Background. Establishing the diagnosis in a child presenting with an atraumatic limp can be difficult. Clinical prediction algorithms have been devised to distinguish septic arthritis (SA) from transient synovitis (TS). Within Europe measurement of the Erythrocyte Sedimentation Rate (ESR) has largely been replaced with assessment of C-Reactive Protein (CRP) as an acute phase protein. We produce a prediction algorithm to determine the significance of CRP in distinguishing between TS and SA. Method. All children with a presentation of ‘atraumatic limp’ and a proven effusion on hip ultrasound between 2004 and 2009 were included. Patient demographics, details of the clinical presentation and laboratory investigations were documented to identify a response to each of the four variables (Weight bearing status, WCC >12,000 cells/m3, CRP >20mg/L and Temperature >38.5°C). SA was defined based upon culture and microscopy of the operative findings. Results. 311 hips were included within the study. Of these 282 were considered to have transient synovitis. 29 patients met criteria to be classified as SA based upon laboratory assessment of the synovial fluid. The introduction of CRP eliminated the need for a four variable model as the use of two variables (CRP and weight bearing status) had similar efficacy. Treating individuals who were non-weight-bearing and a CRP >20mg/L as SA correctly classified 94.8% individuals, with a sensitivity of 75.9%, specificity of 96.8%, positive predictive value of 71.0%, and negative predictive value of 97.5%. CRP was a significant independent predictor of septic arthritis. Conclusions. CRP was a strong independent risk factor of septic arthritis, and its inclusion within a regression model simplifies the diagnostic algorithm. Nevertheless, this and other models are generally more reliable in excluding SA, than confirming SA, and therefore a clinician's acumen remains important in identifying SA in those individuals with a single abnormal variable

We herein report a case of isolated hip pain in a four year old boy. The importance of this project is the unusual history, presentation, ultrasound, MRI and blood culture results and treatment, which lead to the diagnosis of adductor pyomyositis with a rare organism (Streptococcus Mitis) in a temperate country. The patient presented with a one day history of malaise, fever, left groin pain and inability to weight bear on the left leg. There was no history of any predisposing infections or recent travel. A working diagnosis of transient synovitis / septic arthritis of the hip was made on clinical examination. Plain radiograph and ultrasound of the hip was normal with no effusion. Two consecutive blood cultures suggested Streptococcus Mitis bacteriaemia and MRI scan confirmed pyomyositis of the left hip adductors that was too small to drain. Streptococcus Mitis is a normal commensal organism of the oral cavity however it can lead to opportunistic infections particularly endocarditis. Echocardiogram revealed no cardiac complications, in particular no endocarditic vegetation. Patient was treated with intravenous benzylpenicillin for a week followed by oral phenoxymethylpenicillin for a week. As it was a soft tissue infection, a short course of antibiotics was sufficient and he made a complete recovery. Adductor pyomyositis must be considered as a differential diagnosis in a child with unusual presentation of hip pain. When an ultrasound is normal, MRI scan is warranted to confirm diagnosis. Septic screen should include blood cultures. The commonest organisms are the Staphylococcus family. However if Streptococcus Mitis is isolated, cardiac sources of infection resulting in septic emboli must be investigated. Repeated MRI scans are required particularly if the patient does not respond to medical management

Pyogenic sacroiliitis (PS) is one of the less frequent localizations among joint infections, near the 1,5%. A late diagnosis generally exists. So we decided to analyze its behaviour in our uniit. A retrospective study of 39 records was carried out, 32 with diagnosis of entrance of PS and 7 with another pathology's diagnosis that turned out to be a PS, among the years 1999 and 2014 in our unit. 27 only fulfilled the requirements to be classified as PS (Clinic features of infection and sacroiliac localization, laboratory exams and Tc-99 bone scintigraphy alterations). 20 males and 7 females (74% males), 52% right sacroiliac joint, only 7 had clinically predisposing conditions (trauma), aged between 3 and 14 years (average 9.6 years). The half time of clinical evolution foresaw to diagnosis was of 4,7 days (6,7 days between 1999–2005 and 3,5 between 2006–2014) (range between 1 and 10 days). The main symptom that motivates the consultation was fever (96%) accompanied by FABER test positive (70%) by buttock pain (52%) and by limping (48%). Laboratory exams: WBC count was normal in 11 cases and elevated in 16 cases too and only in 5 cases with left deviation (PMNs elevated); CRP higher than 55 mg/dl in 23 patients (100% over 20mg/dl), ERS with value average of 72 mmHg/hour (27–111). Blood cultures were positive in 70% and the Staphylococcus aureus was the main bacteria founded (89%). No radiological alterations were found initially. The TC-99 bone scintigraphy was positive in all cases after the third day. All patients had a 5 to 12 days course of intravenous antibiotics (oxacillin + amikacin in 96% of patients) and then completed 4 weeks with oral oxacillin. All patients recovered without sequel. Blood cultures may be obtained prior the antibiotics’ administration. The Staphylococcus aureus is by far the most frequent germ involved in this process, and it may guide the empiric antibiotic therapy. The precocious antibiotic treatment solves the case without sequels. The PS is an uncommon pathology in children that makes it often not recognized initially. Wrong diagnosis such as appendicitis, transient synovitis of the hip, discitis, etc. can be avoided if PS is sought in a systematic way

Aim. This study aims to determine the value of MRI in children with hip pain which remained unexplained following routine investigations including ultrasound examination. Materials and methods. Retrospective review of clinical notes and MRI findings in all children who received and MRI scan for undiagnosed hip pain over three years. Results. Fifty five children underwent an MRI scan of their hips for unexplained hip pain. 29 were male and 26 were female. The mean age was 10.9 years. The MR study provided a diagnosis in 22 children (40%), and was normal in 33 children (60%). Five cases were considered to be due to transient synovitis. Three children were diagnosed as osteoid osteoma. Two children were were found to have trochanteric bursitis. Two children were shown to have muscle trauma (one child with adductor trauma and one child with piriformis trauma). Two children were diagnosed with non-specific bone oedema. The remaining eight children were diagnosed with Perthes' disease, haemarthrosis, sacro-iliac infection, synovitis secondary to juvenile idiopathic arthritis, ischio-pubic osteochondrosis, acetabular dysplasia, Klippel-Trenaunay syndrome and resolution of an eosinophilic granuloma. None of the children discharged following a normal scan has subsequently presented with hip disease. Conclusions. It is concluded that MRI is useful in the diagnosis of hip pain in children in whom routine investigation has not yielded an answer