Misconceptions about childhood acute osteomyelitis

Bacterial osteomyelitis in pediatric patients: a comprehensive review

Bacterial osteomyelitis, an inflammatory response in the bone caused by microorganisms, typically affects the metaphysis in the skeletally immature. Bacterial osteomyelitis possesses a significant diagnostic challenge in pediatric patients due to its nonspecific clinical presentation. Because the metaphysis is the primary focus of infection in skeletally immature patients, understanding the normal physiologic, maturation process of bones throughout childhood allows to understand the pathophysiology of osteomyelitis. Timely and accurate diagnosis is crucial to initiate appropriate treatment, and prevent long-term sequelae and efforts must be made to isolate the causative organism. The potential causative organism changes according to the age of the patient and underlying medical conditions. Staphylococcus Aureus is the most common isolated bacteria in pediatric pyogenic osteomyelitis whereas Kingella Kingae is the most common causative agent in children aged 6 months to 4 years. Imaging plays a pivotal role in the diagnosis, characterization, evaluation of complications, and follow up of bacterial osteomyelitis. Imaging also plays a pivotal role in the evaluation of potential neoplastic and non-neoplastic mimickers of osteomyelitis. In children, MRI is currently the gold standard imaging modality when suspecting bacterial osteomyelitis, whereas surgical intervention may be required in order to isolate the microorganism, treat complications, and exclude mimickers.

Subsequent Complications of Pediatric Patients With Osteomyelitis and Accompanying Subperiosteal Abscess

BACKGROUND

Subperiosteal abscesses (SAs) are a complication of osteomyelitis that requires surgical intervention. This study aimed to characterize the occurrence of subsequent complications in pediatric patients with osteomyelitis and accompanying SA.

METHODS

Fourteen pediatric patients with SAs were included. We recorded clinical information, including age at diagnosis, interval (days) between the onset of symptoms and diagnosis, location of SAs (long/flat bone), pathogens [methicillin-resistant Staphylococcus aureus (MRSA)/non-MRSA], treatment period (days) and any subsequent complications. Patients were classified based on SAs with or without complications. Mann-Whitney U and Fisher exact tests were used for statistical analyses, and data are expressed as median and interquartile range.

RESULTS

Six patients (42.9%) had subsequent complications. There were significant differences in location of SAs between these two groups (long/flat bone, with versus without complication = 6/0 versus 3/5; P = 0.031). No significant differences were observed between the groups in terms of age [with versus without complication = 13.8 (9.7-24.5) versus 556.3 (5.0-107.8) months; P = 0.491], the interval (days) between symptoms onset and diagnosis [with versus without complications = 5 (1-10) versus 5 (3-6.5) days; P = 0.950], pathogenesis (MRSA/non-MRSA, with versus without complication = 4/2 versus 2/6; P = 0.277) and treatment period [with versus without complication = 50.5 (31-57) versus 29 (24.5-41.5) days; P = 0.108].

CONCLUSIONS

Pediatric patients with SAs in the long bones have a higher likelihood of experiencing subsequent complications than those with SAs in flat bones. Physicians should carefully manage this vulnerable patient group.

Role of ultrasound in the treatment of pediatric infectious diseases: case series and narrative review

BACKGROUND

Infectious diseases are common in pediatric patients. In these patients, ultrasound is a useful imaging modality that involves no irradiation or sedation and can be performed repeatedly at the patient's bedside. The purpose of this review was to show pediatric cases with infectious disease that used ultrasound to decide the methods of treatment.

DATA SOURCES

Literature review was performed using Pubmed as the medical database source. No year-of-publication restriction was placed. The mesh terms used were: "ultrasound", "sonography", "infectious disease", "treatment", "antibiotics", "surgical intervention", "pediatric", "children", "deep neck abscess", "pyothorax", "empyema", "pneumonia", "urinary tract infection", "intra-abdominal abscess", "soft tissue infection", "septic arthritis", "osteomyelitis", and "surgical site infection".

RESULTS

We presented pediatric case series with infectious diseases, including deep neck abscess, pyothorax and empyema, pneumonia, urinary tract infection, intra-abdominal abscess, soft tissue infection, septic arthritis and osteomyelitis, and surgical-site infection. Ultrasound was useful for evaluating the extent and location of inflammation and abscess and for decision-making concerning surgical intervention.

CONCLUSION

Knowledge of these sonographic findings is important for sonographers during examinations and for physicians when determining the treatment plan and period of antibiotic therapy for infected lesions.

Magnetic resonance imaging protocols for pediatric acute hematogenous osteomyelitis

Pediatric musculoskeletal infection can be a challenging clinical diagnosis. MRI protocols should be tailored appropriately to diagnose and localize sites of infection, to determine alternative pathologies that could explain the child's presentation, and to identify complications that could alter treatment or lead to devastating consequences in growing bones. In this review, we discuss MRI protocols tailored for suspected acute appendicular musculoskeletal infection in children. These protocols are based on patient age in order to generally reflect the developmental stage of the child, the corresponding relevant anatomy and physiology, and the skeletal maturity-dependent physiopathology of musculoskeletal infections.

Pediatric Musculoskeletal Infections: Imaging Guidelines and Recommendations

Pediatric musculoskeletal infections often pose a diagnostic challenge due to their frequently vague and nonspecific clinical presentation. Imaging evaluation is a crucial component to diagnostic workup of these entities. Changed epidemiology of these infections over the past 2 decades has resulted in increases in both disease incidence and severity in the pediatric population. Prompt and accurate diagnosis is essential in order to reduce the risk of morbid sequelae, and to optimize patient management. In this article, the unique pathophysiology of musculoskeletal infections and characteristic imaging findings in children compared with adults are reviewed.

Predilection for developing a hematogenous orthopaedic implant-associated infection in older versus younger mice

Background

The pathogenesis of hematogenous orthopaedic implant-associated infections (HOIAI) remains largely unknown, with little understanding of the influence of the physis on bacterial seeding. Since the growth velocity in the physis of long bones decreases during aging, we sought to evaluate the role of the physis on influencing the development of Staphylococcus aureus HOIAI in a mouse model comparing younger versus older mice.

Methods

In a mouse model of HOIAI, a sterile Kirschner wire was inserted retrograde into the distal femur of younger (5–8-week-old) and older (14–21-week-old) mice. After a 3-week convalescent period, a bioluminescent Staphylococcus aureus strain was inoculated intravenously. Bacterial dissemination to operative and non-operative legs was monitored longitudinally in vivo for 4 weeks, followed by ex vivo bacterial enumeration and X-ray analysis.

Results

In vivo bioluminescence imaging and ex vivo CFU enumeration of the bone/joint tissue demonstrated that older mice had a strong predilection for developing a hematogenous infection in the operative legs but not the non-operative legs. In contrast, this predilection was less apparent in younger mice as the infection occurred at a similar rate in both the operative and non-operative legs. X-ray imaging revealed that the operative legs of younger mice had decreased femoral length, likely due to the surgical and/or infectious insult to the more active physis, which was not observed in older mice. Both age groups demonstrated substantial reactive bone changes in the operative leg due to infection.

Conclusions

The presence of an implant was an important determinant for developing a hematogenous orthopaedic infection in older but not younger mice, whereas younger mice had a similar predilection for developing periarticular infection whether or not an implant was present. On a clinical scale, diagnosing HOIAI may be difficult particularly in at-risk patients with limited examination or other data points. Understanding the influence of age on developing HOIAI may guide clinical surveillance and decision-making in at-risk patients.

Role of ultrasound in the diagnosis of paediatric acute osteomyelitis

Aim

The aims of our study were to evaluate cases of extremity pain or swelling in paediatric patients using USG to diagnose acute osteomyelitis, and correlate USG findings with MRI findings.

Material and methods

18 paediatric patients with extremity pain or swelling were evaluated. After the clinical and laboratory work-up, imaging was done using radiographic examination, USG and MRI of the affected limb.

Results

5 patients (27.8%) out of 18 were diagnosed with acute osteomyelitis based on USG findings, confirmed by MRI and surgical drainage. The mean age of the patients with acute osteomyelitis was 8.2 years. Male children were more commonly affected as compared to female. The distal metaphysis of the femur was the most common site involved (80%). The right lower limb was more commonly affected. The most frequent presentation was pain at the affected site. On USG, deep soft tissue fluid collection around the bone was present in all cases (100%). Periosteal thickening or elevation with subperiosteal fluid collection was seen in 4 cases (80%). Increased vascularity within or around the periosteum on colour Doppler was seen in 4 cases (80%).

Conclusions

Acute osteomyelitis is a common entity in the paediatric population, presenting with acute limb pain and swelling. Early diagnosis and management of acute osteomyelitis are essential to prevent serious complications. USG can play an important role in the early diagnosis of paediatric acute osteomyelitis, and should be incorporated into the treatment protocols followed in cases of suspected acute osteomyelitis. MRI should be reserved as problem-solving tool.

Acute Hematogenous Osteomyelitis in Children: Clinical Presentation and Management

Acute hematogenous osteomyelitis (AHO) is a common invasive infection encountered in the pediatric population. In addition to the acute illness, AHO has the potential to create long-term morbidity and functional limitations. While a number of pathogens may cause AHO, Staphylococcus aureus is the most common organism identified. Despite the frequency of this illness, little high-quality data exist to guide providers in the care of these patients. The literature is reviewed regarding the epidemiology, microbiology and management of AHO in children. A framework for empiric therapy is provided drawing from the available literature and published guidelines.

NF-κB/TWIST1 Mediates Migration and Phagocytosis of Macrophages in the Mice Model of Implant-Associated Staphylococcus aureus Osteomyelitis

Staphylococcus aureus (S. aureus) infection-induced osteomyelitis is a great challenge in clinic treatment. Identification of the essential genes and biological processes that are specifically changed in mononuclear cells at an early stage of S. aureus osteomyelitis is of great clinical significance. Based on transcriptional dataset GSE16129 available publicly, a bioinformatic analysis was performed to identify the differentially expressed genes of osteomyelitis caused by S. aureus infection. ERBB2, TWIST1, and NANOG were screened out as the most valuable osteomyelitis-related genes (OMRGs). A mice model of implant-associated S. aureus osteomyelitis was used to verify the above genes. We found significantly up-regulated expression of TWIST1 in macrophages and accumulation of macrophages around the infected implant. Meanwhile, S. aureus infection increased the expression of TWIST1, MMP9, and MMP13, and stimulated the migration and phagocytosis function of Raw 264.7 cells. Additionally, knock-down of the expression of TWIST1 by siRNA could significantly down-regulate MMP9 and MMP13 and suppress the migration and phagocytosis ability of macrophages in response to S. aureus infection. Furthermore, we found that NF-κB signaling was activated in Raw 264.7 cells by S. aureus and that inhibition of NF-κB signaling by Bay11-7082 blocked the expression of TWIST1, MMP9, and MMP13 as well as cell migration and phagocytosis evoked by S. aureus. Our findings demonstrate that NF-κB/TWIST1 is necessary for migration and phagocytosis of macrophages in response to S. aureus infection. Our study highlights the essential role of NF-κB/TWIST1 in early innate immune response to S. aureus infection in bone.

Physeal bridges: causes, diagnosis, characterization and post-treatment imaging

The cartilaginous primary physis, or growth plate, at the end of long bones in children allows for longitudinal bone growth. A variety of insults to the physis can lead to physeal bridge formation, which in turn can lead to limb-shortening and angular deformities. This paper begins with a description of the causes, risk factors and mechanisms by which bridges form. Then it reviews the use of imaging in the diagnosis and characterization of bridges and in the evaluation of treatment and post-treatment complications. It is important for radiologists taking care of children to be aware of the indirect and direct imaging findings of physeal bridges to aid in their diagnosis, to be able to characterize bridges as part of preoperative planning, and to know the imaging finding of post-resection complications.

Management of acute osteomyelitis: a ten-year experience

Osteomyelitis is an infection of the bone; proper management requires prolonged antibiotic treatment. Controversy exists as to when a patient should transition from intravenous to oral antibiotics. However, due to the high bioavailability of some oral antibiotics, optimal time to transition from high to low bioavailability antibiotics is a more valid consideration. Additionally, there are questions surrounding the efficacy of certain antibiotics, specifically trimethoprim-sulfamethoxazole (TMP-SMX), in treating osteomyelitis. After obtaining Institutional Review Board approval from both universities, a retrospective chart review was conducted, utilizing an author-created severity scale, on all patients seen by Pediatric Infectious Diseases at the Universities of Michigan and Toledo with an acute osteomyelitis diagnosis from 2002-2012. There were 133 patients, 106 treated successfully. Success was defined in this study specifically as treatment of <14 weeks without recurrence within 30 days of stopping antibiotics or permanent site disability. Seventeen patients were treated with TMP-SMX at comparable cure rates. Patients with pre-existing bone defects (noted in radiological reports), initial erythrocyte sedimentation rate (ESR)≥70, hematogenous osteomyelitis with soft tissue extension, and skull osteomyelitis were associated with increased failure rate. Switch to low bioavailability antibiotics occurred, on average, at 3.5 weeks; however, switching before then was not associated with decreased cure rate. As prevalence of methicillin-resistant Staphylococcus aureus (MRSA), especially clindamycin-resistant MRSA, increases, TMP-SMX appears to be an acceptable antibiotic. There does not appear to be a minimum length of high bioavailability treatment required for cure. Prior bone defect, extensive infection, ESR≥70, or skull osteomyelitis may be indications for more aggressive management.

Osteoarticular Infections in Children

For a child with a suspected bone or joint infection, knowledge of the workup and initial therapy is important to provide quality care. Fever and pain are hallmarks of a pediatric osteoarticular infection, although occasionally the signs and symptoms can be more subtle. The use of C-reactive protein to diagnose and validate effective management of treatment has become standard. Multiple reports confirm the success of much shorter intravenous (IV) courses than traditionally taught. The ideal IV and oral antibiotic duration, as well as defining the markers indicating need for surgical intervention, are questions yet to be answered.

The imaging of osteomyelitis

Osteomyelitis is an important cause of morbidity and mortality in children and adults. Imaging plays a crucial role in establishing a timely diagnosis and guiding early management, with the aim of reducing long-term complications. Recognition of the imaging features of osteomyelitis requires a good understanding of its pathogenesis. In this review, the key imaging findings in osteomyelitis are correlated with the underlying pathological processes. There is a particular emphasis on magnetic resonance imaging (MRI), which is the best available imaging modality owing to its high sensitivity for detecting early osteomyelitis, excellent anatomical detail and superior soft tissue resolution. However, other modalities such as nuclear medicine and computed tomography (CT) are also useful in many clinical contexts, and will also be described in this review.