[The Value of Conventional Radiographs of the Pelvis in Detection of Perthes Disease 3 Months After an Episode of Acute Transient Synovitis].

Background: Transient synovitis is the most common hip joint disorder in children. Perthes disease occurs around the same age and may not be distinguishable to an episode of transient synovitis in the early stage. Therefore all children in our clinic with transient synovitis underwent a follow-up X-ray 3 months later to detect Perthes disease at an early stage. The aim of the study was to evaluate, if a follow-up X-ray is necessary for all children with suspected transient synovitis or if the clinical follow-up can lead to the indication for a follow-up X-ray. Patients and Method: Retrospective study including all children treated with the diagnosis of transient synovitis between 2004 and 2010. 198 patients with the diagnosis of a transient synovitis were included. We analyzed the radiological and clinical findings initially and after at least 3 month follow-up. Results: In the time between the episode of transient synovitis and follow-up 20 children did not remain symptom-free (10.1%). Of these patients 16 had a normal radiological follow-up and 4 (2%) were diagnosed with Perthes disease. All children which remained symptom-free between the episode of transient synovitis and the follow-up had a negative follow-up X-ray (sensitivity 0.2, specifity 1.0). Conclusion: A follow-up X-ray in detection of Perthes disease for children with transient synovitis appears to be necessary only if they have recurrent or persisting symptoms in the clinical course between the episode of transient synovitis and the 3-months-follow-up. A good patient history and an expert clinical follow-up examination are mandatory to decide whether a follow-up X-ray is needed.