The crucial differentiation between septic arthritis and transient synovitis of the hip in children can be difficult. In 1999, Kocher et al introduced four clinical predictors which were highly predictive (99.6%) of septic arthritis. These included fever (temperature ≥ 38.5°C), inability to bear weight, white blood-cell count > 12.0 × 10. 9. cells/L and ESR ≥ 40 mm/hr; CRP ≥ 20 mg/L was later added as a fifth predictor. We retrospectively evaluated these predictors to differentiate septic arthritis from transient synovitis of the hip in children over a four-year period in a primary referral general hospital. When all five were positive, the predicted probability of septic arthritis in this study was only 59.9%, with fever being the best predictor. When applied to low-prevalence diseases, even highly specific tests yield a high number of false positives and the predictive value is thereby diminished. Clinical predictors should be applied with caution when assessing a child with an irritable hip, and a high index of suspicion, and close observation of patients at risk should be maintained

We used ultrasonography to examine 36 children suffering from transient synovitis and 12 children with early Perthes' disease. Widening of the joint space was revealed by ultrasonography in all affected hips with either disease. In the patients with transient synovitis, capsular distension was attributed to synovial effusion, while in the patients with Perthes' disease it was produced by thickening of the synovial membrane. Neither capsular distension nor thickening of the joint cartilage was seen in the contralateral normal hip in the patients with transient synovitis, but they were common in early Perthes' disease. Ultrasonography may provide significant diagnostic clues to differentiate early Perthes' from transient synovitis

A prospective study was made of 119 children with transient synovitis or any other cause for synovial effusion and elevated intra-articular pressure. During a follow-up of one year not one case of Perthes' disease was diagnosed and the late clinical and radiographic changes were minimal with moderate overgrowth of the femoral head in 33% and widening of the joint space in 14.2%. Our results do not support the widely accepted concept that Perthes' disease develops as a result of the period of elevated intra-articular pressure found in transient synovitis. Further research into this and Perthes' disease should follow the premise that they are two different diseases without any aetiological connection

We reviewed 15 children with transient synovitis of the hip who had aspiration of an effusion under local anaesthesia with ultrasound guidance. There were no significant complications; aspiration was useful for diagnosis and gave considerable symptomatic relief. We discuss the role of ultrasound in diagnosis and treatment

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

In a prospective five-year study, 294 episodes of acute transient synovitis of the hip were diagnosed in 275 children. The average annual incidence was 0.2% and the accumulated risk of suffering at least one episode was 3%. The risk of recurrence was 20 times greater than the risk of having a single episode. Perthes' disease was diagnosed from one to five months after the acute attack of synovitis in 10 cases (3.4%). Review of the initial radiographs revealed signs of avascular necrosis in three of the 10 cases, and an increased joint space in five. Only two cases had had completely normal radiographs. The value of routine radiographs taken after three months was minimal. Factors associated with the incidence of Perthes' disease included prolonged time in traction before the range of hip movement became normal, increase in joint space on the initial radiographs and the recurrence of hip symptoms after initial relief

The pathogenesis of Perthes' disease has been related to increased intra-articular pressure secondary to a joint effusion. The pressure within the hip in different positions was measured in eight children with transient synovitis and four with the synovial stage of Perthes' disease. In the position of comfort for the hip this pressure was always less than the arteriolar blood pressure and in a supine position it did not exceed the systolic blood pressure. However, in extension with medial rotation the intra-articular pressure always became several times the systolic blood pressure. This high pressure was also recorded in the stable lateral position which occurs normally during sleep. It is concluded that in the presence of a synovial effusion in the hip, a position of extension and medial rotation causes an increase in intra-articular pressure which may compromise the blood supply to the capital epiphysis of the femur

Acute bone and joint infections in children are serious, and misdiagnosis can threaten limb and life. Most young children who present acutely with pain, limping, and/or loss of function have transient synovitis, which will resolve spontaneously within a few days. A minority will have a bone or joint infection. Clinicians are faced with a diagnostic challenge: children with transient synovitis can safely be sent home, but children with bone and joint infection require urgent treatment to avoid complications. Clinicians often respond to this challenge by using a series of rudimentary decision support tools, based on clinical, haematological, and biochemical parameters, to differentiate childhood osteoarticular infection from other diagnoses. However, these tools were developed without methodological expertise in diagnostic accuracy and do not consider the importance of imaging (ultrasound scan and MRI). There is wide variation in clinical practice with regard to the indications, choice, sequence, and timing of imaging. This variation is most likely due to the lack of evidence concerning the role of imaging in acute bone and joint infection in children. We describe the first steps of a large UK multicentre study, funded by the National Institute for Health Research, which seeks to integrate definitively the role of imaging into a decision support tool, developed with the assistance of individuals with expertise in the development of clinical prediction tools. Cite this article: Bone Joint J 2023;105-B(3):227–229

Clinical prediction algorithms are used to differentiate transient synovitis from septic arthritis. These algorithms typically include the erythrocyte sedimentation rate (ESR), although in clinical practice measurement of the C-reactive protein (CRP) has largely replaced the ESR. We evaluated the use of CRP in a predictive algorithm. The records of 311 children with an effusion of the hip, which was confirmed on ultrasound, were reviewed (mean age 5.3 years (0.2 to 15.1)). Of these, 269 resolved without intervention and without long-term sequelae and were considered to have had transient synovitis. The remaining 42 underwent arthrotomy because of suspicion of septic arthritis. Infection was confirmed in 29 (18 had micro-organisms isolated and 11 had a high synovial fluid white cell count). In the remaining 13 no evidence of infection was found and they were also considered to have had transient synovitis. In total 29 hips were categorised as septic arthritis and 282 as transient synovitis. The temperature, weight-bearing status, peripheral white blood cell count and CRP was reviewed in each patient. A CRP > 20 mg/l was the strongest independent risk factor for septic arthritis (odds ratio 81.9, p < 0.001). A multivariable prediction model revealed that only two determinants (weight-bearing status and CRP > 20 mg/l) were independent in differentiating septic arthritis from transient synovitis. Individuals with neither predictor had a < 1% probability of septic arthritis, but those with both had a 74% probability of septic arthritis. A two-variable algorithm can therefore quantify the risk of septic arthritis, and is an excellent negative predictor.

Background: Distinguishing septic arthritis from transient synovitis of the hip in children can be both crucial and challenging. In 1999, Kocher et al suggested four clinical predictors, fever > 38.5°C, inability to weight bear, WBC count > 12.0x109/L, and ESR> 40mm/hr; that, when combined were highly predictive of septic arthritis in children (99.6%). This figure was challenged by Luhmann et al, stating that the clinical prediction did not exceed 59%. In 2006, Caird et al recommended adding CRP of > 20mg/L as a fifth predictor. Aims: To assess the value and accuracy of clinical prediction algorithms in distinguishing septic arthritis from transient synovitis of the hip in children in our hospital. Methods: A retrospective review of all children admitted to our institution with painful hips was carried out over a period of four years (Feb 2003 to Mar 2007). One-hundred and twenty-two admissions (115 patients, 7 re-admissions) were reviewed. Results: 79 patients (64.8%) were males. The mean age was 6 years (9 months to 15 years). 86 patients (70.5%) were diagnosed with transient synovitis. All the 7 re-admissions were from this group. Only one of the re-admissions was diagnosed with confirmed septic arthritis. 4 patients (3.3%) were diagnosed with definite septic arthritis with positive cultures from the hip, and 1 (0.8%) with probable septic arthritis (negative culture). The presence of the clinical predictors was compared between the transient synovitis and septic arthritis groups, using Fisher’s exact test. Only the raised temperature and CRP were found to be significantly different (p< 0.05). Only two children (40%) with confirmed septic arthritis had four or more predictors (one had all five, and the other was able to partially weight bear). The third child had a raised temperature and CRP, and the fourth had a raised temperature only. The fifth patient (20%) was diagnosed with probable septic arthritis. His cultures were negative, but he was already on intravenous antibiotics. This patient did not have any of the predictors on admission (temperature was 38.3°C, CRP 10.7). However, he spiked a temperature of 40°C 24 hours post admission despite being on antibiotics, and his CRP increased to 34.5mg/L. In the transient synovitis group, two patients (2.2%) had positive five predictors, but were proven to have transient synovitis secondary to a urinary tract infection and gastroenteritis. 47 patients (51.6%) did not have any of the predictors, and 6 patients (6.6%) had three or more positive predictors. Conclusion: Although clinical predictors are helpful in distinguishing septic arthritis from transient synovitis, there were false negative and false positive findings in the study. The predictors cannot be considered alone, and ultimately clinical judgement must be exercised to ensure that cases of septic arthritis are not missed

“Subacute Synovities of the Hip”, which runs a more fluctuant clinical progress and slower response to treatment than those of acute transient synovitis, is always posing diagnostic and management challenge in children presented with acute hip pain. This study aims to identify the special features of this distinct entity, and the important diagnostic parameters in differentiation of acute transient synovitis, subacute arthritis and also septic arthritis in children presented with acute painful pain. From 1985–1999, 427 children have been admitted into our centre with subsequent diagnosis of acute transient synovitis, subacute synovitis & septic arthritis. 320 cases with full records are available for review, with 270 cases 85%) having acute transient synovitis, 35 cases (10%) of subacute arthritis and 15 cases (5%) of septic arthritis. Statistical results showed that patient having subacute arthritis different significantly from those with acute transient synovitis in terms of age of presentation & duration of symptoms before hospitalization. Moreover, patient having transient synovitis significantly different from those with septic arthritis in terms of temperature on admission, ESR and White Cell Count

Introduction: Evaluation of acute hip pain in children can be challenging, because there are several diagnoses to consider. Most patients have a transient synovitis of the hip, which is a benign and self-limited condition. However, its similarities with other more serious disease make the diagnosis one of exclusion. In the Children’s Hospital of Geneva, children presenting with an acute hip pain are treated according to a specific screening protocol including blood sample with rheumatoid panel, hip ultrasound, and conventional X-rays. The objective of our study were to assess the efficacy of the screening protocol on the final diagnosis. We also provided a better characterization of transient synovitis of the hip. Methods: We retrospectively reviewed the medical records of children who had the investigation’s protocol between 1999 and 2003. Results: 269 medical records were reviewed comprising 66.2% of boys and 33.8% of girls, with a mean age of 5.5 years. Prior to presentation, 68.4% of children reported pain of < 24 hours in duration. Limp or refusal to bear weight was observed in all cases. According to the Kocher’s predictors of septic arthritis of the hip (fever, non weight-bearing, ESR > 40 mm/h, serum WBC count of > 12000 cells/mm3), 62% had zero predictor, 22% had one, 15% two, 1% three, and none four. A positive rheumatoid factor test was found in 18% of children, whereas 16% of patients had a positive antinuclear antibody test. During hospitalisation one child was diagnosed as having septic arthritis. The remaining patients were diagnosed by exclusion as having a transient synovitis of the hip since clinical follow-up was normal at 6 weeks. Conclusion: Transient synovitis of the hip is a diagnosis of exclusion, and septic arthritis is the main condition to rule out. Using Kocher’s predictors of septic arthritis is useful for distinction between both conditions early at presentation. In our collective, only 3 patients with transient synovitis had a three of four predictors. Our study also showed that screening for a rheumatologic disease should not be done routinely at the first episode of hip pain. Indeed, positive tests were never confirmed with a clinical situation evocative of rheumatologic disease. More selective criteria should be used before doing a rheumatologic panel. Furthermore our work emphasizes the economical impact of a management of this frequent condition with less blood investigations

1. Transient synovitis is an acute, and at times exudative, condition of the synovial membrane. 2. There is no particular association with injury or with upper respiratory infection. 3. The course is short and benign with complete resolution. The occasional hip with chronic or recurrent symptoms can be distinguished from Legg-Perthes' disease by the shorter history, normal radiographs and the complete resolution. 4. There is no evidence that transient synovitis leads to avascular changes in the femoral head

Displacement and blurring of the soft-tissue shadows about the hip has been described in several conditions, particularly in transient synovitis. A study was made between such displacements and the posture commonly adopted by an "irritable hip". Examination of radiographs of normal hips, and of those in cases of transient synovitis and Perthes' disease showed that the appearance of "capsular swelling" is related to the position of lateral rotation and abduction. This was confirmed by anatomical dissections of the lateral plane, which appears to be an intermuscular plane lying anterior to the hip, and an explanation is given for the blurring which may accompany its lateral displacement. "Capsular swelling" appears to be a radiological artefact

Purpose. To evaluate the efficacy of Kocher's criteria to differentiate between transient synovitis and septic arthritis in children. Methods and results. 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. 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 prediction for two variables (CRP and weight bearing status) was of 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. Conclusion. Mathematical models using common variables used in clinical practice are a useful way of considering ‘risk’ in SA. However, whilst such models correctly classify the majority of individuals they are by no means failsafe. Such models are more reliable in excluding SA, than including SA, and therefore a clinician's acumen remains important in identifying SA in those individuals with a single abnormal variable

During the last decade the important role of ultrasound in the study of congenital and acquired diseases in Paediatric Orthopaedics is all the more established and reinforced. The early diagnosis and management of hip disorders during the neonatal period, is of great importance. In this period the skeleton is mostly cartilagenous and can be imaged better and more accurately with the use of ultrasound compared to radiography. Moreover, during growth, diseases, such as transient synovitis of the hip, are imaged better by ultrasound than radiologically. In a two year period 2001–2002 ultrasound examination was used in 990 children which presented clinical findings of suspected hip disease, either congenital (mostly DDH), or acquired, such as transient synovitis, Perthes, SCFE and others. Furthermore, of great interest was one rare case of deep venous thrombosis, in a 13-year old girl. The last was diagnosed by ultrasound. In all cases, significant help was provided to the clinical doctor and important information was derived, regarding the differential diagnosis and management. The quality of imaging and evaluation of the ultrasound findings is fundamental for the successful application of the method. The above requirements are established by the experience and scientific sufficiency of the doctor performing the examination

The limping or non-weight bearing child can present a difficult diagnostic dilemma. It may be possible to avoid admission of a large proportion of these patients if septic arthritis or other serious pathology can be exclude d. We have established a continuing, prospective study of all patients admitted for hip pain (with normal radiographs) to Starship Children’s’ Hospital between two and 13 years of age. Forty-two patients had a final diagnosis of transient synovitis. Only two patients during an eight month period had septic arthritis. Due to small numbers of patients with serious pathology we compared the transient synovitis group with a retrospective review of those with septic arthritis treated at Starship Hospital in the previous four years. Following comparisons of these two groups, we found that there was a greater incidence of septic arthritis in Maori and Pacific Islanders and septic arthritis tended to occur in younger children. The patients’ initial history, temperature, white cell count and ESR were sensitive in discriminating between septic arthritis and irritable hip. Once the diagnosis of “irritable hip” was made it was unlikely to be altered. We therefore would recommend that it is possible to avoid admission in a large number of these patients. We would however continue to recommend admission for those with a clear history of current illness, Maori or Pacific Islanders, children under the age of four, those with an elevated temperature, and any patient with an elevated white cell count especially neutrophil count or ESR

Background. Establishing the diagnosis in a child presenting with an atraumatic limp can be challenging. There is particular difficulty distinguishing septic arthritis (SA) from transient synovitis (TS) and consequently clinical prediction algorithms have been devised to differentiate the conditions using the presence of fever, raised erythrocyte sedimentation rate (ESR), raised white cell count (WCC) and inability to weight bear. Within Europe measurement of the ESR has largely been replaced with assessment of C-reactive protein (CRP) as an acute phase protein. We have evaluated the utility of including CRP in a clinical prediction algorithm to distinguish TS from 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 four variables (Weight bearing status, WCC >12,000 cells/m3, CRP >20mg/L and Temperature >38.5 degrees C. The definition of SA was based upon microscopy and culture of the joint fluid collected at arthrotomy. 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. An algorithm that indicated a diagnosis of SA in individuals who could not weight-bear and who had a CRP >20mg/L correctly classified SA in 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, such that a two-variable model correctly classified 95% individuals with SA. Nevertheless, this and similar algorithms 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

Background. We herein report a case of isolated hip pain in a four year old boy. The unique aspect of this case study is the unusual history, presentation, ultrasonography, MRI and blood culture results, which lead to the diagnosis and treatment of adductor pyomyositis with a rare organism (Streptococcus Mitis) in a temperate country. The objectives of this case study is to discuss the key learning outcomes with respect to assessment and management of this case. Methods. 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 trauma, predisposing infections or recent travel. A working diagnosis of transient synovitis / septic arthritis of the hip was made on clinical examination. Results. 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. Conclusion. 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 causative 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. Level of Evidence. IV