A Novel Classification System Based on Dissemination of Musculoskeletal Infection is Predictive of Hospital Outcomes

Navigating the Enigma of Pediatric Musculoskeletal Infections: A Race Against Time

Musculoskeletal infection (MSKI) in children is a critical condition in pediatric orthopedics due to the potential for serious adverse outcomes, including multiorgan dysfunction syndrome, which can lead to death. The diagnosis and treatment of MSKI continue to evolve with advancements in infectious organisms, diagnostic technologies, and pharmacologic treatments. It is imperative for pediatric orthopedic surgeons and medical teams to remain up to date with the latest MSKI practices.

CRP Predicts the Need to Escalate Care After Initial Debridement for Musculoskeletal Infection

BACKGROUND

Musculoskeletal infections (MSKIs) are a major cause of morbidity in the pediatric population and account for nearly 1 in every 10 consultations with a pediatric orthopaedic provider at a tertiary care center. To prevent or deescalate the risk of adverse medical and musculoskeletal outcomes, timely medical intervention in the form of antibiotics and potential surgical debridement is required. While there have been numerous studies indicating the value of laboratory testing during the initial workup of a child with MSKI, few studies to date have examined the utility of longitudinal assessment of laboratory measures in the acute setting to monitor the efficacy of antibiotic therapy and/or surgical intervention. The purpose of this investigation was to retrospectively determine whether measuring changes in the inflammatory response could indicate the need for escalated care. Specifically, this study examined the hypothesis that serial measurements of C-reactive protein (CRP), immediately preoperatively and 2 days after surgical debridement, could predict the need for medical (change in antibiotics) or surgical (additional debridement) escalation.

METHODS

Retrospective review of pediatric patients undergoing operative debridement for the treatment of MSKI between September 2009 and December 2015 from whom laboratory data (CRP) was obtained preoperatively and at postoperative day (POD) 2. Patient demographics, the need for escalated care, and patient outcomes were evaluated.

RESULTS

Across 135 pediatric patients, preoperative CRP values >90 mg/L and a positive change in CRP at POD2 effectively predicted the need for escalation of care after initial surgical debridement (Area under the Receiver Operator Curve: 0.883). For each 10-unit increase in preoperative CRP or postoperative change in CRP, there was a 21% or 22% increased risk of needing escalated care, respectively. Stratification by preoperative CRP >90 mg/L and change in CRP postoperatively likewise correlated with increased rates of disseminated disease, percent tissue culture positivity, length of stay, and rate of adverse outcomes.

CONCLUSIONS

This study demonstrates the utility of serial CRP to assess the need for escalated care in patients being treated for MSKI. As serial CRP measurements become standard of practice in the acute setting, future prospective studies are needed to optimize the timing of CRP reassessment during inpatient hospitalization to prognosticate patient outcomes, weighing both improvements of patient care and clinical burden.

LEVEL OF EVIDENCE

Level III-retrospective comparative study.

Effects of prophylactic antibiotic administration and antibiotic timing on culture results and clinical outcomes of paediatric musculoskeletal infection: a protocol for a randomised controlled clinical trial

INTRODUCTION

Musculoskeletal infection (MSI) is a common cause of morbidity among the paediatric population. Some clinicians recommend withholding prophylactic antibiotics until culture collection with an aim to improve the culture sensitivity. However, a recent retrospective study reported that prophylactic antibiotic administration did not affect culture sensitivities in either disseminated or local MSI in paediatric population, which is surprising. The aim of the present study is to investigate the effects of prophylactic antibiotic administration and the timing of antibiotic administration on culture sensitivity and clinical outcomes of paediatric MSI.

METHODS AND ANALYSIS

A randomised controlled clinical trial will be carried out. Individuals aged 0-18 years with a diagnosis of MSI will be screened and evaluated at the Shenzhen Children's Hospital. The participants will be randomly allocated into four groups, and they will receive the antibiotic treatment at different time points, that is, 1 week, 3 days, 1 day prior to tissue culture collection and 1 day after tissue culture collection, respectively. The primary outcome will be culture sensitivity. In addition, the disease-related markers including white blood cell count, C reactive protein, erythrocyte sedimentation rate, vital signs as well as the length of hospital stay will be measured or recorded accordingly. Using χ² tests, the rates of positive cultures will be compared between different groups. Statistical comparisons between the different patient groups regarding the confounding and outcome variables will be conducted using independent t-tests, Mann-Whitney U tests, χ² tests and Fisher's exact tests as appropriate with the significance level set to 5% (p<0.05).

ETHICS AND DISSEMINATION

This study has received ethical approval. The findings will be disseminated both in scientific conferences and peer-reviewed journal.

TRIAL REGISTRATION NUMBER

ChiCTR2100041631.

Clinical Scores Predict Acute and Chronic Complications in Pediatric Osteomyelitis: An External Validation

BACKGROUND

Pediatric acute hematogenous osteomyelitis (AHO) outcomes are highly dependent on the disease severity. Recently, the A-SCORE and C-SCORE, were proposed as predictors of an acute complicated course and chronic morbidity, respectively. The purpose of this study was to externally validate the A-SCORE and C-SCORE at a single institution.

METHODS

This IRB-approved retrospective chart review included AHO patients admitted at a tertiary referral hospital between October 1, 2015 and December 31, 2019. The inclusion criteria were ages 0 to 18 and clinical response to treatment. The exclusion criteria were immunocompromised status or penetrating inoculation.

RESULTS

The A-SCORE demonstrated an area under the receiver operator curve (ROC area) of >86% with regards to all acute complications. It also demonstrated sensitivities >85% and specificities >92% at the cut-off of 4 (Youden index) for all acute complications. The C-SCORE demonstrated an ROC area of 100% with regards to chronic osteomyelitis. It also demonstrated sensitivities >70% and specificities >93% for the chronic morbidity variables seen in our population at the cut-off of 3 (Youden index.).

CONCLUSIONS

These novel composite clinical scores, in combination with clinical judgment, could help guide early care decisions. The A-SCORE and C-SCORE are useful risk stratification tools in the management of pediatric AHO and in predicting acute complicated courses or chronic sequelae of AHO, respectively. These scoring systems, if integrated into standardized pediatric AHO guidelines, can allow clinicians to stratify the AHO population and guide clinical decision making.

LEVEL OF EVIDENCE

Level III (prognostic study, retrospective chart review).

Utility of Inflammatory Markers in Hospitalized Children With Skin Erythema

BACKGROUND

There is overlap in the clinical presentations of superficial skin infections (eg, cellulitis) and deeper infections (eg, osteomyelitis). Inflammatory markers are frequently obtained in hospitalized patients with cellulitis. However, it is unknown whether inflammatory markers discriminate between superficial and deeper infections.

METHODS

We performed a retrospective review of children hospitalized with erythema on the skin and diagnoses of cellulitis, bursitis, myositis, osteomyelitis, and/or tenosynovitis. Patients were grouped into superficial infection (cellulitis and bursitis) and deeper infection (myositis, tenosynovitis, osteomyelitis). We compared C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) values between the two groups and constructed receiver operating characteristic curves to determine optimal cutoff values.

RESULTS

Among 168 children hospitalized with skin erythema, 122 patients had superficial and 46 patients had deeper infections. Mean CRP and ESR were significantly higher in patients with deeper infections (CRP: 8.3 [±9.6] mg/dL versus 2.8 [±3.5] mg/dL; P < .001; ESR: 48.3 [±28.6] mm/h versus 21.8 [±16.0] mm/h; P < .001). Neither WBC nor fever was significantly different between groups. CRP ≥2 mg/dL and ESR ≥30 mm/h were associated with deeper infections (CRP: odds ratio: 4.77; 95% confidence interval: 2.24-10.15; ESR: odds ratio: 7.93; 95% confidence interval: 3.46-17.67). When CRP and ESR were below these cutoffs, the negative predictive value was 89%.

CONCLUSIONS

Among patients presenting with skin erythema, CRP ≥2 mg/dL and ESR ≥30 mm/hr were significantly associated with deeper infection, whereas values below these cutoffs were reassuring against deeper infection. Future study of inflammatory markers in skin and soft tissue infections may help develop tailored testing strategies.

Prediction of Adverse Outcomes in Pediatric Acute Hematogenous Osteomyelitis

BACKGROUND

Clinicians cannot reliably predict complications of acute hematogenous osteomyelitis (AHO).

METHODS

Consecutive cases of AHO from 2 pediatric centers in the United States were analyzed retrospectively to develop clinical tools from data obtained within 96 hours of hospitalization to predict acute and chronic complications of AHO. Two novel composite prediction scores derived from multivariable logistic regression modeling were compared with a previously published severity of illness (SOI) score, C-reactive protein (CRP), and erythrocyte sedimentation rate (ESR) using area under the receiver operating characteristic curve analyses.

RESULTS

The causative organisms were identified in 73% of 261 cases. Bacteremia (45%), abscesses (38%), and associated suppurative arthritis (23%) were relatively common. Acute or chronic complications occurred in 24% and 11% of patients, respectively. Multivariable logistic regression identified bone abscess (odds ratio [OR], 2.3 [95% confidence interval {CI}, 1.0-5.2]), fever > 48 hours (OR, 2.7 [95% CI, 1.2-6.0]), suppurative arthritis (OR, 3.2 [95% CI, 1.3-7.5]), disseminated disease (OR, 4.6 [95% CI, 1.5-14.3]), and delayed source control (OR, 5.1 [95% CI, 1.4-19.0]) as strong predictors of acute complications. In a separate model, CRP ≥ 100 mg/L at 2-4 days after antibiotics (OR, 2.7 [95% CI, 1.0-7.3]), disseminated disease (OR, 3.3 [95% CI, 1.1-10.0]), and requirement for bone debridement (OR, 6.7 [95% CI, 2.1-21.0]) strongly predicted chronic morbidity. These variables were combined to create weighted composite prediction scores for acute (A-SCORE) and chronic (C-SCORE) osteomyelitis, which were superior to SOI, CRP, and ESR and had negative predictive values > 90%.

CONCLUSIONS

Two novel composite clinical scores were superior to existing tools to predict complications of pediatric AHO.

The Heterogeneity of Pediatric Knee Infections: A Retrospective Analysis

BACKGROUND

Musculoskeletal infection is a major cause of morbidity in the pediatric population. Despite the canonical teaching that an irritable joint and signs of infection likely represent an infected joint space, recent evidence in the pediatric hip has demonstrated that alternative diagnoses are equally or more likely and that combinations of pathologies are common. The knee is the second most commonly infected joint in children, yet there remains a paucity of available data regarding the epidemiology and workup of the infected pediatric knee. The authors hypothesize that there is heterogeneity of pathologies, including combinations of pathologies, that presents as a potentially infected knee in a child. The authors aim to show the utility of magnetic resonance imaging and epidemiologic and laboratory markers in the workup of these patients.

METHODS

A retrospective review of all consults made to the pediatric orthopaedic surgery team at a single tertiary care center from September 2009 through December 2015 regarding a concern for potential knee infection was performed. Excluded from the study were patients with penetrating trauma, postoperative infection, open fracture, no C-reactive protein (CRP) within 24 hours of admission, sickle cell disease, an immunocompromised state, or chronic osteomyelitis.

RESULTS

A total of 120 patients were analyzed in this study. There was marked variability in pathologies. Patients with isolated osteomyelitis or osteomyelitis+septic arthritis were older, had an increased admission CRP, were more likely to be infected with Staphylococcus aureus, required an increased duration of antibiotics, and had an increased incidence of musculoskeletal complications than patients with isolated septic arthritis.

CONCLUSIONS

When considering a child with an irritable knee, a heterogeneity of potential underlying pathologies and combinations of pathologies are possible. Importantly, the age of the patient and CRP can guide a clinician when considering further workup. Older patients with a higher admission CRP value warrant an immediate magnetic resonance imaging, as they are likely to have osteomyelitis, which was associated with worse outcomes when compared with patients with isolated septic arthritis.

LEVEL OF EVIDENCE

Level III-retrospective research study.

Staphylococcus aureus Osteomyelitis: Bone, Bugs, and Surgery

Osteomyelitis, or inflammation of bone, is most commonly caused by invasion of bacterial pathogens into the skeleton. Bacterial osteomyelitis is notoriously difficult to treat, in part because of the widespread antimicrobial resistance in the preeminent etiologic agent, the Gram-positive bacterium Staphylococcus aureus Bacterial osteomyelitis triggers pathological bone remodeling, which in turn leads to sequestration of infectious foci from innate immune effectors and systemically delivered antimicrobials. Treatment of osteomyelitis therefore typically consists of long courses of antibiotics in conjunction with surgical debridement of necrotic infected tissues. Even with these extreme measures, many patients go on to develop chronic infection or sustain disease comorbidities. A better mechanistic understanding of how bacteria invade, survive within, and trigger pathological remodeling of bone could therefore lead to new therapies aimed at prevention or treatment of osteomyelitis as well as amelioration of disease morbidity. In this minireview, we highlight recent developments in our understanding of how pathogens invade and survive within bone, how bacterial infection or resulting innate immune responses trigger changes in bone remodeling, and how model systems can be leveraged to identify new therapeutic targets. We review the current state of osteomyelitis epidemiology, diagnostics, and therapeutic guidelines to help direct future research in bacterial pathogenesis.

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.

Knee orthopedic problems in newborns and infancy: a review

PURPOSE OF REVIEW

We present the reader with insight on the most common disorders of the knee in newborns and infants. Knee issues in this population may confuse the first contact physicians due to certain peculiarities of the immature immune system, small size and underdevelopment of joint anatomy. Data presented here are recent and significant, and something to bear in mind when caring for children of this age.

RECENT FINDINGS

With the advent of new diagnostic methods, a shift in the causative agent of pediatric knee infections has been noted. Minimally invasive methods such as arthrocentesis and arthroscopy are successfully employed in treatment of knee problems in newborns and infants. A trial of conservative therapy in congenital patellar instability can give good results, and obviate the need for surgery in some cases. Various syndromes that affect the knee have specific characteristics that need to be recognized early to avoid problems in the future.

SUMMARY

Although rare, knee problems in infants can and do occur. Their cause varies significantly and good outcomes require a multidisciplinary approach. Early diagnosis, referral and initiation of treatment protocols can significantly influence the fate of the joint and with it the patients' functional status for life.

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.

C-Reactive Protein Predicts Risk of Venous Thromboembolism in Pediatric Musculoskeletal Infection

BACKGROUND

The rate of venous thromboembolism in children with musculoskeletal infections (MSKIs) is markedly elevated compared with hospitalized children in general. Predictive biomarkers to identify high-risk patients are needed to prevent the significant morbidity and rare mortality associated with thrombotic complications. We hypothesize that overactivation of the acute phase response is associated with the development of pathologic thrombi and we aim to determine whether elevations in C-reactive protein (CRP) are associated with increased rates of thrombosis in pediatric patients with MSKI.

METHODS

A retrospective cohort study measuring CRP in pediatric MSKI patients with or without thrombotic complications.

RESULTS

The magnitude and duration of elevation in CRP values correlated with the severity of infection and the development of pathologic thrombosis. In multivariable logistic regression, every 20 mg/L increase in peak CRP was associated with a 29% increased risk of thrombosis (P<0.001). Peak and total CRP were strong predictors of thrombosis with area under the receiver-operator curves of 0.90 and 0.92, respectively.

CONCLUSIONS

Future prospective studies are warranted to further define the discriminatory power of CRP in predicting infection-provoked thrombosis. Pharmacologic prophylaxis and increased surveillance should be strongly considered in patients with MSKI, particularly those with disseminated disease and marked elevation of CRP.

LEVEL OF EVIDENCE

Level III.

Similar Clinical Severity and Outcomes for Methicillin-Resistant and Methicillin-Susceptible Staphylococcus aureus Pediatric Musculoskeletal Infections

BACKGROUND

Prior studies of pediatric musculoskeletal infection have suggested that methicillin-resistant Staphylococcus aureus (MRSA) infections result in worse outcomes compared with infections with methicillin-susceptible S aureus (MSSA) strains. Based on these results, clinical prediction algorithms have been developed to differentiate between MRSA and MSSA early in a patient's clinical course. This study compares hospital outcomes for pediatric patients with MRSA and MSSA musculoskeletal infection presenting to the emergency department at a large tertiary care children's hospital.

METHODS

A retrospective study identified pediatric patients with S aureus musculoskeletal infection over a 5-year period (2008-2013) by sequential review of all pediatric orthopedic consults. Relevant demographic information, laboratory values, and clinical outcomes were obtained from the electronic medical record.

RESULTS

Of the 91 identified cases of S aureus pediatric musculoskeletal infection, there were 49 cases of MRSA infection (53%) and 42 cases of MSSA infection (47%). There were no significant differences between MRSA and MSSA infections in median hospital length of stay (4.8 vs 5.7 days, P = .50), febrile days (0.0 vs 1.5 days, P = .10), and antibiotic duration (28 vs 34 days, P = .18). Methicillin-resistant S aureus infections were more likely to require operative intervention than MSSA infection (85% vs 62%, P = .15). A logistic regression model based on C-reactive protein, temperature, white blood cell count, pulse, and respiratory rate at presentation demonstrated poor ability to differentiate between MRSA and MSSA infection.

CONCLUSIONS

The results demonstrated no significant differences between MSSA and MRSA musculoskeletal infections for most hospital outcomes measured. However, MRSA infections required more operative interventions than MSSA infections. In addition, a predictive model based on severity markers obtained at presentation was unable to effectively differentiate between MRSA and MSSA infection. The clinical utility and capacity for early differentiation of MRSA and MSSA depends on virulence patterns that may vary temporally and geographically.