Adjacent segment infection following instrumented fusion for lumbar degenerative disease: A case series of eight cases and review of literature

Adjacent segment infection following instrumented fusion for lumbar degenerative disease: A case series of eight cases and review of literature | 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 Research Article Adjacent segment infection following instrumented fusion for lumbar degenerative disease: A case series of eight cases and review of literature Yuhan Lin, Fengguang Wei, Boling Liu, Aixing Pan, Wenlong Wang, and 4 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7385163/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 6 You are reading this latest preprint version Abstract Background Adjacent segment infection (ASI) following instrumented lumbar fusion for lumbar degenerative disease(LDD) remains a rarely documented complication. While a few case reports have described this entity, to our knowledge this represents the first case series systematically characterizing ASI in the context of non-infectious lumbar degenerative disease. Methods This study analyzed 8 cases of ASI following instrumented lumbar fusion for LDD at a single institution, including 5 in-house cases (0.24% incidence among 2,075 surgeries) and 3 external referrals. Comprehensive data collection encompassed demographics, clinical presentation, comorbidities, inflammatory markers, multi-modal microbiological profiling, surgical parameters, infection timelines, and treatment outcomes. Results The cohort (median age 68.5 years, 6 males, 2 females) all presented with chronic back pain without fever, 62.5% exhibiting radiculopathy. Systemic inflammation markers showed universal ESR elevation, CRP elevation in 87.5%. Characteristic imaging findings revealed: All proximal pedicle screws demonstrated loosening signs, with halo signs universally present, cutting displacement occurred in 75%. ASI manifested at 2–58 months postoperatively (median 5.5 months), exclusively involving cranial adjacent segments (75% L1-L3). The pathogens were identified in all cases (including Mycobacterium tuberculosis, Moraxella osloensis, Prevotella bivia and Staphylococcus epidermidis ). Blood cultures were universally negative, while metagenomic next-generation sequencing (mNGS) detected pathogens in 62.5% and tissue cultures yielded pathogens in 50%. All patients underwent posterior-only approach debridement with fusion and instrumented revision. At a mean follow-up of 23 months, all patients demonstrated significant VAS score reduction and complete clinical resolution without recurrence. Conclusions ASI is relatively rare in clinical practice, predominantly manifesting as delayed-onset low-virulence infections. These patients frequently present with proximal instrumentation failure and demonstrate high failure rates with conservative management, thus early surgical intervention is strongly recommended. Trial registration Not applicable. This retrospective study did not require trial registration. Adjacent segment infection Degenerative lumbar disease Instrumented lumbar fusion metagenomic next-generation sequencing (mNGS) Revision spinal surgery Figures Figure 1 Figure 2 Introduction Instrumented lumbar fusion serves as a cornerstone procedure in spinal surgery for lumbar degenerative disease (LDD) including spondylolisthesis and stenosis. Postoperative infection represents one of the most prevalent complications, typically defined as surgical site infection (SSI) occurring at the operative spinal segments, with reported incidence rates ranging from 0.7–12%[ 1 ]. Current research predominantly focuses on SSI, while reports on adjacent segment infection (ASI) remain comparatively scarce. With advancements in diagnostic and therapeutic techniques, ASI has gradually gained recognition. The first ASI case reported by Kulkarni and Hee [ 2 ] described a C4-5 level epidural abscess developing after C5-C7 fusion. Basu et al. [ 3 ] documented a similar case of sinus tract formation with purulent discharge two weeks post C5-7 anterior cervical discectomy and fusion (ACDF), resulting in adjacent spinal segment infection. Lange et al. [ 4 ] described two ASI recurrences after surgery for lumbar spondylodiscitis, and Farah et al. [ 5 ] reported one ASI following surgery for thoracic spondylodiscitis. In a series of 23 patients, Siam et al. [ 6 ] reported for the first time in 2016 a prevalence of 1.9% of ASI after surgical fusion for spondylodiscitis. Zou et al. [ 7 ] reported 10 cases of fungal infections subsequent to lumbar discectomy, demonstrating progressive spread to adjacent segments. However, these ASI cases occurred after surgical treatment of spondylodiscitis. In non-infectious spinal surgeries, this complication demonstrates significantly lower incidence. We conducted a PubMed/Medline search and review of the available literature up to May 2025. This phenomenon has been described only in 6 published case reports about 10 patients[ 8 – 13 ] (Table 3 ). Therefore, this study presents the first case series of ASI following thoracolumbar fusion under non-infectious contexts. This study will systematically elucidate the clinical characteristics, analyze the pathophysiological mechanisms, investigate the pathogen spectrum, assess the risk factors, and evaluate the treatment strategies of ASI to provide a comprehensive clinical profile. Table 3 Previously reported cases of ASI in the context of non-infectious thoracolumbar degenerative disease Reference Case Age (y)/sex Initial Diagnosis Initial Surgery Time to infection(mo) Causative organism Treatment Outcome Formica, et al. [ 8 ] 1 69/F ASD T10-ilium PSF 1.5 Staphylococcus capitis post.revision (Undefined) Undefined Xin, et al. [ 9 ] 2 68/F LDD L4-5 PLIF 0.23* Negative Empiric ABx ×10wk Symptom Relief Nagoshi, et al. [ 10 ] 3 68/M LDD L3-S1 PLIF 21 MRSA PD and ASF (Fractionated) Clinical Cure 4 59/M LDD L3-5 PLIF, L2-3PLF 68 Streptococcus intermedius PD and ASF, post. instrumentation(Fractionated) Clinical Cure 5 47/M VBF T12-L2 ASF 48 Staphylococcus capitis Empiric ABx ×4wk Symptom Relief Iwami, et al. [ 11 ] 6 72/F ASD T10-ilium PSF 12 MRSA ASF + PSF, extended fixation to Th5(Fractionated) Clinical Cure 7 76/F ASD T10-ilium PSF 13 Staphylococcus epidermidis ASF + PSF, extended fixation to Th5 Clinical Cure Wang, et al. [ 12 ] 8 69/F LDD L3-5 PLIF, L2-3PLF 2 Negative L1-2 PDF and L1-L5 post. instrumentation Clinical Cure Mallepally, et al. [ 13 ] 9 61/F OVCF ant. T12 Corp + T9-L2 PSF 4 Mycobacterium tuberculosis AD and post. extended fixation to Th5 Clinical Cure 10 65/F OVCF ant. L1 Corp + T11-L3 PSF 4 Mycobacterium tuberculosis AD and post. extended fixation to Th7 Clinical Cure ASD, adult spinal deformity; LDD, Lumbar degenerative disease; VBF, vertebral burst fracture; OVCF,Osteoporotic Vertebral Compression Fracture; MRSA, methicillin-resistant Staphylococcus aureus; ASF, Anterior spinal fusion; Empiric ABx, EmpiricAntibiotic Therapy; NA, not available; PSF, posterior spinal fusion; PDF, posterior debridement fusion; AD, anterior debridement; post: posterior; Corp, Corpectomy. 0.23month = 1week Methods We reviewed all cases that underwent instrumented lumbar spinal fusion in our institute between October 2019 and March 2023. Postoperative ASI occurred in 5 cases (out of 2,075 cases operated, with an infection rate of 0.24%) and 3 cases were referred from other institutions (a total of 8 cases included). Data were collected on demographics, presenting signs and symptoms, and comorbidities. Information was obtained concerning spinal involvement level, pre-operative inflammatory markers [white blood cell count (WBC), neutrophil percentage(NEUT%), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), procalcitonin (PCT)], microbiological studies [metagenomic next-generation sequencing (mNGS), T-SPOT.TB assay, blood/tissue cultures, biopsy], and imaging modalities. Additional data were recorded, including the initial surgical approach, time to infection onset postoperatively, revision techniques, and prognostic outcomes. Result This retrospective series comprised 8 consecutive patients (6 males, 2 females) with a median age of 68.5 years (range: 53–82). All cases were afebrile at presentation but manifested chronic back pain (VAS: median 7, range: 5–9). Neurological involvement was observed in 62.5% (5/8) cases, presenting as lower extremity radiculopathy. Comorbidities included hypertension (n = 7), diabetes mellitus (n = 1). Systemic inflammation was evident in: Elevated ESR in all patients (median: 70 mm/h), CRP elevation (median: 20.3 mg/L) in 87.5% (7/8), Leukocytosis in 12.5% (1/8, Case 1; WBC 12.7×10⁹/L), NEUT% elevation (median: 72.9% ) and PCT elevation in 50% (4/8). Notably, Case 3 demonstrated concurrent perianal abscess which exhibited the highest CRP (181.5 mg/L) and PCT (30.6 ng/mL) levels (Table 1 ). Additionally, one case (Case 8) developed postoperative urinary tract infection following the initial surgical procedure, which resolved completely with appropriate antimicrobial therapy. Table 1 Demographics and comorbidities of patients and Clinical, laboratory data Case Age(y)/sex Temperature (℃) VAS Neurologic deficits Comorbidities WBC (cells/mm 3 ) NEUT% CRP (mg/L) ESR (mm/hr) PCT (ng/mL) 1 63/F 37.1 8 Radiculopathy HTN 12.7 76.6 110.16 62 < 0.05 2 75/M 36.7 7 None HTN, AF 6.4 69.2 9.66 103 < 0.05 3 71/M 36.5 9 Radiculopathy PA, HTN,RA 7.1 95.1 181.5 87 30.56 4 82/F 36.9 7 None HTN, DM 8.8 78 8.5 90 < 0.05 5 66/M 36.6 7 None HTN 7.8 76.3 43.73 45 0.105 6 53/M 36.7 5 Radiculopathy / 10.1 68.6 31 62 23.92 7 72/M 36.8 6 Radiculopathy HTN 5 58.6 5.3 35 < 0.05 8 65/M 36.4 6 Radiculopathy UTI, HTN 6.6 61 8.8 78 0.17 M, male; F, female; VAS, visual analog scale; WBC, white blood count; NEUT%: Neutrophil Percentage; CRP, C-reactive protein; ESR, erythrocyte sedimentation rate; PCT, Procalcitonin; HTN, Hypertension; AF, Atrial fibrillation; RA, Rheumatoid arthritis; DM, diabetes mellitus;PA, Perianal abscess; UTI, urinary tract infection; / = no comorbidities. All 8 patients exhibited cranial single-segment ASI involvement. Imaging revealed significant endplate erosion with vertebral destruction in 87.5% (7/8, excluding Case 5), universal cranial pedicle screw loosening with halo signs, and cutting displacement in 75% (excluding Cases 5–6). One case with an intradural abscess (Case 1, tuberculosis). The time to infection onset postoperatively ranged from 2 to 58 months (median 5.5 months), with a late-onset outlier at 58 months (Case 7). The affected segments included L2–3 (n = 3), L1-2 (n = 3), L3-4 (n = 1), and T12-L1 (n = 1)(Table 2 ). Table 2 Clinical, operative, and postoperative data Case Initial Diagnosis Initial Surgery Infection segment Time to infection(mo) Surgical technique mNGS T-SPOT.TB Blood Culture Tissue Culture Biopsy FU period (mo) VAS FU 1 LDD L3-5 PLIF L2-3 14 L2-3 PDF; T12-L4 post. instrumentation Mycobacterium tuberculosis Pos Neg Neg Pos 34 2 2 LDD L2-5 PLIF L1-2 4 L1-2 PDF; T12-L4 post. instrumentation Moraxella osloensis Neg Neg Neg Pos 46 2 3 LDD L2-4 PLIF, L1-2PLF T12-L1 3 T12-L1 PDF; T10-L4 post. instrumentation Prevotella bivia Neg Neg Neg Pos 51 2 4 LDD L3-5 PLIF, L2-3PLF L1-2 7 L1-2 PDF; L1-L3 post. instrumentation Neg Neg Neg Staphylococcus epidermidis Pos 12 2 5 LDD L4-S1 PLIF L3-4 2 L3-4 PDF; L2-S1 post. instrumentation Staphylococcus epidermidis Neg Neg Neg Pos 23 2 6 LDD L2-5 PLIF L1-2 18 L1-2 PDF; L1-L2 post. instrumentation Staphylococcus warneri Neg Neg Staphylococcus epidermidis Pos 4 3 7 LDD L3-5 PLIF L2-3 58 L2-3 PDF; L2-L3 post. instrumentation Neg Pos Neg Staphylococcus epidermidis Neg 4 2 8 LDD L3-5 PLIF L2-3 4 L2-3 PDF; L1-L4 post. instrumentation Neg Pos Neg Staphylococcus epidermidis Pos 12 2 LDD, Lumbar degenerative disease; PLIF,posterior lumbar interbody fusion; PLF,posterolateral fusion; mNGS, Metagenomic next-generation sequencing; Pos, Positive; Neg, Negative; VAS, visual analog scale; FU, follow-up; PDF, posterior debridement with fusion. Microbiological profiling revealed discordant results across modalities: Blood cultures were universally negative, whereas mNGS detected microbial signatures in 62.5% (5/8), identifying Mycobacterium tuberculosis, Moraxella osloensis, Prevotella bivia , and two coagulase-negative staphylococci species ( Staphylococcus epidermidis and Staphylococcus warneri ). Immunological testing showed 37.5% T-SPOT.TB positivity (3/8), though only one case correlated with tuberculosis. Tissue-based analyses demonstrated discordant culture positivity rates between specimen types, with 0% positivity in tissue fragment cultures versus 50% positivity in tissue fluid cultures (4/8 growing Staphylococcus epidermidis ). Histopathological evidence of inflammation was observed in 87.5% of biopsies (7/8). Collectively, microbial pathogens were identified through comprehensive diagnostic approaches in all cases(Table 2 ). All patients underwent definitive surgical management involving a standardized posterior approach for lesion resection and autologous bone graft fusion, coupled with revision instrumentation to restore spinal stability. Broad-spectrum antimicrobial therapy, initiated immediately postoperatively, was subsequently tailored according to culture-guided susceptibility profiles, with a duration of 6 weeks for antibacterial agents and extended to 12 months for antitubercular regimens. At a mean follow-up of 23 months post-revision, all patients demonstrated significant VAS score reduction and complete clinical resolution without recurrence (Table 2 ). Case presentations Case 4 A 79-year-old female with hypertension and diabetes underwent L2-3 posterolateral fusion (PLF) and L3-5 posterior lumbar interbody fusion (PLIF) for lumbar stenosis. Postoperative imaging confirmed proper implant positioning without screw cut-out. Seven months postoperatively, the patient developed low back pain (VAS 4) with percussion tenderness at the proximal incision site, without concurrent fever or radiating pain to the lower extremities. The original surgical incision remained well-healed without evidence of erythema/swelling. Although imaging demonstrated intact hardware fixation, MRI detected nonspecific inflammatory alterations at L1-2 without definitive endplate/osseous destruction. Normal inflammatory biomarkers (WBC/ESR/CRP) prompted conservative management through activity modification and oral linezolid therapy (0.6g q12h). Two months later, worsening pain (VAS 7) emerged with imaging demonstrating proximal screw loosening, endplate erosion, and osteolysis. Elevated ESR (103 mm/hr) and mild CRP/NEUT% elevation were noted, though blood cultures and T-SPOT.TB were negative. Revision surgery involving L1-2 posterior debridement with fusion and L1-L3 instrumentation was performed. Intraoperative cultures yielded Staphylococcus epidermidis , while mNGS returned negative results. Histopathological examination verified chronic inflammatory infiltration. Postoperative targeted antibiotics were administered for 6 weeks. At the 12-month follow-up, the patient reported functional recovery (VAS 2), and CT confirmed L1-2 fusion with stable implants (Fig. 1 ). Case 8 A 64-year-old hypertensive male underwent L3-5 PLIF for spondylolisthesis with stenosis at an external institution. Postoperative imaging showed proper implant positioning without screw cut-out. Two weeks postoperatively, the patient developed isolated fever without back pain or wound complications. Urine culture identified Enterococcus faecalis infection, which resolved with ceftriaxone therapy. Four months later, he presented with recurrent low back pain (VAS 4) and left lower extremity radiculopathy. The surgical incision exhibited intact healing. Imaging revealed proximal screw loosening/cut-out, L2-3 disc space collapse, endplate erosion, and inflammatory signal changes. An endoscopic spinal decompression was performed externally with symptomatic relief, though no sequential antibiotic therapy was administered. Eleven months post-index surgery, worsening low back pain (VAS 5) emerged with bilateral lower extremity radiculopathy, numbness, and weakness. Physical examination demonstrated bilateral quadriceps, extensor hallucis longus and ankle dorsiflexor weakness (right > left), positive straight leg raise tests, and negative Babinski signs. Elevated inflammatory markers (ESR 103 mm/hr, PCT 0.17 ng/mL, CRP 8.8 mg/L) were observed despite negative blood cultures. T-SPOT.TB returned positive. Radiographic progression showed advanced screw loosening, L2-3 disc collapse with endplate destruction, and osteolytic changes. Revision surgery included L2-3 debridement, autograft fusion, and instrumentation extension to L1-L4. Intraoperative cultures grew Staphylococcus epidermidis , while mNGS remained negative. Histopathology confirmed chronic inflammatory infiltrates. Postoperative culture-directed antibiotics for 6 weeks achieved infection resolution. Twelve-month follow-up demonstrated maintained implant stability, L2-3 bony fusion without recurrence, and restored functional capacity (VAS 2; Fig. 2 ). Discusion Clinical characteristics To date, the incidence of ASI following lumbar fusion under non-infectious contexts remains unreported in the literature. In our study, there were a total of 8 ASI cases—5 occurring within our hospital and 3 transferred from external institutions. The infection rate in our hospital was 0.24% (5/2075), markedly lower than the 1.9% infection rate reported by Siam et al. [ 6 ] in infectious settings. The clinical presentation of ASI predominantly manifests as progressive back pain exacerbation. In our cohort, all cases presented without fever or wound complications, demonstrating delayed onset (median 5.5 months), suggesting a pathophysiology dominated by low-grade microbial persistence rather than acute virulence. Notable diagnostic markers included universal ESR elevation (median 70 mm/h) and CRP elevation in 87.5% of cases, while procalcitonin exhibited limited sensitivity (50% >0.05 ng/mL). This biomarker profile aligns with chronic biofilm-mediated infections characterized by sustained local inflammatory stimulation alongside attenuated systemic immune activation. Among the eight cases, T-SPOT.TB testing yielded positive results in three patients (37.5%), with only one confirmed Mycobacterium tuberculosis infection (positive predictive value 33.3%). The five negative cases showed no tuberculous involvement (negative predictive value 100%), indicating greater diagnostic utility in ruling out tuberculosis[ 14 ]. MRI reliably detected inflammatory edema signals in all patients, with its high sensitivity and superior soft tissue/bony visualization earning strong consensus recommendation as the primary diagnostic modality[ 15 ].The consistent radiographic triad of proximal screw halo signs (100%), endplate erosion (87.5%), and cutting displacement (75%) provides critical diagnostic clues, though differentiation from mechanical failure remains challenging. Predilection Sites and Risk Factors In previous studies on ASI following thoracolumbar fusion (Table 3 ), the cases included 4 adult spinal deformity, 2 osteoporotic vertebral compression fractures, 1 vertebral burst fracture, and 4 lumbar degenerative disease (LDD). The involved segments were thoracic in 6 cases and lumbar in 4 cases. When combined with our cohort (totaling 12 LDD patients), the distribution of infection sites was as follows: L1-2 (5 cases), L2-3 (4 cases), L3-4 (2 cases), and T12-L1 (1 case). Both groups (Table 1 vs. Table 3 ) comprised elderly patients (median age 68.5 vs. 68 years), with all infections exclusively involving single cranial adjacent segments. Notably, previous studies lacked detailed comorbidity descriptions. In our cohort, hypertension was present in 87.5% of cases and diabetes mellitus in 12.5%. Two patients had concurrent systemic infections (1 perianal abscess and 1 transient urinary tract infection). However, the absence of bacteremia (negative blood cultures) and distinct bacterial profiles between these infections and ASI lesions preclude establishing a causal relationship. These findings suggest that advanced age and hypertension represent potential risk factors for ASI, with the upper lumbar segments (L1–L3) identified as the predominant sites of occurrence. Pathophysiological mechanisms The pathogenesis of spondylodiscitis involves septic emboli occluding vertebral endplate arterioles, leading to ischemic infarction and subsequent infectious spread [ 16 ]; However, ASI exhibits fundamentally distinct pathomechanisms due to spinal implant presence, which remain uncharted. Our cohort analysis identifies a biomechanical-immunological cascade as the fundamental pathomechanism for ASI. Central to this model is the universal observation of proximal screw loosening, which initiated progressive implant instability leading to pedicular and endplate microfractures. These mechanical failures generate hypoxic microhematomas at the disc-endplate interface—creating privileged niches for bacterial colonization. Low-virulence pathogens then hematogenously seed these sites, with subsequent reactivation driven principally by age-related immunosenescence (reflected in our cohort's mean age of 68.3 years). Crucially, anatomic predilection data (75% involvement at L1-L3) correlates with biomechanical stress patterns adjacent to fusion constructs, substantiating this cascade's spatial logic. Divergent from conventional theories that emphasize iatrogenic contamination [ 2 , 4 , 9 , 12 ] (e.g., via retractors or malpositioned screws) or direct surgical seeding [ 9 ], our cases demonstrated intact cranial endplates during index procedures—effectively excluding these pathways. While Bose et al.'s hematogenous hypothesis [ 17 ] provides a partial framework, our model significantly refines it by establishing biomechanical trigger events (screw loosening → microtrauma) as essential precursors to bacterial colonization. This mechanistic progression further integrates and extends Nagoshi's ASDeg correlation [ 10 ] and Iwami's PJK-associated infections [ 11 ]: rather than treating ASDeg as a comorbidity, we position it as the initiating vector where altered spinal load distribution precipitates mechanical failure, microvascular compromise, and ultimately microbial proliferation. Hypertension likely exacerbates this cascade through microcirculatory dysfunction—a clinically modifiable risk factor warranting targeted investigation. Collectively, these findings redefine ASDeg not merely as degenerative change but as the essential pathogenic engine driving ASI development in instrumented spines. While cohort homogeneity (single-center, PLIF procedures) limits generalizability, the consistent biomechanical trigger (screw loosening) across all cases suggests mechanistic reproducibility. Validation in multi-center cohorts with varied fusion approaches remains imperative. Microbial Identification Identifying the specific germ causing an infection is crucial for proper treatment, as different pathogens require different antibiotics and treatment approaches [ 18 , 19 ]. While traditional microbial culture remain the standard diagnostic method, they're time-consuming and have a low positivity rate (only approximately 20–50%)[ 20 , 21 ], clinical/imaging findings often precede microbiological confirmation, with 40% remaining culture-negative[ 22 ]. The low virulence of ASI pathogens renders their diagnosis particularly difficult. In Siam et al.'s case series of 23 patients [ 6 ], bacterial pathogens were undetected in 12 cases (52.2%). This diagnostic challenge was similarly observed in ASI cases reported by Xin et al. [ 9 ] and Wang et al. [ 12 ], where microbial identification remained unsuccessful despite comprehensive investigations. Metagenomic next-generation sequencing (mNGS), an emerging molecular diagnostic method, has attracted considerable clinical attention. Two recent studies conducted at our institution demonstrated that mNGS exhibits significantly superior diagnostic sensitivity compared to conventional culture methods (77.78% vs. 27.16%, p < 0.01), while maintaining comparable specificity (90.32% vs. 96.77%) [ 23 ]. These findings position mNGS as an essential adjunct to traditional diagnostics, particularly effective in detecting pathogens in primary pyogenic spinal infections [ 24 ]. In our cohort, mNGS demonstrated a detection rate of 62.5%, surpassing the 50% yield of conventional microbial cultures – a finding consistent with prior research. Blood cultures universally negative, reflecting ASI's low-virulence profile. Recent work by Kim et al. [ 25 ] has demonstrated that incubating biopsy specimens in blood culture bottles can enhance detection rates(84.2% vs. 44.8%). Mirroring this methodology in our series, specimens from all 8 patients underwent parallel processing through both conventional tissue fragment culturing and tissue fluid cultures (mechanical homogenization with saline followed by liquid inoculation into blood culture bottles). Our results revealed complete diagnostic failure (0% positivity) in traditional tissue fragment cultures versus 50% pathogen identification through the enhanced liquid culture protocol. Through this complementary multi-modal culture strategy, we achieved comprehensive pathogen identification across all cases. Analysis of our cohort combined with prior ASI studies (Tables 2 & 3 , total n = 18, 16 with confirmed pathogens) revealed a predominance of staphylococcal species ( Staphylococcus epidermidis n = 8; methicillin-resistant Staphylococcus aureus [MRSA ] n = 2) and opportunistic pathogens ( Moraxella osloensis, Prevotella bivia, Streptococcus intermedius ; n = 3), collectively accounting for 13/16 cases (81.3%). This microbial profile aligns with the clinical characteristics of low-virulence chronic infections, demonstrating predictable pathogen tropism in implant-associated spinal infections. Our cohort further reinforces S. epidermidis’s role as the principal ASI pathogen, a finding obscured in prior studies by methodological limitations. Treatment strategies The subsequent management and outcome differ for delayed versus acute deep SSIs. For acute infection, antibiotic administration is preferable for its powerful ability to eliminating infection[ 9 ]. However, when it comes to delayed SSI, because of an indolent course, the bacteria have enough time to adhere to implant and form a glycocalyx layer, resisting the penetration of antibiotics and host immune factors[ 26 ], leading to loosening and interfering with fusion[ 27 ]. A comprehensive review of existing studies on ASI demonstrates that surgical intervention was ultimately required in over 90% of documented cases[ 2 – 13 ]. The primary surgical indications encompass failure of conservative management, neurological compromise, and spinal instability [ 28 ]. While combined anterior-posterior approaches were predominantly selected in previous studies [ 10 – 11 , 13 ], this approach carries higher surgical trauma, particularly for elderly patients. Wang et al. [ 12 ] demonstrated that isolated posterior debridement and fusion is safe and effective, which aligns with our institutional experience. Spinal stability constitutes a critical determinant in the therapeutic management of spinal infections [ 29 ]. Spinal stability restoration proves imperative given universal proximal instrumentation failure in ASI, as evidenced by Nagoshi's [ 10 ] reported 100% reoperation rate (2/2 cases) following initial non-instrumented revisions. Our cohort (n = 8) demonstrated universal proximal screw loosening mandating posterior debridement with extended instrumentation, achieving immediate load-bearing restoration while minimizing surgical trauma. Postoperative metrics revealed significant back pain relief, early brace-assisted ambulation, and 100% infection resolution without recurrence throughout the average 23-month follow-up period, validating the efficacy of this surgical protocol. Based on our institutional experience mitigating ASI risk, we propose three targeted prevention principles for lumbar fusion: Minimized Fusion Segments in LDD: Restrict instrumentation to essential levels, particularly avoiding prophylactic extension to L1-L3. Proximal Screw Positioning Protocol: Anchor proximal screws sufficiently below superior endplates to preserve microvascular and endplate integrity. Enhanced Surveillance in High-Risk Cohorts: For elderly or immunocompromised patients, implementing serological surveillance (ESR/CRP) during follow-up. Unexplained elevation of these biomarkers should prompt immediate diagnostic evaluation for potential ASI, enabling early detection and intervention to mitigate progressive complications. The main limitations of this study are the the retrospective designs of the study with a low level of evidence, constrained statistical power from limited sample size (n = 8) and restricted generalizability of single-center data, necessitating multicenter prospective trials to validate identified risk factor associations through longitudinal observation. Conclusion ASI following instrumented lumbar fusion for LDD represents a rare clinical entity, predominantly manifesting as delayed-onset low-virulence infections. It is hypothesized that the pathogenesis may involve ASDeg and hematogenous seeding mechanisms. These patients frequently present with proximal instrumentation failure and demonstrate high failure rates with conservative management, thus early surgical intervention is strongly recommended. Abbreviations ASI Adjacent Segment Infection LDD Lumbar Degenerative Disease mNGS Metagenomic Next-generation Sequencing SSI Surgical Site Infection VAS Visual Analog Score PLF Posterolateral Fusion PLIF Posterior Lumbar Interbody Fusion WBC White Blood Cell Count NEUT% Neutrophil Percentage ESR Erythrocyte Sedimentation Rate CRP C-reactive Protein PCT Procalcitonin Declarations Data Availability All data generated or analysed during this study are included in this article. Further enquiries can be directed to the corresponding author. Acknowledgments The author thank Sanming First Hospital, The First Affiliated Hospital of Fujian Medical University, and Ningde Hospital for providing initial surgical data and imaging of the referred patients. Funding This study was supported by the Fujian Provincial Clinical Medical Research Center for First Aid and Rehabilitation in Orthopedic Trauma (2020Y2014). Ethics declarations Ethics approval and consent to participate Ethical approval for this study was obtained from the the Ethics Committee of the Fuzhou Second General Hospital (Ethics Number: 2025112) and study was conducted under the guidance of the Declaration of Helsinki. All participants signed a written informed consent form. Consent for publication We obtained the written informed consent of all participants and agreed to publish all the personal information contained in the data set. Competing interests The authors declared no potential conflicts of interest with respect to the research, authorship, and publication of this article. Authors' Contributions YL and HW conceived and designed the study; YL and BL developed the methodology; FW, WW, and WS curated data; TS and SL validated results; WW and AP performed formal analysis; BL and HW supervised the research; YL wrote the original draft. All authors read and approved the final manuscript. 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Metagenomic next-generation sequencing for the clinical identification of spinal infection-associated pathogens. Front Cell Infect Microbiol. 2025;14:1437665. 10.3389/fcimb.2024.1437665 . Published 2025 Jan 7. Li Z, Zhang Q, Lian X, et al. Value of metagenomic next-generation sequencing in the diagnosis of native pyogenic spinal infections: a multicenter, retrospective observational study. Spine J. 2025;25(4):640–8. 10.1016/j.spinee.2024.11.004 . Kim KJ, Kim DH, Nam KH, et al. Blood culture bottles meet the operating room: enhancing the diagnostic accuracy of infectious spondylitis through open microsurgical biopsy and intraoperative inoculation. Eur J Clin Microbiol Infect Dis. 2024;43(10):1969–76. 10.1007/s10096-024-04914-8 . Di Silvestre M, Bakaloudis G, Lolli F, Giacomini S. Late-developing infection following posterior fusion for adolescent idiopathic scoliosis. Eur Spine J. 2011;20(Suppl 1):S121–7. 10.1007/s00586-011-1754-1 . Epub 2011 Apr 20. PMID: 21505809; PMCID: PMC3087047. Duarte RM, Vaccaro AR. Spinal infection: state of the art and management algorithm. Eur Spine J. 2013;22(12):2787–99. 10.1007/s00586-013-2850-1 . Dragsted C, Aagaard T, Ohrt-Nissen S, Gehrchen M, Dahl B. Mortality and health-related quality of life in patients surgically treated for spondylodiscitis. J Orthop Surg (Hong Kong). 2017;25(2):2309499017716068. 10.1177/2309499017716068 . Talia AJ, Wong ML, Lau HC, Kaye AH. Safety of instrumentation and fusion at the time of surgical debridement for spinal infection. J Clin Neurosci. 2015;22(7):1111–6. 10.1016/j.jocn.2014.12.028 . Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Reviewers agreed at journal 25 Oct, 2025 Reviewers invited by journal 10 Oct, 2025 Editor invited by journal 04 Sep, 2025 Editor assigned by journal 04 Sep, 2025 Submission checks completed at journal 03 Sep, 2025 First submitted to journal 03 Sep, 2025 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. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7385163","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":533201921,"identity":"1a93429c-f37e-4960-b662-278c9ebf92ae","order_by":0,"name":"Yuhan Lin","email":"","orcid":"","institution":"Fuzhou Second General Hospital","correspondingAuthor":false,"prefix":"","firstName":"Yuhan","middleName":"","lastName":"Lin","suffix":""},{"id":533201922,"identity":"1f233bb4-dd03-4572-a980-3addf5ad8c2b","order_by":1,"name":"Fengguang Wei","email":"","orcid":"","institution":"Fujian University of Traditional Chinese 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19:33:01","extension":"html","order_by":13,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":126122,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-7385163/v1/6017eade79a9ad2c3299b7db.html"},{"id":94226432,"identity":"9c17b53a-29f2-44b5-bf88-6d75ac8dab23","added_by":"auto","created_at":"2025-10-23 19:49:01","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":2953444,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003e(a)\u003c/strong\u003e A 79-year-old female patient received L2-3 PLF and L3-5 PLIF for lumbar canal stenosis \u003cstrong\u003e(b)\u003c/strong\u003e Seven months post-surgery, X-ray demonstrated intact hardware fixation, MRI detected inflammatory alterations at L1-2 without definitive endplate/osseous destruction \u003cstrong\u003e(c)\u003c/strong\u003e Nine months post-surgery, imaging demonstrating proximal screw loosening, endplate erosion, and osteolysis \u003cstrong\u003e(d)\u003c/strong\u003e Revision surgery involving L1-2 debridement with fusion, L1-L3 instrumentation \u003cstrong\u003e(e) \u003c/strong\u003eTwelve-month follow-up CT confirmed L1-2 fusion with stable implants\u003c/p\u003e","description":"","filename":"Figure115.png","url":"https://assets-eu.researchsquare.com/files/rs-7385163/v1/26338f169eace77b2988cc39.png"},{"id":94225739,"identity":"a81de03a-831b-4c76-bb78-0549978fe081","added_by":"auto","created_at":"2025-10-23 19:33:01","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":2642812,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003e(a) \u003c/strong\u003eA 64-year-old male patient received L3-5 PLIF for lumbar spondylolisthesis with stenosis \u003cstrong\u003e(b) \u003c/strong\u003eFour months post-surgery, Imaging revealed proximal screw loosening/cut-out, L2-3 disc space collapse, endplate erosion, and inflammatory signal changes \u003cstrong\u003e(c)\u003c/strong\u003e Eleven months post-index surgery, Radiographic progression showed advanced screw loosening, L2-3 disc collapse with endplate destruction, and osteolytic changes \u003cstrong\u003e(d) \u003c/strong\u003eRevision surgery involving L2-3 debridement with fusion, L1-L4 instrumentation \u003cstrong\u003e(e) \u003c/strong\u003eTwelve-month follow-up imaging confirmed L2-3 fusion with stable screw.\u003c/p\u003e","description":"","filename":"Figure217.png","url":"https://assets-eu.researchsquare.com/files/rs-7385163/v1/0ba3b5f65b5c7fec2bd772ac.png"},{"id":94226433,"identity":"e90495ba-a464-4cff-9d5b-0ed3fa427651","added_by":"auto","created_at":"2025-10-23 19:49:10","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":8830606,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7385163/v1/d1e48419-f962-4e10-8734-15c0aed12750.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Adjacent segment infection following instrumented fusion for lumbar degenerative disease: A case series of eight cases and review of literature","fulltext":[{"header":"Introduction","content":"\u003cp\u003eInstrumented lumbar fusion serves as a cornerstone procedure in spinal surgery for lumbar degenerative disease (LDD) including spondylolisthesis and stenosis. Postoperative infection represents one of the most prevalent complications, typically defined as surgical site infection (SSI) occurring at the operative spinal segments, with reported incidence rates ranging from 0.7\u0026ndash;12%[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Current research predominantly focuses on SSI, while reports on adjacent segment infection (ASI) remain comparatively scarce. With advancements in diagnostic and therapeutic techniques, ASI has gradually gained recognition. The first ASI case reported by Kulkarni and Hee [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e] described a C4-5 level epidural abscess developing after C5-C7 fusion. Basu et al. [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e] documented a similar case of sinus tract formation with purulent discharge two weeks post C5-7 anterior cervical discectomy and fusion (ACDF), resulting in adjacent spinal segment infection. Lange et al. [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e] described two ASI recurrences after surgery for lumbar spondylodiscitis, and Farah et al. [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e] reported one ASI following surgery for thoracic spondylodiscitis. In a series of 23 patients, Siam et al. [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e] reported for the first time in 2016 a prevalence of 1.9% of ASI after surgical fusion for spondylodiscitis. Zou et al. [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e] reported 10 cases of fungal infections subsequent to lumbar discectomy, demonstrating progressive spread to adjacent segments.\u003c/p\u003e\u003cp\u003eHowever, these ASI cases occurred after surgical treatment of spondylodiscitis. In non-infectious spinal surgeries, this complication demonstrates significantly lower incidence. We conducted a PubMed/Medline search and review of the available literature up to May 2025. This phenomenon has been described only in 6 published case reports about 10 patients[\u003cspan additionalcitationids=\"CR9 CR10 CR11 CR12\" citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e] (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e3\u003c/span\u003e). Therefore, this study presents the first case series of ASI following thoracolumbar fusion under non-infectious contexts. This study will systematically elucidate the clinical characteristics, analyze the pathophysiological mechanisms, investigate the pathogen spectrum, assess the risk factors, and evaluate the treatment strategies of ASI to provide a comprehensive clinical profile.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003ePreviously reported cases of ASI in the context of non-infectious thoracolumbar degenerative disease\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"9\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eReference\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCase\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eAge (y)/sex\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eInitial Diagnosis\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eInitial Surgery\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eTime to\u003c/p\u003e\u003cp\u003einfection(mo)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eCausative organism\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003eTreatment\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e\u003cp\u003eOutcome\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFormica, et al. [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e69/F\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eASD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eT10-ilium PSF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e1.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u003cem\u003eStaphylococcus capitis\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003epost.revision (Undefined)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eUndefined\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eXin, et al. [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e68/F\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eLDD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eL4-5 PLIF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.23*\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eNegative\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eEmpiric ABx \u0026times;10wk\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eSymptom Relief\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eNagoshi, et al. [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e68/M\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eLDD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eL3-S1 PLIF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e21\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u003cem\u003eMRSA\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003ePD and ASF (Fractionated)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eClinical Cure\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e59/M\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eLDD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eL3-5 PLIF, L2-3PLF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e68\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u003cem\u003eStreptococcus intermedius\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003ePD and ASF, post. instrumentation(Fractionated)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eClinical Cure\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e47/M\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eVBF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eT12-L2 ASF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e48\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u003cem\u003eStaphylococcus capitis\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eEmpiric ABx \u0026times;4wk\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eSymptom Relief\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eIwami, et al. [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e72/F\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eASD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eT10-ilium PSF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e12\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u003cem\u003eMRSA\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eASF\u0026thinsp;+\u0026thinsp;PSF, extended\u003c/p\u003e\u003cp\u003efixation to Th5(Fractionated)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eClinical Cure\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e76/F\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eASD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eT10-ilium PSF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e13\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u003cem\u003eStaphylococcus epidermidis\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eASF\u0026thinsp;+\u0026thinsp;PSF, extended\u003c/p\u003e\u003cp\u003efixation to Th5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eClinical Cure\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eWang, et al. [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e69/F\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eLDD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eL3-5 PLIF, L2-3PLF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eNegative\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eL1-2 PDF and L1-L5 post. instrumentation\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eClinical Cure\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMallepally, et al.\u003c/p\u003e\u003cp\u003e[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e61/F\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eOVCF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eant. T12 Corp\u0026thinsp;+\u0026thinsp;T9-L2 PSF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u003cem\u003eMycobacterium tuberculosis\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eAD and post. extended\u003c/p\u003e\u003cp\u003efixation to Th5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eClinical Cure\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e65/F\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eOVCF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eant. L1 Corp\u0026thinsp;+\u0026thinsp;T11-L3 PSF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u003cem\u003eMycobacterium tuberculosis\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eAD and post. extended\u003c/p\u003e\u003cp\u003efixation to Th7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eClinical Cure\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"9\" nameend=\"c9\" namest=\"c1\"\u003e\u003cp\u003eASD, adult spinal deformity; LDD, Lumbar degenerative disease; VBF, vertebral burst fracture; OVCF,Osteoporotic Vertebral Compression Fracture; MRSA, methicillin-resistant Staphylococcus aureus; ASF, Anterior spinal fusion; Empiric ABx, EmpiricAntibiotic Therapy; NA, not available; PSF, posterior spinal fusion; PDF, posterior debridement fusion; AD, anterior debridement; post: posterior; Corp, Corpectomy. 0.23month\u0026thinsp;=\u0026thinsp;1week\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003eWe reviewed all cases that underwent instrumented lumbar spinal fusion in our institute between October 2019 and March 2023. Postoperative ASI occurred in 5 cases (out of 2,075 cases operated, with an infection rate of 0.24%) and 3 cases were referred from other institutions (a total of 8 cases included).\u003c/p\u003e\u003cp\u003eData were collected on demographics, presenting signs and symptoms, and comorbidities. Information was obtained concerning spinal involvement level, pre-operative inflammatory markers [white blood cell count (WBC), neutrophil percentage(NEUT%), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), procalcitonin (PCT)], microbiological studies [metagenomic next-generation sequencing (mNGS), T-SPOT.TB assay, blood/tissue cultures, biopsy], and imaging modalities. Additional data were recorded, including the initial surgical approach, time to infection onset postoperatively, revision techniques, and prognostic outcomes.\u003c/p\u003e"},{"header":"Result","content":"\u003cp\u003eThis retrospective series comprised 8 consecutive patients (6 males, 2 females) with a median age of 68.5 years (range: 53–82). All cases were afebrile at presentation but manifested chronic back pain (VAS: median 7, range: 5–9). Neurological involvement was observed in 62.5% (5/8) cases, presenting as lower extremity radiculopathy. Comorbidities included hypertension (n = 7), diabetes mellitus (n = 1). Systemic inflammation was evident in: Elevated ESR in all patients (median: 70 mm/h), CRP elevation (median: 20.3 mg/L) in 87.5% (7/8), Leukocytosis in 12.5% (1/8, Case 1; WBC 12.7×10⁹/L), NEUT% elevation (median: 72.9% ) and PCT elevation in 50% (4/8). Notably, Case 3 demonstrated concurrent perianal abscess which exhibited the highest CRP (181.5 mg/L) and PCT (30.6 ng/mL) levels (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Additionally, one case (Case 8) developed postoperative urinary tract infection following the initial surgical procedure, which resolved completely with appropriate antimicrobial therapy.\u003c/p\u003e\u003cdiv class=\"gridtable\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eDemographics and comorbidities of patients and Clinical, laboratory data\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"11\"\u003e\u003c/colgroup\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCase\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAge(y)/sex\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eTemperature\u003c/p\u003e\u003cp\u003e(℃)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eVAS\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eNeurologic deficits\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eComorbidities\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eWBC\u003c/p\u003e\u003cp\u003e(cells/mm\u003csup\u003e3\u003c/sup\u003e)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003eNEUT%\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e\u003cp\u003eCRP\u003c/p\u003e\u003cp\u003e(mg/L)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c10\"\u003e\u003cp\u003eESR\u003c/p\u003e\u003cp\u003e(mm/hr)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c11\"\u003e\u003cp\u003ePCT\u003c/p\u003e\u003cp\u003e(ng/mL)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e63/F\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e37.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eRadiculopathy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eHTN\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e12.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e76.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e110.16\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e62\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e\u0026lt; 0.05\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e75/M\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e36.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eNone\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eHTN, AF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e6.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e69.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e9.66\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e103\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e\u0026lt; 0.05\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e71/M\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e36.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eRadiculopathy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003ePA, HTN,RA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e7.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e95.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e181.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e87\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e30.56\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e82/F\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e36.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eNone\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eHTN, DM\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e8.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e78\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e8.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e90\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e\u0026lt; 0.05\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e66/M\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e36.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eNone\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eHTN\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e7.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e76.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e43.73\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e45\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e0.105\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e53/M\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e36.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eRadiculopathy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e/\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e10.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e68.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e31\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e62\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e23.92\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e72/M\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e36.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eRadiculopathy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eHTN\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e58.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e5.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e35\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e\u0026lt; 0.05\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e65/M\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e36.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eRadiculopathy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eUTI, HTN\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e6.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e61\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e8.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e78\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e0.17\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"11\" nameend=\"c11\" namest=\"c1\"\u003e\u003cp\u003eM, male; F, female; VAS, visual analog scale; WBC, white blood count; NEUT%: Neutrophil Percentage; CRP, C-reactive protein; ESR, erythrocyte sedimentation rate; PCT, Procalcitonin; HTN, Hypertension; AF, Atrial fibrillation; RA, Rheumatoid arthritis; DM, diabetes mellitus;PA, Perianal abscess; UTI, urinary tract infection; / = no comorbidities.\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/table\u003e\u003c/div\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eAll 8 patients exhibited cranial single-segment ASI involvement. Imaging revealed significant endplate erosion with vertebral destruction in 87.5% (7/8, excluding Case 5), universal cranial pedicle screw loosening with halo signs, and cutting displacement in 75% (excluding Cases 5–6). One case with an intradural abscess (Case 1, tuberculosis). The time to infection onset postoperatively ranged from 2 to 58 months (median 5.5 months), with a late-onset outlier at 58 months (Case 7). The affected segments included L2–3 (n = 3), L1-2 (n = 3), L3-4 (n = 1), and T12-L1 (n = 1)(Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e\u003cdiv class=\"gridtable\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c12\" colnum=\"12\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c13\" colnum=\"13\"\u003e\u003c/div\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003e Clinical, operative, and postoperative data\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"13\"\u003e\u003c/colgroup\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCase\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eInitial Diagnosis\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eInitial Surgery\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eInfection segment\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eTime to infection(mo)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eSurgical technique\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003emNGS\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003eT-SPOT.TB\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e\u003cp\u003eBlood Culture\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c10\"\u003e\u003cp\u003eTissue Culture\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c11\"\u003e\u003cp\u003eBiopsy\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c12\"\u003e\u003cp\u003eFU\u003c/p\u003e\u003cp\u003eperiod (mo)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c13\"\u003e\u003cp\u003eVAS FU\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eLDD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eL3-5 PLIF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eL2-3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e14\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eL2-3 PDF;\u003c/p\u003e\u003cp\u003eT12-L4 post. instrumentation\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u003cem\u003eMycobacterium tuberculosis\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003ePos\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eNeg\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003eNeg\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003ePos\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003e34\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eLDD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eL2-5 PLIF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eL1-2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eL1-2 PDF;\u003c/p\u003e\u003cp\u003eT12-L4 post. instrumentation\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u003cem\u003eMoraxella osloensis\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eNeg\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eNeg\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003eNeg\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003ePos\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003e46\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eLDD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eL2-4 PLIF, L1-2PLF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eT12-L1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eT12-L1 PDF;\u003c/p\u003e\u003cp\u003eT10-L4 post. instrumentation\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u003cem\u003ePrevotella bivia\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eNeg\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eNeg\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003eNeg\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003ePos\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003e51\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eLDD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eL3-5 PLIF, L2-3PLF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eL1-2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eL1-2 PDF;\u003c/p\u003e\u003cp\u003eL1-L3 post. instrumentation\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eNeg\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eNeg\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eNeg\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e\u003cem\u003eStaphylococcus epidermidis\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003ePos\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003e12\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eLDD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eL4-S1 PLIF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eL3-4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eL3-4 PDF;\u003c/p\u003e\u003cp\u003eL2-S1 post. instrumentation\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u003cem\u003eStaphylococcus epidermidis\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eNeg\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eNeg\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003eNeg\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003ePos\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003e23\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eLDD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eL2-5 PLIF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eL1-2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e18\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eL1-2 PDF;\u003c/p\u003e\u003cp\u003eL1-L2 post. instrumentation\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u003cem\u003eStaphylococcus warneri\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eNeg\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eNeg\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e\u003cem\u003eStaphylococcus epidermidis\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003ePos\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eLDD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eL3-5 PLIF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eL2-3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e58\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eL2-3 PDF;\u003c/p\u003e\u003cp\u003eL2-L3 post. instrumentation\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eNeg\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003ePos\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eNeg\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e\u003cem\u003eStaphylococcus epidermidis\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003eNeg\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eLDD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eL3-5 PLIF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eL2-3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eL2-3 PDF;\u003c/p\u003e\u003cp\u003eL1-L4 post. instrumentation\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eNeg\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003ePos\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eNeg\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e\u003cem\u003eStaphylococcus epidermidis\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003ePos\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003e12\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"13\" nameend=\"c13\" namest=\"c1\"\u003e\u003cp\u003eLDD, Lumbar degenerative disease; PLIF,posterior lumbar interbody fusion; PLF,posterolateral fusion; mNGS, Metagenomic next-generation sequencing; Pos, Positive; Neg, Negative; VAS, visual analog scale; FU, follow-up; PDF, posterior debridement with fusion.\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/table\u003e\u003c/div\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eMicrobiological profiling revealed discordant results across modalities: Blood cultures were universally negative, whereas mNGS detected microbial signatures in 62.5% (5/8), identifying \u003cem\u003eMycobacterium tuberculosis, Moraxella osloensis, Prevotella bivia\u003c/em\u003e, and two coagulase-negative staphylococci species (\u003cem\u003eStaphylococcus epidermidis\u003c/em\u003e and \u003cem\u003eStaphylococcus warneri\u003c/em\u003e). Immunological testing showed 37.5% T-SPOT.TB positivity (3/8), though only one case correlated with tuberculosis. Tissue-based analyses demonstrated discordant culture positivity rates between specimen types, with 0% positivity in tissue fragment cultures versus 50% positivity in tissue fluid cultures (4/8 growing \u003cem\u003eStaphylococcus epidermidis\u003c/em\u003e). Histopathological evidence of inflammation was observed in 87.5% of biopsies (7/8). Collectively, microbial pathogens were identified through comprehensive diagnostic approaches in all cases(Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eAll patients underwent definitive surgical management involving a standardized posterior approach for lesion resection and autologous bone graft fusion, coupled with revision instrumentation to restore spinal stability. Broad-spectrum antimicrobial therapy, initiated immediately postoperatively, was subsequently tailored according to culture-guided susceptibility profiles, with a duration of 6 weeks for antibacterial agents and extended to 12 months for antitubercular regimens. At a mean follow-up of 23 months post-revision, all patients demonstrated significant VAS score reduction and complete clinical resolution without recurrence (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e\n\u003ch3\u003eCase presentations\u003c/h3\u003e\n\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\u003ch2\u003eCase 4\u003c/h2\u003e\u003cp\u003eA 79-year-old female with hypertension and diabetes underwent L2-3 posterolateral fusion (PLF) and L3-5 posterior lumbar interbody fusion (PLIF) for lumbar stenosis. Postoperative imaging confirmed proper implant positioning without screw cut-out.\u003c/p\u003e\u003cp\u003eSeven months postoperatively, the patient developed low back pain (VAS 4) with percussion tenderness at the proximal incision site, without concurrent fever or radiating pain to the lower extremities. The original surgical incision remained well-healed without evidence of erythema/swelling. Although imaging demonstrated intact hardware fixation, MRI detected nonspecific inflammatory alterations at L1-2 without definitive endplate/osseous destruction. Normal inflammatory biomarkers (WBC/ESR/CRP) prompted conservative management through activity modification and oral linezolid therapy (0.6g q12h).\u003c/p\u003e\u003cp\u003eTwo months later, worsening pain (VAS 7) emerged with imaging demonstrating proximal screw loosening, endplate erosion, and osteolysis. Elevated ESR (103 mm/hr) and mild CRP/NEUT% elevation were noted, though blood cultures and T-SPOT.TB were negative. Revision surgery involving L1-2 posterior debridement with fusion and L1-L3 instrumentation was performed. Intraoperative cultures yielded \u003cem\u003eStaphylococcus epidermidis\u003c/em\u003e, while mNGS returned negative results. Histopathological examination verified chronic inflammatory infiltration. Postoperative targeted antibiotics were administered for 6 weeks. At the 12-month follow-up, the patient reported functional recovery (VAS 2), and CT confirmed L1-2 fusion with stable implants (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eCase 8\u003c/h3\u003e\n\u003cp\u003eA 64-year-old hypertensive male underwent L3-5 PLIF for spondylolisthesis with stenosis at an external institution. Postoperative imaging showed proper implant positioning without screw cut-out. Two weeks postoperatively, the patient developed isolated fever without back pain or wound complications. Urine culture identified \u003cem\u003eEnterococcus faecalis\u003c/em\u003e infection, which resolved with ceftriaxone therapy.\u003c/p\u003e\u003cp\u003eFour months later, he presented with recurrent low back pain (VAS 4) and left lower extremity radiculopathy. The surgical incision exhibited intact healing. Imaging revealed proximal screw loosening/cut-out, L2-3 disc space collapse, endplate erosion, and inflammatory signal changes. An endoscopic spinal decompression was performed externally with symptomatic relief, though no sequential antibiotic therapy was administered.\u003c/p\u003e\u003cp\u003eEleven months post-index surgery, worsening low back pain (VAS 5) emerged with bilateral lower extremity radiculopathy, numbness, and weakness. Physical examination demonstrated bilateral quadriceps, extensor hallucis longus and ankle dorsiflexor weakness (right\u0026thinsp;\u0026gt;\u0026thinsp;left), positive straight leg raise tests, and negative Babinski signs. Elevated inflammatory markers (ESR 103 mm/hr, PCT 0.17 ng/mL, CRP 8.8 mg/L) were observed despite negative blood cultures. T-SPOT.TB returned positive. Radiographic progression showed advanced screw loosening, L2-3 disc collapse with endplate destruction, and osteolytic changes.\u003c/p\u003e\u003cp\u003eRevision surgery included L2-3 debridement, autograft fusion, and instrumentation extension to L1-L4. Intraoperative cultures grew \u003cem\u003eStaphylococcus epidermidis\u003c/em\u003e, while mNGS remained negative. Histopathology confirmed chronic inflammatory infiltrates. Postoperative culture-directed antibiotics for 6 weeks achieved infection resolution. Twelve-month follow-up demonstrated maintained implant stability, L2-3 bony fusion without recurrence, and restored functional capacity (VAS 2; Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e"},{"header":"Discusion","content":"\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\u003ch2\u003eClinical characteristics\u003c/h2\u003e\u003cp\u003eTo date, the incidence of ASI following lumbar fusion under non-infectious contexts remains unreported in the literature. In our study, there were a total of 8 ASI cases\u0026mdash;5 occurring within our hospital and 3 transferred from external institutions. The infection rate in our hospital was 0.24% (5/2075), markedly lower than the 1.9% infection rate reported by Siam et al. [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e] in infectious settings. The clinical presentation of ASI predominantly manifests as progressive back pain exacerbation. In our cohort, all cases presented without fever or wound complications, demonstrating delayed onset (median 5.5 months), suggesting a pathophysiology dominated by low-grade microbial persistence rather than acute virulence. Notable diagnostic markers included universal ESR elevation (median 70 mm/h) and CRP elevation in 87.5% of cases, while procalcitonin exhibited limited sensitivity (50% \u0026gt;0.05 ng/mL). This biomarker profile aligns with chronic biofilm-mediated infections characterized by sustained local inflammatory stimulation alongside attenuated systemic immune activation. Among the eight cases, T-SPOT.TB testing yielded positive results in three patients (37.5%), with only one confirmed \u003cem\u003eMycobacterium tuberculosis\u003c/em\u003e infection (positive predictive value 33.3%). The five negative cases showed no tuberculous involvement (negative predictive value 100%), indicating greater diagnostic utility in ruling out tuberculosis[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. MRI reliably detected inflammatory edema signals in all patients, with its high sensitivity and superior soft tissue/bony visualization earning strong consensus recommendation as the primary diagnostic modality[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e].The consistent radiographic triad of proximal screw halo signs (100%), endplate erosion (87.5%), and cutting displacement (75%) provides critical diagnostic clues, though differentiation from mechanical failure remains challenging.\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003ePredilection Sites and Risk Factors\u003c/h3\u003e\n\u003cp\u003eIn previous studies on ASI following thoracolumbar fusion (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e3\u003c/span\u003e), the cases included 4 adult spinal deformity, 2 osteoporotic vertebral compression fractures, 1 vertebral burst fracture, and 4 lumbar degenerative disease (LDD). The involved segments were thoracic in 6 cases and lumbar in 4 cases. When combined with our cohort (totaling 12 LDD patients), the distribution of infection sites was as follows: L1-2 (5 cases), L2-3 (4 cases), L3-4 (2 cases), and T12-L1 (1 case). Both groups (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e1\u003c/span\u003e vs. Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e3\u003c/span\u003e) comprised elderly patients (median age 68.5 vs. 68 years), with all infections exclusively involving single cranial adjacent segments. Notably, previous studies lacked detailed comorbidity descriptions. In our cohort, hypertension was present in 87.5% of cases and diabetes mellitus in 12.5%. Two patients had concurrent systemic infections (1 perianal abscess and 1 transient urinary tract infection). However, the absence of bacteremia (negative blood cultures) and distinct bacterial profiles between these infections and ASI lesions preclude establishing a causal relationship. These findings suggest that advanced age and hypertension represent potential risk factors for ASI, with the upper lumbar segments (L1\u0026ndash;L3) identified as the predominant sites of occurrence.\u003c/p\u003e\n\u003ch3\u003ePathophysiological mechanisms\u003c/h3\u003e\n\u003cp\u003eThe pathogenesis of spondylodiscitis involves septic emboli occluding vertebral endplate arterioles, leading to ischemic infarction and subsequent infectious spread [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]; However, ASI exhibits fundamentally distinct pathomechanisms due to spinal implant presence, which remain uncharted. Our cohort analysis identifies a biomechanical-immunological cascade as the fundamental pathomechanism for ASI. Central to this model is the universal observation of proximal screw loosening, which initiated progressive implant instability leading to pedicular and endplate microfractures. These mechanical failures generate hypoxic microhematomas at the disc-endplate interface\u0026mdash;creating privileged niches for bacterial colonization. Low-virulence pathogens then hematogenously seed these sites, with subsequent reactivation driven principally by age-related immunosenescence (reflected in our cohort's mean age of 68.3 years). Crucially, anatomic predilection data (75% involvement at L1-L3) correlates with biomechanical stress patterns adjacent to fusion constructs, substantiating this cascade's spatial logic.\u003c/p\u003e\u003cp\u003eDivergent from conventional theories that emphasize iatrogenic contamination [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e] (e.g., via retractors or malpositioned screws) or direct surgical seeding [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e], our cases demonstrated intact cranial endplates during index procedures\u0026mdash;effectively excluding these pathways. While Bose et al.'s hematogenous hypothesis [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e] provides a partial framework, our model significantly refines it by establishing biomechanical trigger events (screw loosening \u0026rarr; microtrauma) as essential precursors to bacterial colonization. This mechanistic progression further integrates and extends Nagoshi's ASDeg correlation [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e] and Iwami's PJK-associated infections [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]: rather than treating ASDeg as a comorbidity, we position it as the initiating vector where altered spinal load distribution precipitates mechanical failure, microvascular compromise, and ultimately microbial proliferation. Hypertension likely exacerbates this cascade through microcirculatory dysfunction\u0026mdash;a clinically modifiable risk factor warranting targeted investigation. Collectively, these findings redefine ASDeg not merely as degenerative change but as the essential pathogenic engine driving ASI development in instrumented spines. While cohort homogeneity (single-center, PLIF procedures) limits generalizability, the consistent biomechanical trigger (screw loosening) across all cases suggests mechanistic reproducibility. Validation in multi-center cohorts with varied fusion approaches remains imperative.\u003c/p\u003e\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\u003ch2\u003eMicrobial Identification\u003c/h2\u003e\u003cp\u003eIdentifying the specific germ causing an infection is crucial for proper treatment, as different pathogens require different antibiotics and treatment approaches [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. While traditional microbial culture remain the standard diagnostic method, they're time-consuming and have a low positivity rate (only approximately 20\u0026ndash;50%)[\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e], clinical/imaging findings often precede microbiological confirmation, with 40% remaining culture-negative[\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. The low virulence of ASI pathogens renders their diagnosis particularly difficult. In Siam et al.'s case series of 23 patients [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e], bacterial pathogens were undetected in 12 cases (52.2%). This diagnostic challenge was similarly observed in ASI cases reported by Xin et al. [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e] and Wang et al. [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e], where microbial identification remained unsuccessful despite comprehensive investigations.\u003c/p\u003e\u003cp\u003eMetagenomic next-generation sequencing (mNGS), an emerging molecular diagnostic method, has attracted considerable clinical attention. Two recent studies conducted at our institution demonstrated that mNGS exhibits significantly superior diagnostic sensitivity compared to conventional culture methods (77.78% vs. 27.16%, p\u0026thinsp;\u0026lt;\u0026thinsp;0.01), while maintaining comparable specificity (90.32% vs. 96.77%) [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. These findings position mNGS as an essential adjunct to traditional diagnostics, particularly effective in detecting pathogens in primary pyogenic spinal infections [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. In our cohort, mNGS demonstrated a detection rate of 62.5%, surpassing the 50% yield of conventional microbial cultures \u0026ndash; a finding consistent with prior research. Blood cultures universally negative, reflecting ASI's low-virulence profile. Recent work by Kim et al. [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e] has demonstrated that incubating biopsy specimens in blood culture bottles can enhance detection rates(84.2% vs. 44.8%). Mirroring this methodology in our series, specimens from all 8 patients underwent parallel processing through both conventional tissue fragment culturing and tissue fluid cultures (mechanical homogenization with saline followed by liquid inoculation into blood culture bottles). Our results revealed complete diagnostic failure (0% positivity) in traditional tissue fragment cultures versus 50% pathogen identification through the enhanced liquid culture protocol.\u003c/p\u003e\u003cp\u003eThrough this complementary multi-modal culture strategy, we achieved comprehensive pathogen identification across all cases. Analysis of our cohort combined with prior ASI studies (Tables\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e2\u003c/span\u003e \u0026amp; \u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e3\u003c/span\u003e, total n\u0026thinsp;=\u0026thinsp;18, 16 with confirmed pathogens) revealed a predominance of staphylococcal species (\u003cem\u003eStaphylococcus epidermidis\u003c/em\u003e n\u0026thinsp;=\u0026thinsp;8; methicillin-resistant Staphylococcus aureus \u003cem\u003e[MRSA\u003c/em\u003e] n\u0026thinsp;=\u0026thinsp;2) and opportunistic pathogens (\u003cem\u003eMoraxella osloensis, Prevotella bivia, Streptococcus intermedius\u003c/em\u003e; n\u0026thinsp;=\u0026thinsp;3), collectively accounting for 13/16 cases (81.3%). This microbial profile aligns with the clinical characteristics of low-virulence chronic infections, demonstrating predictable pathogen tropism in implant-associated spinal infections. Our cohort further reinforces S. epidermidis\u0026rsquo;s role as the principal ASI pathogen, a finding obscured in prior studies by methodological limitations.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\u003ch2\u003eTreatment strategies\u003c/h2\u003e\u003cp\u003eThe subsequent management and outcome differ for delayed versus acute deep SSIs. For acute infection, antibiotic administration is preferable for its powerful ability to eliminating infection[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. However, when it comes to delayed SSI, because of an indolent course, the bacteria have enough time to adhere to implant and form a glycocalyx layer, resisting the penetration of antibiotics and host immune factors[\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e], leading to loosening and interfering with fusion[\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. A comprehensive review of existing studies on ASI demonstrates that surgical intervention was ultimately required in over 90% of documented cases[\u003cspan additionalcitationids=\"CR3 CR4 CR5 CR6 CR7 CR8 CR9 CR10 CR11 CR12\" citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. The primary surgical indications encompass failure of conservative management, neurological compromise, and spinal instability [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. While combined anterior-posterior approaches were predominantly selected in previous studies [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e], this approach carries higher surgical trauma, particularly for elderly patients. Wang et al. [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e] demonstrated that isolated posterior debridement and fusion is safe and effective, which aligns with our institutional experience. Spinal stability constitutes a critical determinant in the therapeutic management of spinal infections [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. Spinal stability restoration proves imperative given universal proximal instrumentation failure in ASI, as evidenced by Nagoshi's [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e] reported 100% reoperation rate (2/2 cases) following initial non-instrumented revisions. Our cohort (n\u0026thinsp;=\u0026thinsp;8) demonstrated universal proximal screw loosening mandating posterior debridement with extended instrumentation, achieving immediate load-bearing restoration while minimizing surgical trauma. Postoperative metrics revealed significant back pain relief, early brace-assisted ambulation, and 100% infection resolution without recurrence throughout the average 23-month follow-up period, validating the efficacy of this surgical protocol.\u003c/p\u003e\u003cp\u003eBased on our institutional experience mitigating ASI risk, we propose three targeted prevention principles for lumbar fusion:\u003c/p\u003e\u003cp\u003e\u003col\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003eMinimized Fusion Segments in LDD: Restrict instrumentation to essential levels, particularly avoiding prophylactic extension to L1-L3.\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003eProximal Screw Positioning Protocol: Anchor proximal screws sufficiently below superior endplates to preserve microvascular and endplate integrity.\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003eEnhanced Surveillance in High-Risk Cohorts: For elderly or immunocompromised patients, implementing serological surveillance (ESR/CRP) during follow-up. Unexplained elevation of these biomarkers should prompt immediate diagnostic evaluation for potential ASI, enabling early detection and intervention to mitigate progressive complications.\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003c/ol\u003e\u003c/p\u003e\u003cp\u003eThe main limitations of this study are the the retrospective designs of the study with a low level of evidence, constrained statistical power from limited sample size (n\u0026thinsp;=\u0026thinsp;8) and restricted generalizability of single-center data, necessitating multicenter prospective trials to validate identified risk factor associations through longitudinal observation.\u003c/p\u003e\u003c/div\u003e"},{"header":"Conclusion","content":"\u003cp\u003eASI following instrumented lumbar fusion for LDD represents a rare clinical entity, predominantly manifesting as delayed-onset low-virulence infections. It is hypothesized that the pathogenesis may involve ASDeg and hematogenous seeding mechanisms. These patients frequently present with proximal instrumentation failure and demonstrate high failure rates with conservative management, thus early surgical intervention is strongly recommended.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cdiv class=\"DefinitionList\"\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eASI\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eAdjacent Segment Infection\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eLDD\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eLumbar Degenerative Disease\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003emNGS\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eMetagenomic Next-generation Sequencing\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eSSI\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eSurgical Site Infection\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eVAS\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eVisual Analog Score\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003ePLF\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003ePosterolateral Fusion\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003ePLIF\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003ePosterior Lumbar Interbody Fusion\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eWBC\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eWhite Blood Cell Count\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eNEUT%\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eNeutrophil Percentage\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eESR\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eErythrocyte Sedimentation Rate\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eCRP\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eC-reactive Protein\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003ePCT\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eProcalcitonin\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003c/div\u003e"},{"header":"Declarations","content":"\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eAll data generated or analysed during this study are included in this article. Further enquiries can be directed to the corresponding author.\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eAcknowledgments\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe author thank Sanming First Hospital, The First Affiliated Hospital of Fujian Medical University, and Ningde Hospital for providing initial surgical data and imaging of the referred patients.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was supported by the Fujian Provincial Clinical Medical Research Center for First Aid and Rehabilitation in Orthopedic Trauma (2020Y2014).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics declarations\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eEthical approval for this study was obtained from the the Ethics Committee of the Fuzhou Second General Hospital (Ethics Number: 2025112) and study was conducted under the guidance of the Declaration of Helsinki. All participants signed a written informed consent form.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe obtained the written informed consent of all participants and agreed to publish all the personal information contained in the data set.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declared no potential conflicts of interest with respect to the research, authorship, and publication of this article.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026apos; \u0026nbsp;Contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eYL and HW conceived and designed the study; YL and BL developed the methodology; FW, WW, and WS curated data; TS and SL validated results; WW and AP performed formal analysis; BL and HW supervised the research; YL wrote the original draft. All authors read and approved the final manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eFei Q, Li J, Lin J, Li D, Wang B, Meng H, Wang Q, Su N, Yang Y. Risk Factors for Surgical Site Infection After Spinal Surgery: A Meta-Analysis. World Neurosurg. 2016;95:507\u0026ndash;15. Epub 2015 Jun 6. PMID: 26054871.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKulkarni AG, Hee HT. Adjacent level discitis after anterior cervical discectomy and fusion (ACDF): a case report. Eur Spine J. 2006;15(5):559\u0026ndash;63. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s00586-005-0003-x\u003c/span\u003e\u003cspan address=\"10.1007/s00586-005-0003-x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBasu S, Sreeramalingam R. Adjacent level spondylodiscitis after anterior cervical decompression and fusion. 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Epub 2010 Feb 27. PMID: 20191397.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eShi T, Lin Y, Zheng X, et al. Metagenomic next-generation sequencing for the clinical identification of spinal infection-associated pathogens. Front Cell Infect Microbiol. 2025;14:1437665. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3389/fcimb.2024.1437665\u003c/span\u003e\u003cspan address=\"10.3389/fcimb.2024.1437665\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. Published 2025 Jan 7.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLi Z, Zhang Q, Lian X, et al. Value of metagenomic next-generation sequencing in the diagnosis of native pyogenic spinal infections: a multicenter, retrospective observational study. 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J Clin Neurosci. 2015;22(7):1111\u0026ndash;6. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.jocn.2014.12.028\u003c/span\u003e\u003cspan address=\"10.1016/j.jocn.2014.12.028\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"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":"bmc-surgery","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bsur","sideBox":"Learn more about [BMC Surgery](http://bmcsurg.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bsur/default.aspx","title":"BMC Surgery","twitterHandle":"@BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Adjacent segment infection, Degenerative lumbar disease, Instrumented lumbar fusion, metagenomic next-generation sequencing (mNGS), Revision spinal surgery","lastPublishedDoi":"10.21203/rs.3.rs-7385163/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7385163/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e\u003cp\u003eAdjacent segment infection (ASI) following instrumented lumbar fusion for lumbar degenerative disease(LDD) remains a rarely documented complication. While a few case reports have described this entity, to our knowledge this represents the first case series systematically characterizing ASI in the context of non-infectious lumbar degenerative disease.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e\u003cp\u003eThis study analyzed 8 cases of ASI following instrumented lumbar fusion for LDD at a single institution, including 5 in-house cases (0.24% incidence among 2,075 surgeries) and 3 external referrals. Comprehensive data collection encompassed demographics, clinical presentation, comorbidities, inflammatory markers, multi-modal microbiological profiling, surgical parameters, infection timelines, and treatment outcomes.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e\u003cp\u003eThe cohort (median age 68.5 years, 6 males, 2 females) all presented with chronic back pain without fever, 62.5% exhibiting radiculopathy. Systemic inflammation markers showed universal ESR elevation, CRP elevation in 87.5%. Characteristic imaging findings revealed: All proximal pedicle screws demonstrated loosening signs, with halo signs universally present, cutting displacement occurred in 75%. ASI manifested at 2\u0026ndash;58 months postoperatively (median 5.5 months), exclusively involving cranial adjacent segments (75% L1-L3). The pathogens were identified in all cases (including \u003cem\u003eMycobacterium tuberculosis, Moraxella osloensis, Prevotella bivia and Staphylococcus epidermidis\u003c/em\u003e). Blood cultures were universally negative, while metagenomic next-generation sequencing (mNGS) detected pathogens in 62.5% and tissue cultures yielded pathogens in 50%. All patients underwent posterior-only approach debridement with fusion and instrumented revision. At a mean follow-up of 23 months, all patients demonstrated significant VAS score reduction and complete clinical resolution without recurrence.\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e\u003cp\u003eASI is relatively rare in clinical practice, predominantly manifesting as delayed-onset low-virulence infections. These patients frequently present with proximal instrumentation failure and demonstrate high failure rates with conservative management, thus early surgical intervention is strongly recommended.\u003c/p\u003e\u003ch2\u003eTrial registration\u003c/h2\u003e\u003cp\u003eNot applicable. This retrospective study did not require trial registration.\u003c/p\u003e","manuscriptTitle":"Adjacent segment infection following instrumented fusion for lumbar degenerative disease: A case series of eight cases and review of literature","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-10-23 19:24:56","doi":"10.21203/rs.3.rs-7385163/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"335372107749879588715081053685950252311","date":"2025-10-25T22:45:01+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-10-10T06:11:26+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-09-04T13:26:06+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-09-04T13:19:57+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-09-03T07:29:24+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Surgery","date":"2025-09-03T07:26:02+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-surgery","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bsur","sideBox":"Learn more about [BMC Surgery](http://bmcsurg.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bsur/default.aspx","title":"BMC Surgery","twitterHandle":"@BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"21d244d3-ffd6-4a9c-9279-59338f6fbeb8","owner":[],"postedDate":"October 23rd, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2025-10-23T19:24:56+00:00","versionOfRecord":[],"versionCreatedAt":"2025-10-23 19:24:56","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7385163","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7385163","identity":"rs-7385163","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}