{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,29]],"date-time":"2026-09-29T04:57:18Z","timestamp":1790657838508,"version":"4.1.0"},"reference-count":16,"publisher":"MDPI AG","issue":"19","license":[{"start":{"date-parts":[[2026,9,24]],"date-time":"2026-09-24T00:00:00Z","timestamp":1790208000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["J. Clin. Med.","JCM"],"abstract":"<jats:p>Background and Objectives: In this study, uncoupled auxiliary trans-sacroiliac (UATS) screws were evaluated as a mechanically independent adjunct to conventional S2-alar-iliac (S2AI) fixation in long lumbopelvic constructs. We assessed their exploratory biomechanical behavior and preliminary clinical feasibility. Methods: Conventional bilateral S2AI fixation and the same construct supplemented with bilateral UATS screws were compared in an exploratory finite element analysis under flexion, extension, lateral bending, and axial rotation. A retrospective clinical series of 26 patients undergoing UATS-supported lumbopelvic reconstruction was also evaluated. Results: Across the four loading modes, the UATS configuration showed lower global implant-system stress (81\u201392% reduction) and lower global sacral stress (43\u201367% reduction) within the computational model. The clinical cohort was revision dominant (25\/26 patients). Mean SIJ-related pain VAS decreased from 8.0 \u00b1 1.5 to 2.4 \u00b1 1.0 and ODI from 68.1% \u00b1 18.1% to 16.7% \u00b1 8.6% at final follow-up (both p &lt; 0.001). These clinical changes reflect the overall reconstructive procedure and cannot be attributed independently to UATS fixation. Conclusions: UATS placement was technically feasible in this small, revision-dominant cohort and altered stress distribution in an exploratory, unvalidated finite element model. The present study does not establish independent clinical efficacy or superiority over established pelvic fixation or SIJ fusion strategies.<\/jats:p>","DOI":"10.3390\/jcm15197447","type":"journal-article","created":{"date-parts":[[2026,9,24]],"date-time":"2026-09-24T16:29:53Z","timestamp":1790267393000},"page":"7447","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Uncoupled Auxiliary S2-Alar-Iliac Screws in Long Lumbopelvic Constructs: Exploratory Finite Element Analysis and Preliminary Clinical Experience"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-3618-6033","authenticated-orcid":false,"given":"Celal Ozbek","family":"Cakir","sequence":"first","affiliation":[{"name":"Department of Neurosurgery, Afyon Park Hospital, Afyon 03100, Turkey"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Murat","family":"Baloglu","sequence":"additional","affiliation":[{"name":"Department of Neurosurgery, Eskisehir City Hospital, Eskisehir 26080, Turkey"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ulkun Unlu","family":"Unsal","sequence":"additional","affiliation":[{"name":"Department of Neurosurgery, Manisa City Hospital, Manisa 45040, Turkey"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hakan","family":"Millet","sequence":"additional","affiliation":[{"name":"Department of Neurosurgery, Eskisehir City Hospital, Eskisehir 26080, Turkey"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Erdal","family":"Yayla","sequence":"additional","affiliation":[{"name":"Department of Neurosurgery, Eskisehir City Hospital, Eskisehir 26080, Turkey"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3703-0492","authenticated-orcid":false,"given":"Eser","family":"Pala","sequence":"additional","affiliation":[{"name":"MarlaDT Engineering, Adalet Mahallesi, Folkart Towers A Kule No:47\/B, Bayrakli, Izmir 35530, Turkey"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6719-5522","authenticated-orcid":false,"given":"Ismail","family":"Bozkurt","sequence":"additional","affiliation":[{"name":"Department of Neurosurgery, Faculty of Medicine, Yuksek Ihtisas University, Ankara 06530, Turkey"},{"name":"Department of Neurosurgery, Medical Park Ankara Hospital, Ankara 06680, Turkey"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,9,24]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"776","DOI":"10.1097\/00007632-200204010-00017","article-title":"Outcome and complications of long fusions to the sacrum in adult spine deformity\u2014Luque-Galveston, combined iliac and sacral screws, and sacral fixation","volume":"27","author":"Emami","year":"2002","journal-title":"Spine"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"1192","DOI":"10.1097\/BRS.0b013e318170fd35","article-title":"Degeneration of sacroiliac joint after instrumented lumbar or lumbosacral fusion: A prospective cohort study over five-year follow-up","volume":"33","author":"Ha","year":"2008","journal-title":"Spine"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"72","DOI":"10.1016\/j.jspd.2017.05.004","article-title":"S2 alar iliac fixation in long segment constructs, a two- to five-year follow-up","volume":"6","author":"Smith","year":"2018","journal-title":"Spine Deform."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"1788","DOI":"10.1007\/s00586-012-2350-8","article-title":"Sacroiliac joint pain after lumbar\/lumbosacral fusion: Current knowledge","volume":"21","author":"Yoshihara","year":"2012","journal-title":"Eur. 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