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

Variation in Early Inflammatory Marker Testing for Infection-Related Hospitalizations in Children

BACKGROUND AND OBJECTIVES

Inflammatory marker testing in children has been identified as a potential area of overuse. We sought to describe variation in early inflammatory marker (C-reactive protein and erythrocyte sedimentation rate) testing for infection-related hospitalizations across children's hospitals and to determine its association with length of stay (LOS), 30-day readmission rate, and cost.

METHODS

We conducted a cross-sectional study of children aged 0 to 17 years with infection-related hospitalizations using the Pediatric Health Information System. After adjusting for patient characteristics, we examined rates of inflammatory marker testing (C-reactive protein or erythrocyte sedimentation rate) during the first 2 days of hospitalization. We used k-means clustering to assign each hospital to 1 of 3 groups on the basis of similarities in adjusted diagnostic testing rates across 12 infectious conditions. Multivariable regression was used to examine the association between hospital testing group and outcomes.

RESULTS

We included 55 771 hospitalizations from 48 hospitals. In 7945 (14.3%), there was inflammatory marker testing in the first 2 days of hospitalization. We observed wide variation in inflammatory marker testing rates across hospitals and infections. Group A hospitals tended to perform more tests than group B or C hospitals (37.4% vs 18.0% vs 10.4%; P < .001) and had the longest adjusted LOS (3.2 vs 2.9 vs 2.8 days; P = .01). There was no significant difference in adjusted 30-day readmission rates or costs.

CONCLUSIONS

Inflammatory marker testing varied widely across hospitals. Hospitals with higher inflammatory testing for one infection tend to test more frequently for other infections and have longer LOS, suggesting opportunities for diagnostic stewardship.

A clinical decision tool for septic arthritis in children based on epidemiologic data of atraumatic swollen painful joints in South Africa

BACKGROUND

In settings with limited access to specialist services, differentiating septic arthritis-a surgical emergency-from non-infectious atraumatic arthropathy in paediatric patients is challenging, especially in a setting with a high burden of tuberculosis (TB). We aimed to investigate the aetiologies of swollen, painful joints in an urban setting in South Africa and determine how clinical and laboratory findings varied with diagnosis.

PATIENTS AND METHODS

A retrospective review of patients aged 12 or younger presenting to a paediatric hospital in Cape Town, South Africa, with atraumatic swollen, painful joints was conducted over a two year period from 2013 to 2015. Children were excluded if they did not have tissue culture or analysis conducted at our facility. Aetiology was classified as non-infectious, TB septic arthritis, or pyogenic arthritis from other bacterial causes.

RESULTS

One hundred and four children met inclusion criteria. Arthritis was classified as non-infectious in 43 (41%), TB in 15 (14%), and pyogenic in 40 (38%), with six (6%) patients never receiving a final diagnosis. Mean C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and white blood cell count (WCC) were all significantly higher in pyogenic infectious arthritis compared with TB and non-infectious arthritis. There were no significant differences in these parameters between non-infectious and TB arthritis. Using cut-point analysis, thresholds were identified predictive of the presence of pyogenic arthritis versus TB or non-infectious arthritis; these included the presence of fever, CRP > 50 mg/L, ESR > 65 mm/h and WCC > 12x10⁹/L. The absence of all of these criteria resulted in a negative predictive value of 100% for pyogenic infection; the presence of three to four criteria resulted in a positive predictive value of 71%.

CONCLUSIONS

Despite insignificant differences in their clinical presentation compared with non-infectious arthidities, 15% of children were diagnosed with tissue-confirmed TB infection. Predictive values of clinical criteria are reduced in our population due to elevated levels of inflammatory markers in all patients. Synovial biopsy to rule out TB is recommended in all patients in a high-burden setting given clinical similarity to non-infectious aetiologies.

Current Variation in Joint Aspiration Practice for the Evaluation of Pediatric Septic Arthritis

Pediatric septic arthritis (SA) is a condition that can be associated with significant morbidity. Although previous research has been on predictive care pathways, scrutiny of the literature continues to reveal wide differences in the patient evaluation and management. The purpose of this study was to define the differences in joint aspiration for the evaluation of pediatric SA across pediatric tertiary care institutions in the United States.

Radiologic Evaluation of the Child with a Limp

A child presenting with a limp can present a diagnostic challenge to pediatricians. Clinical presentation, age, and history all contribute to the initial differential diagnosis; however, imaging plays a key role in the ultimate diagnosis, and the correct imaging study is essential to save time and health care expenses. This article will present a few of the more common causes of a limp and the recently updated imaging recommendations from the American College of Radiology to aid in final diagnosis. [Pediatr Ann. 2020;49(9):e395-e402.].

Pigmented Villonodular Synovitis Mimicking an Acute Septic Hip in an Eight-Year-Old Male

Pigmented villonodular synovitis (PVNS) is a less common but known cause of joint pain in the adult population. PVNS in pediatric patients is even more rare, with only case reports of occurrence in persons under the age of 18 years. Presentation is typically that of more insidious pain and limited range of motion, and is primarily seen in the knee joint. Diagnosis can be suspected with imaging, but ultimately surgical intervention is needed for tissue confirmation. We present a case of PVNS in a pediatric patient with acute symptoms concerning for a septic joint. The patient’s workup revealed a large effusion on hip ultrasound, with operative intervention pursued and further imaging deferred given the patient's symptom burden. A 4 × 1 × 1.5 cm intra-articular pigmented mass excised from the synovium in the operating room. The patient’s symptoms improved after the procedure, with pathology showing sheets of plump mononuclear cells in a collagenized stroma with hemosiderin deposits, confirming the diagnosis. This case highlights the importance of keeping non-infectious etiologies in the differential diagnosis of acute onset joint pain.

Septic Arthritis: An Evidence-Based Review of Diagnosis and Image-Guided Aspiration

OBJECTIVE. The purpose of this evidence-based review is to equip radiologists to discuss and interpret findings obtained with various imaging modalities, guide patient selection for percutaneous aspiration, and safely perform arthrocentesis to assess for infection in both native and prosthetic joints. CONCLUSION. Septic arthritis is an emergency that can lead to rapidly progressive, irreversible joint damage. Despite the urgency associated with this diagnosis, there remains a lack of consensus regarding many aspects of the management of native and periprosthetic joint infections.

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.].

Defining the volume of consultations for musculoskeletal infection encountered by pediatric orthopaedic services in the United States

Objective

Adequate resources are required to rapidly diagnose and treat pediatric musculoskeletal infection (MSKI). The workload MSKI consults contribute to pediatric orthopaedic services is unknown as prior epidemiologic studies are variable and negative work-ups are not included in national discharge databases. The hypothesis was tested that MSKI consults constitute a substantial volume of total consultations for pediatric orthopaedic services across the United States.

Study design

Eighteen institutions from the Children’s ORthopaedic Trauma and Infection Consortium for Evidence-based Study (CORTICES) group retrospectively reviewed a minimum of 1 year of hospital data, reporting the total number of surgeons, total consultations, and MSKI-related consultations. Consultations were classified by the location of consultation (emergency department or inpatient). Culture positivity rate and pathogens were also reported.

Results

87,449 total orthopaedic consultations and 7,814 MSKI-related consultations performed by 229 pediatric orthopaedic surgeons were reviewed. There was an average of 13 orthopaedic surgeons per site each performing an average of 154 consultations per year. On average, 9% of consultations were MSKI related and 37% of these consults yielded positive cultures. Finally, a weak inverse monotonic relationship was noted between percent culture positivity and percent of total orthopedic consults for MSKI.

Conclusion

At large, academic pediatric tertiary care centers, pediatric orthopaedic services consult on an average of ~3,000 ‘rule-out’ MSKI cases annually. These patients account for nearly 1 in 10 orthopaedic consultations, of which 1 in 3 are culture positive. Considering that 2 in 3 consultations were culture negative, estimating resources required for pediatric orthopaedic consult services to work up and treat children based on culture positive administrative discharge data underestimates clinical need. Finally, ascertainment bias must be considered when comparing differences in culture rates from different institution’s pediatric orthopaedics services, given the variability in when orthopaedic physicians become involved in a MSKI workup.

Fifteen-minute consultation: The limping child

The limping child is a common presentation to paediatric services. In most instances the cause is benign with few, if any, investigations required. There is, however, always that concern that the limping child may have an underlying limb-threatening or life-threatening disease. This poses a challenge to clinicians, who must find that balance between correctly identifying disease early and avoiding the risks and harms of overinvestigation. In this article we discuss the diagnostic approach to the limping child and present a structure for assessment, investigation and risk management.

The predictive value of synovial glucose level in septic arthritis

The aim of this study was to investigate the ability of the joint fluid glucose level to detect septic arthritis. Thirty joints in 30 patients with suspected septic arthritis were evaluated. When glucose level was less than 40 mg/dl, we performed arthrotomy. Eleven patients had joint fluid glucose levels less than 40 mg/dl. All 11 (100%) had positive joint fluid cultures. Conversely, 19 patients had synovial glucose levels of at least 40 mg/dl. Six (31.6%) of these had positive joint fluid cultures. The remaining 13 were diagnosed with transient synovitis. Patients with joint fluid glucose levels less than 40 mg/dl should be suspected septic arthritis.

Differential MRI findings of transient synovitis of the hip in children when septic arthritis is suspected according to symptom duration

We investigated the differential MRI findings in children with transient synovitis of the hip in whom septic arthritis was suspected. Under the hypothesis that disease progression can alter representative MRI findings, we stratified these findings in accordance with symptom duration as this can correlate with disease progression. We analyzed 65 children who underwent MRI for acute hip pain and who were suspected of having a septic condition (i.e. presented with fever or increased inflammatory markers) when the imaging was performed. Symptom duration was defined as the interval from the first presentation of hip pain to the MRI scan. We divided the patients into two subgroups according to symptom duration: patients with short symptom duration (≤2 days, short-term subgroup, n = 30) and those with long symptom duration (≥3 days, long-term subgroup, n = 35). Twenty-eight (43.1%) of the study subjects were diagnosed with septic arthritis. Whereas only a high-grade joint effusion was a significant MRI finding differentiating septic arthritis from transient synovitis in the whole cohort, the presence of contralateral joint effusion in the short-term subgroup (P = 0.024) and the absence of a change/enhancement of the signal intensity of soft tissue in the long-term subgroup (P < 0.001) were significant predictors of transient synovitis. The significances of differential MRI findings for septic arthritis and transient synovitis seem to change according to symptom duration. We suggest that symptom duration, which may correlate with disease progression, should also be considered when interpreting MRIs of children under suspicion of septic arthritis.

The Utility of Leukocyte Esterase Strip Test in the Diagnosis of Pediatric Septic Arthritis

BACKGROUND

Most tests used to diagnose pediatric septic arthritis are either not accurate or do not produce rapid results. A leukocyte esterase (LE) strip test has previously been validated for the diagnosis of adult native and periprosthetic joint infections. The purpose of this prospective study was to: (1) evaluate the performance characteristics of the LE strip test in the diagnosis of pediatric septic arthritis and (2) determine the false positive rate of LE strip test on the aseptic synovial fluid (SF).

METHODS

Between May 2016 and November 2018, SF was obtained from children who were hospitalized at our tertiary referral center on the basis of suspicion of septic arthritis. All patients underwent arthrocentesis, and the aspirate was tested with LE strip test, leukocyte count, and culture. Twenty-five patients satisfied the inclusion criteria. For the second part of the study, SF from 25 children undergoing surgery for developmental dysplasia of the hip was collected and tested with LE strip test, leukocyte count, and culture.

RESULTS

In the first part of this study, 19 joints were classified as septic and 6 as aseptic. Considering a positive LE strip test ("++" and "+++" readings) indicative of septic arthritis yielded a sensitivity of 100%, specificity of 83%, positive predictive value of 95%, and negative predictive value of 100%. In the second part, all 25 patients with an aseptic SF had a negative test result ("-" and "+" readings).

CONCLUSIONS

The LE strip test seems to be a valuable additional tool in the diagnosis of pediatric septic arthritis. The LE strip test has the advantages of being inexpensive and simple, providing real-time results and having a perfect negative predictive value to rule out the diagnosis of septic arthritis.

LEVEL OF EVIDENCE

Level II-diagnostic.

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.

Diagnóstico microbiológico de artritis séptica en niños usando botellas de hemocultivos como un método alternativo

Introducción: La artritis séptica (AS) se define como la infección del espacio articular que afecta cualquier articulación, es más frecuente en niños menores de 5 años y su principal causa es la diseminación hematógena. El diagnóstico etiológico es difícil en niños, logrando aislamiento en menos de la mitad de los casos. Se evaluó el rendimiento diagnóstico de la botella de hemocultivo (BHC) como medio alternativo para la siembra del líquido sinovial comparado con los medios convencionales (MC). Metodología: Estudio de cohorte prospectivo realizado en centro de tercer nivel de 2011-2016, niños de 0 a 12 años con diagnóstico clínico de artritis séptica y disponibilidad de las dos muestras tomadas en cirugía. Resultados: Ingresaron 60 pacientes, masculinos 56%, mediana de edad 48 meses y tiempo de síntomas 58 horas (48-192); 33,3% con antecedente de trauma; 30% recibieron antibióticos previos. Articulaciones afectadas: cadera 44%, rodilla 28% y tobillo 18%. En 39 pacientes (65%) se tomaron hemocultivos; de estos 19 (49%) fueron positivos, todos para S. aureus. Se obtuvo confirmación en líquido sinovial por cualquier método en 27 pacientes (45%), positivos en ambos 21,6%, en MC 13,3% y en BHC 10%, los microorganismos más frecuentes SAMS 21,6%, SAMR 8,3%, S. pyogenes 3,3%, SEMR 3,3%, S. pneumoniae 1,6%, N. meningitidis 1,6%, no se aisló K. kingae. El tratamiento antibiótico más utilizado fueron los betalactamicos, mediana de estancia 18(12-25,5) días, mortalidad del 3,3%. Conclusión: Las BHC son un complemento al medio sólido convencional y aumentaron la confirmación etiológica de artritis séptica del 35% al 45%.

Repeat irrigation & debridement for patients with acute septic knee arthritis: Incidence and risk factors

BACKGROUND

Septic knee arthritis is considered an orthopedic emergency due to its significant morbidity and potential to be life-threatening. One important outcome in treatment of septic knee arthritis is whether return to the operating room for repeat irrigation and debridement is required. This complication presents extra burden to the patient, as well as to the health care system. This study aims to first isolate the incidence of repeat irrigation and debridement at the authors' home institution and then define risk factors for repeat washout for septic arthritis of the knee.

METHODS

Records from all patients at a single academic institution with acute septic knee arthritis who had arthroscopic or open I&D of the knee joint from January 2005-December 2015 were collected retrospectively. Patients were initially identified on the basis of diagnosis coding in the institution's medical information system. Following collection/screening based on strict inclusion/exclusion criteria, a cohort of 63 patients was ultimately included. 18 patients were assigned to a "repeat washout" (RW) cohort and 45 patients were assigned to a "no repeat washout" (NRW) cohort. Univariate analyses and multivariable regression models were performed between the two washout cohorts to identify variables associated with repeat washout.

RESULTS

Patients requiring a repeat washout (RW) had a statistically significant association with African American/Hispanic race, higher BUN levels, higher serum white blood cell (WBC) count on admission, concurrent infection, and isolated bacteremia when compared to those patients who did not require a repeat washout (NRW) (all respective P < 0.05). Multivariable regression analysis demonstrated concurrent infection and higher synovium WBC count to increase the risk for another repeat washout. Patients who had a concurrent infection were shown to have nearly 12-fold higher odds of needing a repeat washout than those without a concurrent infection (95% CI:2.40-56.88; P = 0.0023). For every 1000 unit increase in synovium WBC count, the odds of needing a repeat washout increased by 1% in patients with concurrent infection (95% CI:1-2%; P = 0.0168).

CONCLUSION

This study retrospectively isolated risk factors associated with repeat surgical lavage. In the multivariable regression analysis, both concurrent infection and increased synovial WBC count were significantly associated with the need for repeat knee I&D. This finding is significant, as it may signify a potential for increased infectious resilience for acute septic arthritis of the knee secondary to seeding from systemic infection, thus requiring multiple I&Ds to meet resolution. This finding may carry clinical significance in the early stages of patient counseling regarding hospital course and prognosis.

LEVEL OF EVIDENCE

IV.

The Limping Child

A limp is a common presentation to pediatricians, emergency centers, and orthopedists. A directed history and physical examination, and the development of a differential diagnosis based on limp type, patient's age, and the anatomic site that is most likely affected, provides a selective approach to diagnostic testing. Laboratory tests are indicated when infection, inflammatory arthritis, or a malignancy is considered. Imaging usually begins with plain radiography. Ultrasonography is valuable in assessing irritable hips. Advanced imaging is done in select cases. Prompt referral to an orthopedist is essential, especially if septic joint, vascular or compartment issues, or open fractures are suspected.

Hip Pain in Children

BACKGROUND

Atraumatic hip pain in children is one of the most common symptoms with which pediatricians, orthopedists, and general practitioners are confronted, with an incidence of 148 cases per 100 000 persons per year.

METHODS

This article is based on publications up to April 2019 that were retrieved by a selective search in the PubMed data- base, including case reports and reviews.

RESULTS

Infants with fever often have purulent coxitis, which can be diagnosed by blood tests and ultrasonography. Toddlers and older children may suffer from painful restriction of motion of the hip joint, associated with limping (antalgic gait) or even the in- ability to walk. The main elements of the differential diagnosis in children aged 2-10 are coxitis fugax and idiopathic necrosis of the femoral head (Perthes disease). In children aged 10 and up, and in adolescents, slipped capital femoral epiphysis (SCFE) is typical. Bone tumors and rheumatic diseases must always be considered as well. The initial diagnostic steps on presentation of a child with restricted hip movement should be plain x-rays and joint ultrasonography for the detection of an effusion. Suspicion of a tumor is the main indication for tomographic imaging (computed tomography or magnetic resonance imaging).

CONCLUSION

The underlying cause of hip pain in children should be diagnosed early to avoid adverse sequelae.

Pediatric Septic Arthritis of the Knee: Predictors of Septic Hip Do Not Apply

BACKGROUND

The early diagnosis of pediatric septic arthritis is paramount to the prevention of long-term sequela. The purpose of this study is to investigate if the commonly used criteria developed by Kocher and colleagues for hip septic arthritis can be used for screening children with suspected septic knee.

METHODS

We retrospectively reviewed the charts of patients under the age of 19, between June 2002 to June 2017, who presented to a major tertiary-care children's hospital with septic knee. Diagnostic criteria included either a positive synovial culture from the knee, synovial white blood cell (WBC)>50,000 cells/mm, or synovial WBC count >25,000 cells/mm and clinical agreement of diagnosis from Infectious Disease and Orthopaedic colleagues. Collected data included the initial criteria described by Kocher and colleagues: history of fever, non-weight-bearing, erythrocyte sedimentation rate, and serum WBC as well as a recently modified criterion: C-reactive protein. Univariate analysis was used to determine the quality of these variables in ruling out septic knee.

RESULTS

One hundred four patient charts were found to meet our inclusion criteria demonstrating C-reactive protein>20 mg/L (75%), fever (65%), non-weight-bearing status (64%), erythrocyte sedimentation rate>40 mm/h (60%), and WBC>12,000 cells/mm (49%). With the 25 different combinations of these predictors adjusted for, in an escalating manner, 0 predictors suggested a sensitivity of 0.02, 1 predictor a sensitivity of 0.06, 2 predictors a sensitivity of 0.2, 3 predictors a sensitivity of 0.32, 4 predictors a sensitivity of 0.3, and 5 predictors a sensitivity of 0.11.

CONCLUSIONS

According to the Kocher criteria of the hip, at 3 or more criteria the probability of septic arthritis becomes 93% with a sensitivity of 0.84 provoking many physicians to use this cutoff in their assessment of hip pain. This study suggests that if these criteria were applied to the knee, 52% of septic knee cases could be missed. There is a need for further investigation of specific criteria of the knee as the markers of the hip septic arthritis are not necessarily applicable in the knee.

LEVEL OF EVIDENCE

Level III.

Diagnostic Performance of C6 Enzyme Immunoassay for Lyme Arthritis

OBJECTIVES

In Lyme disease endemic areas, initial management of children with arthritis can be challenging because diagnostic tests take several days to return results, leading to potentially unnecessary invasive procedures. Our objective was to examine the role of the C6 peptide enzyme immunoassay (EIA) test to guide initial management.

METHODS

We enrolled children with acute arthritis undergoing evaluation for Lyme disease presenting to a participating Pedi Lyme Net emergency department (2015-2019) and performed a C6 EIA test. We defined Lyme arthritis with a positive or equivocal C6 EIA test result followed by a positive supplemental immunoblot result and defined septic arthritis as a positive synovial fluid culture result or a positive blood culture result with synovial fluid pleocytosis. Otherwise, children were considered to have inflammatory arthritis. We report the sensitivity and specificity of the C6 EIA for the diagnosis of Lyme arthritis.

RESULTS

Of the 911 study patients, 211 children (23.2%) had Lyme arthritis, 11 (1.2%) had septic arthritis, and 689 (75.6%) had other inflammatory arthritis. A positive or equivocal C6 EIA result had a sensitivity of 100% (211 out of 211; 95% confidence interval [CI]: 98.2%-100%) and specificity of 94.2% (661 out of 700; 95% CI: 92.5%-95.9%) for Lyme arthritis. None of the 250 children with a positive or equivocal C6 EIA result had septic arthritis (0%; 95% CI: 0%-1.5%), although 75 children underwent diagnostic arthrocentesis and 27 underwent operative joint washout.

CONCLUSIONS

In Lyme disease endemic areas, a C6 EIA result could be used to guide initial clinical decision-making, without misclassifying children with septic arthritis.

Intramedullary nailing for pertrochanteric fractures of proximal femur: a consecutive series of 323 patients treated with two devices

Introduction

Pertrochanteric fractures (PFs) frequently affect the lower limb of osteoporotic patients and represent an important cause of morbidity and mortality in the elderly. In this prospective randomized controlled trial, we have compared functional and radiological results and complications of patients affected by PFs treated with two intramedullary proximal femoral nails.

Materials

We enrolled 323 subjects with PFs, classified according to AO/OTA system as 31.A1 (pertrochanteric simple) and 31.A2 (pertrochanteric multifragmentary). Patients were divided into two groups according to the osteosynthesis devices: group A, Elos-Intrauma® nail (155 cases) and group B, Gamma 3-Stryker® nail (168 cases). Pre-operatively, the baseline characteristics of each patient (gender, age, weight and BMI) were collected. Intraoperative blood loss, subjective pain by visual analogue scale (VAS), esthetic satisfaction, functional scores of the hip by Harris Hip Score (HHS), and Western Ontario and McMaster Universities Arthritis Index (WOMAC) were noted. The post-operative degree of fracture reduction was assessed. Each patient had a minimum follow-up of 12 months.

Results

The study group was composed of 106 male and 217 female with an average age of 85.4 (range, 65–90, standard deviation (SD) 5.95) years. No statistical differences about sex and age distribution were noted between the two groups. Group A reported lower intraoperative blood loss, 45 ml vs 51 ml, respectively (p < 0.001). There was not any statistical difference about operative time. Group A had a better reduction of fracture (p = 0.0347). The greatest difference was detectable comparing subgroups 31.A2 (p = 0.032). There were no statistical differences about complication frequency and the overall rate was 25% (80 cases). Finally, there was no difference in terms of VAS, HHS, and WOMAC score between the two groups on each follow-up. Patients of group A showed a higher subjective satisfaction index at 1 post-operative year, 7.42 (SD 1.19) vs 6.45 (SD 1.35) of group B (p < 0.001).

Conclusion

Elos® nail is a reliable device on a short-term follow-up and represents an alternative choice to the Gamma 3® nail, a well-known and appreciated system for over 25 years.

Child with serogroup W135 primary meningococcal septic arthritis

Over the last decade, there has been a concerning increase in the number of invasive meningococcal serotype W infections in Europe. Although sepsis and meningitis are the most feared complications, focal complications of systemic disease such as pneumonia, pericarditis and arthritis can also occur. We present a rare case of isolated meningococcal W135 arthritis of the hip without invasive meningococcal disease in a 6-year-old patient.

An infective cause for the limping child

A 7-year-old girl presented with left hip pain and a limp, in the absence of any other systemic features, having recently been treated for a urinary tract infection. Examination revealed limited active hip movements on the left, with a tendency to weight bear on the contralateral side. Biochemical investigations were significant for raised inflammatory markers, and subsequent MRI imaging revealed osteomyelitis of the left pubis and ischium with an associated large soft tissue collection. Treatment was bimodal with surgical drainage and long-term antibiotics. The patient consequently recovered, without significant effect on either growth or mobility.

Pyogenic Arthritis

The incidence of septic arthritis among children in developed countries is estimated to be 4 to 10 cases per 100,000 children per year, peaking at about age 3 years. The most common causative organism is Staphylococcus aureus, although the microbiology varies by age. Prompt diagnosis and treatment is critical to prevent long-term sequelae. Empiric therapy should target the most likely causative organism(s) and total duration generally falls between 10 days and 4 weeks depending on clinical course, patient age, and organism. A short intravenous course is sufficient in most cases. Unusual and alternate causes of arthritis should be considered in special cases. [Pediatr Ann. 2019;48(9):e354-e359.].

Experience With a Care Process Model in the Evaluation of Pediatric Musculoskeletal Infections in a Pediatric Emergency Department

OBJECTIVES

Care process models (CPMs) for certain conditions have improved clinical outcomes in children. This study describes the implementation and impact of a CPM for the evaluation of musculoskeletal infections in a pediatric emergency department (ED).

METHODS

A retrospective pre-post intervention study was performed to analyze the impact of a musculoskeletal infection CPM. Patients were identified retrospectively through electronic order history for imaging of an extremity or joint and recommended laboratory tests. Clinical outcomes evaluated included hospital length of stay (LOS), time to magnetic resonance imaging (MRI), time to administration of antibiotics, hospital admission rate, and 30-day readmission rate.

RESULTS

Musculoskeletal infection evaluations completed in the ED were reviewed from 1 year before implementation (n = 383) and 2 years after implementation (n = 1219) of the CPM. A significant improvement in the time to antibiotic administration for all patients (4.3 vs 3.7 hours, P < 0.05) and for patients with confirmed musculoskeletal infections (9.5 vs 4.9 hours, P < 0.05) was observed after the implementation of the CPM. The overall time to MRI (13.2 vs 10.3 hours, P = 0.29) and hospital LOS (4.7 vs 3.7 days, P = 0.11) were improved for all patients but were not statistically significant. The admission rate and 30-day readmission were similar before and after the implementation of the CPM.

CONCLUSIONS

The implementation of a musculoskeletal infection CPM has standardized the approach to the evaluation and diagnosis of musculoskeletal infections resulting in a significant decrease in the time to administer antibiotics and a downward trend in time to MRI and hospital LOS.

Synovial fluid cell counts and its role in the diagnosis of paediatric septic arthritis

PURPOSE

Clinical presentation of paediatric septic arthritis (SA) can be similar to other joint pathologies. Despite potential for infection in all major joints, most diagnostic criteria are based on values from the hip. This study identifies the best joint aspirate values in diagnosing SA in all joints.

METHODS

In all, 166 patients who underwent 172 joint aspirations at the authors' institution between 01 September 2004 and 01 September 2014 were retrospectively identified. Recorded measures included age, sex, duration of symptoms, fever history, weight-bearing status, aspiration results, serum results and antibiotic administration. Patients were placed in the following four categories: 'culture confirmed SA' (C-SA), 'suspected SA' (S-SA), 'Other' and 'Other-rheumatologic' (Other-R), a subcategory of 'Other'.

RESULTS

Most common sites of aspiration were the knee (55%) and hip (29%). Diagnostic grouping was as follows: C-SA = 44, S-SA = 45, Other = 83 (Other-R = 21). Fever and non-weight-bearing prior to admission were useful predictors of SA, though in C-SA patients, 21% did not have a fever and 23% could weight bear at the time of admission. Aspirate white blood cell (WBC) count was significantly greater in both C-SA (92 000 cells/hpf) and S-SA (54 000) than in Other (10 000) and Other-R (18 000) patients. The percentage of polymorphonuclear (%PMN) was also significantly greater in C-SA (81.1%) and S-SA (80.9%) than in Other (57.9%) and Other-R (63.3%).

CONCLUSION

Joint aspirate values, especially %PMN, are valuable in diagnosing SA. Additionally, antibiotics pre-aspiration did not affect %PMN, facilitating subsequent diagnosis of infection. Lastly, while aspirate WBC count was a valuable indicator of SA, this finding is not as definitive as previous research suggests.

LEVEL OF EVIDENCE

IV Case Series.

Clinical Features and Outcomes of Children with Culture-Negative Septic Arthritis

BACKGROUND

Septic arthritis is a serious infection, but the results of blood and joint fluid cultures are often negative in children. We describe here the clinical features and management of culture-negative septic arthritis in children at our hospital and their outcomes.

METHODS

We performed a retrospective review of a cohort of children with septic arthritis who were hospitalized at Children's Hospital of Philadelphia between January 2002 and December 2014. Culture-negative septic arthritis was defined as a joint white blood cell count of >50000/μL with associated symptoms, a clinical diagnosis of septic arthritis, and a negative culture result. Children with pretreatment, an intensive case unit admission, Lyme arthritis, immunodeficiency, or surgical hardware were excluded. Treatment failure included a change in antibiotics, surgery, and/or reevaluation because of a lack of improvement/worsening.

RESULTS

We identified 157 children with septic arthritis. The patients with concurrent osteomyelitis (n = 28) had higher inflammatory marker levels at presentation, had a longer duration of symptoms (median, 4.5 vs 3 days, respectively; P < .001), and more often had bacteremia (46.4% vs 6.2%, respectively; P < .001). Among children with septic arthritis without associated osteomyelitis, 69% (89 of 129) had negative culture results. These children had lower C-reactive protein levels (median, 4.0 vs 7.3 mg/dL, respectively; P = .001) and erythrocyte sedimentation rates (median, 39 vs 51 mm/hour, respectively; P = .01) at admission and less often had foot/ankle involvement (P = .02). Among the children with culture-negative septic arthritis, the inpatient treatment failure rate was 9.1%, and treatment failure was more common in boys than in girls (17.1% vs 3.8%, respectively; P = .03). We found no association between treatment failure and empiric antibiotics or patient age. No outpatient treatment failures occurred during the 6-month follow-up period, although 17% of the children discharged with a peripherally inserted central catheter line experienced complications, including 3 with bacteremia.

CONCLUSIONS

The majority of septic arthritis infections at our institution were culture negative. Among patients with culture-negative infection, empiric antibiotics failed for 9% and necessitated a change in therapy. More sensitive diagnostic testing should be implemented to elucidate the causes of culture-negative septic arthritis in children.

Predicting Periarticular Infection in Children With Septic Arthritis of the Hip: Regionally Derived Criteria May Not Apply to All Populations

BACKGROUND

The management of septic arthritis of the hip in children can be complicated by the presence of additional coexisting periarticular infections (PAIs). Criteria predicting the presence of PAI have recently been proposed by Rosenfeld and colleagues with the goal of using magnetic resonance imaging (MRI) efficiently in the workup of septic arthritis. The purpose of this study was to determine the applicability of recently published predictive criteria for PAI (developed in the Southwestern United States using a variety of joints) to septic arthritis of the hip treated at a large Northeastern tertiary care center.

METHODS

We studied patients treated for septic arthritis of the hip with irrigation and debridement in a large Northeastern tertiary care center over a 10-year period. Laboratory and clinical variables related to presentation, treatment, and outcome were collected. Subjects with and without a perioperative MRI were compared with published criteria by Rosenfeld and colleagues.

RESULTS

Fifty-one subjects (53 hips) were identified with a mean age of 7.0 years (range, 1.2 to 19.3 y) and mean follow-up was 16 months (range, 2 to 85 mo). MRIs were obtained in 20 subjects (43%). Coexisting osteomyelitis was revealed in 7/20 of these studies (35% of MRIs); 4 of which showed coexisting intramuscular abscesses. Within our MRI cohort, the Rosenfeld criteria were found to have a sensitivity of 86%, a specificity of 54%, and a false-positive rate of 50% for the hip (compared with originally reported sensitivity of 90%, specificity of 67%, and false-positive rate of 33%). Overall, advanced imaging changed management in 5/51 patients (9%) by influencing the need for further treatment, whereas the remainder underwent isolated treatment of the septic hip joint with no adverse outcomes. One patient in the MRI cohort (without PAI) developed osteonecrosis of the femoral head.

CONCLUSIONS

We found lower sensitivity and specificity and higher false-positive rates for the Rosenfeld criteria in the hip for our geographically distinct population. Using the Rosenfeld criteria, MRIs would have been ordered unnecessarily in half of our series. Because of potential differences in regional microbiology and anatomic-specific factors, general predictive criteria for coexisting PAI based a single geographic region may be less generalizable to cases of hip sepsis in other geographic areas such as the Northeastern United States.

LEVEL OF EVIDENCE

Level 4-retrospective cohort study.

Biomarkers for Infection in Children: Current Clinical Practice and Future Perspectives

Biomarkers have become an integral part of the clinical decision-making process of clinicians dealing with febrile children. C-reactive protein, procalcitonin and white blood cell count are probably the most studied ones. Crucial to using biomarkers is the understanding of how a test result will alter post-test probabilities and then impact on clinical decision making. Improved analytical and computational platforms have enabled the next generation of advanced biomarker discovery studies. Promising combinations of candidate biomarkers for a diverse spectrum of febrile illnesses, such as viral and bacterial infections, have been identified using proteomics, RNA gene expression and metabolomics.

Ruptured Appendicitis and Retrocecal Abscess Masquerading as Knee Pain in a Pediatric Patient: A Case Report

BACKGROUND

Knee pain has a variety of etiologies in the pediatric population, including septic arthritis, osteomyelitis, fracture, ligamentous injury, and neoplasms. Extrinsic sources of knee pain may also be intra-abdominal, although abdominal pathology is much more likely to manifest as hip or proximal thigh musculature pain.

CASE REPORT

A 5-year-old healthy male presented with atraumatic right knee pain, discomfort with weightbearing, fever, and elevated inflammatory laboratory markers. Physical examination and magnetic resonance imaging findings of the knee were benign, leading to low clinical suspicion for knee septic arthritis. Blood cultures were positive for a gastrointestinal organism, Granulicatella adiacens, suggesting abdominal pathology leading to referred pain. Ultrasound evaluation and computed tomography (CT) of the abdomen revealed a large abscess secondary to perforated appendicitis, which was treated with CT-guided drainage and i.v. antibiotics. The patient's musculoskeletal pain subsided with treatment of the appendicitis. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Acute appendicitis may present as knee pain, with other signs and symptoms mimicking septic arthritis, such as fever, inability to bear weight, and elevated inflammatory markers. Considering an array of differential diagnoses in pediatric patients with apparent knee septic arthritis is crucial to prevent delay in diagnosis of alternative infectious sources.

Septic Arthritis of the Hip-Risk Factors Associated With Secondary Surgery

INTRODUCTION

Septic arthritis of the hip (SAH) is a common condition encountered by pediatric orthopaedic surgeons and is treated with arthrotomy and irrigation. Depending on the response to initial treatment, some patients require surgical treatment beyond the index procedure. The purpose of this study was to investigate risk factors for repeat surgical intervention after initial arthrotomy for presumed SAH.

METHODS

A multicenter retrospective review of all children who underwent surgical arthrotomy for presumed SAH over a ten-year period was conducted. Variables queried included demographics, clinical presentation, laboratory parameters, imaging, infecting organism, presence of osteomyelitis, and surgical interventions performed. Logistic regression was used to predict the risk of a second procedure. Chi-square was used to compare patients who required further surgery and those who did not.

RESULTS

One hundred and thirty-eight patients (139 hips) qualified for inclusion. The average age at initial surgery was 6.1 years (range, zero to 17 years), and 57% of the patients were male. Concomitant osteomyelitis was diagnosed in 55 cases (40%). An infecting organism was identified from 70 (50%) index intraoperative cultures, with Staphylococcus aureus infections (methicillin-resistant Staphylococcus aureus [MRSA], 27; methicillin-sensitive Staphylococcus aureus, 25) being the most frequent. Fifty-six patients (41%) underwent subsequent surgical intervention, at an average of 5.5 days (range, 2 to 95) from the index procedure. Independent risk factors for repeat surgical procedures included presenting C-reactive protein >10 mg/dL (P = 0.002) and presenting erythrocyte sedimentation rate >40 (P = 0.011). The odds of repeat surgical intervention were significantly increased by the presence of concomitant osteomyelitis (odds ratio, 3.4; P = 0.001) and positive index intraoperative cultures for MRSA (odds ratio, 1.19; P = 0.001). Preoperative MRI before the index procedure was not universal (73/138; 53%), and acquisition of preoperative MRI was not associated with secondary surgical intervention (P = 0.389).

DISCUSSION

Forty-one percent of children in this multicenter cohort underwent at least one repeat surgical procedure after the index arthrotomy for management of presumed SAH. Risk factors for return to the operating room include elevated initial erythrocyte sedimentation rate and C-reactive protein, infection with MRSA, and presence of osteomyelitis.

LEVEL OF EVIDENCE

Level 3, case-cohort series. Type of evidence, therapeutic.

Osteosarcoma of the Proximal Femur Mimicking Septic Arthritis of the Hip: A diagnostic dilemma

Septic arthritis is a surgical emergency requiring prompt drainage of the accumulation of pus in the joint. We report an eight-year-old boy who was referred to the Armed Forces Hospital, Salalah, Oman, in 2016 with limping and pain in his right hip along with an abduction deformity. He was initially diagnosed with synovitis and underwent conservative management. However, two weeks later, he presented to another centre due to persistent pain. Magnetic resonance imaging was suggestive of septic arthritis or osteomyelitis. Eight weeks later, the patient presented again to the Armed Forces Hospital. An arthrotomy was performed, during which an amount of what appeared to be frank pus was drained; however, cultures of the intraoperative samples returned no growth. A histopathological analysis revealed an osteosarcoma. The patient was subsequently referred elsewhere and underwent neoadjuvant chemotherapy and limb salvage surgery. Several months later, he relapsed and developed extensive pulmonary metastasis and died as a result of progressive deterioration.

Effects of Antibiotic Timing on Culture Results and Clinical Outcomes in Pediatric Musculoskeletal Infection

INTRODUCTION

Musculoskeletal infection (MSI) is a common cause of morbidity and hospital resource utilization in the pediatric population. Many physicians prefer to withhold antibiotics until tissue cultures can be taken in an effort to improve culture yields. However, there is little evidence that this practice improves culture results or outcomes in pediatric MSI. Therefore, investigating the effects of antibiotic timing may lead to improved clinical practice guidelines for treating children with MSI.

METHODS

An IRB-approved retrospective review was conducted that identified 113 patients aged 0 to 18 who presented to the pediatric emergency room at a tertiary care children's hospital with MSI from 2008 to 2013. Demographic data, culture results, severity markers, and intervention timing were obtained from the medical record. Logistic regression and Cox survival analysis were performed to determine the relationship of antibiotic timing with culture sensitivity and time to discharge.

RESULTS

No difference was seen in culture sensitivity antibiotic administration in either the local (55% culture before antibiotics vs. 89% after antibiotics) or disseminated group (76% before vs. 79% after), which persisted when further accounting for disease severity with C-reactive protein. However, later administration of antibiotics in the local infection group correlated with a decreased likelihood of discharge (3.91 d when cultured before antibiotics vs. 2.93 d when cultured after antibiotics; hazard ratio, 0.53; P<0.05). In patients with disseminated infection, antibiotic administration was not shown to correlate with any difference in time to discharge (hazard ratio, 1.08).

CONCLUSIONS

The authors were surprised to find that tissue culture sensitivities were not decreased by antibiotic administration in either local or disseminated MSI, suggesting that antibiotic administration should not be delayed to obtain tissue cultures. The correlation of earlier antibiotic administration with shorter length of stay in children with local MSI led the authors to conclude that antibiotics should be initiated as quickly as possible. Further study is necessary to confirm these findings and establish clinical practice guidelines.

LEVEL OF EVIDENCE

Level III-retrospective cohort.

A Clinical Prediction Algorithm to Stratify Pediatric Musculoskeletal Infection by Severity

OBJECTIVE

There are currently no algorithms for early stratification of pediatric musculoskeletal infection (MSKI) severity that are applicable to all types of tissue involvement. In this study, the authors sought to develop a clinical prediction algorithm that accurately stratifies infection severity based on clinical and laboratory data at presentation to the emergency department.

METHODS

An IRB-approved retrospective review was conducted to identify patients aged 0 to 18 who presented to the pediatric emergency department at a tertiary care children's hospital with concern for acute MSKI over a 5-year period (2008 to 2013). Qualifying records were reviewed to obtain clinical and laboratory data and to classify in-hospital outcomes using a 3-tiered severity stratification system. Ordinal regression was used to estimate risk for each outcome. Candidate predictors included age, temperature, respiratory rate, heart rate, C-reactive protein (CRP), and peripheral white blood cell count. We fit fully specified (all predictors) and reduced models (retaining predictors with a P-value ≤0.2). Discriminatory power of the models was assessed using the concordance (c)-index.

RESULTS

Of the 273 identified children, 191 (70%) met inclusion criteria. Median age was 5.8 years. Outcomes included 47 (25%) children with inflammation only, 41 (21%) with local infection, and 103 (54%) with disseminated infection. Both the full and reduced models accurately demonstrated excellent performance (full model c-index 0.83; 95% confidence interval, 0.79-0.88; reduced model 0.83; 95% confidence interval, 0.78-0.87). Model fit was also similar, indicating preference for the reduced model. Variables in this model included CRP, pulse, temperature, and an interaction term for pulse and temperature. The odds of a more severe outcome increased by 30% for every 10 U increase in CRP.

CONCLUSIONS

Clinical and laboratory data obtained in the emergency department may be used to accurately differentiate pediatric MSKI severity. The predictive algorithm in this study stratifies pediatric MSKI severity at presentation irrespective of tissue involvement and anatomic diagnosis. Prospective studies are needed to validate model performance and clinical utility.

LEVEL OF EVIDENCE

Level II-prognostic study.

Septic arthritis of the pediatric hip: update on diagnosis and treatment

PURPOSE OF REVIEW

To review the clinical diagnosis, management and natural history of septic arthritis of the hip (SAH) in the pediatric patient, and to highlight new information that may improve the management of these patients.

RECENT FINDINGS

The basics of management of possible pediatric SAH have remained largely unchanged for generations. New questions have been raised regarding the role and timing of advanced imaging (MRI) in the evaluation of patients with possible SAH. Published criteria have been derived to guide the need for MRI studies in these patients. Validation of these guidelines continues. Recent reviews have highlighted the possibility of Lyme disease as a potential cause of monoarticular pediatric hip pain. The role of PCR technology in the diagnosis and management of SAH remains unclear at this time.

SUMMARY

The child with a limp remains a common and urgent clinical concern. There may be expanded roles for MRI and PCR to better diagnose and treat the involved joint itself, as well as any associated nonarticular area of infection. Lyme disease should remain on the list of possible differential diagnoses in this population, particularly in geographic areas where the disease vector is known to be endemic.

Can a Septic Hip Decision Rule Aid in the Evaluation of Suspected Pediatric Musculoskeletal Infections?

BACKGROUND

Musculoskeletal (MSK) infections can be difficult to diagnose in acute care settings. The utility of clinical decision tools for pediatric MSK infections in an emergency department has not been well studied.

OBJECTIVE

Our aim was to evaluate the performance of a septic hip clinical decision rule (CDR) in the evaluation of pediatric musculoskeletal infections.

METHODS

We performed a retrospective study of children evaluated for an MSK infection in our emergency department from 2014 to 2016. Data collection included demographics, discharge diagnoses, and clinical/laboratory predictors from the CDR. A χ² analysis and Wilcoxon rank-sum tests compared patients with and without MSK infections. Logistic regression analysis examined the predictors for MSK infections. A receiver operating characteristic (ROC) curve was calculated to evaluate the performance of the predictors.

RESULTS

Of 996 evaluations included in the final analysis, 109 (10.9%) had MSK infections. In a multivariable model, an adjusted odds ratio (OR) was significant for fever (OR 3.9, 95% confidence interval [CI] 2.4-6.4), refusal to bear weight/pseudoparalysis (OR 4.4, 95% CI 2.7-7.1), and C-reactive protein (CRP) > 2.0 mg/dL (OR 5.4, 95% CI 3.2-9.1). The probability of infection was 75.1% with five predictors present, 1.9% for zero predictors, and 5.1% if one predictor was present. An ROC curve showed an area under the curve of 0.82, indicating moderate accuracy.

CONCLUSIONS

A septic hip CDR demonstrates a low predicted probability of an MSK infection with zero or one clinical predictor present and moderate predictability with all five predictors. Fever, refusal to bear weight/pseudoparalysis, and CRP > 2.0 mg/dL performed best and should alert providers to consider other MSK infections in addition to septic arthritis.

Septic arthritis of the hip and knee treated surgically in pediatric patients: Analysis of the Kids' Inpatient Database

OBJECTIVE

This study evaluated incidence over time, any association between race and demographics, and hospital-related parameters in pediatric patients with septic hip or knee arthritis.

METHODS

The Kids' Inpatient Database was used to identify all children with a diagnosis of septic hip or knee arthritis who underwent incision and drainage (1997-2012).

RESULTS

Between 1997 and 2012, overall incidence of septic arthritis of the knee (0.20-0.33 per 100,000) and hip (0.12-0.18 per 100,000) increased.

CONCLUSION

Incidence of pediatric septic joint arthritis, an emergent orthopaedic condition, has increased over time. Patient demographics may vary with respect to both age and race.

Femoral Neck Aspiration Aids in the Diagnosis of Osteomyelitis In Children With Septic Hip

BACKGROUND

The role of femoral aspiration (FA) in the treatment of septic arthritis of the hip is controversial. The purpose of this study was to determine if FA conducted concomitantly with irrigation and debridement (I&D) of the septic hip aids in microorganism and osteomyelitis identification and alters the treatment plan, or if the risks of the procedure outweigh its potential benefit. We also compare preoperative magnetic resonance imaging (MRI) with FA for diagnosis of osteomyelitis cooccurring with septic arthritis.

METHODS

Retrospective review was performed of all patients treated at a single institution between January 2003 and June 2014 for suspected septic hip arthritis. Eighty-three patients were identified with suspected or confirmed septic arthritis and 28 patients (33%) had cooccurring osteomyelitis. Demographic and clinical data were recorded for each patient. The sensitivity and specificity of FA and MRI for diagnosing osteomyelitis were determined.

RESULTS

Among the 83 patients with confirmed or suspected septic arthritis, 31 patients (37%) had a FA performed at the time of the hip I&D, resulting in positive cultures in 17 patients. All of these patients had other positive cultures (blood and/or joint fluid) that grew the same organism. 54 patients (65%) had a preoperative MRI. The MRI was falsely negative in 10 patients, 6 of whom had a positive FA resulting in appropriate management of osteomyelitis. Missed or delayed diagnosis of osteomyelitis resulted in significant morbidity in 3 patients (avascular necrosis and femoral neck fracture, extensive lower extremity osteomyelitis, and subtrochanteric fracture with malunion). No complications associated with FA were identified. FA and MRI were found to have sensitivity/specificity for osteomyelitis of 100%/100% and 38%/95%, respectively.

CONCLUSIONS

Although FA did not improve microorganism identification, it did aid in the diagnosis of cooccurring osteomyelitis when treating children with septic arthritis, especially in patients with false negative MRI findings for osteomyelitis. We recommend FA at the time of septic hip I&D as its benefits appear to far outweigh its risks.

LEVEL OF EVIDENCE

Level III-diagnostic study.

Imaging of the limping child

Limping is a challenging symptom in the pediatric patient as the diagnosis can range from traumatic, malformative, infectious/inflammatory and neoplastic diseases. In this paper, we propose a schematic imaging algorithm to the limping child in three different age groups (Toddler: 1-3years, child: 4-10 years; adolescent: 11-16 years) based on presence of signs of infection, any specific localization of pain, and history of trauma. In this setting, the most common imaging pitfalls are also summarised. Finally, a literature review of the main differential causes of limping in the pediatric patient is reported.

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.

Early diagnosis of septic arthritis in immunocompromised patients

OBJECTIVES

Septic arthritis results in rapid joint destruction if not properly diagnosed and treated. A work up for septic arthritis includes a peripheral white blood cell count, inflammatory markers, and a joint aspiration. In the general population, the interpretation of these labs has been well-defined by prior studies. To this point, no study has determined how immunosuppressive states affect this work up.

METHODS

Patients with immunosuppressive conditions who received a joint aspiration for a painful joint were retrospectively identified. Laboratory results from their work up were gathered and analyzed.

RESULTS

216 patients were included in the study, 21 of whom were diagnosed with septic arthritis. The average aspiration WBC count was 74,190 with 88% PMNs. 81% had a positive gram stain.

DISCUSSION

Laboratory values for immunosuppressed patients with septic arthritis were similar to those associated with septic arthritis in historical general population controls.