Diagnostic Challenges in Adolescent Septic Arthritis: A Case Report and Literature Review

Diagnostic Challenges in Adolescent Septic Arthritis: A Case Report and Literature Review | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Case Report Diagnostic Challenges in Adolescent Septic Arthritis: A Case Report and Literature Review Fangjun Xiao, Wenli Luo, Yifei Liufu, Xinguo Zhang, Yu Huang, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8306344/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background Septic arthritis of the hip (SAH) is a severe and potentially disabling infectious condition in pediatric patients. Early diagnosis can be challenging due to atypical presentations, including the absence of classical signs of infection such as fever and leukocytosis. This case report explores the diagnostic challenges and highlights the importance of imaging and joint fluid analysis in diagnosing culture-negative septic arthritis of the hip. Case Presentation A 12-year-old boy presented with progressively worsening right hip pain, initially misdiagnosed as transient synovitis. Laboratory findings included The patient presented with a normal white blood cell count (8.56*10 9 /L), but markedly elevated C-reactive protein (CRP, 167.2 mg/L) and erythrocyte sedimentation rate (ESR, 95 mm/h). The synovial fluid analysis revealed an increase in neutrophils, elevated lactate dehydrogenase levels, and decreased glucose levels, while both blood and synovial fluid cultures were negative. MRI revealed bone marrow edema and joint effusion, raising suspicion for septic arthritis. Despite the absence of a confirmed pathogen, clinical presentation, synovial fluid analysis, and imaging findings led to the diagnosis of septic arthritis. The patient underwent arthroscopic lavage and received empirical antibiotic therapy, resulting in significant clinical improvement. Conclusion This case underscores the diagnostic difficulty in pediatric culture-negative septic arthritis, particularly in the absence of fever and with normal white blood cell counts. MRI plays a pivotal role in early detection and assessment of complications. Prompt surgical intervention and empirical antibiotic therapy remain crucial for successful management. Clinicians should maintain a high index of suspicion for atypical presentations to prevent delays in diagnosis and avoid long-term complications. Septic-arthritis Culture-negative Diagnosis Empirical antibiotic therapy Figures Figure 1 Figure 2 Introduction Septic arthritis of the hip (SAH) is a serious infectious disease requiring urgent intervention( 1 ). The occurrence rate of SAH is approximately 5–18/100,000 children with a higher prevalence noted in low- and middle-income nations( 2 ). Without prompt and appropriate therapy, it may lead to severe outcomes, including avascular necrosis, cartilage damage, joint instability, limb length differences, widespread infection, and future development of osteoarthritis ( 3 – 5 ). Taphylococcus aureus remains the predominant causative organism, while some rare microorganisms,such as brucella and tuberculosis, should be considered in endemic regions( 6 ). Diagnosing SAH in pediatric patients can be challenging due to the nonspecific and often subtle nature of initial clinical symptoms( 7 , 8 ). Unlike adults who typically present with localized pain, swelling, and fever, children may exhibit irritability, limp, refusal to bear weight, or referred pain—frequently to the knee rather than the hip—making early diagnosis difficult( 9 ). Laboratory markers such as white blood cell count, C-reactive protein (CRP), and erythrocyte sedimentation rate (ESR) may provide supportive evidence, yet they are not always elevated in early stages or atypical cases. Moreover, early radiographs are frequently unremarkable, while ultrasound and magnetic resonance imaging (MRI) have proven to be more sensitive modalities for detecting joint effusion, synovitis, and early osteoarticular changes( 10 ). Given the aggressive nature of this condition, prompt diagnosis and initiation of treatment—including empirical broad-spectrum intravenous antibiotics, surgical drainage, and joint decompression—are critical to preventing long-term morbidity. This case report presents an adolescent with culture-negative SAH who lacked classical systemic signs of infection. It underscores the importance of maintaining a high index of suspicion in atypical presentations and highlights the role of advanced imaging and joint fluid analysis in early recognition and management. Case Report A 12-year-old boy with no previous medical history presented with right hip pain that had developed 7 days earlier. He initially sought medical attention at a local clinic and was misdiagnosed with transient synovitis, for which bed rest was prescribed. However, his symptoms did not improve and progressively worsened, prompting a visit to our hospital. Upon admission, the patient was hemodynamically stable and afebrile. Nevertheless, he complained of severe pain in the right hip and refused to bear weight. While lying supine, he maintained his hip in a flexed, abducted, and internally rotated position. Due to the pain, both passive and active movements of the right hip were significantly restricted. Physical examination of the remaining musculoskeletal system and other organ systems revealed no significant abnormalities. No palpable lymphadenopathy or hepatosplenomegaly was observed. Laboratory investigations showed a normal white blood cell count of 8.56 × 10⁹/L, with a normal neutrophil ratio (51%) and lymphocyte ratio (34%). However, the erythrocyte sedimentation rate was markedly elevated at 95 mm/h, and the C-reactive protein (CRP) level was significantly increased to 167.2 mg/L. Blood cultures were negative. Anteroposterior pelvic radiographs and frog-leg lateral views of both hips, along with ultrasound and MRI, were performed. The radiographs showed no significant abnormalities (Fig. 1 ). Ultrasound revealed mild synovial thickening in the right hip, with anechoic joint effusion measuring approximately 11 mm in depth. Prior to further therapeutic intervention, a hip MRI was performed. Compared to the contralateral side, MRI demonstrated bone marrow edema involving the right acetabulum and femoral head, with distension of the right joint capsule, joint effusion, surrounding soft tissue edema, and irregularity of the right acetabular surface. These findings raised concern for SAH. (Figs. 2 ). Based on the current evidences, SAH was considered the primary differential diagnosis. However, the patient was afebrile, had no relevant infectious history, and his symptoms did not improve with conservative treatment. Diagnostic arthrocentesis of the right hip was performed, yielding serous yellow fluid (Fig. 3 ). Gram staining and bacterial cultures were obtained. Cytological analysis of the synovial fluid revealed a predominance of neutrophils (91%). Biochemical analysis showed elevated lactate dehydrogenase (LDH) at 811 U/L and decreased glucose concentration at 3.4 mmol/L. No microorganisms were identified on Gram staining, and cultures yielded no growth after 5 days. To prevent any specific microorganisms from being missed, blood samples were collected from both arms of the patient and subjected to both anaerobic and aerobic cultures. The incubation period was extended to 10 days, yet the final culture results still showed no bacterial growth. Despite the absence of a confirmed pathogen, the patient's clinical presentation and laboratory/imaging findings strongly suggested a purulent joint infection. Therefore, arthroscopic lavage of the right hip joint was performed using 6 liters of 0.9% saline. A drainage tube was inserted, and the wound was closed in layers. Empiric antibiotic therapy targeting common causative organisms of SAH was initiated, starting with intravenous ceftriaxone for 14 days, followed by oral cefprozil until one week after normalization of CRP and ESR levels. Following the initiation of treatment, the patient showed significant clinical improvement. Before discharge, we conducted an ultrasound examination on the patient and found no joint effusion.This case report was prepared approximately three months after the patient’s treatment. Verbal consent for publication was obtained through a brief telephone conversation with the patient’s mother and written consent was subsequently obtained. The patient reported no residual pain or functional limitations and had resumed all activities of daily living, including sports. Discussion SAH in children is a potentially devastating condition that requires prompt diagnosis and treatment to prevent irreversible joint damage and long-term disability( 11 ). However, the diagnosis can be particularly challenging when classical systemic signs of infection, such as fever and leukocytosis, are absent, and microbiological cultures yield negative results( 12 ). This case highlights the diagnostic difficulties in a 12-year-old boy presenting with progressive right hip pain, absence of fever, normal white blood cell count, and negative blood and synovial fluid cultures. Although both blood and synovial fluid cultures were ultimately negative, septic arthritis remained the primary concern throughout his initial workup. This is because the severity of his symptoms, his refusal to bear weight, and the profound elevation of CRP are classic 'red flags' that mandate an aggressive diagnostic approach to exclude SAH and prevent catastrophic joint destruction. The supporting MRI findings of joint effusion, bone marrow edema, and soft tissue inflammation further heightened this suspicion.The main alternative considerations included an inflammatory arthropathy, such as juvenile idiopathic arthritis (JIA), or a Malignancy. However, the monoarticular onset and absence of other systemic features make classic JIA less probable. Malignancy (e.g., Ewing sarcoma), while a critical exclusion, was deemed less likely in the absence of a soft tissue mass, cortical destruction, night pain, or cytopenias.Therefore, despite the negative cultures, the overall clinical picture— dominated by severe pain, functional impairment, and significant biochemical inflammation—is most consistent with a diagnosis of culture-negative septic arthritis. Early in the disease course, the patient was misdiagnosed with transient synovitis, a benign and self-limiting condition( 13 ). Although both transient synovitis and SAH can present with hip pain, limp, and reduced range of motion, the persistent and worsening symptoms in our case, despite rest, raised concern for a more serious pathology( 14 ). The modified Kocher-Caird criteria, including fever, inability to bear weight, erythrocyte sedimentation rate (ESR) > 40 mm/h, white blood cell (WBC) count > 12,000/mm³, and C-reactive protein (CRP) level > 20 mg/L, have been widely applied to distinguish septic arthritis from transient synovitis( 7 ). This patient met three of the Kocher criteria. Importantly, MRI findings played a pivotal role in raising suspicion for SAH. The presence of joint effusion, synovial thickening, and diffuse marrow edema involving the femoral head and acetabulum strongly indicated an infectious etiology( 15 ). Notably, the diminished enhancement of the femoral head on MRI suggested possibililty of early avascular necrosis, emphasizing the urgency for intervention( 16 ). Despite the absence of fever, normal peripheral WBC count, and sterile cultures, several factors supported the diagnosis of SAH: (a) elevated CRP and ESR levels; (b) synovial fluid analysis showing a predominantly neutrophilic profile (91% neutrophils); (c) decreased glucose and elevated lactate dehydrogenase in the joint fluid; and (d) rapid clinical improvement following joint lavage and empirical antibiotic therapy. Culture-negative SAH is not uncommon, with reported rates up to 50% in pediatric series, often attributed to prior antibiotic exposure, fastidious organisms, or low bacterial load( 11 ). The use of arthroscopic lavage allowed effective removal of purulent material while minimizing surgical trauma( 17 ). The use of arthroscopic lavage was favored over arthrotomy because it is minimally invasive, ensures effective drainage, and is associated with faster recovery in pediatric patients. Current literature supports arthroscopy as an effective alternative to open procedures in managing pediatric SAH( 17 , 18 ).Postoperative intravenous ceftriaxone followed by oral cephalosporins led to a marked clinical and biochemical improvement, further supporting an infectious etiology. In a study involving 198 SAH patients, it was found that pediatric SAH cases presented with afebrile symptoms, low CRP levels, and negative Staphylococcus aureus cultures, yet responded effectively to combined intravenous and oral antibiotic therapy( 11 ), indicating that this approach is effective for treating atypical SAH. In contrast, the negative culture results in this case suggest that early empirical coverage of common pathogens can achieve significant therapeutic efficacy even when the causative agent remains unidentified. This further supports the recommendation in current guidelines that treatment should not be delayed due to negative culture results( 19 ). This case reveals the importance of early intervention for SAH with negative results. However, we acknowledge several limitations in the present study. First, although synovial fluid culture was performed, advanced molecular testing—including broad-range PCR and next-generation sequencing—was not conducted as the patient declined these options due to cost considerations. Second, the absence of post-treatment follow-up MRI and ultrasound after 3 month represents another limitation. Conclusion This case highlights the diagnostic challenge of culture-negative SAH of the hip in children and the importance of a high index of suspicion for SAH in children presenting with persistent joint pain, particularly in the absence of classical systemic signs such as fever and leukocytosis. A high index of clinical suspicion, supported by imaging findings and synovial fluid analysis, is essential for early diagnosis. MRI plays a critical role in detecting early joint and bone involvement, while prompt surgical intervention and empirical antibiotic therapy are key to favorable outcomes. Clinicians should remain vigilant for atypical presentations to avoid delayed diagnosis and prevent serious complications. Declarations Acknowledgements Not applicable. Authors ’ contributions Conceptualization: FX, WL,YL; Data curation and analysis: YL, XZ, YH;Writing and visualization: FX, YL; Review and Editing: BZ, JY. Funding Not applicable. Data availability This is a retrospective case report, and the data only include X-ray images And MRI images. All data generated or analyzed during this study are included in this published article. Ethics approval and consent to participate This study is a retrospective study that analyzes anonymized medical records without involving any personally identifiable patient information. Therefore, individual patient consent for publication is not applicable to this study. Consent for publication Written informed consent was obtained from the legally authorized representative for publication of this case report. Competing interests The authors declare no competing interests. Clinical trial number not applicable. References Castellazzi L, Mantero M, Esposito S. Update on the Management of Pediatric Acute Osteomyelitis and Septic Arthritis. Int J Mol Sci. 2016;17(6). doi:10.3390/ijms17060855 Tretiakov M, Cautela FS, Walker SE, Dekis JC, Beyer GA, Newman JM, et al. Septic arthritis of the hip and knee treated surgically in pediatric patients: Analysis of the Kids' Inpatient Database. J Orthop. 2019;16(1):97-100. doi:10.1016/j.jor.2018.12.017 Duman S, Camurcu Y, Ucpunar H, Çöbden A, Karahan N, Sofu H. Arthroscopic Treatment of Acute Septic Arthritis of the Hip Joint in Pediatric Patients Aged 10 Years or Younger. Arthroscopy. 2020;36(2):464-72. doi:10.1016/j.arthro.2019.08.031 Montgomery NI, Epps HR. Pediatric Septic Arthritis. 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J Bone Joint Surg Am. 1999;81(12):1662-70. doi:10.2106/00004623-199912000-00002 Mooney JF, 3rd, Murphy RF. Septic arthritis of the pediatric hip: update on diagnosis and treatment. Curr Opin Pediatr. 2019;31(1):79-85. doi:10.1097/mop.0000000000000703 Ben-Zvi L, Sebag D, Izhaki G, Katz E, Bernfeld B. Diagnosis and Management of Infectious Arthritis in Children. Curr Infect Dis Rep. 2019;21(7):23. doi:10.1007/s11908-019-0678-5 Sanpera I, Salom M, Alves C, Eastwood D. Diagnosis and management of septic arthritis: A current concepts review. J Child Orthop. 2025;19(1):14-9. doi:10.1177/18632521241311302 Darraj H, Hakami KM, Zogel B, Maghrabi R, Khired Z. Septic Arthritis of the Knee in Children. Cureus. 2023;15(9):e45659. doi:10.7759/cureus.45659 Gaulrapp H, Schoof P, Schönecker G. Transient Hip Synovitis, 146 Cases, Origin and Duration. Z Orthop Unfall. 2025. doi:10.1055/a-2533-4972 QingSong T, XinLing M, Xiang R, Kang Z, Jie H. Clinical indicators for distinguishing septic arthritis from paediatric transient synovitis of the hip: a systematic review and meta-analysis. BMC Infect Dis. 2024;24(1):1432. doi:10.1186/s12879-024-10341-z Adam M, Ibrahim B, Khidir R, Elmahdi E, Ahmed S, Ahmed A. Usefulness of MRI findings in differentiating between septic arthritis and transient synovitis of hip joint in children: A systematic review and meta-analysis. Eur J Radiol Open. 2022;9:100439. doi:10.1016/j.ejro.2022.100439 Corin N, Bennet S, Hill J, Thomas S. Magnetic resonance imaging in the evaluation of suspected hip sepsis in children. J Child Orthop. 2022;16(5):409-15. doi:10.1177/18632521221126922 Donders CM, Spaans AJ, Bessems J, van Bergen CJA. Arthrocentesis, arthroscopy or arthrotomy for septic knee arthritis in children: a systematic review. J Child Orthop. 2021;15(1):48-54. doi:10.1302/1863-2548.15.200129 Donders CM, Spaans AJ, van Wering H, van Bergen CJ. Developments in diagnosis and treatment of paediatric septic arthritis. World J Orthop. 2022;13(2):122-30. doi:10.5312/wjo.v13.i2.122 Benito N, Martínez-Pastor JC, Lora-Tamayo J, Ariza J, Baeza J, Belzunegui-Otano J, et al. Executive summary: Guidelines for the diagnosis and treatment of septic arthritis in adults and children, developed by the GEIO (SEIMC), SEIP and SECOT. Enferm Infecc Microbiol Clin (Engl Ed). 2024;42(4):208-14. doi:10.1016/j.eimce.2023.07.007 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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1","display":"","copyAsset":false,"role":"figure","size":166314,"visible":true,"origin":"","legend":"\u003cp\u003eX-ray of the bilateral femur shows restricted positioning, with no other abnormalities detected. \u003cstrong\u003e(A) \u003c/strong\u003eAnteroposterior pelvic radiograph; \u003cstrong\u003e(B)\u003c/strong\u003eBilateral frog-leg lateral views\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-8306344/v1/544ce9bd3041dacf50f1a9c7.png"},{"id":99320191,"identity":"2a343767-e3fe-4ec7-9771-af5e232f3da9","added_by":"auto","created_at":"2025-12-31 16:38:23","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":356512,"visible":true,"origin":"","legend":"\u003cp\u003eBilateral hip magnetic resonance imaging (MRI). \u003cstrong\u003e(A) \u003c/strong\u003eCoronal view. \u003cstrong\u003e(B)\u003c/strong\u003e Axial view. The pink arrow indicates joint effusion, and the blue arrow points to bone marrow edema.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-8306344/v1/758d5486cd20969a578c63a8.png"},{"id":106094108,"identity":"4ac41a1a-c762-45b5-9d46-b7bb691afd0a","added_by":"auto","created_at":"2026-04-03 11:41:02","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":957941,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8306344/v1/ec2c40f9-ecb7-46ab-8693-aea38514d272.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Diagnostic Challenges in Adolescent Septic Arthritis: A Case Report and Literature Review","fulltext":[{"header":"Introduction","content":"\u003cp\u003eSeptic arthritis of the hip (SAH) is a serious infectious disease requiring urgent intervention(\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e). The occurrence rate of SAH is approximately 5\u0026ndash;18/100,000 children with a higher prevalence noted in low- and middle-income nations(\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e). Without prompt and appropriate therapy, it may lead to severe outcomes, including avascular necrosis, cartilage damage, joint instability, limb length differences, widespread infection, and future development of osteoarthritis (\u003cspan additionalcitationids=\"CR4\" citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e). \u003cem\u003eTaphylococcus aureus\u003c/em\u003e remains the predominant causative organism, while some rare microorganisms,such as brucella and tuberculosis, should be considered in endemic regions(\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eDiagnosing SAH in pediatric patients can be challenging due to the nonspecific and often subtle nature of initial clinical symptoms(\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e). Unlike adults who typically present with localized pain, swelling, and fever, children may exhibit irritability, limp, refusal to bear weight, or referred pain\u0026mdash;frequently to the knee rather than the hip\u0026mdash;making early diagnosis difficult(\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e). Laboratory markers such as white blood cell count, C-reactive protein (CRP), and erythrocyte sedimentation rate (ESR) may provide supportive evidence, yet they are not always elevated in early stages or atypical cases. Moreover, early radiographs are frequently unremarkable, while ultrasound and magnetic resonance imaging (MRI) have proven to be more sensitive modalities for detecting joint effusion, synovitis, and early osteoarticular changes(\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eGiven the aggressive nature of this condition, prompt diagnosis and initiation of treatment\u0026mdash;including empirical broad-spectrum intravenous antibiotics, surgical drainage, and joint decompression\u0026mdash;are critical to preventing long-term morbidity. This case report presents an adolescent with culture-negative SAH who lacked classical systemic signs of infection. It underscores the importance of maintaining a high index of suspicion in atypical presentations and highlights the role of advanced imaging and joint fluid analysis in early recognition and management.\u003c/p\u003e"},{"header":"Case Report","content":"\u003cp\u003eA 12-year-old boy with no previous medical history presented with right hip pain that had developed 7 days earlier. He initially sought medical attention at a local clinic and was misdiagnosed with transient synovitis, for which bed rest was prescribed. However, his symptoms did not improve and progressively worsened, prompting a visit to our hospital. Upon admission, the patient was hemodynamically stable and afebrile. Nevertheless, he complained of severe pain in the right hip and refused to bear weight. While lying supine, he maintained his hip in a flexed, abducted, and internally rotated position. Due to the pain, both passive and active movements of the right hip were significantly restricted. Physical examination of the remaining musculoskeletal system and other organ systems revealed no significant abnormalities. No palpable lymphadenopathy or hepatosplenomegaly was observed. Laboratory investigations showed a normal white blood cell count of 8.56 \u0026times; 10⁹/L, with a normal neutrophil ratio (51%) and lymphocyte ratio (34%). However, the erythrocyte sedimentation rate was markedly elevated at 95 mm/h, and the C-reactive protein (CRP) level was significantly increased to 167.2 mg/L. Blood cultures were negative. Anteroposterior pelvic radiographs and frog-leg lateral views of both hips, along with ultrasound and MRI, were performed. The radiographs showed no significant abnormalities (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eUltrasound revealed mild synovial thickening in the right hip, with anechoic joint effusion measuring approximately 11 mm in depth. Prior to further therapeutic intervention, a hip MRI was performed. Compared to the contralateral side, MRI demonstrated bone marrow edema involving the right acetabulum and femoral head, with distension of the right joint capsule, joint effusion, surrounding soft tissue edema, and irregularity of the right acetabular surface. These findings raised concern for SAH. (Figs.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eBased on the current evidences, SAH was considered the primary differential diagnosis. However, the patient was afebrile, had no relevant infectious history, and his symptoms did not improve with conservative treatment. Diagnostic arthrocentesis of the right hip was performed, yielding serous yellow fluid (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). Gram staining and bacterial cultures were obtained. Cytological analysis of the synovial fluid revealed a predominance of neutrophils (91%). Biochemical analysis showed elevated lactate dehydrogenase (LDH) at 811 U/L and decreased glucose concentration at 3.4 mmol/L. No microorganisms were identified on Gram staining, and cultures yielded no growth after 5 days. To prevent any specific microorganisms from being missed, blood samples were collected from both arms of the patient and subjected to both anaerobic and aerobic cultures. The incubation period was extended to 10 days, yet the final culture results still showed no bacterial growth.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eDespite the absence of a confirmed pathogen, the patient's clinical presentation and laboratory/imaging findings strongly suggested a purulent joint infection. Therefore, arthroscopic lavage of the right hip joint was performed using 6 liters of 0.9% saline. A drainage tube was inserted, and the wound was closed in layers. Empiric antibiotic therapy targeting common causative organisms of SAH was initiated, starting with intravenous ceftriaxone for 14 days, followed by oral cefprozil until one week after normalization of CRP and ESR levels. Following the initiation of treatment, the patient showed significant clinical improvement. Before discharge, we conducted an ultrasound examination on the patient and found no joint effusion.This case report was prepared approximately three months after the patient\u0026rsquo;s treatment. Verbal consent for publication was obtained through a brief telephone conversation with the patient\u0026rsquo;s mother and written consent was subsequently obtained. The patient reported no residual pain or functional limitations and had resumed all activities of daily living, including sports.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eSAH in children is a potentially devastating condition that requires prompt diagnosis and treatment to prevent irreversible joint damage and long-term disability(\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e). However, the diagnosis can be particularly challenging when classical systemic signs of infection, such as fever and leukocytosis, are absent, and microbiological cultures yield negative results(\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e). This case highlights the diagnostic difficulties in a 12-year-old boy presenting with progressive right hip pain, absence of fever, normal white blood cell count, and negative blood and synovial fluid cultures. Although both blood and synovial fluid cultures were ultimately negative, septic arthritis remained the primary concern throughout his initial workup. This is because the severity of his symptoms, his refusal to bear weight, and the profound elevation of CRP are classic 'red flags' that mandate an aggressive diagnostic approach to exclude SAH and prevent catastrophic joint destruction. The supporting MRI findings of joint effusion, bone marrow edema, and soft tissue inflammation further heightened this suspicion.The main alternative considerations included an inflammatory arthropathy, such as juvenile idiopathic arthritis (JIA), or a Malignancy. However, the monoarticular onset and absence of other systemic features make classic JIA less probable. Malignancy (e.g., Ewing sarcoma), while a critical exclusion, was deemed less likely in the absence of a soft tissue mass, cortical destruction, night pain, or cytopenias.Therefore, despite the negative cultures, the overall clinical picture\u0026mdash; dominated by severe pain, functional impairment, and significant biochemical inflammation\u0026mdash;is most consistent with a diagnosis of culture-negative septic arthritis.\u003c/p\u003e \u003cp\u003eEarly in the disease course, the patient was misdiagnosed with transient synovitis, a benign and self-limiting condition(\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e). Although both transient synovitis and SAH can present with hip pain, limp, and reduced range of motion, the persistent and worsening symptoms in our case, despite rest, raised concern for a more serious pathology(\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e). The modified Kocher-Caird criteria, including fever, inability to bear weight, erythrocyte sedimentation rate (ESR)\u0026thinsp;\u0026gt;\u0026thinsp;40 mm/h, white blood cell (WBC) count\u0026thinsp;\u0026gt;\u0026thinsp;12,000/mm\u0026sup3;, and C-reactive protein (CRP) level\u0026thinsp;\u0026gt;\u0026thinsp;20 mg/L, have been widely applied to distinguish septic arthritis from transient synovitis(\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e). This patient met three of the Kocher criteria.\u003c/p\u003e \u003cp\u003eImportantly, MRI findings played a pivotal role in raising suspicion for SAH. The presence of joint effusion, synovial thickening, and diffuse marrow edema involving the femoral head and acetabulum strongly indicated an infectious etiology(\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e). Notably, the diminished enhancement of the femoral head on MRI suggested possibililty of early avascular necrosis, emphasizing the urgency for intervention(\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eDespite the absence of fever, normal peripheral WBC count, and sterile cultures, several factors supported the diagnosis of SAH: (a) elevated CRP and ESR levels; (b) synovial fluid analysis showing a predominantly neutrophilic profile (91% neutrophils); (c) decreased glucose and elevated lactate dehydrogenase in the joint fluid; and (d) rapid clinical improvement following joint lavage and empirical antibiotic therapy. Culture-negative SAH is not uncommon, with reported rates up to 50% in pediatric series, often attributed to prior antibiotic exposure, fastidious organisms, or low bacterial load(\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe use of arthroscopic lavage allowed effective removal of purulent material while minimizing surgical trauma(\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e). The use of arthroscopic lavage was favored over arthrotomy because it is minimally invasive, ensures effective drainage, and is associated with faster recovery in pediatric patients. Current literature supports arthroscopy as an effective alternative to open procedures in managing pediatric SAH(\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e).Postoperative intravenous ceftriaxone followed by oral cephalosporins led to a marked clinical and biochemical improvement, further supporting an infectious etiology. In a study involving 198 SAH patients, it was found that pediatric SAH cases presented with afebrile symptoms, low CRP levels, and negative \u003cem\u003eStaphylococcus aureus\u003c/em\u003e cultures, yet responded effectively to combined intravenous and oral antibiotic therapy(\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e), indicating that this approach is effective for treating atypical SAH. In contrast, the negative culture results in this case suggest that early empirical coverage of common pathogens can achieve significant therapeutic efficacy even when the causative agent remains unidentified. This further supports the recommendation in current guidelines that treatment should not be delayed due to negative culture results(\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThis case reveals the importance of early intervention for SAH with negative results. However, we acknowledge several limitations in the present study. First, although synovial fluid culture was performed, advanced molecular testing\u0026mdash;including broad-range PCR and next-generation sequencing\u0026mdash;was not conducted as the patient declined these options due to cost considerations. Second, the absence of post-treatment follow-up MRI and ultrasound after 3 month represents another limitation.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThis case highlights the diagnostic challenge of culture-negative SAH of the hip in children and the importance of a high index of suspicion for SAH in children presenting with persistent joint pain, particularly in the absence of classical systemic signs such as fever and leukocytosis. A high index of clinical suspicion, supported by imaging findings and synovial fluid analysis, is essential for early diagnosis. MRI plays a critical role in detecting early joint and bone involvement, while prompt surgical intervention and empirical antibiotic therapy are key to favorable outcomes. Clinicians should remain vigilant for atypical presentations to avoid delayed diagnosis and prevent serious complications.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u003c/strong\u003e\u003cstrong\u003e\u0026rsquo;\u003c/strong\u003e\u003cstrong\u003econtributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eConceptualization:\u0026nbsp;FX, WL,YL; Data curation and analysis:\u0026nbsp;YL, XZ, YH;Writing and visualization:\u0026nbsp;FX, YL; Review and Editing:\u0026nbsp;BZ, JY.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis is a retrospective case report, and the data only include X-ray images And MRI images. All data generated or analyzed during this study are included in this published article.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study is a retrospective study that analyzes anonymized medical records without involving any personally identifiable patient information. Therefore, individual patient consent for publication is not applicable to this study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWritten informed consent was obtained from the legally authorized representative for publication of this case report.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eClinical trial number\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;not applicable.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eCastellazzi L, Mantero M, Esposito S. Update on the Management of Pediatric Acute Osteomyelitis and Septic Arthritis. Int J Mol Sci. 2016;17(6). doi:10.3390/ijms17060855\u003c/li\u003e\n\u003cli\u003eTretiakov M, Cautela FS, Walker SE, Dekis JC, Beyer GA, Newman JM, et al. Septic arthritis of the hip and knee treated surgically in pediatric patients: Analysis of the Kids\u0026apos; Inpatient Database. J Orthop. 2019;16(1):97-100. doi:10.1016/j.jor.2018.12.017\u003c/li\u003e\n\u003cli\u003eDuman S, Camurcu Y, Ucpunar H, \u0026Ccedil;\u0026ouml;bden A, Karahan N, Sofu H. Arthroscopic Treatment of Acute Septic Arthritis of the Hip Joint in Pediatric Patients Aged 10 Years or Younger. Arthroscopy. 2020;36(2):464-72. doi:10.1016/j.arthro.2019.08.031\u003c/li\u003e\n\u003cli\u003eMontgomery NI, Epps HR. Pediatric Septic Arthritis. Orthop Clin North Am. 2017;48(2):209-16. doi:10.1016/j.ocl.2016.12.008\u003c/li\u003e\n\u003cli\u003eThompson RM, Gourineni P. Arthroscopic Treatment of Septic Arthritis in Very Young Children. J Pediatr Orthop. 2017;37(1):e53-e7. doi:10.1097/bpo.0000000000000659\u003c/li\u003e\n\u003cli\u003eCohen E, Katz T, Rahamim E, Bulkowstein S, Weisel Y, Leibovitz R, et al. Septic arthritis in children: Updated epidemiologic, microbiologic, clinical and therapeutic correlations. Pediatr Neonatol. 2020;61(3):325-30. doi:10.1016/j.pedneo.2020.02.006\u003c/li\u003e\n\u003cli\u003eCaird MS, Flynn JM, Leung YL, Millman JE, D\u0026apos;Italia JG, Dormans JP. Factors distinguishing septic arthritis from transient synovitis of the hip in children. A prospective study. J Bone Joint Surg Am. 2006;88(6):1251-7. doi:10.2106/jbjs.E.00216\u003c/li\u003e\n\u003cli\u003eKocher MS, Zurakowski D, Kasser JR. Differentiating between septic arthritis and transient synovitis of the hip in children: an evidence-based clinical prediction algorithm. J Bone Joint Surg Am. 1999;81(12):1662-70. doi:10.2106/00004623-199912000-00002\u003c/li\u003e\n\u003cli\u003eMooney JF, 3rd, Murphy RF. Septic arthritis of the pediatric hip: update on diagnosis and treatment. Curr Opin Pediatr. 2019;31(1):79-85. doi:10.1097/mop.0000000000000703\u003c/li\u003e\n\u003cli\u003eBen-Zvi L, Sebag D, Izhaki G, Katz E, Bernfeld B. Diagnosis and Management of Infectious Arthritis in Children. Curr Infect Dis Rep. 2019;21(7):23. doi:10.1007/s11908-019-0678-5\u003c/li\u003e\n\u003cli\u003eSanpera I, Salom M, Alves C, Eastwood D. Diagnosis and management of septic arthritis: A current concepts review. J Child Orthop. 2025;19(1):14-9. doi:10.1177/18632521241311302\u003c/li\u003e\n\u003cli\u003eDarraj H, Hakami KM, Zogel B, Maghrabi R, Khired Z. Septic Arthritis of the Knee in Children. Cureus. 2023;15(9):e45659. doi:10.7759/cureus.45659\u003c/li\u003e\n\u003cli\u003eGaulrapp H, Schoof P, Sch\u0026ouml;necker G. Transient Hip Synovitis, 146 Cases, Origin and Duration. Z Orthop Unfall. 2025. doi:10.1055/a-2533-4972\u003c/li\u003e\n\u003cli\u003eQingSong T, XinLing M, Xiang R, Kang Z, Jie H. Clinical indicators for distinguishing septic arthritis from paediatric transient synovitis of the hip: a systematic review and meta-analysis. BMC Infect Dis. 2024;24(1):1432. doi:10.1186/s12879-024-10341-z\u003c/li\u003e\n\u003cli\u003eAdam M, Ibrahim B, Khidir R, Elmahdi E, Ahmed S, Ahmed A. Usefulness of MRI findings in differentiating between septic arthritis and transient synovitis of hip joint in children: A systematic review and meta-analysis. Eur J Radiol Open. 2022;9:100439. doi:10.1016/j.ejro.2022.100439\u003c/li\u003e\n\u003cli\u003eCorin N, Bennet S, Hill J, Thomas S. Magnetic resonance imaging in the evaluation of suspected hip sepsis in children. J Child Orthop. 2022;16(5):409-15. doi:10.1177/18632521221126922\u003c/li\u003e\n\u003cli\u003eDonders CM, Spaans AJ, Bessems J, van Bergen CJA. Arthrocentesis, arthroscopy or arthrotomy for septic knee arthritis in children: a systematic review. J Child Orthop. 2021;15(1):48-54. doi:10.1302/1863-2548.15.200129\u003c/li\u003e\n\u003cli\u003eDonders CM, Spaans AJ, van Wering H, van Bergen CJ. Developments in diagnosis and treatment of paediatric septic arthritis. World J Orthop. 2022;13(2):122-30. doi:10.5312/wjo.v13.i2.122\u003c/li\u003e\n\u003cli\u003eBenito N, Mart\u0026iacute;nez-Pastor JC, Lora-Tamayo J, Ariza J, Baeza J, Belzunegui-Otano J, et al. Executive summary: Guidelines for the diagnosis and treatment of septic arthritis in adults and children, developed by the GEIO (SEIMC), SEIP and SECOT. Enferm Infecc Microbiol Clin (Engl Ed). 2024;42(4):208-14. doi:10.1016/j.eimce.2023.07.007\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Septic-arthritis, Culture-negative, Diagnosis, Empirical antibiotic therapy","lastPublishedDoi":"10.21203/rs.3.rs-8306344/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8306344/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eSeptic arthritis of the hip (SAH) is a severe and potentially disabling infectious condition in pediatric patients. Early diagnosis can be challenging due to atypical presentations, including the absence of classical signs of infection such as fever and leukocytosis. This case report explores the diagnostic challenges and highlights the importance of imaging and joint fluid analysis in diagnosing culture-negative septic arthritis of the hip.\u003c/p\u003e\u003ch2\u003eCase Presentation\u003c/h2\u003e \u003cp\u003eA 12-year-old boy presented with progressively worsening right hip pain, initially misdiagnosed as transient synovitis. Laboratory findings included The patient presented with a normal white blood cell count (8.56*10\u003csup\u003e9\u003c/sup\u003e /L), but markedly elevated C-reactive protein (CRP, 167.2 mg/L) and erythrocyte sedimentation rate (ESR, 95 mm/h). The synovial fluid analysis revealed an increase in neutrophils, elevated lactate dehydrogenase levels, and decreased glucose levels, while both blood and synovial fluid cultures were negative. MRI revealed bone marrow edema and joint effusion, raising suspicion for septic arthritis. Despite the absence of a confirmed pathogen, clinical presentation, synovial fluid analysis, and imaging findings led to the diagnosis of septic arthritis. The patient underwent arthroscopic lavage and received empirical antibiotic therapy, resulting in significant clinical improvement.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eThis case underscores the diagnostic difficulty in pediatric culture-negative septic arthritis, particularly in the absence of fever and with normal white blood cell counts. MRI plays a pivotal role in early detection and assessment of complications. Prompt surgical intervention and empirical antibiotic therapy remain crucial for successful management. Clinicians should maintain a high index of suspicion for atypical presentations to prevent delays in diagnosis and avoid long-term complications.\u003c/p\u003e","manuscriptTitle":"Diagnostic Challenges in Adolescent Septic Arthritis: A Case Report and Literature Review","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-12-30 09:53:00","doi":"10.21203/rs.3.rs-8306344/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"581900fa-6748-4663-bac2-384d5763c02e","owner":[],"postedDate":"December 30th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-04-02T07:58:35+00:00","versionOfRecord":[],"versionCreatedAt":"2025-12-30 09:53:00","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8306344","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8306344","identity":"rs-8306344","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}