Metaphyseal osteomyelitis in children: how often does MRI-documented joint effusion or epiphyseal extension of edema indicate coexisting septic arthritis?

Predicting the presence of adjacent septic arthritis in children with acute hematogenous osteomyelitis

INTRODUCTION

This study conducted statistical analysis of clinical data from cases of acute hematogenous osteomyelitis (AHO) with or without concomitant septic arthritis, with the objective of identifying factors that are indicative of concomitant septic arthritis. Predictive models will be developed to predict coexisting infections, with one that is independent of MR findings and another that incorporates MRI data.

METHODS

A retrospective review of 127 children (132 cases of AHO) treated for AHO was performed. All patients underwent MRI. The data encompassed various demographic, clinical, and diagnostic factors. Graphical and logistical regression analysis was used to determine variables independently predictive of adjacent infection. Optimal cutoff values were determined for each variable and a prediction model was created. Finally, the model was applied to our patient database and each patient with isolated AHO, or concomitant infection was stratified based upon the number of positive predictive factors.

RESULTS

The overall incidence of coexisting septic arthritis in patients with AHO was 52.2% (69/132). Four risk factors (age below 4 years, a history of preceding infection, platelet count > 390.5 × 10^9/L, and absolute neutrophil count < 5.45 × 10^3 cells/ml) were found to be predictive of concomitant infection and were included in the algorithm. Patients with ≥ 2 risk factors were classified as high risk for AHO with concomitant infection (Sensitivity: 79.41% (95% CI: [64.10%, 94.71%]), Specificity: 76.56% (95% CI: [58.61%, 94.51%]), Positive Predictive Value (PPV): 78.26% (95% CI: [63.43%, 93.09%]), and Negative Predictive Value (NPV): 77.78% (95% CI: [61.02%, 94.54%]). In MRI, joint effusion was the primary indicator of concomitant septic arthritis in patients with AHO, followed by the absence of subperiosteal abscess. The presence of subperiosteal abscess in the absence of joint effusion was highly correlated with isolated AHO, showing a 100% occurrence rate (39/39).

CONCLUSIONS

Our study successfully identified several risk factors and radiologic signs associated with concomitant septic arthritis in patients with AHO. These findings can assist clinicians in early recognition and management of coexisting infections, especially in situations where MRI is not readily available or when its findings are inconclusive. Timely identification of these factors is crucial for appropriate treatment planning and improved patient outcomes.

A Rare Case of Spontaneous Elbow Osteomyelitis Presenting With Aseptic Effusion

Spontaneous osteomyelitis of the capitellum is an exceptionally rare condition, particularly in the absence of identifiable risk factors or inciting events. This case report describes a previously healthy 20-year-old male who presented with progressive elbow pain and swelling, initially raising suspicion for septic arthritis. Point-of-care ultrasound (POCUS) identified a significant joint effusion, and subsequent arthrocentesis revealed purulent fluid with a high white blood cell count, strongly suggestive of a septic joint. The patient was treated empirically with antibiotics and underwent surgical debridement, but cultures from both the arthrocentesis and the surgical washout were negative. Further imaging with MRI ultimately revealed findings consistent with osteomyelitis of the capitellum. This case highlights the diagnostic challenges associated with musculoskeletal infections, particularly in atypical sites like the capitellum, and underscores the importance of advanced imaging modalities such as MRI when initial diagnostics are inconclusive. The report also emphasizes the utility of POCUS in identifying joint effusions and guiding arthrocentesis in the emergency setting. Early recognition and appropriate management of osteomyelitis are crucial to avoid serious complications such as chronic infection, joint dysfunction, or limb deformity. This case contributes to the limited literature on capitellum osteomyelitis, particularly in the setting of an aseptic effusion, and advocates for the integration of multidisciplinary approaches and advanced diagnostic tools in the evaluation of pediatric and young adult musculoskeletal infections. Further research is needed to better understand the pathophysiology and management of rare presentations like this one.

Optimal Timing for Advanced Imaging in Childhood Bone and Joint Infection

OBJECTIVE

Advanced imaging in the management of childhood bone and joint infection (BJI) has the potential to improve disease outcomes. Knowledge about the optimal timing for magnetic resonance imaging (MRI) in relation to both surgically and nonsurgically managed BJI is limited. This study examines the impact of MRI timing on number of surgeries, length of stay (LOS), hospitalization cost, and disease recurrence in childhood BJI.

METHODS

This is a retrospective review of patients younger than 16 years with acute hematogenous osteomyelitis (AHO) or septic arthritis (SA) treated in the Auckland region from 2018 to 2023. Cases undergoing MRI as part of diagnostic workup were included. Treatment, hours between admission and MRI, LOS, hospitalization cost, and infection recurrence were assessed.

RESULTS

There were 563 cases of BJI, of which 390 met the inclusion criteria. Cases were primarily AHO (85%). The percentage of cases having MRI increased over time from 54% (2018) to 80% (2023). Locally disseminated infections such as subperiosteal abscess or adjacent septic arthritis occurred in 48%. Children with preoperative (n = 145) versus postoperative MRI (n = 60) had a lower reoperation rate (33% vs 77%, P = 0.001) and shorter LOS (14.1 vs 22.4 d, P = 0.002). Hospitalization costs appeared lower but did not differ statistically ($59,419 vs $159,353, P = 0.12). In nonoperative cases, LOS was shorter if an MRI occurred within 48 hours of admission (7.3 vs 10 d, P = 0.03). Disease recurrence was not associated with MRI timing.

CONCLUSION

Overall, children with BJI who underwent MRI scans before surgery had lower reoperation rates. Children receiving MRIs within 48 hours of admission had shorter LOS.

Ultrasonography for the Detection of Osteomyelitis in Pediatric Patients With Soft Tissue Infection: A Pilot Study

OBJECTIVES

To demonstrate the usefulness of ultrasonography for differentiating soft tissue infections with or without osteomyelitis in pediatric patients who underwent ultrasonography and subsequent magnetic resonance imaging (MRI).

METHODS

Twenty-three patients were classified into 2 groups: 12 patients with and 11 patients without osteomyelitis based on MRI. Osteomyelitis using ultrasound is characterized by the presence of bone cortex irregularity and/or subperiosteal abscess formation. The diagnostic performance of ultrasonography for detecting osteomyelitis and subperiosteal abscess formation was compared with that of MRI. Diagnostic accuracy, sensitivity, specificity, positive predictive value, and negative predictive value were calculated with 95% confidence intervals (CIs).

RESULTS

Of 12 osteomyelitis cases, 11 had abnormal bone marrow enhancement (one residual case did not undergo contrast enhancement study) and 5 had subperiosteal abscesses. The diagnostic accuracy of ultrasonography for osteomyelitis was 82.6% (number of correct diagnosis of osteomyelitis/total number = 19/23; 95% CI, 61.2-95.0) and for detecting periosteal abscess was 95.7% (number of correct diagnosis of periosteal abscess/total number = 22/23; 95% CI, 78.1-99.9), respectively. The sensitivity and specificity of ultrasonography for detecting osteomyelitis were 66.7% (95% CI, 34.9-90.1) and 100% (95% CI, 71.5-100), respectively. The sensitivity and specificity of ultrasonography for detecting periosteal abscess were 80% (95% CI, 28.4-99.5), and 100% (95% CI, 81.5-100), respectively. One-third of osteomyelitis cases could not be detected using ultrasonography.

CONCLUSIONS

Ultrasonography may be useful for diagnosing osteomyelitis in pediatric patients; however, the technique appears limited by low sensitivity. However, it is more accurate for diagnosis of periosteal abscess in these patients.

Application of AI-assisted MRI for the identification of surgical target areas in pediatric hip and periarticular infections

OBJECTIVE

To develop an AI-assisted MRI model to identify surgical target areas in pediatric hip and periarticular infections.

METHODS

A retrospective study was conducted on the pediatric patients with hip and periarticular infections who underwent Magnetic Resonance Imaging(MRI)examinations from January 2010 to January 2023 in three hospitals in China. A total of 7970 axial Short Tau Inversion Recovery (STIR) images were selected, and the corresponding regions of osteomyelitis (label 1) and abscess (label 2) were labeled using the Labelme software. The images were randomly divided into training group, validation group, and test group at a ratio of 7:2:1. A Mask R-CNN model was constructed and optimized, and the performance of identifying label 1 and label 2 was evaluated using receiver operating characteristic (ROC) curves. Calculation of the average time it took for the model and specialists to process an image in the test group. Comparison of the accuracy of the model in the interpretation of MRI images with four orthopaedic surgeons, with statistical significance set at P < 0.05.

RESULTS

A total of 275 patients were enrolled, comprising 197 males and 78 females, with an average age of 7.10 ± 3.59 years, ranging from 0.00 to 14.00 years. The area under curve (AUC), accuracy, sensitivity, specificity, precision, and F1 score for the model to identify label 1 were 0.810, 0.976, 0.995, 0.969, 0.922, and 0.957, respectively. The AUC, accuracy, sensitivity, specificity, precision, and F1 score for the model to identify label 2 were 0.890, 0.957, 0.969, 0.915, 0.976, and 0.972, respectively. The model demonstrated a significant speed advantage, taking only 0.2 s to process an image compared to average 10 s required by the specialists. The model identified osteomyelitis with an accuracy of 0.976 and abscess with an accuracy of 0.957, both statistically better than the four orthopaedic surgeons, P < 0.05.

CONCLUSION

The Mask R-CNN model is reliable for identifying surgical target areas in pediatric hip and periarticular infections, offering a more convenient and rapid option. It can assist unexperienced physicians in pre-treatment assessments, reducing the risk of missed and misdiagnosis.

Methods to Reduce Cost of Treatment in Childhood Bone and Joint Infection: A Systematic Review

BACKGROUND

Childhood bone and joint infection (BJI) is a potentially severe disease with consequences for growth and development. Critically unwell children may require prolonged hospitalization and multiple surgeries. Acknowledging rising healthcare costs and the financial impact of illness on caregivers, increased efforts are required to optimize treatment. This systematic review aims to characterize existing costs of hospital care and summarize strategies, which reduce treatment expense.

METHODS

A systematic review of the literature was performed from January 1, 1980, to January 31, 2024. Data were extracted on hospitalization costs for pediatric BJI by decade and global region. Results have been converted to cost per day in US dollars with purchase parity for 2023. Studies reporting innovations in clinical care to reduce length of stay (LOS) and simplify treatment were identified. Studies trialing shorter antibiotic treatment were only included if they specifically reported changes in LOS.

RESULTS

Twenty-three studies met inclusion criteria; of these, a daily hospitalization cost could be derived from 7 publications. Overall hospitalization cost and inpatient charges rose steeply from the 1990s to the 2020s. By contrast, average LOS seems to have decreased. Cost per day was higher in the United States than in Europe and higher for cases with confirmed methicillin-resistant Staphylococcus aureus. Sixteen studies report innovations to optimize care. For studies where reduced LOS was achieved, early magnetic resonance imaging with immediate transfer to theater when necessary and discharge on oral antibiotics were consistent features.

CONCLUSION

Rising costs of hospital care and economic consequences for families can be mitigated by simplifying treatment for childhood BJI. Hospitals that adopt protocols for early advanced imaging and oral antibiotic switch may provide satisfactory clinical outcomes at lower cost.

LEVEL OF EVIDENCE

Level III. See Instructions for Authors for a complete description of levels of evidence.

High-resolution ultrasound in the evaluation of musculoskeletal infections

Soft tissue and osseous musculoskeletal infections are common but can be difficult to diagnose clinically. Signs, symptoms, and physical examination findings may be nonspecific, and laboratory values can be inconclusive. The extent of disease may also be underestimated on physical examination. Soft tissue infections most commonly occur secondary to direct inoculation from broken skin and less frequently due to the seeding of the soft tissues from hematogenous spread, while osseous infections are more commonly due to hematogenous seeding. Infections may also be iatrogenic, following surgery or other procedural interventions. High-resolution ultrasound is an extremely useful imaging modality in the evaluation of musculoskeletal soft tissue and joint infections, and can occasionally be used to evaluate osseous infections as well. Ultrasound can aid in the early diagnosis of musculoskeletal infections, allowing for prompt treatment, decreased risk of complications, and treatment optimization. Ultrasound is sensitive and specific in evaluating soft tissue edema and hyperemia; soft tissue abscesses; joint, bursal and tendon sheath effusions/synovitis; and subperiosteal abscesses. This article describes the typical high-resolution grayscale as well as color and power Doppler ultrasound imaging findings of soft tissue infections including cellulitis, fasciitis, necrotizing deep soft tissue infection, pyomyositis, soft tissue abscess, infectious bursitis, and infectious tenosynovitis. Ultrasound findings of septic arthritis as well as osteomyelitis, such as subperiosteal spread of infection (subperiosteal abscess). are also reviewed. In addition, the use of ultrasound to guide fluid and tissue sampling is discussed.

Ten-year Review of Acute Pediatric Hematogenous Osteomyelitis at a New Zealand Tertiary Referral Center

BACKGROUND

Acute hematogenous osteomyelitis (AHO) remains a cause of severe illness among children with the possibility of long-term consequences for growth and development. Recent research has highlighted an unusually high burden of disease in the New Zealand population compared with other Western regions. We have sought to identify trends in presentation, diagnosis, and management of AHO, with added focus on ethnicity and access to health care.

METHODS

A 10-year retrospective review of all patients <16 years with presumed AHO presenting to a tertiary referral center between 2008 and 2018 was performed.

RESULTS

One hundred fifty-one cases met inclusion criteria. The median age was 8 years with a male predominance (69.5%). Staphylococcus aureus was the most common pathogen using traditional laboratory culture method (84%). The number of cases per year decreased from 2008 to 2018. Assessment using New Zealand deprivation scores showed Māori children were most likely to experience socioeconomic hardship ( P ≤0.01). Median distance traveled by families to first hospital consult was 26 km (range 1 to 178 km). Delayed presentation was associated with need for prolonged antibiotic therapy. Incidence of disease varied by ethnicity with 1:9000 cases per year for New Zealand European, 1:6500 for Pacific, and 1:4000 for Māori. Overall recurrence rate was 11%.

CONCLUSIONS

The incidence of AHO in New Zealand is concerningly high within Māori and Pacific populations. Future health interventions should consider environmental, socioeconomic, and microbiological trends in the burden of disease.

LEVEL OF EVIDENCE

Retrospective study, Level III.

ACR Appropriateness Criteria® Osteomyelitis or Septic Arthritis-Child (Excluding Axial Skeleton)

Imaging plays an integral role in the evaluation of suspected musculoskeletal infections in children, not only in the accurate identification of infection such as osteomyelitis or septic arthritis, but also in guiding management. Various diagnostic modalities serve different purposes in the assessment of suspected pediatric musculoskeletal infections. The purpose of this document is to provide imaging guidance in the most frequently encountered clinical scenarios in which osteomyelitis and/or septic arthritis are suspected, outside of the axial skeleton. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion.

[Acute haematogenous osteomyelitis in Lisbon: An unexpectedly high association with myositis and arthritis]

INTRODUCTION

Despite the current trend towards less aggressive therapeutic approaches, acute haematogenous osteomyelitis (AHO) continues to be a challenge and is associated with significant morbidity worldwide. Our aim was to determine if 80% compliance with current protocol was achieved, identify complications and associated risk factors and analyse trends in aetiology and management of AHO in children.

METHODS

We conducted a longitudinal, observational, single-centre study in patients with AHO aged less than 18 years admitted to a paediatric hospital, between 2008 and 2018, divided into 2 cohorts (before and after 2014). Demographic, clinical data and disease progression were analysed.

RESULTS

The study included 71 children with AHO, 56% male, with a median age of 3 years (interquartile range, 1-11). We found a 1.8-fold increase of cases in the last 5 years. The causative agent was identified in 37% of cases: MSSA (54%), MRSA (4%), Streptococcus pyogenes (19%), Kingella kingae (12%), Streptococcus pneumoniae (8%), and Neisseria meningitidis (4%). Complications were identified in 45% of patients and sequelae in 3.6%. In recent years, there was an increase in myositis (30% vs. 7%; p=0.02), septic arthritis (68% vs. 37.2%; p=0.012) and in the proportion of patients treated for less than 4 weeks (37% vs. 3.5%; p=0.012), with a similar sequelae rates. The risk factors for complications were age 3 or more years, CRP levels of 20mg/l or higher, time elapsed between onset and admission of 5 or more days and positive culture, although on multivariate analysis only positive culture was significant. The presence of complications was a risk factor for sequelae at 6 months.

CONCLUSIONS

Our study confirms that AHO can be aggressive. The identification of risk factors for complications may be fundamental for management.

MRI nomenclature for musculoskeletal infection

The Society of Skeletal Radiology (SSR) Practice Guidelines and Technical Standards Committee identified musculoskeletal infection as a White Paper topic, and selected a Committee, tasked with developing a consensus on nomenclature for MRI of musculoskeletal infection outside the spine. The objective of the White Paper was to critically assess the literature and propose standardized terminology for imaging findings of infection on MRI, in order to improve both communication with clinical colleagues and patient care.A definition was proposed for each term; debate followed, and the committee reached consensus. Potential controversies were raised, with formulated recommendations. The committee arrived at consensus definitions for cellulitis, soft tissue abscess, and necrotizing infection, while discouraging the nonspecific term phlegmon. For bone infection, the term osteitis is not useful; the panel recommends using terms that describe the likelihood of osteomyelitis in cases where definitive signal changes are lacking. The work was presented virtually to SSR members, who had the opportunity for review and modification prior to submission for publication.

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.

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.

Evaluation of the current use of imaging modalities and pathogen detection in children with acute osteomyelitis and septic arthritis

Diagnostic tools for the management of acute osteomyelitis (OM) and septic arthritis (SA) have improved over the last decade. To investigate the influence and availability of magnetic resonance imaging (MRI) and nucleic acid testing (NAT), a retrospective cohort study was done. Patients admitted with acute OM or SA between 2005 and 2014 were identified using ICD-10 discharge codes. Ninety-six children were identified: OM, n = 45; SA, n = 42; and OM + SA, n = 9. Diagnostic imaging was performed in 100% of OM or OM + SA and 95% of SA patients. MRI was performed in 85% of OM patients, 26% of SA patients and 100% OM + SA patients. In patients with OM or SA, concomitant joint/bone involvement was detected in 24 and 36% of patients, respectively. In 58% of patients, a pathogen was detected (Staphylococcus aureus, Streptococcus pyogenes and Streptococcus pneumoniae being most common). Blood and tissue culture were positive in 41 and 86% for OM patients and in 14 and 41%, respectively, for SA patients. In 42% of patients, no pathogen was identified, of which 40% had no material for blood or tissue culture/NAT taken.

CONCLUSION

Optimal use of imaging modalities including MRI and systematic pathogen detection including NAT should be advocated to limit use of broad spectrum antibiotics and treatment duration. What is Known: • Magnetic resonance imaging and sonography have the best sensitivity for detection of acute osteomyelitis and septic arthritis in children. • Systematic use of blood cultures, tissue cultures and nucleic acid testing improves pathogen detection in children with acute osteomyelitis and septic arthritis. What is New: • The added value of imaging modalities other than magnetic resonance and sonography for detection of osteomyelitis and septic arthritis is limited, and their routine use should be questioned. • Despite availability of optimal pathogen detection methods, missed opportunities to improve pathogen detection are frequent.

[Acute haematogenous osteomyelitis in children : Diagnostic algorithm and treatment strategies]

Acute haematogenous osteomyelitis (AHO) in children is a severe condition. A delay in diagnosis and insufficient treatment may result in deformities, chronicity and sepsis. Therefore a structured diagnostic workup has to be followed in order to diagnose or rule out osteomyelitis. To identify the causative agent for targeted antibiotic treatment, a bone biopsy or puncture should be performed. However, approximately 25% of cases are culture-negative even after biopsy. The knowledge of the typical age-dependent bacterial spectrum is essential for empirical antibiotic therapy. The principal causative organism is Staphylococcus aureus. Surgery is not routinely required in paediatric acute osteomyelitis but surgical intervention is indicated if an abscess is detected. Secondary septic arthritis is a serious complication which has to be treated immediately by surgical intervention. Nevertheless, complete regeneration can be expected in up to 80% of children with AHO.

The Contemporary Microbiology and Rates of Concomitant Osteomyelitis in Acute Septic Arthritis

BACKGROUND

Septic arthritis (SA) and acute osteomyelitis (AO) are among the most common serious bacterial infections of childhood. Knowledge of the microbiology of SA is critical to treatment. Awareness of the presence of attendant AO is also important to guide clinical management. We sought to describe the current microbiology of SA in children and clinical features associated with coexisting AO.

MATERIALS AND METHODS

Patients with SA were identified from the infectious diseases consult service records from 2010 to 2014. Patients with penetrating/open trauma and orthopedic hardware in situ were excluded.

RESULTS

A total of 168 patients with SA were included. The most common causative organism was Staphylococcus aureus accounting for 47.7% of cases (29.1% were methicillin-susceptible S. aureus and 18.5% were methicillin-resistant S. aureus), followed by group A streptococcus (GAS, 8.9%). The proportion of cases due to GAS increased from 2011 to 2014 (3.3%-16.7%; P = 0.1). One hundred eight (64.3%) patients had concurrent AO. The presence of osteomyelitis was associated with older median age (5.9 vs. 2.4 years; P = 0.04), a longer duration of symptoms (5 vs. 2.5 days; P < 0.001), S. aureus (62.1% vs. 21.7%; P < 0.001), bacteremia (46.2% vs. 20.3%; P = 0.001), a longer duration of fever after admission (5 vs. 2 days; P < 0.001) and a longer length of stay (10 vs. 6 days; P < 0.001).

CONCLUSIONS

Methicillin-resistant S. aureus continues to be an important cause of SA though GAS may be increasing in frequency. The presence of concomitant osteomyelitis is higher than previously reported and associated with older age, a longer duration of symptoms and fever, bacteremia and S. aureus.

Septic Arthritis of the Pediatric Shoulder: From Infancy to Adolescence

Background. Septic arthritis of the glenohumeral joint in the pediatric population (<18 yo) is not commonly described in the literature. There is a corresponding paucity of information regarding its presentation and treatment. Methods. An IRB approved review of patients treated with irrigation and debridement by the Orthopaedic Department was completed. This retrospective study includes four patients, presenting from 2005 to 2015, with septic arthritis of the shoulder. Results. The mean age (M age) at presentation was 5 years, with a range of 1 month to 15 years. Patients presented on average after 7 days with pain and a mean temperature of 39°C, erythrocyte sedimentation rate of 66 mm/hr, a C-reactive protein level of 11.17 g/dL, and a white blood cell count of 20.2 × 10(3)/mcL. Staphylococcus aureus, Candida albicans, and Pseudomonas aeruginosa were cultured from the wounds. All cases were treated operatively with irrigation and debridement and with antimicrobial therapy. Patients received antibiotics for an average of 6 weeks. Conclusion. Septic arthritis of the shoulder occurs in all pediatric ages. Successful treatment of septic arthritis of the shoulder was accomplished in four cases without division of the biceps sheath, with an average follow-up of 8 months.