Differentiating between septic arthritis and transient synovitis of the hip in children: an evidence-based clinical prediction algorithm

Septic Arthritis of the Hip in the Setting of Hemophagocytic Lymphohistiocytosis: A Case Report

CASE

A twenty-two-month-old boy with septic hip arthritis had persistent elevated inflammatory markers and daily fevers despite multiple antibiotic regimens and repeated surgical debridements yielding negative cultures. After exhaustive work-up for other infectious, rheumatologic, and immunologic etiologies, he met diagnostic criteria for hemophagocytic lymphohistiocytosis (HLH) and developed cultures positive for fungal hip arthritis. Following treatment for HLH and fungal hip arthritis, he improved and was discharged.

CONCLUSION

No previous report in the literature specifically associates HLH with septic hip arthritis, to our knowledge. Surgeons should suspect underlying immunologic deficiencies and atypical infectious causes of septic arthritis when usual treatment modalities have failed.

Septic arthritis and acute rheumatic fever in children: the diagnostic value of serological inflammatory markers

INTRODUCTION

Joint pain and raised inflammatory markers are features of both acute rheumatic fever (ARF) and septic arthritis, often posing a diagnostic challenge to clinicians. Important differences in the presenting serological inflammatory marker profile may assist patient diagnosis, however, as clinical experience suggests that ARF is associated with a higher erythrocyte sedimentation rate (ESR), whereas other serological markers may be similarly elevated in these 2 conditions.

OBJECTIVE

The goal of this study was to determine the diagnostic value of serological inflammatory markers and white cell count (WCC) in children presenting with acute joint pain secondary to ARF or septic arthritis.

METHODS

Data were obtained from the Auckland regional rheumatic fever database and hospital computer records between 2005 and 2012. Records of all patients under the age of 16 years who were admitted with a new diagnosis of ARF or septic arthritis were analyzed. The diagnosis of ARF was defined on the basis of the New Zealand modification of the Jones Criteria, and the diagnosis of septic arthritis was defined on the basis of joint fluid cytology and culture. Baseline characteristics, serological inflammatory markers, and serum WCC were compared between the ARF and septic arthritis patient groups.

RESULTS

Children with ARF displayed significantly higher ESR, higher serum C-reactive protein, and lower serum WCC than children with septic arthritis on presentation to hospital. In children presenting with monoarthritis, an ESR>64.5, serum WCC<12.1×109/L, and age above 8.5 years were found to be significant independent predictors of ARF. Children with all 3 predictors had a 71% risk for ARF and a 29% risk for septic arthritis. A significant proportion (30%) of children with the final diagnosis of ARF initially presented with monoarthritis; 14% of these children (5/34) had received nonsteroidal anti-inflammatory medication before hospital presentation, and 74% of these children (25/34) had abnormal echocardiograms on admission.

CONCLUSIONS

ARF and septic arthritis are important diagnoses to consider in children presenting with acute joint pain in New Zealand. A significant proportion of patients with ARF initially present with acute monoarthritis. Serological inflammatory markers and WCC on presentation differ significantly between children with ARF and septic arthritis.

Aetiology of arthritis in hospitalised children: an observational study

BACKGROUND AND OBJECTIVE

Arthritis in children has many causes and includes septic and viral arthritis, reactive arthritis and juvenile idiopathic arthritis (JIA). We aimed to describe the different types of arthritis among children hospitalised for a first episode of arthritis.

DESIGN

Retrospective, descriptive case series study.

SETTING

A French tertiary care centre.

PATIENTS

Children under 16 years of age hospitalised for an arthritis episode between 1 January 2008 and 31 December 2009.

MAIN OUTCOME MEASURES

Demographic and clinical features were compared with χ(2) or Fisher's exact tests and non-parametric tests.

RESULTS

173 children were hospitalised for a first episode of arthritis during the study period, with a male/female ratio of 1.14. The most frequent cause of hospitalisation was septic arthritis (43.4% of cases, 69.3% of which were due to Kingella kingae and 10.7% to Staphylococcus aureus). JIA was responsible for 8.1% of cases and arthritis without any definitive diagnosis for 40.4%. Median age at diagnosis was 2.7 years (IQR 0.3-14.6) and was lower in the septic arthritis group (1.5 years; 1.1-3.4) than in the JIA group (4.7 years; 2.5-10.9) (p<0.01). Septic arthritis involved a single joint in 97.3% of cases, while JIA involved four joints in 14.3% of cases and two to four joints in 28.6% of cases (p<0.01).

CONCLUSIONS

Septic arthritis was the most frequent cause of arthritis in hospitalised children. Despite the increasing application of microbiological molecular methods to synovial fluid analysis, further measures are required to improve the diagnosis of arthritis of unknown cause.

Aspirations of the ilium and proximal femur increase the likelihood of culturing an organism in patients with presumed septic arthritis of the hip

PURPOSE

To test the hypothesis that collecting material for culture from metaphyseal bone of the ilium and proximal femur at the time of a hip aspiration will increase the sensitivity to detect an infectious organism in patients with presumed septic arthritis of the hip.

METHODS

We retrospectively reviewed a series of 36 patients with presumed septic arthritis of the hip, based on clinical exam and serum inflammatory markers, who underwent aspirations of hip synovial fluid as well as blood from the ilium and proximal femur. Culture results from aspirates of synovial fluid and bone and tissue from capsule were compared to determine the sensitivities and specificities of a synovial aspirate alone versus synovial aspirate plus aspirates of the ilium and proximal femur to detect infection.

RESULTS

The sensitivity of hip synovial fluid aspirates to detect infection via positive culture was only 63 %, though this increased significantly to 100 % when the results of cultures of aspirates of the ilium and proximal femur were included. The specificities were equivalent in both modalities (≥90 %). We conclude that obtaining aspirates of the ilium and proximal femur at the time of hip synovial fluid aspiration increases the likelihood that the procedure will return an infectious organism.

CONCLUSION

Positive cultures from a child with a septic hip or peri-articular hip infection help to efficiently and effectively guide antibiotic treatment. The child with a septic hip or peri-articular hip infection and positive cultures is likely to receive more narrow-spectrum therapy, potentially decreasing the overuse of broad-spectrum antibiotics.

LEVEL OF EVIDENCE

DIAGNOSTIC STUDY LEVEL III: Development of diagnostic criteria on the basis of a series of non-consecutive patients (with universally applied reference "gold standard").

Kingella kingae infections in children

BACKGROUND

Improvements in culture techniques and molecular detection methods have led to findings indicating that, particularly in infants and young children, Kingella kingae is a significantly more important pathogen than previously thought. However, despite this, the pediatric community is still largely unaware of the existence of this organism. The aim of this review is therefore to summarise current knowledge of the epidemiology, transmission, clinical presentation, diagnosis and treatment of K. kingae infections in children.

DISCUSSION

K. kingae is a common coloniser of the oropharynx, can be transmitted from child to child, and can cause outbreaks of infection. Invasive infections almost exclusively occur in children aged between six months and four years of age, and involve mainly joints and bone, less frequently the endocardium, and very rarely other localisations. With the exception of bacteremia and endocarditis, which can be followed by severe complications, the diseases due to K. kingae are usually accompanied by mild to moderate clinical signs and symptoms, and only slightly altered laboratory data. Moreover, they generally respond to widely used antibiotics, although resistant strains are reported. However, the mild symptoms and limited increase in the levels of acute phase reactants create problems because K. kingae disease may be confused with other clinical conditions that have a similar clinical picture.

CONCLUSIONS

Although K. kingae was identified more than 50 years ago, it is poorly known by pediatricians and is not systematically sought in laboratories. Education is therefore necessary in order to reduce the risk of outbreaks, permit the early identification of K. kingae infections, and allow the prompt prescription of adequate therapeutic regimens capable of avoiding the risk of a negative evolution in those cases in which this elusive pathogen can cause significant clinical problems.

Efficacy of Hip Arthroscopy for the Management of Septic Arthritis: A Systematic Review

PURPOSE

This systematic review assessed the role of hip arthroscopic irrigation and debridement for eradication of infection in native joints to ascertain outcomes and complications associated with this surgical approach.

METHODS

The Medline, Embase, and PubMed databases were searched on July 20, 2014, for English-language studies that addressed arthroscopic treatment of native septic hip arthritis. The studies were systematically screened and data abstracted in duplicate, with qualitative findings presented.

RESULTS

There were 11 eligible studies (1 case-control study, 8 case series, and 2 case reports) reporting on 65 patients (65 hips) treated by arthroscopic irrigation and debridement for septic hip arthritis. The mean length of patient follow-up was 19.1 months (range, 6 to 84 months). The indications for surgery were as follows: pyrexia, anterior groin or hip pain with limited hip range of motion and an inability to bear weight, associated leukocytosis, an elevated erythrocyte sedimentation rate or C-reactive protein level, and/or hip imaging or aspiration results consistent with infection. Specific contraindications for surgery reported across studies included tuberculous of fungal infection, coexistence of osteomyelitis, immunocompromised individuals, and pre-existing surgery on the affected hip. The initial rate of infection eradication was 100%. All studies reported significant improvements in patient pain and function. Improvements were also observed in range of motion, as well as across both the Bennett radiographic and clinical assessments and Harris Hip Score. No complications, major or minor, were reported, and only 1 of 65 hips (1.5%) required revision arthroscopy for recurrence because of a methicillin-resistant Staphylococcus aureus infection.

CONCLUSIONS

Arthroscopic native hip irrigation and debridement for septic arthritis appear to comprise a safe and effective treatment option for selected patients (e.g., no deformity, no bacterial infections, and not immunocompromised). Timely diagnosis and intervention, however, remain the most critical prognostic factors for successful outcomes.

LEVEL OF EVIDENCE

Level IV, systematic review of Level IV and V studies.

Pediatric Rheumatology for the Primary Care Clinicians-Recognizing Patterns of Disease

This review presents a diagnostic approach to musculoskeletal and rheumatic diseases in children for primary care clinicians. The focus is on juvenile idiopathic arthritis (JIA) as the major arthritis disease in children. It is necessary to know the personalities of these JIA categories. It is also crucial to be able to recognize the common infectious, orthopedic and mechanical, malignant, genetic, other rheumatic diseases, and other miscellaneous syndromes that can mimic JIA. To do so requires recognition of clinical patterns using a thorough musculoskeletal and rheumatic history and repeated complete physical exams with emphasis on the musculoskeletal exam. It also requires targeted and limited laboratory testing with careful follow-up over time.

Infections and arthritis

Bacteria, viruses, fungi, and parasites can all cause arthritis of either acute or chronic nature, which can be divided into infective/septic, reactive, or inflammatory. Considerable advances have occurred in diagnostic techniques in the recent decades resulting in better treatment outcomes in patients with infective arthritis. Detection of emerging arthritogenic viruses has changed the epidemiology of infection-related arthritis. The role of viruses in the pathogenesis of chronic inflammatory arthritides such as rheumatoid arthritis is increasingly being recognized. We discuss the various causative agents of infective arthritis and emphasize on the approach to each type of arthritis, highlighting the diagnostic tests, along with their statistical accuracy. Various investigations including newer methods such as nucleic acid amplification using polymerase chain reaction are discussed along with the pitfalls in interpreting the tests.

Improving diagnostic efficiency: analysis of pelvic MRI versus emergency hip aspiration for suspected hip sepsis

BACKGROUND

Accurately diagnosing and treating childhood hip sepsis is challenging. Adjacent bone and soft-tissue infections are common and can lead to delayed and inappropriate treatment. This study evaluated the effect of early advanced imaging (bone scan, magnetic resonance imaging) in the management of suspected hip sepsis.

METHODS

A retrospective review of pediatric patients admitted between 2003 and 2009 with suspected hip sepsis was performed. Patients were classified into 2 categories: group I-immediate hip aspiration or group II-advanced imaging performed before intervention.

RESULTS

In total, 130 patients (53 in group I and 77 in group II) were included. No significant differences were found between the groups with regard to laboratory values, temperature, number of anesthetics, and length of hospital stay. However, patients in group I were younger than in group II (5.4 vs. 7.3 y, P=0.02) and more patients in group I were unable to bear weight on the affected limb compared with group II (83% vs. 61%, P=0.009). In group I, 36 patients (68%) had a septic hip compared with 35 patients (45%) in group II. In group I, 16 patients (30%) required reoperation versus 13 (17%) patients in group II. Results from the multivariate analysis demonstrated that reoperation was required 2.8 times (95% confidence interval, 1.12-6.78) more often in group I as compared with group II (P=0.03).

CONCLUSIONS

Advanced imaging performed before hip aspiration improves diagnostic efficacy and may decrease the need for reoperation.

LEVEL OF EVIDENCE

III.

Epidemiology, diagnosis, and treatment of pericapsular pyomyositis of the hip in children

BACKGROUND

The yield of synovial fluid cultures in patients meeting clinical criteria for septic hip arthritis remains low. In the presence of positive blood cultures, these patients are diagnosed and treated as "presumed septic arthritis." We hypothesized that some of these patients may instead have an extra-articular infection, such as pericapsular pyomyositis.

METHODS

An IRB-approved prospective study of children with suspected septic hip arthritis at a tertiary care children's hospital over a 2-year time period was conducted. Children were evaluated with a previously published clinical algorithm with the addition of magnetic resonance imaging (MRI).

RESULTS

Of the 53 patients presenting with an acutely irritable hip, 32% were found to have pericapsular pyomyositis, whereas 15% were diagnosed with septic arthritis. Although C-reactive protein (CRP, ≥33.1 mg/L) performed well at predicting infection, there were no significant differences in CRP, erythrocyte sedimentation rate, white blood cell count, temperature, or weight-bearing status in children with septic arthritis compared with pericapsular pyomyositis. In addition to MRI, there was a difference in the size of hip effusion on ultrasound, which was significantly smaller in cases of pericapsular pyomyositis. CRP (≥74.3 mg/L) was found to be predictive of need for surgical intervention in children with pericapsular pyomyositis.

CONCLUSIONS

Correct anatomic diagnosis of the site of infection is essential for the efficient care of the child. Herein, we found that pericapsular pyomyositis is twice as common as septic arthritis in children presenting with an acutely irritable hip. Clinical algorithms are incapable of differentiating these pathologies suggesting that both be considered under the current diagnosis previously referred to as "presumed septic arthritis." Incorrect diagnosis of a septic arthritis in the presence of a pericapsular pyomyositis could potentially lead to unnecessary debridement of the joint in the presence of extra-articular infection, thus contaminating the joint. Conversely, debriding the joint instead of the epicenter of the infection can prolong the infectious process. For these reasons, we conclude that MRI has the potential to improve the clinical care of children by providing a more precise diagnosis.

LEVEL OF EVIDENCE

Level II-"Diagnostic" [Development of diagnostic criteria on the basis of consecutive patients (with universally applied reference "gold" standard)].

Medial approach for drainage of the obturator musculature in children

BACKGROUND

In a recent study designed to determine the anatomic location of infection in children presenting with acute hip pain, fever, and elevated inflammatory markers, we demonstrated the incidence of infection of the musculature surrounding the hip to be greater than twice that of septic arthritis. Importantly, the obturator musculature was infected in >60% of cases. Situated deep in the pelvis, surrounding the obturator foramen, debridement of these muscles and placement of a drain traditionally requires an extensive ilioinguinal or Pfannenstiel approach, placing significant risk to the surrounding neurovascular structures. We hypothesized that the obturator internus and externus could be successfully debrided using a limited medial approach.

METHODS

An IRB-approved prospective study of children (0 to 18 y) evaluated in the pediatric emergency department by an orthopaedic surgeon to rule out septic hip arthritis at a tertiary care children's hospital (July 1, 2010 to June 30, 2012) was conducted. Infected obturator musculature was identified and confirmed using magnetic resonance imaging. Cadaveric dissection was performed comparing the ilioinguinal, Pfannenstiel, and proposed minimally invasive medial approach. The proposed approach was utilized to debride and place drains in 7 consecutive patients.

RESULTS

Anatomic information gained from magnetic resonance images of patients with abscess within the obturator musculature, and from the results of cadaveric studies, allowed for planning of a novel surgical approach. We found that through the surgical approach used to perform an osteotomy of the ischium (Tonnis) the obturator externus could be debrided through the adductor brevis and the obturator internus could be debrided through the obturator foramen. Using our medial approach, resolution of symptoms in all children who underwent surgical drainage resulted without complication.

CONCLUSIONS

Our medial approach can safely access the obturator musculature for abscess decompression and drain placement with successful results. Advantages to this approach include: lower risk to neurovascular structures within the pelvis, less soft tissue trauma, and similarity to current techniques used for adductor lengthening, medial reduction of the dislocated hip, and osteotomy of the ischium.

LEVEL OF EVIDENCE

Level II.

The limping child

Limping is a symptom of varied diagnoses in children and adolescents and can present a difficult diagnostic challenge for primary care clinicians. A careful and systematic evaluation can shorten the long list of potential diagnoses to direct appropriate diagnostic tests to determine the cause of the problem. Trauma and infections are the most common causes of limping. Inflammatory conditions, developmental diagnoses,and overuse injuries are other causes. Although rare, malignancies such as osteosarcoma and blood cell cancers must also be considered as potential causes of limping in children and adolescents.• Limping presents a diagnostic challenge due to the number of possible causes.• On the basis of consensus, diagnostic laboratory tests that include complete blood count, erythrocyte sedimentation rate,C-reactive protein, and blood cultures should be ordered if suspicion is high for infectious etiology.• On the basis of consensus, orthopedic emergencies are vascular compromise, compartment syndrome, and open fractures.• On the basis of moderate evidence and consensus, compartment syndrome in children presents with the three "As" analgesia,anxiety, and agitation. (4)• On the basis of strong evidence and consensus, septic arthritis asa diagnosis increases with the number of Kocher criteria present(temperature >38.5°C, white blood cell count >12,000/mL[12109/L], erythrocyte sedimentation rate >40 mm/h, and inability to bear weight). (8)• On the basis of moderate evidence and consensus, laboratory studies are not always definitive for diagnosis of juvenile idiopathic arthritis. (13)• On the basis of consensus, it is always important to examine the joint above and the joint below the area of the chief compliant,specifically when looking at slipped capital femoral epiphysis and Legg-Calvé-Perthes disease.

Emergency department evaluation and treatment of pediatric orthopedic injuries

Orthopedic injuries in children are unique when compared to those of adults because of the physiologic differences, especially the growth plates, stronger periosteum, and dynamic state of growth. The approach to the orthopedically injured child requires a gentle yet thorough focus with consideration of the growth plates as a primary area of weakness and growth when the child sustains an injury. Understanding the developmental stages of bones is paramount to being able to manage any injuries. Finally, what appears to be a benign injury may portend more serious issues, because nonaccidental trauma must always be considered in the evaluation of the injured child.

Preoperative antibiotics for septic arthritis in children: delay in diagnosis

PURPOSE

To review the records of 50 children who underwent open joint washout for septic arthritis with (n=25) or without (n=25) preoperative antibiotics.

METHODS

Records of 50 children who underwent open joint washout for presumed septic arthritis with (n=25) or without (n=25) preoperative antibiotics were reviewed. 17 boys and 8 girls aged 3 weeks to 16 years (median, 1.5 years) who were prescribed preoperative antibiotics before joint washout were compared with 12 boys and 13 girls aged one month to 14 years (median, 2 years) who were not. Following arthrotomy and washout, all patients were commenced on high-dose intravenous antibiotics. Patients were followed up for 6 to 18 months until asymptomatic.

RESULTS

Patients who were referred from places other than our emergency department were twice as likely to have been prescribed preoperative antibiotics (p=0.0032). Patients prescribed preoperative antibiotics had a longer median (range) time from symptom onset to joint washout (8 [2-23] vs. 4 [1-29] days, p=0.05) and a higher mean erythrocyte sedimentation rate (93.1 vs. 54.3 mm/h, p=0.023) at presentation. Nonetheless, the 2 groups were comparable for weight bearing status, fever, and positive culture, as well as the mean (range) duration of antibiotic treatment (4.9 [4-7] vs. 4.7 [1-8] weeks, p=0.586).

CONCLUSION

Preoperative antibiotics should be avoided in the management of septic arthritis in children. Their prescription delays diagnosis and definitive surgery, and leads to additional washouts and complications. A high index of suspicion and expedite referral to a specialist paediatric orthopaedic unit is needed if septic arthritis is suspected.

Management of pediatric patients with synovial fluid white blood-cell counts of 25,000 to 75,000 cells/mm³ after aspiration of the hip

BACKGROUND

In this study, we sought to elucidate the presentation, clinical course, treatments pursued, final diagnosis, and risk factors for septic arthritis in a series of children with hip pain and intermediate synovial fluid values (white blood-cell [WBC] counts of 25,000 to 75,000 cells/mm(3) [25 to 75 × 10(9) cells/L]).

METHODS

We reviewed the records of pediatric patients who underwent hip aspiration between 2005 and 2012 at a tertiary-care pediatric hospital. Demographic data, laboratory values, final diagnosis, and treatment details were recorded for the subpopulation of patients with an aspirate WBC count of 25,000 to 75,000 cells/mm(3) (25 to 75 × 10(9) cells/L). Univariate and multivariable logistic regression analysis was used to assess risk factors for septic arthritis of the hip across final diagnostic groups and subgroups with WBC values of <50,000 and ≥50,000 cells/mm(3) (<50 and ≥50 × 10(9) cells/L).

RESULTS

Forty-six children (twenty-seven males and nineteen females) with a mean age of 7.6 years met the inclusion criteria. The final diagnoses were septic arthritis of the hip (n = 15; 33%), Lyme arthritis (n = 13; 28%), transient synovitis (n = 8; 17%), and other findings (n = 10; 22%). Subjects with a synovial fluid WBC count of ≥50,000 cells/mm(3) (≥50 × 10(9) cells/L) were more likely to be diagnosed with septic arthritis of the hip (odds ratio, 4.4; 95% confidence interval, 1.1 to 16.9; p = 0.03). While septic arthritis of the hip was the most common diagnosis (48%) in patients with WBC values of ≥50,000 cells/mm(3) (≥50 × 10(9) cells/L), it also represented 17% of cases with WBC values of <50,000 cells/mm(3) (<50 × 10(9) cells/L).

CONCLUSIONS

Septic arthritis of the hip is the most common ultimate diagnosis in children with synovial fluid WBC values of 25,000 to 75,000 cells/mm(3) (25 to 75 × 10(9) cells/L) following hip aspiration, and it should be high on the differential diagnosis, even in cases with synovial fluid WBC values of <50,000 cells/mm(3) (<50 × 10(9) cells/L).

Evaluating the child with acute hip pain ("irritable hip") in a Lyme endemic region

OBJECTIVES

To estimate the prevalence of Lyme infection among children presenting with acute, nontraumatic hip pain in a Lyme endemic region and to investigate predictors of Lyme disease among children with suspected transient synovitis.

STUDY DESIGN

Retrospective cross-sectional study of children with unilateral hip pain who were brought to an academic pediatric emergency department. Cases were identified by specific discharge diagnoses or radiologic imaging. Lyme infection was determined by serologic criteria, and a minimum prevalence was estimated for the entire study population; maximum estimate was determined for those who had Lyme testing. Multivariate regression was used to identify discriminating clinical findings for Lyme disease among those with nonseptic arthritis.

RESULTS

Three hundred eighty-five children with a median age of 5.4 years were studied; 15% of children had fever ≥38.0°C and 40% had pain for less than 24 hours at evaluation. Lyme infection was identified in 5.2% (95% CI 3.2%-7.9%). A maximum estimate of Lyme disease was calculated to be 8.0% (95% CI 4.9%-12.0%). Regression analysis did not identify any practical clinical predictors of Lyme infection.

CONCLUSIONS

Lyme infection occurred in approximately 5% of children with acute, nontraumatic hip pain who were evaluated in a pediatric emergency department in a Lyme endemic region. Based on this estimate, we do not recommend routine Lyme testing when transient synovitis is suspected; however, Lyme testing should be considered in children having laboratory studies obtained for alternative diagnoses such as septic/pyogenic arthritis and for those with an atypical clinical course for transient synovitis.

Kingella kingae: carriage, transmission, and disease

Kingella kingae is a common etiology of pediatric bacteremia and the leading agent of osteomyelitis and septic arthritis in children aged 6 to 36 months. This Gram-negative bacterium is carried asymptomatically in the oropharynx and disseminates by close interpersonal contact. The colonized epithelium is the source of bloodstream invasion and dissemination to distant sites, and certain clones show significant association with bacteremia, osteoarthritis, or endocarditis. Kingella kingae produces an RTX (repeat-in-toxin) toxin with broad-spectrum cytotoxicity that probably facilitates mucosal colonization and persistence of the organism in the bloodstream and deep body tissues. With the exception of patients with endocardial involvement, children with K. kingae diseases often show only mild symptoms and signs, necessitating clinical acumen. The isolation of K. kingae on routine solid media is suboptimal, and detection of the bacterium is significantly improved by inoculating exudates into blood culture bottles and the use of PCR-based assays. The organism is generally susceptible to antibiotics that are administered to young patients with joint and bone infections. β-Lactamase production is clonal, and the local prevalence of β-lactamase-producing strains is variable. If adequately and promptly treated, invasive K. kingae infections with no endocardial involvement usually run a benign clinical course.

The role of ultrasound in the emergency department evaluation of the acutely painful pediatric hip

Children presenting with hip pain or a limp are a diagnostic challenge for the clinician. The differential diagnosis is extensive, and the workup can be broad. This review focuses on differentiating between transient synovitis and septic arthritis of the hip. The role of bedside ultrasound in the clinical evaluation of these patients is addressed, including the technique and appropriate indications for bedside ultrasound of the hip in the emergency department.

Transient synovitis, septic hip, and Legg-Calvé-Perthes disease: an approach to the correct diagnosis

Transient synovitis, septic hip, and Legg-Calvé-Perthes disease are common conditions in children. Distinguishing between these disorders can be a diagnostic challenge. Similar presentations, in an age group difficult to examine, coupled with literature that is confusing creates difficulty. It is important to make the correct diagnosis of septic hip in a timely fashion to avoid serious and potentially crippling consequences. As there is no single test for discriminating between these conditions, knowledge of the nuances of clinical presentation, physical examination, laboratory investigations, and imaging is essential. Judicious use of clinical algorithms can complement clinical acumen.

Differentiating Kingella kingae septic arthritis of the hip from transient synovitis in young children

OBJECTIVE

To conduct a retrospective multicenter study to assess the ability of a predictive algorithm to differentiate between children with Kingella kingae infection of the hip and those with transient synovitis.

STUDY DESIGN

Medical charts of 25 Israeli and 9 Spanish children aged 6-27 months with culture-proven K kingae arthritis of the hip were reviewed, and information on the 4 variables included in the commonly used Kocher prediction algorithm (body temperature, refusal to bear weight, leukocytosis, and erythrocyte sedimentation rate) was gathered.

RESULTS

Patients with K kingae arthritis usually presented with mildly abnormal clinical picture and normal serum levels of or near-normal acute-phase reactants. Data on all 4 variables were available for 28 (82%) children, of whom 1 child had none, 6 children had 1, 13 children had 2, 5 had 3, and only 3 children had 4 predictors, implying ≤ 40% probability of infectious arthritis in 20 (71%) children.

CONCLUSIONS

Because of the overlapping features of K kingae arthritis of the hip and transient synovitis in children younger than 3 years of age, Kocher predictive algorithm is not sensitive enough for differentiating between these 2 conditions. To exclude K kingae arthritis, blood cultures and nucleic acid amplification assay should be performed in young children presenting with irritation of the hip, even in the absence of fever, leukocytosis, or a high Kocher score.

Lyme arthritis of the pediatric ankle

Lyme arthritis results from acute inflammation caused by the spirochete Borrelia burgdorferi. The number of cases per year has been rising since 2006, with a majority of patients being affected in the northeastern United States. Development of Lyme arthritis is of particular importance to the orthopedic surgeon because Lyme arthritis often presents as an acute episode of joint swelling and tenderness and may be confused with bacterial septic arthritis. Considering the vast difference in treatment management between these 2 pathologies, differentiating between them is of critical importance. Septic arthritis often needs to be addressed surgically, whereas Lyme arthritis can be treated with oral antibiotics alone. Laboratory testing for Lyme disease often results in a delay in diagnosis because many laboratories batch-test Lyme specimens only a few times per week because of increased expense. The authors present a case of Lyme arthritis in the pediatric ankle in an endemic region. No clear algorithm exists to delineate between septic arthritis and Lyme arthritis of the joint. Improved clinical guidelines for the identification and diagnosis of Lyme arthritis of the ankle are important so that appropriate antibiotics can be used and surgery can be avoided.

[Arthroscopic therapy of septic hip infections in childhood]

OBJECTIVE

The treatment goal is to rapidly make a diagnosis and establish an effective arthroscopic therapy in order to allow the hip joint to develop normally throughout childhood with respect to anatomical and functional development.

INDICATIONS

Coxarthritis suspected of being septic arthritis

CONTRAINDICATIONS

No experience with arthroscopy, osteomyelitis of the dorsal femoral neck requiring an intervention. Relative contraindication: absence of cannulated systems.

SURGICAL TECHNIQUE

Arthroscopic lavage of the hip joint, including revision of the femoral neck and debridement of osteomyelitis of the femoral neck with placement of an antibiotic carrier if necessary. The arthroscopy is performed using the two portal technique, placing the patient supine on a normal operation table (traction table not required).

POSTOPERATIVE MANAGEMENT

Drain for 2-3 days with mobilization after removal of the drainage. A second look arthroscopy is not normally planned but may become necessary in cases without improvement of the clinical or laboratory test parameters and after follow-up magnetic resonance imaging (MRI).

RESULTS

The two portal hip joint arthroscopy using an irrigation volume of 6-9 l is an efficient minimally invasive method to safely treat septic arthritis of the hip joint with or without concomitant femoral neck osteomyelitis. It is associated with low morbidity and offers all advantages of an arthroscopic procedure. Out of 23 children 19 could be sufficiently treated by a single arthroscopic lavage of the hip joint. In three patients an additional osseous component required a second intervention. Out of 23 children 22 achieved an excellent Harris hip score, with one girl only achieving a moderate outcome. The 22 children had an unrestricted hip function at follow-up and could return fully to previous activity levels.

Lyme arthritis of the pediatric lower extremity in the setting of polyarticular disease

BACKGROUND

Lyme arthritis can be readily treated with use of oral antibiotics without any need for surgery. In Lyme-endemic areas, differentiating between Lyme arthritis and septic arthritis can be difficult. Laboratory testing for Lyme disease often results in a delay in diagnosis because many labs batch-test Lyme specimens only two times per week due to lack of equipment or increased expense. Delayed diagnosis can lead to unneeded surgery in cases in which the surgeon indicates the patient for a joint irrigation and debridement (I & D) for possible septic arthritis while waiting for Lyme serology results. The purpose of this study was to develop an algorithm for the treatment of patients with possible Lyme arthritis, with particular attention to poly-articular involvement.

METHODS

Thirty-nine patients with poly-articular Lyme arthritis, including ankle involvement, were reviewed retrospectively. Patients were included if the ankle was involved, if they were less than 18 years of age, and had available laboratory information and a serologic diagnosis of Lyme disease.

RESULTS

Only two patients had isolated ankle involvement; of those with poly-articular involvement, 34 patients had ankle/knee involvement. Nine patients presented with pain in the ankle with passive range of motion (PROM) (22 %); two (4.8 %) had refusal to bear weight, and 10 (24 %) had an antalgic gait. All patients had a positive Western blot. Ten patients had a peripheral white blood cell (WBC) count >12,500/mm(3) , and 16 patients had an erythrocyte sedimentation rate (ESR) >40 mm/h.

CONCLUSION

Without immediate availability of Lyme serology, the decision to perform surgical drainage of a swollen joint in the setting of possible Lyme arthritis versus septic bacterial arthritis remains a clinical dilemma. Our data suggests that patients presenting with one or fewer Kocher criteria symptoms, poly-articular disease, and minimal pain with PROM have Lyme, rather than septic, arthritis. These patients can be treated with joint aspiration for cultures, appropriate antibiotics for Lyme disease, and careful serial exams while waiting for results of Lyme serology rather than immediate surgical I & D.

Independent analysis of a clinical predictive algorithm to identify methicillin-resistant Staphylococcus aureus osteomyelitis in children

BACKGROUND

The number of serious, life-threatening musculoskeletal infections in children due to methicillin-resistant Staphylococcus aureus (MRSA) infections is increasing. The early identification of the bacteria causing osteomyelitis is critical to determine the appropriate antibiotic treatment. A recent study proposed a clinical algorithm to predict which infections were caused by MRSA by stratifying basic clinical values at the time of admission for children with osteomyelitis. The purpose of this study is to apply that predictive algorithm on an independent patient population to determine its wider applicability.

METHODS

This was a retrospective chart review at a tertiary care children's hospital. All children who were treated for a culture-positive osteomyelitis were identified over a 3-year period. The previously reported predictors, determined by multivariate regression analysis, of MRSA infection (temperature >38°C, hematocrit <34%, white blood cell count >12,000/µL, and C-reactive protein >13 mg/L) were determined for each patient. The number of positive predictors was then correlated with the percentage of cases that were MRSA positive.

RESULTS

A total of 58 patients with culture-positive osteomyelitis were identified from 2008 to 2010. Sixteen of the infections were caused by MRSA (overall 26%). The percentage of patients with MRSA osteomyelitis according to the number of risk factors were as follows: all 4 risk factors, 50% (1 out of 2 patients); 3 risk factors, 42% (5 out of 12 patients); 2 risk factors, 21% (4 out of 19 patients); 1 risk factor, 50% (6 out of 12 patients); and 0 risk factor, 0% (0 out of 13 patients).

CONCLUSIONS

The previously reported clinical predictive algorithm had a relatively poor diagnostic performance in this independent patient population. Specifically, the percentages of MRSA were the same for 1 risk factor compared with 4 (50%). Differences in bacteria strain, host responses, and a variety of other confounding variables could be responsible for these differences. Specific genetic markers may be the best early test to identify MRSA infections in the future.

LEVEL OF EVIDENCE

Level III-case-control series.

Another look: is there a flaw to current hip septic arthritis diagnostic algorithms?

BACKGROUND

Septic arthritis is an emergency. In 1999 Kocher et al. identified four clinical criteria to distinguish hip septic arthritis from transient synovitis in children (nonweightbearing, erythrocyte sedimentation rate ≥ 40 mm/L, white blood cell count > 12 × 10(9)/L, temperature > 38.5°C). Subsequent authors evaluating the same criteria produced conflicting results. This calls into question the use of such diagnostic algorithms. The reasons for the differences remain unclear.

QUESTIONS/PURPOSES

To what degree do studies, evaluating the predictive ability of diagnostic algorithms for septic arthritis, differ with regard to their results? Why do these differences exist? Is there a flaw in the statistical handling of the data?

METHODS

Using PubMed, original studies evaluating the clinical criteria for distinguishing hip septic arthritis and transient synovitis in children were identified. Clinical and statistical methods were examined.

RESULTS

Six studies evaluated the clinical criteria. Two found all four criteria able to distinguish septic arthritis from transient synovitis. There was significant variation between the studies in the risk engendered by the presence of each criteria. The differences were the result of the fact that in all cases, sample sizes were too small and in three cases, there were too few episodes of septic arthritis for a reliable predictive algorithm to be produced.

CONCLUSIONS

Differing results between studies appear as a result of sample size and insufficient cases of septic arthritis in some cohorts. Transferable and reliable results can be achieved if sufficiently large samples with an adequate number of cases of septic arthritis are recruited.

Kingella kingae septic arthritis in children: recognising an elusive pathogen

PURPOSE

Kingella kingae is an increasingly identified cause of musculoskeletal infections in young children. We report our experience with a recently developed polymerase chain reaction (PCR) method and review the clinical course of children diagnosed with K. kingae septic arthritis in a tertiary referral paediatric hospital.

METHODS

All positive cases of K. kingae identified by PCR analysis of synovial fluid from August 2010 until July 2013 were included. A chart review was undertaken to determine history, presentation and management.

RESULTS

27 Children (14 male, 13 female) had PCR positive synovial fluid samples for K. kingae with median age of 19 months (range 4 months to 5 years 3 months). The sites of infection were knee (17 cases), hip (2 cases), ankle (5 cases), shoulder (2 cases) and elbow. The median temperature on presentation was 37.1 °C, median peripheral white blood cell count 12.4 (9.9-13.8) × 10(9)/L, erythrocyte sedimentation rate 55 (48-60) mm/h and C-reactive protein 24 (8-47) mg/L. The median synovial fluid white cell count was 21.8 (16.7-45.0) × 10(9)/L. Routine cultures identified K. kingae in only two synovial fluid samples. Two samples were additionally positive for Staphylococcus aureus.

CONCLUSIONS

Kingella kingae is a significant cause of septic arthritis in young children. The authors recommend maintaining a high index of suspicion in young children presenting with joint inflammation, especially if indices of infection are mild. It appears likely that children historically treated with antibiotics for "culture negative" septic arthritis were infected with K. kingae. PCR techniques for detection of K. kingae should be encouraged.

The epidemiology of transient synovitis in Liverpool, UK

BACKGROUND

The epidemiology of transient synovitis is poorly understood, and the aetiology is unknown, although a suggestion of a viral association predominates.

PURPOSE

This population-based study investigated the epidemiology in order to formulate aetiological theories of pathogenesis.

PATIENT AND METHODS

Cases in Merseyside were identified between 2004 and 2009. Incidence rates were determined and analysed by age, sex, season and region of residence. Socioeconomic deprivation scores were generated using the Index of Multiple Deprivation, allocated by postcode. Poisson confidence intervals were calculated and Poisson regression was used to check for trends.

RESULTS

Two hundred and fifty-nine cases were identified over 5.5 years. The annual incidence was 25.1 (95 % CI 22.1-28.5) per 100,000 0-14 year-olds. Male to female ratio was 3.2:1 (p < 0.001). Mean age at presentation was 5.4 years (95 % CI 5.0-5.8), which demonstrated a near-normal distribution. No relationship was identified between seasonality and incidence (p = 0.64). A correlation was identified with socioeconomic deprivation in Merseyside: incidence rate ratio 1.16 (95 % CI 1.06-1.26, p < 0.001), although further analysis within the subregion of Liverpool did not confirm this finding (p = 0.35).

CONCLUSIONS

The normal distribution for age at disease presentation suggests a specific disease entity. The absence of seasonality casts some doubt on the popular theory of a viral aetiology. The absence of a consistent socioeconomic gradient in both Merseyside and Liverpool challenges a previous suggestion of an association with Perthes' disease. This paper provides ecological evidence that may challenge existing aetiological theories, though transient synovitis remains an enigma.

Transient synovitis of the hip: a comprehensive review

Transient synovitis is a benign, self-limiting condition that is diagnosed after the exclusion of more serious causes of acute hip pain in children. Although its etiology remains unclear, it is largely believed to be viral in nature. Transient synovitis typically presents as an acute onset of thigh pain with a limp or an unwillingness to bear weight. It can be distinguished from similar conditions by the absence of fever, as well as unremarkable bloodwork (WBC, CRP, ESR), radiographs, and hip aspiration. Conservative treatment and observation are the mainstay of management. Resolution of symptoms generally occurs by 1 week and may be accelerated by NSAIDs. Although numerous papers have emerged over the years with an effort to advance our understanding, many questions remain about its pathomechanics, etiology, and how to exclude other more serious conditions that present similarly.

Synovial fluid findings in children with knee monoarthritis in lyme disease endemic areas

BACKGROUND

Although Lyme and septic arthritis of the knee may have similar clinical presentations, septic arthritis requires prompt identification and treatment to avoid joint destruction. We sought to determine whether synovial fluid cell counts alone can discriminate between Lyme, septic, and other inflammatory arthritis.

METHODS

We conducted a retrospective cohort study of children aged 1 to 18 years with knee monoarthritis who presented to 1 of 2 pediatric emergency departments located in Lyme endemic areas. We included children who had both a synovial fluid culture and an evaluation for Lyme disease. Septic arthritis was defined as a positive synovial fluid culture or synovial fluid pleocytosis (white blood cell [WBC] ≥40,000 cells/μL) with a positive blood culture. Lyme arthritis was defined as positive Lyme serology without a positive bacterial culture. All other children were considered to have other inflammatory arthritis. We compared the synovial fluid counts by arthritis type.

RESULTS

We identified 384 children with knee monoarthritis, of whom 19 (5%) had septic arthritis, 257 (67%) had Lyme arthritis and 108 (28%) had other inflammatory arthritis. Children with other inflammatory arthritis had lower synovial WBC and absolute neutrophil count, as well as percent neutrophils, than those with either Lyme or septic arthritis. There were no significant differences in the synovial fluid WBC, absolute neutrophil count, and percent neutrophils for children with Lyme and septic arthritis.

CONCLUSIONS

In Lyme endemic areas, synovial fluid results alone do not differentiate septic from Lyme arthritis. Therefore, other clinical or laboratory indicators are needed to direct the care of patients with knee monoarthritis.

The diagnostic accuracy of inflammatory blood markers for purulent flexor tenosynovitis

PURPOSE

For patients with purulent flexor tenosynovitis, our purpose was to (1) calculate the diagnostic accuracy of white blood count (WBC), erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) for those who underwent surgical drainage, (2) to correlate these markers for those treated with antibiotics alone, and (3) to evaluate the accuracy of diagnosis for surgical patients.

METHODS

A total of 82 consecutive patients (71 surgical and 11 nonsurgical) with flexor tenosynovitis were identified from orthopedic databases at 2 academic centers. We evaluated inflammatory markers (WBC, ESR, and CRP), radiographs, descriptions of surgical findings, and intraoperative cultures for all patients. For nonsurgical patients, we evaluated inflammatory markers for possible correlation with the presumed diagnosis of purulent flexor tenosynovitis. For surgical patients, sensitivity, specificity, positive predictive value, and negative predictive value were calculated individually for inflammatory markers.

RESULTS

For nonsurgical patients, WBC, ESR, and CRP were elevated in 3 of 11 patients (27%), 6 of 8 patients (75%), and 6 of 7 patients (86%), respectively. For surgical patients, the intraoperative findings or cultures were consistent with infection in 69 of 71 cases (97%), whereas calcific tendinitis was diagnosed in 2 cases. Cultures were positive in 56 patients (79%). All 3 markers had a specificity and positive predictive value of 100%. For WBC, ESR, and CRP, respectively, the sensitivity was 39%, 41%, and 76% and the negative predictive value was 4%, 3%, and 13%.

CONCLUSIONS

Commonly used inflammatory blood markers (WBC, ESR, and CRP) may be helpful in diagnosing purulent flexor tenosynovitis. If the levels of any of these markers are elevated in patients suspected of having the diagnosis, the likelihood of infection is extremely high. However, with low negative predictive values, these markers cannot reliably rule out infection.

TYPE OF STUDY/LEVEL OF EVIDENCE

Diagnostic III.

Septic arthritis of the neonatal hip: acute management and late reconstruction

Septic arthritis of the hip in neonates is rare but can have devastating consequences. Presenting signs and symptoms may differ from those encountered in older children, which may result in diagnostic challenge or delay. Many risk factors predispose neonates to septic arthritis, including the presence of transphyseal vessels and invasive procedures. Bacterial infection of the joint occurs via hematogenous invasion, extension from an adjacent site, or direct inoculation. A strong correlation exists between younger age at presentation and severity of residual hip deformity. Diagnosis is based on clinical examination, laboratory markers, and ultrasound evaluation. Early management includes parenteral antibiotics and surgical drainage. Late-stage management options include femoral and pelvic osteotomies, trochanteric arthroplasty, arthrodesis, pelvic support procedures, and nonsurgical measures. Early diagnosis and management continues to be the most important prognostic factor for a favorable outcome in the neonate with septic arthritis.

Use of real-time polymerase chain reaction for the diagnosis of infection and differentiation between gram-positive and gram-negative septic arthritis in children

BACKGROUND

Diagnosis and identification of the etiological agent of septic arthritis (SA) in children is an important issue, as early treatment based on accurate diagnosis of joint infections can prevent potentially disabling complications. The purpose of this study was to evaluate the efficacy of real-time polymerase chain reaction (PCR) for the diagnosis of SA in children.

PATIENTS AND METHODS

Twenty children with suspected SA who had joint pain and underwent surgical treatment were enrolled in this study. Their preoperative clinical and laboratory findings were investigated. Tissues obtained during operation were subjected to microbiological culture and real-time PCR, including methicillin-resistant Staphylococcus (MRS)-specific PCR and broad range universal PCR. Infection was confirmed if the result of microbiological culture was positive. Furthermore, abnormal clinical and laboratory findings and improvement in the symptoms and posttreatment data were also defined as the final diagnosis of infection.

RESULTS

Out of the 20 patients, 19 were diagnosed with the infection. The remaining patient was postoperatively diagnosed with juvenile idiopathic arthritis. Abnormal preoperative body temperatures, white blood cell counts, C-reactive protein levels, and erythrocyte sedimentation rates were observed in 6, 9, 15, and 12 cases, respectively. The results of microbiological culture, MRS-PCR, and universal PCR were positive in 9, 2, and 15 cases, respectively. Analysis of the melting peak in universal PCR revealed that of the 15 cases, 10 had gram-positive and 5 had gram-negative infections. The sensitivity and specificity for the diagnosis of SA were, respectively, 0.47 and 1.00 in microbiological culture and 0.79 and 1.00 in real-time PCR.

CONCLUSIONS

Successful diagnosis of infection and differentiation between gram-positive and gram-negative bacteria were achieved using MRS-PCR and universal PCR. Hence, real-time PCR is useful and has greater sensitivity than microbial culture for diagnosing SA in children.

LEVEL OF EVIDENCE

Level II diagnostic study investigating a diagnostic test.

Ultrasound-guided musculoskeletal procedures in children

Ultrasound is an excellent tool to evaluate many pediatric musculoskeletal conditions. It may be used for both diagnosis and for guidance for therapeutic procedures. With US, the radiologist can readily evaluate the contralateral side for comparison. No sedation is typically required and ionizing radiation is avoided. Real-time information is obtained with US and the portability of US allows for the performance of bedside interventions in children who cannot be transported or are clinically unstable. Limitations of US compared with MRI and CT include limited field of view, inability to evaluate the bone marrow and user dependence of image and exam quality. In this article, we discuss common US-guided musculoskeletal procedures in children, including hip aspiration, joint injection, soft-tissue biopsy and foreign body removal.

Distinguishing Lyme from septic knee monoarthritis in Lyme disease-endemic areas

OBJECTIVE

Because Lyme and septic arthritis may present similarly, we sought to identify children with knee monoarthritis at low risk for septic arthritis who may not require arthrocentesis.

METHODS

We performed a retrospective study of children with knee monoarthritis presenting to 1 of 2 pediatric centers, both located in Lyme disease-endemic areas. Septic arthritis was defined by a positive result on synovial fluid culture or synovial fluid pleocytosis with a positive blood culture result. Lyme arthritis was defined as a positive Lyme serologic result or physician-documented erythema migrans rash. All other children were considered to have other inflammatory arthritis. A clinical prediction model was derived by using recursive partitioning to identify children at low risk for septic arthritis, and the model was then externally validated.

RESULTS

We identified 673 patients with knee monoarthritis; 19 (3%) had septic arthritis, 341 (51%) had Lyme arthritis, and 313 (46%) had other inflammatory arthritis. The following predictors of knee septic arthritis were identified: peripheral blood absolute neutrophil count ≥10 × 10(3) cells per mm(3) and an erythrocyte sedimentation rate ≥40 mm/hour. In the validation population, no child with a absolute neutrophil count <10 × 10(3) cells per mm(3) and an erythrocyte sedimentation rate <40 mm/hour had septic arthritis (sensitivity: 6 of 6 [100%], 95% confidence interval [CI]: 54-100; specificity: 87 of 160 [54%], 95% CI: 46-62). Overall, none of the 19 children with septic arthritis were classified as low risk (10%, 95% CI: 0-17).

CONCLUSIONS

Laboratory criteria can be used to identify children with knee monoarthritis at low risk for septic arthritis who may not require diagnostic arthrocentesis.

The value of hip aspiration in pediatric transient synovitis

INTRODUCTION

Hip transient synovitis (TS) is a common pediatric orthopaedic problem. Although a self-limiting illness, it often makes the patient temporarily disabled and poses a diagnostic difficulty because of its similarity to septic arthritis in clinical manifestations. The aim of this study was to evaluate the use of a single ultrasound-guided hip aspiration as a treatment modality for TS.

METHODS

Between the years 1984 and 1989, 112 children with TS were treated through bed rest and using nonsteroidal anti-inflammatory drugs (group 1). Between the years 1990 and 1999, 119 children diagnosed with TS were treated using hip aspiration, bed rest, and nonsteroidal anti-inflammatory drugs (group 2). Recovery parameters were compared between these patient groups.

RESULTS

Twenty-four hours after admission, limping was noted in 92% and 10% of the patients in groups 1 and 2, respectively, (P < 0.001). Refusal to bear weight was observed in 14% and 1% in groups 1 and 2, respectively, (P < 0.001), and hip joint pain was reported in 81% and 6% in groups 1 and 2, respectively, (P < 0.001). Larger joint effusions were found to be the reason behind the inability to bear weight.

CONCLUSIONS

Pain due to TS may be because of capsule stretching owing to the accumulation of joint effusion. Ultrasound-guided hip aspiration relieves pain and limitation in movement and provides rapid differential diagnosis from septic arthritis of the hip joint.

Community-associated, methicillin-susceptible, and methicillin-resistant Staphylococcus aureus bone and joint infections in children: experience from India

Previously, the treatment of Staphylococcus aureus infections was less complex, as most of those isolated were susceptible to β-lactam antibiotics. In recent years, there has been a marked increase in the incidence of invasive community-acquired (CA) methicillin-resistant S. aureus (MRSA) among children worldwide. However, data on the clinical characteristics and outcomes related to pediatric bone and joint infections caused by CA-S. aureus are very limited in India. In this tertiary hospital-based study, 74 patients with invasive S. aureus less than 18 years of age were identified between January 2004 and December 2008. All patients fulfilled the case definition of CA-S. aureus with evidence of infection before admission; they presented to our hospital without previous antibiotic use and were culture positive for S. aureus within 48 h of admission. All data including demographics, clinical features, treatment protocol, laboratory findings, and antimicrobial susceptibilities were recorded and compared using the SPSS 11.5 statistical software. Of the 74 patients with culture-positive S. aureus bone and joint infection, 41 had MRSA (55%). Forty-nine patients (66.2%) had osteomyelitis, of whom 29 (59.18%) had MRSA and 25 (33.7%) had septic arthritis, of whom 12 (48%) had MRSA. The MRSA group had a significantly higher erythrocyte sedimentation rate, C-reactive protein value, neutrophil count, and white blood cell count (P<0.05). The MRSA group also had longer duration of febrile days, hospital stay, and antibiotic course compared with the methicillin-susceptible S. aureus (MSSA) group (P<0.05). A clinical predictive algorithm was developed using seven significant independent multivariate predictors, with the probability of MRSA being 94% if all seven predictors were positive and 9% if five predictors were positive. Resistance to many classes of antibiotics was noted among S. aureus isolates including trimethoprim-sulfamethoxazole (MRSA 80%, MSSA 24%), erythromycin (MRSA 83%, MSSA 67%), clindamycin (MRSA 54%, MSSA 34%), and ciprofloxacin (MRSA 61%, MSSA 48%). No vancomycin resistance was observed. The morbidity associated with MRSA bone and joint infection in children is significantly higher than that caused by MSSA. Early diagnosis at the primary healthcare level and treatment with appropriate antistaphylococcal therapy are crucial to achieve optimal clinical outcomes. High levels of antimicrobial resistance of both MSSA and MRSA isolates to several classes of antibiotics are a major concern warranting the need for antimicrobial stewardship and ongoing surveillance.

The spectrum of group A streptococcal joint pathology in the acute care setting

OBJECTIVES

Group A streptococcus (GAS) is a frequent cause of pediatric musculoskeletal infections including septic arthritis, acute rheumatic fever (ARF), and a more benign arthritis called post-streptococcal reactive arthritis. Children with painful joints are frequently evaluated in the acute care setting, and because the presentation of each of these entities is similar, the diagnosis can be difficult to make. Five cases of children with GAS arthridities are presented to demonstrate the spectrum of GAS-associated joint pathologies encountered in the acute care setting and also to discuss how GAS laboratory tests may assist in the evaluation and management of children presenting with a painful joint.

METHODS

Five cases of GAS-associated joint pathology are presented. Evaluation of these patients was conducted using a diagnostic algorithm derived from a literature review of post-streptococcal reactive arthritis and ARF, as well as the current clinical practice guideline for the diagnosis and treatment of septic arthritis.

RESULTS

The 5 cases presented include 1 case of transient synovitis, 2 cases of inflammatory synovitis, 1 case of septic arthritis, and 1 case of ARF.

CONCLUSIONS

Determining the cause of joint pain in the acute care setting is challenging. The addition of the GAS laboratory tests to a diagnostic algorithm based on clinical examination and monitoring systemic inflammation can help to identify patients with ARF and septic arthritis in the acute care setting. In addition, GAS-specific laboratory tests may help to identify cases of nonseptic, non-ARF GAS joint pathology.

Of bugs and joints: the relationship between infection and joints

The association between microbes and joints has existed since antiquity, and remains complex. Diagnosis is often times difficult to determine despite highly suspicious clinical characteristics for the presence of an underlying infection. Over the several past decades, considerable advances have occurred in diagnostic methodologies and therapy. However, the morbidity and mortality of septic arthritis remains high. Great advances have occurred in the diagnosis, pathogenesis, and therapeutic management of reactive arthritis, and there is evidence that when the responsible microorganism is Chlamydia trachomathis, complete remission and cure is possible. Emergent infections, especially viral, has been recognized, i.e. HIV, hepatitis C, and most recently Chikengunya virus, and in the case of HIV associated articular manifestations, the introduction of HAART has resulted in a decrease in the incidence and development of newer complications such as the immune reconstitution syndrome. The infectious etiology of rheumatoid arthritis is being strongly considered once again, and the exciting association with periodontal disease is at the forefront of intense research. The gut microbiota is also being investigated and new and most interesting data is being gathered of the potential role of commensal gut organisms and the pathogenesis of rheumatoid arthritis.

The fate of acutely inflamed joints with a negative synovial fluid culture

PURPOSE

The purpose of this study was to evaluate the management and fate of acutely inflamed joints with a negative synovial fluid culture.

METHODS

Between January and December 2009, all the patients who presented to our institution with an acutely inflamed joint and were subjected to microbiological assessment of their synovial fluid, were included in the study. Patients with a positive synovial fluid culture, a prosthetic joint replacement in situ and where an aspirate was obtained for a rheumatological diagnosis were excluded. This cohort was then divided into two groups depending on whether a diagnosis could be established through the course of their treatment. Group I included patients in whom a diagnosis could be established and group II included patients in whom a diagnosis could not be established. A thorough review of the patients' medical records and the hospital database was performed. Following this, a database consisting of the patient demographics, clinical features, investigations, treatment and outcome was created.

RESULTS

A total of 144 patients met the inclusion criteria (group I: 95, group II: 49). The most commonly affected joint in both the groups was the knee. The average time to presentation was shorter in group II. Clinical findings at presentation were comparable in both groups. However, inflammatory markers were more likely to be raised in group II in comparison with group I. Eighty-two percent of group II required antibiotic treatment compared with 15% of group I. The mean duration of antibiotic treatment in group I was ten days and in group II was 26 days. Mean hospital stay differed significantly between the two groups, with group II being more than twice as long as compared with group I (p=0.001). The rate of mortality was also higher in group II (8.2%, p=0.03).

CONCLUSION

Our study shows that patients presenting with an acutely inflamed joint and a negative synovial fluid culture in whom a diagnosis cannot be established during their hospital stay have a longer hospital stay and an increased rate of mortality as compared with patients in whom a diagnosis can be established.

Usefulness of dynamic contrast-enhanced MRI in differentiating between septic arthritis and transient synovitis in the hip joint

OBJECTIVE

The purpose of this study was to show the usefulness of dynamic contrast-enhanced MRI (DCE-MRI) and to determine the optimal time window in MRI for differentiating between septic arthritis and transient synovitis in painful hip joints.

MATERIALS AND METHODS

Eighteen patients who underwent DCE-MRI were enrolled, and the final diagnoses were septic arthritis (n = 7) and transient synovitis (n = 11). The enhancement patterns of DCE-MRI were dichotomized according to the shape of the time-signal intensity curves. The time at the maximal difference in the signal intensity between two time-signal intensity curves of both femoral heads was recorded. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were calculated. Receiver operating characteristic curves were calculated.

RESULTS

Six of seven patients with septic arthritis in the hip joint had decreased enhancement during the early phase of DCE-MRI. The enhancement difference between the two patient groups was statistically significant (p = 0.0498). The time at the maximal difference in the signal intensity between two time-signal intensity curves of both femoral heads was approximately 3.5 minutes. The area under the receiver operating characteristic curve for predicting septic arthritis was 0.792.

CONCLUSION

DCE-MRI is useful in differentiating between septic hip arthritis and transient synovitis. If static contrast-enhanced coronal MRI is used, the optimal time for the acquisition of contrast-enhanced coronal MRI is approximately 3.5 minutes.