Metalwork Allergy Rates in Patients Following Scoliosis Corrective Surgery and Posterior Spinal Instrumentation: A Systematic Review

Metalwork Allergy Rates in Patients Following Scoliosis Corrective Surgery and Posterior Spinal Instrumentation: A Systematic Review | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Systematic Review Metalwork Allergy Rates in Patients Following Scoliosis Corrective Surgery and Posterior Spinal Instrumentation: A Systematic Review Jack Dowling, Jamie O'Grady, Luke McGarry This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7965284/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 07 Mar, 2026 Read the published version in European Spine Journal → Version 1 posted 9 You are reading this latest preprint version Abstract Background: Metal hypersensitivity following spinal instrumentation represents an uncommon but clinically significant complication that can lead to implant failure, persistent pain, and revision surgery. The prevalence and characteristics of metal allergies in scoliosis surgery patients remain poorly characterised. Objective : To systematically review the literature on rates of metalwork allergy in patients who have undergone scoliosis corrective surgery, with specific focus on severity, type, and duration from surgery to diagnosis, as well as treatment options, and need for reintervention. Methods: A systematic literature search was conducted following PRISMA 2020 guidelines across PubMed and Embase databases from inception to October 2025. Studies reporting metal hypersensitivity rates, types, severity, and time from presentation to diagnosis in scoliosis or posterior spinal fixation patients were included. Results: Six studies met inclusion criteria, encompassing 806 participants. The confirmed metal allergy rate was 3.0% in paediatric populations. Nickel was the most common allergen, followed by cobalt and chromium. Most reactions were moderate severity (96.8%), with duration to diagnosis ranging from 1 month to 15 years post-surgery. Conclusions : Metal hypersensitivity after scoliosis surgery occurs in approximately 3–4% of patients, predominantly manifesting as moderate-severity local reactions to nickel-containing implants within 2–5 years post-operatively. Figures Figure 1 Introduction Scoliosis corrective surgery involving metallic spinal instrumentation has become increasingly common, with over 38,000 procedures performed annually in paediatric populations alone [1,2]. While these procedures generally achieve excellent clinical outcomes, metal hypersensitivity reactions represent a rare but potentially serious complication that can compromise surgical success. Metal hypersensitivity typically manifests as a delayed-type (Type IV) immune reaction mediated by T-lymphocytes responding to metal ions released from implanted devices [3–5]. The clinical presentation can range from localised skin reactions to systemic inflammatory responses requiring implant removal and revision surgery. Despite growing awareness of this complication, systematic data on prevalence, clinical characteristics, and risk factors in scoliosis patients remain limited. This systematic review aims to synthesize available evidence on metalwork allergy rates following scoliosis corrective surgery, with particular attention to allergy severity, type, duration from surgery to diagnosis, and treatment options. Methods Search Strategy This systematic review was conducted according to PRISMA 2020 guidelines. Comprehensive searches were performed in PubMed (MEDLINE) and Embase databases from inception through October 7, 2025. The search strategy combined relevant terms including: “Scoliosis” OR "Spinal Fusion” OR "spinal fusion” OR "spine fusion”, AND “Hypersensitivity" OR "Dermatitis, Allergic Contact” OR "metal allergy” OR "metal hypersensitivity” OR "metal sensitivity” OR "implant allergy” OR "implant hypersensitivity” OR "titanium allergy” OR "nickel allergy” OR "chromium allergy” OR "cobalt allergy” OR "delayed hypersensitivity” AND “Reoperation" OR “Revision" OR "reoperation" OR "implant removal” OR "hardware removal" OR “severity" OR "time to diagnosis” OR "duration" OR "postoperative complications” OR "treatment outcome"and related MeSH terms. Study Selection Criteria Inclusion Criteria: Studies reporting metal hypersensitivity rates in patients undergoing scoliosis or posterior spinal instrumentation surgery English-language publications Original research including case series, cohort studies, cross-sectional studies, and case reports Studies providing data on allergy severity, type, or timing of diagnosis Exclusion Criteria: Review articles and editorials Conference abstracts without full-text availability Studies focusing on non-spinal orthopaedic procedures Animal or in vitro studies Studies without metal allergy outcome data Non-scoliosis and non posterior spinal instrumentation data Data Extraction and Quality Assessment Three reviewers independently screened titles, abstracts, and full texts. Data extracted included study characteristics, metal allergy rates, allergen types, reaction severity, time to diagnosis, treatment and clinical outcomes. One author was nominated to assess discrepancies. Study quality was assessed using appropriate tools for each study design. Level of evidence followed the Oxford Centre for Evidence-Based Medicine criteria [12]. The MURAD tool was used to evaluate the quality of case reports [13] . Murad tool consists of eight items divided into four domains: selection, ascertainment, causality and reporting. Study Selection Results The search strategy identified 298 records from database searches. After removing duplicates (n = 14), 283 records underwent title and abstract screening. Following exclusion of 272 (based on irrelevant records, 11 full-text articles were assessed for eligibility. Five studies were excluded for various reasons: no scoliosis or non posterior spinal instrumentation-specific (n = 2) and review articles (n = 2), and conference abstracts (n = 1). Six studies met final inclusion criteria for qualitative synthesis. Figure 1.PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) flowchart for study inclusion. Table 1 Study characteristics Author Year of Publication Country Publication Type Level of Evidence Number of patients Assessment tool Detection rate Emmert et al 2025 USA Retrospective cohort study III 796 Oxford 3% Saini et al 2021 USA Case report V 1 MURAD N/A Zielinski et al 2020 USA Case report V 1 MURAD N/A Kim 2019 South Korea Case report V 1 MURAD N/A Shang et al 2014 China Case report V 1 MURAD N/A Towers et al 2019 USA Case report V 1 MURAD N/A Results Study Characteristics Six studies were included: one high-quality retrospective cohort study and six low-quality case reports. The studies encompassed 806 total participants, with sample sizes ranging from single case reports to 798 patients. The largest study by Emmert et al. ( 2025 ) examined 796 paediatric patients undergoing spinal instrumentation from 2014–2020 [6]. Five case reports described individual patients with notable metal hypersensitivity reactions following spinal surgery [7–11]. Metal Allergy Rates The confirmed metal allergy rate was 3.0% (26/796) in the paediatric spinal instrumentation cohort after patch metal allergy testing (PMAT) verification. Initial screening identified 14.8% (118/796) as potentially allergic, but confirmatory testing reduced this to 3.0% [6]. The cohort study was the only study to diagnose the patients with a metal allergy with PMAT. The five case reports made the diagnosis of metal allergy as a diagnosis of exclusion, with resolution of symptoms following removal [7–11]. Types of Metal Allergens Nickel: Nickel emerged as the most prevalent allergen across all studies. In the paediatric cohort, nickel hypersensitivity affected 2.5% of all instrumented patients (20/796). It was also identified as the allergen in one of the five case reports [9]. Cobalt: Cobalt was the second most common allergen, affecting 1.1% of paediatric spinal patients (9/796)[6]. One Case report documented cobalt sensitivity in spinal fusion patients [7]. Chromium and Manganese: Chromium and Manganese were less common but clinically significant allergens. One case report described sensitivity to both chromium and manganese following thoracic instrumentation [7]. Copper affected 0.1% of paediatric patients [6]. Notably, no patients demonstrated hypersensitivities to ammonium, vanadium, or chromium. Furthermore titanium, being widely used in spinal implants, has not been shown, with formal PMAT, to be the cause of metalwork hypersensitivity reactions.. However, case reports suggested possible titanium hypersensitivity in systemic reactions [8,10,11]. Severity of Allergic Reactions Based on available data from 31 patients with either confirmed metal allergies, reactions were classified as: Mild: 0 patients (0%) - No cases documented Moderate: 30 patients (96.8%) - Localised skin reactions, positive patch tests, contact dermatitis [6–9,11]. Severe: 1 patient (3.2%) - Systemic symptoms including severe anorexia, fatigue, and 25kg weight loss [10]. Based on data from 31 patients with confirmed metal allergies, reactions were classified as mild (0%), moderate (96.8%0 and severe (3.2%) [6–11]. Most cases involved moderate, localised reactions confirmed by patch testing, while a single case presented systemic symptoms, that resolves after implant removal [10]. Types of Allergic Reactions The distribution of reaction types among the 31 confirmed cases was: Local/Patch Test Positive: 26 patients (83.9%) - Predominantly from screening programs [6] Contact Dermatitis: 4 patients (12.9%) - Localised skin rash overlying surgical site [7–9,11]. Systemic Reactions: 1 patient (3.2%) - Constitutional symptoms without skin involvement [10]. The predominance of local reactions likely reflects the detection method, as most cases were identified through systematic patch testing rather than symptomatic presentation [6]. Duration from Surgery to Diagnosis Time from surgery to allergy diagnosis showed considerable variation: 0–6 months: 3 patient (9.7%) - Pain, localised rash [8,10,11] 2–5 years: 1 patient (3.2%) - Contact dermatitis at 2 years post-surgery [7] > 5 years: 1 patient (3.2%) Notable case reports at 15 years post-surgery [9] Not reported: 26 patients (83.9%) - Screening study without symptom onset timing [6] Clinical Outcomes and Management Patients with confirmed metal hypersensitivity required various interventions: Hardware Removal or Replacement: Four case reports documented resolution of symptoms following removal of metalwork [8–11]. In these reports, metalwork was not replaced. One case report documented successful resolution following removal of offending implants and replacement with alternative materials. Pure titanium replacement was effective in cases of cobalt/chromium sensitivity [7]. Symptom Resolution: Complete symptom resolution occurred within 2–6 weeks following appropriate hardware changes. One patient experienced rapid weight gain and improved stamina after implant removal [7–11]. Discussion The findings of this systematic review indicate that clinically significant metal hypersensitivity occurs in approximately 3–4% of patients undergoing spinal instrumentation, with nickel being the predominant allergen. Clinical Implications The 3% confirmed allergy rate in paediatric spinal patients suggests that routine preoperative metal allergy testing may not be cost-effective for all patients. However, the number needed to treat (NNT) of 5 for patients with positive screening history suggests targeted testing in high-risk individuals may be valuable [6]. The predominance of nickel sensitivity has important implications for implant selection. Modern spinal instrumentation systems, while primarily titanium-based, may contain trace amounts of nickel that could trigger reactions in sensitised individuals. Surgeons should consider obtaining detailed implant composition data and using pure titanium or alternative materials in patients with known nickel allergy. Temporal Patterns The wide range in time to diagnosis (1 month to 15 years) suggests that metal hypersensitivity should remain in the differential diagnosis for patients with persistent unexplained symptoms, even years after successful surgery. Early presentations may indicate more severe systemic reactions, while delayed presentations typically manifest as localised skin changes [7–11]. The limited data suggest most symptomatic reactions occur within 1 month to 2 years of surgery, though delayed presentations up to 15 years have been documented [9]. Limitations Several limitations affect the interpretation of these findings. The literature is dominated by case reports and small observational studies, limiting the ability to establish definitive prevalence rates. The largest study focused on paediatric patients, and generalisability to adult scoliosis populations remains uncertain [6]. There is a lack of distinction of metal allergy rates, between scoliosis and other spinal procedures, potentially affecting outcome specificity. Additionally, detection bias is likely present, as systematic screening programs identify more subclinical allergies than symptomatic surveillance alone. The lack of standardised severity grading systems across studies hampered direct comparisons. Future research should adopt standardised classification systems for both reaction severity and clinical presentation. Future Research Directions Several research priorities emerge from this review. Large-scale prospective studies specifically focused on adult and paediatric scoliosis populations are needed to establish definitive prevalence rates. Standardised protocols for preoperative screening, particularly in high-risk patients, require development and validation. Investigation of genetic or immunologic markers that might predict metal hypersensitivity risk could enable personalised approaches to implant selection. Additionally, long-term follow-up studies are needed to understand the natural history of subclinical metal sensitivity detected through screening programs. Conclusions Metal hypersensitivity following scoliosis corrective surgery occurs in approximately 3–4% of patients, with nickel representing the most common allergen. Most reactions are moderate in severity and manifest as local skin responses rather than systemic symptoms. Data suggests most symptomatic reactions occur within 1 month to 2 years of surgery, though delayed presentations up to 15 years have been documented' While routine preoperative screening may not be indicated for all patients, targeted testing should be considered for individuals with a history of metal sensitivity or contact dermatitis. Surgeons should maintain awareness of this complication in patients with persistent unexplained symptoms following spinal instrumentation and consider metal hypersensitivity in the differential diagnosis. The current evidence base is limited by small study sizes and heterogeneous methodology. Future research should focus on large-scale prospective studies with standardised outcome measures to better characterise prevalence, risk factors, and optimal management strategies for metal hypersensitivity in scoliosis surgery patients. Declarations Author Contribution J.D. - wrote manuscript, prepared tables and figuresJ.O. G. - reviewed papersL.Mc.G - reviewed papers Data Availability Data and references provided within manuscript References Weinstein SL, Dolan LA, Cheng JC, Danielsson A, Morcuende JA (2008) Adolescent idiopathic scoliosis. Lancet 371(9623):1527–1537 Sucato DJ (2008) Idiopathic Scoliosis in Adolescents. N Engl J Med 358:834–841 Hallab NJ, Caicedo M, McAllister K, Jacobs JJ (2001) Hypersensitivity to Orthopedic Implants: A Review of the Literature. Biomaterials 22(2):219–230 Fischer LA, Johansen JD, Menné T (2016) Hypersensitivity Reactions to Implanted Metal Devices. J Invest Allergol Clin Immunol 26(5):295–302 Thyssen JP, Menné T (2010) Metal allergy—a review on manifestations, mechanisms and handling. Contact Dermat 62(1):1–28 Emmert A, Patel R, Zhao L et al (2025) Prevalence of metal hypersensitivity in pediatric spine instrumentation: a retrospective cohort study. J Spinal Disorders Tech 38(1):45–53 Saini H, Wang AY, Kosarchuk JJ, Yigitbilek F, Kouhsari LM, Arkun K, Riesenburger RI, Safain MG (2021a) Metal allergy hypersensitivity after posterior thoracic spinal fusion: A case report and review of the literature. Surgical Neurology International , 12, p.635. https://doi.org/10.25259/sni_1139_2021 Zielinski J, Lacy TA, Phillips JH (2014) Carbon Coated Implants as a New Solution for Metal Allergy in Early-Onset Scoliosis: A Case Report and Review of the Literature. Spine Deformity 2(1):76–80. https://doi.org/10.1016/j.jspd.2013.09.002 Kim J (2020) A rare case of delayed hypersensitivity reaction to metal ions secondary to a remnant pedicle screw fragment after spinal arthrodesis. Acta Orthop Traumatol Turc 54(4):461–464. https://doi.org/10.5152/j.aott.2020.20148 Towers WS, Kurtom K (2020) Rare Systemic Response to Titanium Spinal Fusion Implant: Case Report. Cureus . https://doi.org/10.7759/cureus.7109 Shang X, Wang L, Kou D, Jia X, Yang X, Zhang M, Tang Y, Wang P, Wang S, Xu Y, Wang H (2014) Metal hypersensitivity in patient with posterior lumbar spine fusion: a case report and its literature review. BMC Musculoskelet Disord 15(1). https://doi.org/10.1186/1471-2474-15-314 Durieux N, Vandenput S, Françoise, Pasleau (2013) [OCEBM levels of evidence system]. PubMed 68(12):644–649 Murad MH, Sultan S, Haffar S, Bazerbachi F (2018) Methodological quality and synthesis of case series and case reports. BMJ Evid Based Med 23(2):60–63 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 07 Mar, 2026 Read the published version in European Spine Journal → Version 1 posted Editorial decision: Revision requested 14 Jan, 2026 Reviews received at journal 28 Dec, 2025 Reviews received at journal 03 Dec, 2025 Reviewers agreed at journal 29 Nov, 2025 Reviewers agreed at journal 25 Nov, 2025 Reviewers invited by journal 25 Nov, 2025 Editor assigned by journal 01 Nov, 2025 Submission checks completed at journal 01 Nov, 2025 First submitted to journal 27 Oct, 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. 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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-7965284","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Systematic Review","associatedPublications":[],"authors":[{"id":552555376,"identity":"97f28c6f-0845-4455-9ad0-c3280b52c56e","order_by":0,"name":"Jack 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1","display":"","copyAsset":false,"role":"figure","size":186252,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003ePRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) flowchart for study inclusion.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-7965284/v1/6f05214a6b5415426d0e4310.png"},{"id":104251148,"identity":"daccdb5d-9551-4b4c-992f-b3e3b955db55","added_by":"auto","created_at":"2026-03-09 16:12:11","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":796521,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7965284/v1/1ec1df9d-77b0-49a6-9468-6e26a81ef05f.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Metalwork Allergy Rates in Patients Following Scoliosis Corrective Surgery and Posterior Spinal Instrumentation: A Systematic Review ","fulltext":[{"header":"Introduction","content":"\u003cp\u003eScoliosis corrective surgery involving metallic spinal instrumentation has become increasingly common, with over 38,000 procedures performed annually in paediatric populations alone [1,2]. While these procedures generally achieve excellent clinical outcomes, metal hypersensitivity reactions represent a rare but potentially serious complication that can compromise surgical success.\u003c/p\u003e\u003cp\u003eMetal hypersensitivity typically manifests as a delayed-type (Type IV) immune reaction mediated by T-lymphocytes responding to metal ions released from implanted devices [3\u0026ndash;5]. The clinical presentation can range from localised skin reactions to systemic inflammatory responses requiring implant removal and revision surgery.\u003c/p\u003e\u003cp\u003eDespite growing awareness of this complication, systematic data on prevalence, clinical characteristics, and risk factors in scoliosis patients remain limited. This systematic review aims to synthesize available evidence on metalwork allergy rates following scoliosis corrective surgery, with particular attention to allergy severity, type, duration from surgery to diagnosis, and treatment options.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003eSearch Strategy\u003c/h2\u003e\u003cp\u003eThis systematic review was conducted according to PRISMA 2020 guidelines. Comprehensive searches were performed in PubMed (MEDLINE) and Embase databases from inception through October 7, 2025. The search strategy combined relevant terms including: \u0026ldquo;Scoliosis\u0026rdquo; OR \"Spinal Fusion\u0026rdquo; OR \"spinal fusion\u0026rdquo; OR \"spine fusion\u0026rdquo;, AND \u0026ldquo;Hypersensitivity\" OR \"Dermatitis, Allergic Contact\u0026rdquo; OR \"metal allergy\u0026rdquo; OR \"metal hypersensitivity\u0026rdquo; OR \"metal sensitivity\u0026rdquo; OR \"implant allergy\u0026rdquo; OR \"implant hypersensitivity\u0026rdquo; OR \"titanium allergy\u0026rdquo; OR \"nickel allergy\u0026rdquo; OR \"chromium allergy\u0026rdquo; OR \"cobalt allergy\u0026rdquo; OR \"delayed hypersensitivity\u0026rdquo; AND \u0026ldquo;Reoperation\" OR \u0026ldquo;Revision\" OR \"reoperation\" OR \"implant removal\u0026rdquo; OR \"hardware removal\" OR \u0026ldquo;severity\" OR \"time to diagnosis\u0026rdquo; OR \"duration\" OR \"postoperative complications\u0026rdquo; OR \"treatment outcome\"and related MeSH terms.\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eStudy Selection Criteria\u003c/h3\u003e\n\u003cp\u003eInclusion Criteria:\u003c/p\u003e\u003cp\u003e\u003cul\u003e\u003cli\u003e\u003cp\u003eStudies reporting metal hypersensitivity rates in patients undergoing scoliosis or posterior spinal instrumentation surgery\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eEnglish-language publications\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eOriginal research including case series, cohort studies, cross-sectional studies, and case reports\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eStudies providing data on allergy severity, type, or timing of diagnosis\u003c/p\u003e\u003c/li\u003e\u003c/ul\u003e\u003c/p\u003e\u003cp\u003eExclusion Criteria:\u003c/p\u003e\u003cp\u003e\u003cul\u003e\u003cli\u003e\u003cp\u003eReview articles and editorials\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eConference abstracts without full-text availability\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eStudies focusing on non-spinal orthopaedic procedures\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eAnimal or in vitro studies\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eStudies without metal allergy outcome data\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eNon-scoliosis and non posterior spinal instrumentation data\u003c/p\u003e\u003c/li\u003e\u003c/ul\u003e\u003c/p\u003e\n\u003ch3\u003eData Extraction and Quality Assessment\u003c/h3\u003e\n\u003cp\u003eThree reviewers independently screened titles, abstracts, and full texts. Data extracted included study characteristics, metal allergy rates, allergen types, reaction severity, time to diagnosis, treatment and clinical outcomes. One author was nominated to assess discrepancies. Study quality was assessed using appropriate tools for each study design. Level of evidence followed the Oxford Centre for Evidence-Based Medicine criteria [12]. The MURAD tool was used to evaluate the quality of case reports [13] .\u003c/p\u003e\u003cp\u003eMurad tool consists of eight items divided into four domains: selection, ascertainment, causality and reporting.\u003c/p\u003e\n\u003ch3\u003eStudy Selection Results\u003c/h3\u003e\n\u003cp\u003eThe search strategy identified 298 records from database searches. After removing duplicates (n\u0026thinsp;=\u0026thinsp;14), 283 records underwent title and abstract screening. Following exclusion of 272 (based on irrelevant records, 11 full-text articles were assessed for eligibility. Five studies were excluded for various reasons: no scoliosis or non posterior spinal instrumentation-specific (n\u0026thinsp;=\u0026thinsp;2) and review articles (n\u0026thinsp;=\u0026thinsp;2), and conference abstracts (n\u0026thinsp;=\u0026thinsp;1). Six studies met final inclusion criteria for qualitative synthesis.\u003c/p\u003e\u003cp\u003e\u003cb\u003eFigure\u0026nbsp;1.PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) flowchart for study inclusion.\u003c/b\u003e\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 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eStudy characteristics\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"8\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" 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=\"char\" char=\".\" 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\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAuthor\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eYear of Publication\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eCountry\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003ePublication Type\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eLevel of Evidence\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eNumber of patients\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eAssessment tool\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003eDetection rate\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eEmmert et al\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e2025\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eUSA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eRetrospective cohort study\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eIII\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e796\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eOxford\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e3%\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eSaini et al\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e2021\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eUSA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eCase report\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eV\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eMURAD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eN/A\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eZielinski et al\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e2020\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eUSA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eCase report\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eV\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eMURAD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eN/A\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eKim\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e2019\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eSouth Korea\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eCase report\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eV\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eMURAD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eN/A\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eShang et al\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e2014\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eChina\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eCase report\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eV\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eMURAD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eN/A\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eTowers et al\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e2019\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eUSA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eCase report\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eV\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eMURAD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eN/A\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":"Results","content":"\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\u003ch2\u003eStudy Characteristics\u003c/h2\u003e\u003cp\u003eSix studies were included: one high-quality retrospective cohort study and six low-quality case reports. The studies encompassed 806 total participants, with sample sizes ranging from single case reports to 798 patients.\u003c/p\u003e\u003cp\u003eThe largest study by Emmert et al. (\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2025\u003c/span\u003e) examined 796 paediatric patients undergoing spinal instrumentation from 2014\u0026ndash;2020 [6]. Five case reports described individual patients with notable metal hypersensitivity reactions following spinal surgery [7\u0026ndash;11].\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eMetal Allergy Rates\u003c/h3\u003e\n\u003cp\u003eThe confirmed metal allergy rate was 3.0% (26/796) in the paediatric spinal instrumentation cohort after patch metal allergy testing (PMAT) verification. Initial screening identified 14.8% (118/796) as potentially allergic, but confirmatory testing reduced this to 3.0% [6].\u003c/p\u003e\u003cp\u003eThe cohort study was the only study to diagnose the patients with a metal allergy with PMAT. The five case reports made the diagnosis of metal allergy as a diagnosis of exclusion, with resolution of symptoms following removal [7\u0026ndash;11].\u003c/p\u003e\n\u003ch3\u003eTypes of Metal Allergens\u003c/h3\u003e\n\u003cp\u003eNickel:\u003c/p\u003e\u003cp\u003eNickel emerged as the most prevalent allergen across all studies. In the paediatric cohort, nickel hypersensitivity affected 2.5% of all instrumented patients (20/796). It was also identified as the allergen in one of the five case reports [9].\u003c/p\u003e\u003cp\u003eCobalt:\u003c/p\u003e\u003cp\u003eCobalt was the second most common allergen, affecting 1.1% of paediatric spinal patients (9/796)[6]. One Case report documented cobalt sensitivity in spinal fusion patients [7].\u003c/p\u003e\u003cp\u003eChromium and Manganese:\u003c/p\u003e\u003cp\u003eChromium and Manganese were less common but clinically significant allergens. One case report described sensitivity to both chromium and manganese following thoracic instrumentation [7]. Copper affected 0.1% of paediatric patients [6].\u003c/p\u003e\u003cp\u003eNotably, no patients demonstrated hypersensitivities to ammonium, vanadium, or chromium. Furthermore titanium, being widely used in spinal implants, has not been shown, with formal PMAT, to be the cause of metalwork hypersensitivity reactions.. However, case reports suggested possible titanium hypersensitivity in systemic reactions [8,10,11].\u003c/p\u003e\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\u003ch2\u003eSeverity of Allergic Reactions\u003c/h2\u003e\u003cp\u003eBased on available data from 31 patients with either confirmed metal allergies, reactions were classified as:\u003c/p\u003e\u003cp\u003e\u003cul\u003e\u003cli\u003e\u003cp\u003eMild: 0 patients (0%) - No cases documented\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eModerate: 30 patients (96.8%) - Localised skin reactions, positive patch tests, contact dermatitis [6\u0026ndash;9,11].\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eSevere: 1 patient (3.2%) - Systemic symptoms including severe anorexia, fatigue, and 25kg weight loss [10].\u003c/p\u003e\u003c/li\u003e\u003c/ul\u003e\u003c/p\u003e\u003cp\u003eBased on data from 31 patients with confirmed metal allergies, reactions were classified as mild (0%), moderate (96.8%0 and severe (3.2%) [6\u0026ndash;11]. Most cases involved moderate, localised reactions confirmed by patch testing, while a single case presented systemic symptoms, that resolves after implant removal [10].\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\u003ch2\u003eTypes of Allergic Reactions\u003c/h2\u003e\u003cp\u003eThe distribution of reaction types among the 31 confirmed cases was:\u003c/p\u003e\u003cp\u003e\u003cul\u003e\u003cli\u003e\u003cp\u003eLocal/Patch Test Positive: 26 patients (83.9%) - Predominantly from screening programs [6]\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eContact Dermatitis: 4 patients (12.9%) - Localised skin rash overlying surgical site [7\u0026ndash;9,11].\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eSystemic Reactions: 1 patient (3.2%) - Constitutional symptoms without skin involvement [10].\u003c/p\u003e\u003c/li\u003e\u003c/ul\u003e\u003c/p\u003e\u003cp\u003eThe predominance of local reactions likely reflects the detection method, as most cases were identified through systematic patch testing rather than symptomatic presentation [6].\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e\u003ch2\u003eDuration from Surgery to Diagnosis\u003c/h2\u003e\u003cp\u003eTime from surgery to allergy diagnosis showed considerable variation:\u003c/p\u003e\u003cp\u003e\u003cul\u003e\u003cli\u003e\u003cp\u003e0\u0026ndash;6 months: 3 patient (9.7%) - Pain, localised rash [8,10,11]\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003e2\u0026ndash;5 years: 1 patient (3.2%) - Contact dermatitis at 2 years post-surgery [7]\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003e\u0026gt;\u0026thinsp;5 years: 1 patient (3.2%) Notable case reports at 15 years post-surgery [9]\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eNot reported: 26 patients (83.9%) - Screening study without symptom onset timing [6]\u003c/p\u003e\u003c/li\u003e\u003c/ul\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec14\" class=\"Section2\"\u003e\u003ch2\u003eClinical Outcomes and Management\u003c/h2\u003e\u003cp\u003ePatients with confirmed metal hypersensitivity required various interventions:\u003c/p\u003e\u003cp\u003eHardware Removal or Replacement: Four case reports documented resolution of symptoms following removal of metalwork [8\u0026ndash;11]. In these reports, metalwork was not replaced. One case report documented successful resolution following removal of offending implants and replacement with alternative materials. Pure titanium replacement was effective in cases of cobalt/chromium sensitivity [7].\u003c/p\u003e\u003cp\u003eSymptom Resolution: Complete symptom resolution occurred within 2\u0026ndash;6 weeks following appropriate hardware changes. One patient experienced rapid weight gain and improved stamina after implant removal [7\u0026ndash;11].\u003c/p\u003e\u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe findings of this systematic review indicate that clinically significant metal hypersensitivity occurs in approximately 3\u0026ndash;4% of patients undergoing spinal instrumentation, with nickel being the predominant allergen.\u003c/p\u003e\u003cdiv id=\"Sec16\" class=\"Section2\"\u003e\u003ch2\u003eClinical Implications\u003c/h2\u003e\u003cp\u003eThe 3% confirmed allergy rate in paediatric spinal patients suggests that routine preoperative metal allergy testing may not be cost-effective for all patients. However, the number needed to treat (NNT) of 5 for patients with positive screening history suggests targeted testing in high-risk individuals may be valuable [6].\u003c/p\u003e\u003cp\u003eThe predominance of nickel sensitivity has important implications for implant selection. Modern spinal instrumentation systems, while primarily titanium-based, may contain trace amounts of nickel that could trigger reactions in sensitised individuals. Surgeons should consider obtaining detailed implant composition data and using pure titanium or alternative materials in patients with known nickel allergy.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec17\" class=\"Section2\"\u003e\u003ch2\u003eTemporal Patterns\u003c/h2\u003e\u003cp\u003eThe wide range in time to diagnosis (1 month to 15 years) suggests that metal hypersensitivity should remain in the differential diagnosis for patients with persistent unexplained symptoms, even years after successful surgery. Early presentations may indicate more severe systemic reactions, while delayed presentations typically manifest as localised skin changes [7\u0026ndash;11].\u003c/p\u003e\u003cp\u003eThe limited data suggest most symptomatic reactions occur within 1 month to 2 years of surgery, though delayed presentations up to 15 years have been documented [9].\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec18\" class=\"Section2\"\u003e\u003ch2\u003eLimitations\u003c/h2\u003e\u003cp\u003eSeveral limitations affect the interpretation of these findings. The literature is dominated by case reports and small observational studies, limiting the ability to establish definitive prevalence rates. The largest study focused on paediatric patients, and generalisability to adult scoliosis populations remains uncertain [6].\u003c/p\u003e\u003cp\u003eThere is a lack of distinction of metal allergy rates, between scoliosis and other spinal procedures, potentially affecting outcome specificity. Additionally, detection bias is likely present, as systematic screening programs identify more subclinical allergies than symptomatic surveillance alone.\u003c/p\u003e\u003cp\u003eThe lack of standardised severity grading systems across studies hampered direct comparisons. Future research should adopt standardised classification systems for both reaction severity and clinical presentation.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec19\" class=\"Section2\"\u003e\u003ch2\u003eFuture Research Directions\u003c/h2\u003e\u003cp\u003eSeveral research priorities emerge from this review. Large-scale prospective studies specifically focused on adult and paediatric scoliosis populations are needed to establish definitive prevalence rates. Standardised protocols for preoperative screening, particularly in high-risk patients, require development and validation.\u003c/p\u003e\u003cp\u003eInvestigation of genetic or immunologic markers that might predict metal hypersensitivity risk could enable personalised approaches to implant selection. Additionally, long-term follow-up studies are needed to understand the natural history of subclinical metal sensitivity detected through screening programs.\u003c/p\u003e\u003c/div\u003e"},{"header":"Conclusions","content":"\u003cp\u003eMetal hypersensitivity following scoliosis corrective surgery occurs in approximately 3\u0026ndash;4% of patients, with nickel representing the most common allergen. Most reactions are moderate in severity and manifest as local skin responses rather than systemic symptoms. Data suggests most symptomatic reactions occur within 1 month to 2 years of surgery, though delayed presentations up to 15 years have been documented'\u003c/p\u003e\u003cp\u003eWhile routine preoperative screening may not be indicated for all patients, targeted testing should be considered for individuals with a history of metal sensitivity or contact dermatitis. Surgeons should maintain awareness of this complication in patients with persistent unexplained symptoms following spinal instrumentation and consider metal hypersensitivity in the differential diagnosis.\u003c/p\u003e\u003cp\u003eThe current evidence base is limited by small study sizes and heterogeneous methodology. Future research should focus on large-scale prospective studies with standardised outcome measures to better characterise prevalence, risk factors, and optimal management strategies for metal hypersensitivity in scoliosis surgery patients.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eJ.D. - wrote manuscript, prepared tables and figuresJ.O. G. - reviewed papersL.Mc.G - reviewed papers\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eData and references provided within manuscript\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eWeinstein SL, Dolan LA, Cheng JC, Danielsson A, Morcuende JA (2008) Adolescent idiopathic scoliosis. Lancet 371(9623):1527\u0026ndash;1537\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSucato DJ (2008) Idiopathic Scoliosis in Adolescents. N Engl J Med 358:834\u0026ndash;841\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHallab NJ, Caicedo M, McAllister K, Jacobs JJ (2001) Hypersensitivity to Orthopedic Implants: A Review of the Literature. Biomaterials 22(2):219\u0026ndash;230\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eFischer LA, Johansen JD, Menn\u0026eacute; T (2016) Hypersensitivity Reactions to Implanted Metal Devices. J Invest Allergol Clin Immunol 26(5):295\u0026ndash;302\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eThyssen JP, Menn\u0026eacute; T (2010) Metal allergy\u0026mdash;a review on manifestations, mechanisms and handling. Contact Dermat 62(1):1\u0026ndash;28\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eEmmert A, Patel R, Zhao L et al (2025) Prevalence of metal hypersensitivity in pediatric spine instrumentation: a retrospective cohort study. J Spinal Disorders Tech 38(1):45\u0026ndash;53\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSaini H, Wang AY, Kosarchuk JJ, Yigitbilek F, Kouhsari LM, Arkun K, Riesenburger RI, Safain MG (2021a) Metal allergy hypersensitivity after posterior thoracic spinal fusion: A case report and review of the literature. \u003cem\u003eSurgical Neurology International\u003c/em\u003e, 12, p.635. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.25259/sni_1139_2021\u003c/span\u003e\u003cspan address=\"10.25259/sni_1139_2021\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZielinski J, Lacy TA, Phillips JH (2014) Carbon Coated Implants as a New Solution for Metal Allergy in Early-Onset Scoliosis: A Case Report and Review of the Literature. Spine Deformity 2(1):76\u0026ndash;80. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jspd.2013.09.002\u003c/span\u003e\u003cspan address=\"10.1016/j.jspd.2013.09.002\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKim J (2020) A rare case of delayed hypersensitivity reaction to metal ions secondary to a remnant pedicle screw fragment after spinal arthrodesis. 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BMC Musculoskelet Disord 15(1). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1186/1471-2474-15-314\u003c/span\u003e\u003cspan address=\"10.1186/1471-2474-15-314\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eDurieux N, Vandenput S, Fran\u0026ccedil;oise, Pasleau (2013) [OCEBM levels of evidence system]. PubMed 68(12):644\u0026ndash;649\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMurad MH, Sultan S, Haffar S, Bazerbachi F (2018) Methodological quality and synthesis of case series and case reports. BMJ Evid Based Med 23(2):60\u0026ndash;63\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":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"european-spine-journal","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"esjo","sideBox":"Learn more about [European Spine Journal](http://link.springer.com/journal/586)","snPcode":"586","submissionUrl":"https://submission.springernature.com/new-submission/586/3","title":"European Spine Journal","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-7965284/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7965284/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground:\u003c/h2\u003e\u003cp\u003eMetal hypersensitivity following spinal instrumentation represents an uncommon but clinically significant complication that can lead to implant failure, persistent pain, and revision surgery. The prevalence and characteristics of metal allergies in scoliosis surgery patients remain poorly characterised.\u003c/p\u003e\u003ch2\u003eObjective :\u003c/h2\u003e\u003cp\u003eTo systematically review the literature on rates of metalwork allergy in patients who have undergone scoliosis corrective surgery, with specific focus on severity, type, and duration from surgery to diagnosis, as well as treatment options, and need for reintervention.\u003c/p\u003e\u003ch2\u003eMethods:\u003c/h2\u003e\u003cp\u003eA systematic literature search was conducted following PRISMA 2020 guidelines across PubMed and Embase databases from inception to October 2025. Studies reporting metal hypersensitivity rates, types, severity, and time from presentation to diagnosis in scoliosis or posterior spinal fixation patients were included.\u003c/p\u003e\u003ch2\u003eResults:\u003c/h2\u003e\u003cp\u003eSix studies met inclusion criteria, encompassing 806 participants. The confirmed metal allergy rate was 3.0% in paediatric populations. Nickel was the most common allergen, followed by cobalt and chromium. Most reactions were moderate severity (96.8%), with duration to diagnosis ranging from 1 month to 15 years post-surgery.\u003c/p\u003e\u003ch2\u003eConclusions :\u003c/h2\u003e\u003cp\u003eMetal hypersensitivity after scoliosis surgery occurs in approximately 3\u0026ndash;4% of patients, predominantly manifesting as moderate-severity local reactions to nickel-containing implants within 2\u0026ndash;5 years post-operatively.\u003c/p\u003e","manuscriptTitle":"Metalwork Allergy Rates in Patients Following Scoliosis Corrective Surgery and Posterior Spinal Instrumentation: A Systematic Review","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-12-01 10:38:20","doi":"10.21203/rs.3.rs-7965284/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-01-14T11:48:08+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-12-28T15:30:23+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-12-03T14:01:09+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"4561083718033730538640150313159248277","date":"2025-11-29T06:56:16+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"28871663762544453512139036443531517808","date":"2025-11-25T22:20:17+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-11-25T20:37:08+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-11-01T13:25:27+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-11-01T13:24:15+00:00","index":"","fulltext":""},{"type":"submitted","content":"European Spine Journal","date":"2025-10-28T03:52:13+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"european-spine-journal","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"esjo","sideBox":"Learn more about [European Spine Journal](http://link.springer.com/journal/586)","snPcode":"586","submissionUrl":"https://submission.springernature.com/new-submission/586/3","title":"European Spine Journal","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"623683fd-5dd4-4548-9669-22bc7dfbcede","owner":[],"postedDate":"December 1st, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2026-03-09T16:07:57+00:00","versionOfRecord":{"articleIdentity":"rs-7965284","link":"https://doi.org/10.1007/s00586-026-09856-7","journal":{"identity":"european-spine-journal","isVorOnly":false,"title":"European Spine Journal"},"publishedOn":"2026-03-07 16:00:11","publishedOnDateReadable":"March 7th, 2026"},"versionCreatedAt":"2025-12-01 10:38:20","video":"","vorDoi":"10.1007/s00586-026-09856-7","vorDoiUrl":"https://doi.org/10.1007/s00586-026-09856-7","workflowStages":[]},"version":"v1","identity":"rs-7965284","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7965284","identity":"rs-7965284","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}