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

Late-Presenting Septic Arthritis of the Hip in Children: Variations in Presentation and a Review of 25 Hips After Surgical Debridement

INTRODUCTION

The septic arthritis of the hip (SAH) is one of the most common musculoskeletal infections occurring in pediatric populations requiring urgent intervention. This study discusses the myriad of clinical and radiological presentations of late-presenting SAH in children and the outcomes of surgical management.

METHODS

After ethical approval, we did retrospective reviews of children treated for late-presenting SAH (after five days of symptoms). We excluded late cases with established sequelae. We recorded age, duration of symptoms, clinical evaluation, and radiographs. We evaluated the final results clinically and radiologically.

RESULTS

Twenty-four patients with 25 hips were eligible for evaluation. At presentation, all had decreased or painful hip movements, but none had a fever. Radiographs revealed the following changes: hip dislocation (four), capital femoral slip (seven), proximal femur/neck osteomyelitis (six), pathological fractured neck femur (two), iliac osteomyelitis (two), and early arthritic changes (two). Hip arthrotomy was done in all cases. Frank pus was found in 21 (84%) cases. Cases with capital slip and fractured neck femur required fixation with two smooth K-wires. Methicillin-resistant Staphylococcus aureus (MRSA) was isolated in three patients and tuberculosis in two cases. Clinical outcomes showed 14 patients with poor outcomes, eight with fair, and two with good. Avascular necrosis (AVN) of the femoral head was noted in 14 hips and complete femoral head resorption in nine.

CONCLUSIONS

The late-presenting SAH in children has a myriad of presentations including dislocation and capital slip with unsatisfactory outcome. However, ongoing local infective processes may necessitate debridement. With limited salvage options available at the sequelae stage, awareness and training for early diagnosis and treatment may be the best way to improve the scenario. We recommend future multicenter randomized studies of predictive factors and indications of arthrotomy in late presenters.

Relevant factors in the diagnosis of concomitant osteomyelitis in pediatric hip septic arthritis. A series of 41 cases treated by hip arthroscopy

INTRODUCTION

Septic arthritis of the hip can appear isolated or concomitant with pelvic osteomyelitis. Delay in the diagnosis of a concomitant osteomyelitis increases the number of required surgeries and of possible complications.

PURPOSE

This study aims to establish relevant factors in the diagnosis of concomitant osteomyelitis in cases with septic arthritis of the hip among paediatric patients.

METHODS

The data were collected between 2005 and 2020. 41 pediatric patients with suspicion of septic arthritis of the hip joint, treated arthroscopically, were included. The following diagnostic test parameters were collected: ultrasound, MRI, X-Rays, blood samples, temperature, and incapacity to bear weight. The data were analysed with the sensitive analysis method using descriptive statistic.

RESULTS

41 patients were analyzed, with an average age of 6.04 y (7 months to 14 years), of which ten patients (24.39%) presented concomitant osteomyelitis. 6 out of ten patients needed secondary surgery. Regarding age, concomitant osteomyelitis was most common in the age group 4-14 years old. Average number of days of clinical symptoms before admission was 6.2 days. 36/41 cases showed CRP values higher than 2 mg/dl. 9/10 cases with concomitant osteomyelitis showed a CRP > 2 mg/dl, with an average value of 8.9 mg/dl. 22/41 patients underwent an MRI, of which nine cases presented a concomitant osteomyelitis. The probability of a child to have septic arthritis of the hip with adjacent osteomyelitis was analysed through a score based on four factors: impossibility to bear weight and/or hip pain in children in the non-walking age category, CRP > 2 mg/dl, age older than > 4 y, symptoms longer than 4 days.

CONCLUSIONS

Children at the age of walking, with incapacity to bear weight, presenting symptoms longer than 4 days and a CRP > 2 mg/dl, should receive an MRI before surgery to exclude adjacent osteomyelitis.

LEVEL OF EVIDENCE

IV.

Predictive Algorithms in the Diagnosis and Management of Pediatric Hip and Periarticular Infection

➤ Although the criteria of Kocher et al. were an important advancement in our ability to diagnose septic arthritis of the hip early, the changing microbial landscape and availability of advanced imaging have rendered it insufficient for contemporary clinical use.➤ Routine use of magnetic resonance imaging and recognition of disseminated disease have prompted the development of algorithms to predict concurrent osteoarticular infection in cases of septic arthritis and osteomyelitis that were previously assumed to be "isolated."➤ Recent research has attempted to stratify childhood bone and joint infection (BJI) by severity to guide treatment planning. This is valuable, as patients with multifocal disease, more virulent pathogens, and immunocompromise can have longer hospital stays and require multiple surgeries.➤ The increasing prevalence of clinical prediction algorithms in childhood BJI is not completely matched by quality in methodology. Clinicians need to be wary of adopting predictive algorithms prior to robust external validation.

Pilot Study Analysis of Serum Cytokines to Differentiate Pediatric Septic Arthritis and Transient Synovitis

BACKGROUND

In pediatric patients, the presentation of the nontraumatic acutely painful joint/limb poses a diagnostic dilemma due to the similarity of presentations of the most likely diagnoses [septic arthritis (SA), transient synovitis (TS), osteomyelitis]. Current tools employed to differentiate these diagnoses rely on nonspecific inflammatory markers, radiologic imaging, and arthrocentesis. Diagnostic algorithms utilizing these clinical, radiographic, and biochemical parameters have produced conflicting results. The purpose of this study was to identify a serum-based inflammatory signature which can differentiate SA from TS in pediatric patients.

METHODS

Serum samples were collected from 22 pediatric patients presenting with joint/extremity pain whose working diagnosis included SA or TS. Each sample was analyzed for serum abundance of 72 distinct biomarkers and cytokines using enzyme linked immunosorbent assay based arrays. Linear discriminant analysis was performed to identify a combinatorial biomarker panel to predict a diagnosis of SA or TS. Efficacy of the biomarker panel was compared with definitive diagnoses as based on laboratory tests, arthrocentesis results, and clinical scenario.

RESULTS

At the time of presentation: (1) mean erythrocyte sedimentation rate in the SA group was 56.6 mm/h and 12.4 mm/h in the TS group (P<0.001), (2) mean C-reactive protein was 55.9 mg/dL in the SA group and 13.7 mg/dL in the TS group (P=0.12), and (3) mean white blood cell was 10.9 k/mm3 in the SA group and 11.0 k/mm3 in the TS group (P=0.95). A combined panel of 72 biomarkers was examined using discriminant analysis to identify a limited set of predictors which could accurately predict whether a patient was diagnosed with SA or TS. A diagnostic algorithm consisting of transforming growth factor alpha, interleukin (IL)-7, IL-33, and IL-28A serum concentration correctly classified 20 of the 22 cases with a sensitivity and specificity of 90.9% (95% confidence interval: 73.9%-100.0%).

CONCLUSION

This study identifies a novel serum-based 4-cytokine panel that accurately differentiates SA from TS in pediatric patients with joint/limb pain.

LEVEL OF EVIDENCE

Level II-diagnostic study.

Test characteristics of history, examination and investigations in the evaluation for septic arthritis in the child presenting with acute non-traumatic limp. A systematic review

BACKGROUND

Septic arthritis is an uncommon but potentially significant diagnosis to be considered when a child presents to the emergency department (ED) with non-traumatic limp. Our objective was to determine the diagnostic accuracy of clinical findings (history and examination) and investigation results (pathology tests and imaging) for the diagnosis of septic arthritis among children presenting with acute non-traumatic limp to the ED.

METHODS

Systematic review of the literature published between 1966 and June 2019 on MEDLINE and EMBASE databases. Studies were included if they evaluated children presenting with lower limb complaints and evaluated diagnostic performance of items from history, physical examination, laboratory testing or radiological examination. Data were independently extracted by two authors, and quality assessment was performed using the Quality Assessment Tool for Diagnostic Accuracy Studies 2 tool.

RESULTS

18 studies were identified, and included 2672 children (560 with a final diagnosis of septic arthritis). There was substantial heterogeneity in inclusion criteria, study setting, definitions of specific variables and the gold standard used to confirm septic arthritis. Clinical and investigation findings were reported using varying definitions and cut-offs, and applied to differing study populations. Spectrum bias and poor-to-moderate study design quality limit their applicability to the ED setting.Single studies suggest that the presence of joint tenderness (n=189; positive likelihood ratio 11.4 (95% CI 5.9 to 22.0); negative likelihood ratio 0.2 (95% CI 0.0 to 1.2)) and joint effusion on ultrasound (n=127; positive likelihood ratio 8.4 (95% CI 4.1 to 17.1); negative likelihood ratio 0.2 (95% CI 0.1 to 0.3)) appear to be useful. Two promising clinical risk prediction tools were identified, however, their performance was notably lower when tested in external validation studies.

DISCUSSION

Differentiating children with septic arthritis from non-emergent disorders of non-traumatic limp remains a key diagnostic challenge for emergency physicians. There is a need for prospectively derived and validated ED-based clinical risk prediction tools.

Characteristics of Pyogenic Musculoskeletal Infections in Older Children and Adolescents

The characteristics and clinical consequences of pyogenic bone and joint infections in older children and adolescents have received little attention. This study evaluated the presentation and complications of musculoskeletal infections involving the pelvis and extremities in children older than 10 years. Thirty patients 10 to 17 years old (mean, 12.7 years old) were treated for musculoskeletal infections. Mean time to diagnosis was 9.2 days. Prior to correct diagnosis, 83% were assessed by at least 1 outpatient provider. At the time of admission, 55% were weight bearing and 93% were afebrile. Twenty-eight percent had a multifocal infection. More than one-third had serious medical complications or orthopedic sequelae; compared with patients without complications, this group had a significantly higher admission C-reactive protein and longer hospital stay. Symptoms of musculoskeletal infection common among young children may be absent in adolescents. Axial imaging is recommended to identify adjacent or multifocal disease. The Kocher criteria are less sensitive for septic hip arthritis in the adolescent population. Prompt recognition and treatment are critical to avoid medical and musculoskeletal complications. [Orthopedics. 2020;43(4):e291-e298.].

A Retrospective Review of Native Septic Arthritis in Patients: Can We Diagnose Based on Laboratory Values?

Introduction The accurate diagnosis of acute septic arthritis is essential to initiating appropriate treatment and minimizing potential cartilage damage. A synovial fluid cell count of 50,000 cells/mm³ has been used as a diagnostic cutoff for acute septic arthritis, although data supporting this is lacking. The purpose of this study was to assess the efficacy of synovial cell counts to predict septic arthritis in patients with symptomatic native joints. Methods A retrospective review was performed of patients who were evaluated for septic arthritis at a single institution with the use of synovial fluid analysis and adjunctive lab tests. Exclusion criteria included history of a total joint arthroplasty of the affected joint or immunocompromised state. A true infection was considered on the basis of positive or negative synovial aspirate cultures. We evaluated the synovial cell count, synovial polymorphonuclear cell percentile (% neutrophils), serum white blood cell (WBC), erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) in order to determine their association and predictive power in a true infection. Results Of the 65 patients included in the study, 40 (61.5%) had a positive culture for septic arthritis and 25 (38.5%) had negative cultures. Patients with positive cultures had a larger median % neutrophils than patients with negative cultures (median: 93 vs. median: 86, P=0.041). They also tended to have higher serum CRP levels compared to negative culture patients (median: 142.30 vs. 34.20, P=0.051). No outcomes were independently highly effective in discriminating between patient groups (area under the curve (AUC) ≤ 0.67). There was no significant difference between the synovial cell counts in patients with culture positive septic arthritis and patients with negative cultures (median: 32435 vs 35385, P = 0.94).  Conclusion Patients with culture proven septic arthritis had larger % neutrophils. However, there were no other statistically significant differences between patient groups regarding ESR, CRP, WBC, or cell count aspiration at the time of diagnosis. No synovial cell count level was highly effective in discriminating patients with a positive culture for septic arthritis from patients with negative cultures.

Septic Arthritis of the Hip in Children: A Critical Analysis Review

Septic arthritis of the hip is a common and potentially devastating condition in children. Septic arthritis is most commonly caused by Staphylococcus aureus, but other pathogens should be considered on the basis of patient age and presence of risk factors. Diagnosis of septic arthritis is based on history and physical examination, laboratory tests, radiographs, ultrasound, and arthrocentesis. Treatment comprises empiric antibiotics and joint debridement, and antibiotics are subsequently tailored on the basis of culture data, local resistance patterns, and clinical response. Late sequelae of septic arthritis include osteonecrosis, chondrolysis, growth disturbance, subluxation or dislocation, and progressive ankylosis. Surgical treatments to address these issues have been described.

A prospective study of screening for musculoskeletal pathology in the child with a limp or pseudoparalysis using erythrocyte sedimentation rate, C-reactive protein and MRI

PURPOSE

To determine if the detection of musculoskeletal pathology in children with a limp or acute limb disuse can be optimized by screening with blood tests for raised inflammatory markers, followed by MRI.

METHODS

This was a prospective observational study. Entry criteria were children (0 to 16 years of age) presenting to our emergency department with a non-traumatic limp or pseudoparalysis of a limb, and no abnormality on plain radiographs. Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) blood tests were performed. Children with ESR > 10 mm/hr or CRP > 10 mg/L underwent a MRI scan. When the location of the pathology causing the limp was clinically unclear, screening images (Cor t1 and Short Tau Inversion Recovery) of both lower limbs from pelvis to ankles ('legogram') was undertaken. Data was gathered prospectively from 100 consecutive children meeting the study criteria.

RESULTS

In all, 75% of children had a positive finding on their MRI. A total of 64% of cases had an infective cause for their symptoms (osteomyelitis, septic arthritis, pyomyositis, fasciitis, cellulitis or discitis). A further 11% had positive findings on MRI from non-infective causes (juvenile idiopathic arthritis, cancer or undisplaced fracture). The remaining 25% had either a normal scan or effusion due to transient synovitis. ESR was a more sensitive marker than CRP in infection, since ESR was raised in 97%, but CRP in only 70%.

CONCLUSION

In our opinion MRI imaging of all children with a limp and either raised ESR or CRP is a sensitive method to minimize the chance of missing important pathology in this group, and is an effective use of MRI resources. We advocate the use of both blood tests in conjunction.

LEVEL OF EVIDENCE

Level II.

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.