Transient synovitis of the hip: Development and validation of a new diagnostic algorithm.

ABSTRACT

AIM: To develop and validate an algorithm to rapidly distinguish transient synovitis (TS) of the hip from differential diagnoses without additional tests. METHODS: This retrospective cohort study included all children admitted for non-traumatic limping in the emergency department at Lille University-Hospital between 2016 and 2020. The gold standard was a definitive diagnosis at follow-up visit. All variables associated with acute limping in children were analysed in univariate and multivariable analyses. An algorithm was then developed using recursive partitioning and validated internally on a subset of patients. RESULTS: There were 995 patients included (mean age 5.3 years; males 63%); 337 had a TS including 210 confirmed at follow-up visit and 354 another diagnosis. After multivariable analysis, the relevant variables for distinguishing between TS and differential diagnoses were age 3-10 years, absence of fever, absence of local inflammation, sudden onset of limping on awakening. An algorithm combining these variables was developed (n = 297) and validated internally (n = 175) for children >12 months with limping for ≤10 days, with a specificity of 98.2% and a positive likelihood ratio of 19.6. No serious differential diagnoses were missed. CONCLUSION: Use of this algorithm enables the diagnosis of TS without additional tests and without missing serious differential diagnoses.