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Differentiating between septic arthritis and transient synovitis of the hip in children: an evidence-based clinical
M S Kocher1, D Zurakowski, J R Kasser
1Department of Biostastics, Orthopaedic Surgery, Children's Hospital, Harvard medical School, Boston, Massachusetts 02115, USA. kocher_m@al.tch.harvard.edu
Insights
Differentiating pediatric septic arthritis from transient synovitis is challenging. A clinical prediction algorithm using fever, non-weight-bearing status, elevated ESR, and high WBC count accurately distinguishes between these hip conditions in children.
Area of Science:
- Pediatric Orthopedics
- Pediatric Infectious Diseases
- Diagnostic Medicine
Background:
- Acutely irritable hip in children presents a diagnostic challenge.
- Distinguishing septic arthritis from transient synovitis is crucial for appropriate management.
- Previous diagnostic methods often lack definitive accuracy.
Purpose of the Study:
- To assess the diagnostic value of clinical variables in differentiating pediatric septic arthritis from transient synovitis.
- To develop and validate an evidence-based clinical prediction algorithm for this differentiation.
Main Methods:
- Retrospective review of children with acutely irritable hip evaluated at a tertiary care center (1979-1996).
- Defined septic arthritis and transient synovitis based on joint fluid analysis, cultures, and clinical course.
- Employed univariate and multiple logistic regression analyses to identify predictors.
- Constructed and tested a probability algorithm using independent multivariate predictors.
Main Results:
- Significant differences (p < 0.05) between septic arthritis and transient synovitis groups included ESR, WBC count, weight-bearing status, fever, temperature, radiographic effusion, chills, antibiotic use, hematocrit, and gender.
- Identified four key predictors for septic arthritis: fever, non-weight-bearing, ESR ≥ 40 mm/hr, and serum WBC count > 12,000/mm³.
- The algorithm demonstrated excellent diagnostic performance, with predicted probabilities ranging from <0.2% (zero predictors) to 99.6% (four predictors).
Conclusions:
- Individual clinical variables show overlap, making differentiation difficult.
- A combined approach using four independent multivariate predictors provides excellent diagnostic accuracy for differentiating pediatric septic arthritis from transient synovitis.
- The developed algorithm offers a valuable tool for clinical decision-making in cases of acutely irritable hip in children.
Background:
A child who has an acutely irritable hip can pose a diagnostic challenge. The purposes of this study were to determine the diagnostic value of presenting variables for differentiating between septic arthritis and transient synovitis of the hip in children and to develop an evidence-based clinical prediction algorithm for this differentiation.
Methods:
We retrospectively reviewed the cases of children who were evaluated at a major tertiary-care children's hospital between 1979 and 1996 because of an acutely irritable hip. Diagnoses of true septic arthritis, presumed septic arthritis, and transient synovitis were explicitly defined on the basis of the white blood-cell count in the joint fluid, the results of cultures of joint fluid and blood, and the clinical course. Univariate analysis and multiple logistic regression analysis were used to compare groups. A probability algorithm for differentiation between septic arthritis and transient synovitis on the basis of independent multivariate predictors was constructed and tested.
Results:
Patients who had septic arthritis differed significantly (p < 0.05) from those who had transient synovitis with regard to the erythrocyte sedimentation rate, serum white blood-cell count and differential, weight-bearing status, history of fever, temperature, evidence of effusion on radiographs, history of chills, history of recent antibiotic use, hematocrit, and gender. Patients who had true septic arthritis differed significantly (p < 0.05) from those who had presumed septic arthritis with regard to history of recent antibiotic use, history of chills, temperature, erythrocyte sedimentation rate, history of fever, gender, and serum white blood-cell differential. Four independent multivariate clinical predictors were identified to differentiate between septic arthritis and transient synovitis: history of fever, non-weight-bearing, erythrocyte sedimentation rate of at least forty millimeters per hour, and serum white blood-cell count of more than 12,000 cells per cubic millimeter (12.0 x 10(9) cells per liter). The predicted probability of septic arthritis was determined for all sixteen combinations of these four predictors and is summarized as less than 0.2 percent for zero predictors, 3.0 percent for one predictor, 40.0 percent for two predictors, 93.1 percent for three predictors, and 99.6 percent for four predictors. The chi-square test for trend and the area under the receiver operating characteristic curve indicated excellent diagnostic performance of this group of multivariate predictors in identifying septic arthritis.
Conclusions:
Although several variables differed significantly between the group that had septic arthritis and the group that had transient synovitis, substantial overlap in the intermediate ranges made differentiation difficult on the basis of individual variables alone. However, by combining variables, we were able to construct a set of independent multivariate predictors that, together, had excellent diagnostic performance in differentiating between septic arthritis and transient synovitis of the hip in children.