 
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