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

Differentiating Between Knee Septic Arthritis and Lyme Arthritis in Children: A Clinical Prediction Algorithm for a Geographically Diverse Population

BACKGROUND

Knee septic arthritis (SA) and Lyme arthritis (LA) often have similar presentations but bacterial SA necessitates urgent surgery. Predictive factors for differentiating SA and other infectious/inflammatory conditions have been published. Our purpose was to test these algorithms using a retrospective multicenter musculoskeletal infection database.

METHODS

Patients ≤18 years old with isolated knee SA or LA were identified. Diagnostic criteria for SA were synovial WBC count >50,000 cells/mm3, imaging with fluid aspiration suggestive of SA, or joint aspirate/tissue sample cultured positive for bacteria. Diagnostic criteria for LA was positive Lyme titer. Demographics, weightbearing status, admission vitals, and laboratory tests were collected. Predictive factors from Baldwin criteria for differentiating knee SA and LA, and Kocher criteria for differentiating hip SA and transient synovitis were tested.

RESULTS

One hundred fifty-five patients (119 SA and 36 LA) were analyzed. Patients with SA were younger (2.2 vs. 8.0 y), more nonweightbearing (74% vs. 33%), had a higher pulse (127 vs. 106), and higher WBC (12.4 vs. 10.2) (all P<0.001).Baldwin criteria (pain with joint motion, history of fever, CRP >40 mg/L, age <2 y) were tested. Pain with motion was not collected in our database. Of the remaining factors, the probability of SA was 63% with 0 and 92% with 3 factors (AUC 0.64). Kocher criteria (nonweightbearing, temperature >101.3°F, WBC >12.0, ESR >40) and CRP >20 mg/L were also tested. The probability of SA was 41% with 0 and 96% with all factors (AUC 0.69).Using our cohort data, regression analysis with backward stepwise elimination determined that age <4 years, nonweightbearing, admission WBC >13.0, platelets <325, and ESR >70 were predictive factors for SA. The probability of SA with 0 factors was 16%, 1 factor 52%, 2 factors 86%, 3 factors 97%, and 4 factors 100% (AUC 0.86).

CONCLUSIONS

Our model identified age <4 years, nonweightbearing, admission WBC >13.0, platelets <325, and ESR >70 as independent predictive factors for knee SA. The more factors present, the higher the likelihood of having SA versus LA.

LEVEL OF EVIDENCE

Diagnostic level III.

Risk of repeated drainage in pediatric septic arthritis: patient or method?

How drainage of septic arthritis should be performed remains controversial. The aim of the present study was to compare arthrocentesis (Ac) using double intra-articular needle lavage to arthrotomy (At) as first-line drainage treatment for pediatric hip and knee septic arthritis. The secondary objective was to identify risk factors of second articular drainage. A retrospective review of medical records of children with knee and hip septic arthritis was conducted. Inclusion criteria were: children treated for septic arthritis between 2014 and 2020 with a positive culture of joint fluid. Clinical, biological, radiographical and ultrasound data were recorded at presentation and during follow-up. Patients were divided into 2 groups according to the type of drainage performed: Ac or At. 25 hips and 44 knees were included, 42 treated by Ac (15 hips, 27 knees) and 27 by At (10 hips, 17 knees). There is no significant difference between Ac and At regarding the need for repeated drainage and Ac nor At was reported as risk factor for repeated drainage. The presence of associated musculoskeletal infection (MSI) was a significant risk factor of repeated drainage [odds ratio = 11.8; 95% confidence interval = 1.2-114.2; P  < 0.001]. Significantly more associated MSI ( P  < 0.001), level I virulence germs ( P  < 0.001) and positive blood culture (<0.001) were found in patients who underwent repeated drainage. There was no significant difference between Ac and At regarding rate of repeated drainage. The risk factors for repeated drainage were: associated with MSI, virulent germs and positive blood culture.

Native Joint Septic Arthritis

Native joint septic arthritis (NJSA) is a severe and rapidly progressing joint infection, predominantly bacterial but also potentially fungal or viral, characterized by synovial membrane inflammation and joint damage, necessitating urgent and multidisciplinary management to prevent permanent joint damage and systemic sepsis. Common in large joints like knees, hips, shoulders, and elbows, NJSA's incidence is elevated in individuals with conditions like rheumatoid arthritis, diabetes, immunosuppression, joint replacement history, or intravenous drug use. This review provides a comprehensive overview of NJSA, encompassing its diagnosis, treatment, antibiotic therapy duration, and surgical interventions, as well as the comparison between arthroscopic and open debridement approaches. Additionally, it explores the unique challenges of managing NJSA in patients who have undergone graft anterior cruciate ligament (ACL) reconstruction. The epidemiology, risk factors, pathogenesis, microbiology, clinical manifestations, diagnosis, differential diagnosis, antibiotic treatment, surgical intervention, prevention, and prophylaxis of NJSA are discussed, highlighting the need for prompt diagnosis, aggressive treatment, and ongoing research to enhance patient outcomes.

What's New in Pediatric Septic Arthritis? A Review of Pertinent Clinical Questions

BACKGROUND

The evaluation and treatment of children with septic arthritis (SA) is challenging and requires an organized approach to address the spectrum of pathogens which appear to aggregate in age-specific groups. Although evidence-based guidelines have recently been published for the evaluation and treatment of children with acute hematogenous osteomyelitis, there is a relative dearth of literature devoted exclusively to SA.

METHODS

Recently published guidance for the evaluation and treatment of children with SA was reviewed and evaluated with respect to pertinent clinical questions to summarize what is new in this area of practice for pediatric orthopaedic surgeons.

RESULTS

Evidence suggests that there is a profound difference between children with primary SA and those who have contiguous osteomyelitis. This disruption of the commonly accepted paradigm of a continuum of osteoarticular infections has important implications in the evaluation and treatment of children with primary SA. Clinical prediction algorithms have been established to help determine the applicability of magnetic resonance imaging during the evaluation of children suspected to have SA. Antibiotic duration for SA has been recently studied with some evidence in favor of short-course parenteral followed by short-course oral therapy may be successful if the pathogen is not methicillin-resistant Staphylococcus aureus .

CONCLUSION

Recent studies of children with SA have provided better guidance for evaluation and treatment to improve diagnostic accuracy, processes of evaluation, and clinical outcomes.

LEVEL OF EVIDENCE

Level 4.

Clinical and Radiographic Outcomes and Treatment Algorithm for Septic Arthritis in Children

BACKGROUND

Septic arthritis (SA) in children is an acute inflammatory disease of the joints. If not treated promptly, it could become a surgical emergency. The incidence of the disease in children in Europe is approximately 2-7 per 100,000 children. The aim of this systematic review was to investigate which of these treatments-arthrocentesis, arthrotomy, and arthroscopy-provides better results in children and when to use them.

METHODS

Three independent authors conducted a systematic review of PubMed, ScienceDirect, and MEDLINE databases to assess studies with any level of evidence that reported the surgical outcome of SA. Two senior investigators evaluated and approved each stage's findings.

RESULTS

A total of 488 articles were found. After screening, we chose 24 articles that were suitable for full-text reading based on the inclusion and exclusion criteria. The results of our analysis showed that there are no numerically significant differences reported in the literature on clinical and radiographic outcomes by surgical technique.

CONCLUSIONS

We developed an algorithm that could be used if septic arthritis is suspected. Based on our results, the surgical technique to be used will depend on the operator who will perform it.

An update on recent progress of the epidemiology, etiology, diagnosis, and treatment of acute septic arthritis: a review

Acute septic arthritis is on the rise among all patients. Acute septic arthritis must be extensively assessed, identified, and treated to prevent fatal consequences. Antimicrobial therapy administered intravenously has long been considered the gold standard for treating acute osteoarticular infections. According to clinical research, parenteral antibiotics for a few days, followed by oral antibiotics, are safe and effective for treating infections without complications. This article focuses on bringing physicians up-to-date on the most recent findings and discussions about the epidemiology, etiology, diagnosis, and treatment of acute septic arthritis. In recent years, the emergence of antibiotic-resistant, particularly aggressive bacterial species has highlighted the need for more research to enhance treatment approaches and develop innovative diagnosis methods and drugs that might combat better in all patients. This article aims to furnish radiologists, orthopaedic surgeons, and other medical practitioners with contemporary insights on the subject matter and foster collaborative efforts to improve patient outcomes. This review represents the initial comprehensive update encompassing patients across all age groups.

Factors associated with subsequent surgery after septic arthritis of the knee in children

BACKGROUND

Septic arthritis of the knee in children is a challenging problem. Surgical debridement is an established treatment, but there is a paucity of literature on long-term prognosis.

AIM

To determine the rates and factors associated with return to surgery (RTS) and readmission after index surgical debridement for septic arthritis of the knee in children.

METHODS

This is a retrospective cohort study that utilizes data from the Healthcare Cost and Utilization Project (HCUP). We included patients between ages 0 to 18 years that underwent surgical debridement for septic arthritis of the knee between 2005 and 2017. Demographic data included age, gender, race, hospital type and insurance type. Clinical data including index admission length of stay (LOS) and Charlson Comorbidity Index (CCI) were available from the HCUP database. Descriptive statistics were used to summarize the data and univariate and multivariate analyses were performed.

RESULTS

Nine-hundred thirty-two cases of pediatric septic knee were included. This cohort was 62.3% male, with mean age of 9.0 (± 6.1) years. Approximately 46% of patients were white and approximately half had Medicaid insurance. Thirty-six patients (3.6%) required RTS at a minimum of 2 year after index surgery, and 172 patients (18.5%) were readmitted at any point. The mean readmission LOS was 11.6(± 11.3) d. Higher CCI was associated with RTS (P = 0.041). There were no significant associations in age, gender, race, insurance type, or type of hospital to which patients presented. Multivariate analysis showed that both increased CCI (P = 0.008) and shorter LOS (P = 0.019) were predictive of RTS.

CONCLUSION

Septic arthritis of the knee is an important condition in children. The CCI was associated with RTS at a minimum of 2 years after index procedure. No association was found with age, gender, race, insurance type, or hospital type. Shorter LOS and CCI were associated with RTS in multivariate analysis. Overall, risk of subsequent surgery and readmission after pediatric septic knee arthritis is low, and CCI and shorter LOS are predictive of RTS.

Seasonal Variation of Pediatric Septic Arthritis in the United States: A PHIS Database Study

BACKGROUND

The presence of seasonal patterns in pediatric septic arthritis cases is a common orthopaedic teaching. Seasonal variation has been seen in centers outside of the United States and with other inflammatory and infectious joint-related conditions within the country, but it is unknown if a seasonal pattern exists among different regions of the United States. The purpose of this study was to examine the seasonal variation of septic arthritis within specific regions across the United States.

METHODS

The Pediatric Health Information System database was queried for all patients 19 years or younger who were treated for septic arthritis. Data from 34 pediatric hospitals in the Pediatric Health Information System initiative were included. Centers were organized by geographical region, and season of presentation was determined using equinoxes/solstices. χ 2 tests were performed to detect seasonal differences in septic arthritis for the entire cohort and separated by geographical region. Proportion differences along with 95% CIs were provided.

RESULTS

Between 2016 and 2019, there were 5764 cases of septic arthritis. Median age at diagnosis was 6.2 years (range: 0 to 19.0 y). Each season contributed 24% to 25% of the total septic arthritis cases, and there were no significant differences detected between the 4 seasons ( P =0.66). There was no seasonal variation seen in the Midwest, South, or West ( P =0.71, 0.98, 0.36, respectively). However, there was seasonal variation in the Northeast ( P =0.05), with fall and summer having a higher percentage of cases (28%) than the winter (21%).

CONCLUSIONS

This study showed no clear seasonal variation in septic arthritis in children across the United States using a national database of pediatric hospital centers. However, there is regional seasonal variation in the Northeast, which may relate to climate differences. With no clear seasonal variation across the United States, continued diligence is needed in diagnosing septic arthritis throughout the year.

LEVEL OF EVIDENCE

Prognostic II.

Acute osteomyelitis of the patella due to Pseudomonas aeruginosa in an immunocompetent child: A case report

RATIONALE

Plentiful vascularity and lack of the physis are thought to render the patella less vulnerable to osteomyelitis. Pseudomonas aeruginosa (PA) is an opportunistic pathogen predominantly affecting immunocompromised hosts. Despite the ubiquitous nature of PA, osteomyelitis of the patella caused by PA has been rarely reported in children.

PATIENT CONCERNS

A 5-year-old boy who had presented with a prolonged history of the left anterior knee pain following minor trauma was diagnosed with prepatellar bacterial cellulitis and bursitis. Afterward, a focal osteolytic lesion emerged at the ventral surface of the patella despite oral and intravenous antibiotic therapy lasting for weeks. We described clinical presentation as well as medical and surgical management of pediatric patellar osteomyelitis secondary to prepatellar septic bursitis.

DIAGNOSES

Pseudomonas aeruginosa-associated osteomyelitis of the patella. Magnetic resonance imaging of the left knee showed a focal destructive change of the ventral half of the cartilaginous patella and a suprapatellar joint effusion. Bacterial culture from the bursa revealed Pseudomonas aeruginosa.

INTERVENTIONS

Systemic inflammation, patellar osteochondral destruction, and purulent synovial fluid of the knee were prolonged for 6 weeks despite antibiotics use deemed appropriate and reparative surgical debridement, whereas they were eventually resolved with a 6-week course of intravenous ceftazidime and cessation of continuous intracapsular irrigation.

OUTCOMES

He was clinically asymptomatic at the latest follow-up but exhibited a minor leg length discrepancy <2 cm associated with overgrowth of the affected femur.

LESSONS

This is a rare case of Pseudomonas osteomyelitis of the patella in a healthy pediatric patient. Uncommon osteochondral sequelae occurred probably because of a protracted arthritis of the affected knee. We would like to emphasize the ineffectiveness of continuous irrigation without antibiotics for Pseudomonas aeruginosa-associated osteomyelitis.

Case report: Acinetobacter baumannii septic arthritis in an immunocompetent infant

Acinetobacter baumannii is a gram-negative coccobacilli, mainly causing nosocomial infections with poor prognosis, especially in patients with prolonged hospitalization or antibiotics administration. A. baumannii pneumonia is the most common clinical form and usually occurs in critically ill patients in the intensive care unit. However, septic arthritis caused by A. baumannii is rarely reported. In this report, we describe a case of A. baumannii septic arthritis combined with incomplete Kawasaki disease in an infant. The child's chief complaint was a 2-week intermittent fever with poor response to antibiotics. Initial physical examination revealed swollen lymph nodes in the neck, pharynx congestion, and the appearance of rashes. Combined with laboratory tests, the diagnosis of incomplete Kawasaki disease was considered. After administration of high-dose intravenous immunoglobulin and corticosteroids, the child's fever improved and periungual desquamation appeared simultaneously. Swelling of the right knee occurred 5 days after the fever improved and imaging tests of MRI and ultrasound suggested the existence of infection. A diagnosis of septic arthritis was established subsequently, and arthroscopy was carried out. A. baumannii was finally identified by metagenomics next-generation sequencing of joint draining fluid for pathogenic microorganisms. Treatment with meropenem was then started. The patient eventually recovered and was discharged from the hospital after 23 days of treatment with meropenem. Although A. baumannii is not a common bacterium of septic arthritis, this rare infection can still occur in infants. Early diagnosis, pathogenic identification, and target antibiotic treatment are important to reduce the occurrence of joint sequelae.

Fever and Knee Effusion in the Pediatric Patient

ABSTRACT

The pediatric patient with fever and knee effusion is always a cause for clinical concern. A thorough history and physical examination is required to guide appropriate diagnostic evaluation and management. Although pediatric knee effusions are common in the setting of trauma, the presence of fever should prompt consideration of infectious, rheumatologic, vasculitic, and malignant etiologies. This review covers the key components of the history, physical examination, diagnostic strategies, common etiologies, and initial management of the pediatric patient with fever and knee effusion.

Diagnostic Utility of Synovial Fluid Cell Counts and CRP in Pediatric Knee Arthritis: A 10-Year Monocentric, Retrospective Study

Background: Orthopedic surgeons often use the intra-articular white blood counts (WBCs) and the percentage of polymorphonuclear cells (PMN) in the diagnosis of an acute swollen and painful knee joint in children. Today, there is no established threshold for the synovial WBC, and their differentiation, as indicative of native joint knee bacterial arthritis. We determine the sensitivity and specificity of synovial WBCs and PMN percentages in the prediction of a community-acquired, acute bacterial native joint septic arthritis (SA) in the pediatric population. Methods: A retrospective study on healthy children 0–16 years of age who underwent knee joint aspiration for a community-acquired, acute irritable knee effusion in our tertiary-care children’s hospital between May 2009 and April 2019 was conducted. We divided the study population into two groups according to the detection of bacterial arthritis in the synovial fluid (bacterial arthritis versus its absence) and compared the intra-articular leukocyte and C-reactive protein (CRP) levels. Results: Overall, we found a statistically significant difference regarding the total CRP (p = 0.017), leukocyte or PMN counts (p ≤ 0.001 in favor of a bacterial arthritis). In contrast, the percentage of the neutrophils was not determinant for the later confirmation of bacterial pathogens, and we were unable to establish diagnostically determining minimal thresholds of the intra-articular CRP and leukocyte levels. Conclusions: This pilot study suggests that either the leukocyte or PMN counts may be associated with a bacterial origin of knee arthritis in children. We plan a larger prospective interventional study in the future to confirm these findings including the investigation of other joint aspirate biomarkers.

Acute osteoarticular infections in children are frequently forgotten multidiscipline emergencies: beyond the technical skills

Acute osteoarticular infections (AOI) should be treated as top emergencies. The first few days following the inception of infection are ultra-critical to long-term prognosis.A comprehensive road map for management of childhood AOI is still lacking despite recent advances in microbiology and imaging (magnetic resonance imaging). The many faces of childhood AOI warrant a multidiscipline approach to management.Laboratory and imaging findings of are still debatable and should not overshadow or delay a management plan based on the experienced physician's clinical judgment.Ample evidence-based practice supports the use of a few days of intravenous antibiotic administration followed by oral therapy until correlative clinical and basic laboratory (acute phase reactants) results improve.The growing body of evidence on 'high-risk' children/neonates of AOI warrants continual clinical extra-vigilance in identifying these patient subsets.Open drainage and debridement remain the mainstay of treatment of septic hips, whereas for other joints the use of alternative surgical techniques should be individualized or on case-by-case basis.Because the consequences of misdiagnosis of AOI are usually grave and permanent, proactive treatment/overtreatment is justified in the event of unconfirmed but suspicious diagnosis. Cite this article: EFORT Open Rev 2021;6:584-592. DOI: 10.1302/2058-5241.6.200155.

Pediatric Septic Arthritis of the Knee Due to a Multi-Sensitive Streptococcus pyogenes Strain Responsive to Clindamycin-A Case Report

Septic arthritis is an inflammatory process usually generated by a bacterial infection. The knee is one of the most frequently involved joints. The etiology varies depending on age, and hematogenous spread remains the primary cause in children. Herein, we report a case of a previously healthy three-year-old female who was referred to our institution for acute swelling of her right knee. After a clinical and radiological diagnosis of septic arthritis, an empirical treatment with a combination of cefotaxime and clindamycin was initiated. The isolation of a multi-sensitive Streptococcus pyogenes strain from the joint’s effusion prompted the discontinuation of clindamycin and the usage of cefotaxime alone. One week later, an ultrasound was executed due to worsening in the patient’s clinical conditions, and an organized corpuscular intra-articular effusion with diffuse synovial thickening was revealed. Cefotaxime was therefore replaced with clindamycin, which improved the symptoms. Despite the antibiotic sensitivity test having revealed a microorganism with sensitivity to both cephalosporin and clindamycin, clinical resistance to cefotaxime was encountered and a shift in the antimicrobial treatment was necessary to ensure a full recovery. This case study confirms that an antibiotic regimen based solely on a susceptibility test may be ineffective for such cases.