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Determining patients at high risk for insufficient implant stability would allow clinicians to adapt the treatment accordingly. The aim of this study was to develop a computational model for quantitative and reliable assessment of the risk of screw loosening.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>A cohort of patient vertebrae with diagnosed screw loosening was juxtaposed to a control group with stable fusion. Imaging data from the two cohorts were used to generate patient-specific biomechanical models of lumbar instrumented vertebral bodies. Single-level finite element models loading the screw in axial or caudo-cranial direction were generated. Further, multi-level models incorporating individualized joint loading were created.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      The simulation results indicate that there is no association between screw pull-out strength and the manifestation of implant loosening (\n                      <jats:italic>p<\/jats:italic>\n                      \u2009=\u20090.8). For patient models incorporating multiple instrumented vertebrae, CT-values and stress in the bone were significantly different between loose screws and non-loose screws (\n                      <jats:italic>p<\/jats:italic>\n                      \u2009=\u20090.017 and\n                      <jats:italic>p<\/jats:italic>\n                      \u2009=\u20090.029, for CT-values and stress, respectively). However, very high distinction (\n                      <jats:italic>p<\/jats:italic>\n                      \u2009=\u20090.001) and predictability (R\n                      <jats:sup>2<\/jats:sup>\n                      <jats:sub>Pseudo<\/jats:sub>\n                      \u2009=\u20090.358, AUC\u2009=\u20090.85) were achieved when considering the relationship between local bone strength and the predicted stress (loading factor). Screws surrounded by bone with a loading factor higher than 25% were likely to be loose, while the chances of screw loosening were close to 0 with a loading factor below 15%.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>The use of a biomechanics-based score for risk assessment of implant fixation failure might represent a paradigm shift in addressing screw loosening after spondylodesis surgery.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1007\/s00586-022-07187-x","type":"journal-article","created":{"date-parts":[[2022,4,23]],"date-time":"2022-04-23T12:02:46Z","timestamp":1650715366000},"page":"2639-2649","update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":38,"title":["Computational model predicts risk of spinal screw loosening in patients"],"prefix":"10.1007","volume":"31","author":[{"given":"Marie-Rosa","family":"Fasser","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gabriela","family":"Gerber","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Caroline","family":"Passaplan","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Fr\u00e9d\u00e9ric","family":"Cornaz","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jess G.","family":"Snedeker","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mazda","family":"Farshad","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3676-008X","authenticated-orcid":false,"given":"Jonas","family":"Widmer","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"297","published-online":{"date-parts":[[2022,4,23]]},"reference":[{"issue":"1","key":"7187_CR1","doi-asserted-by":"publisher","first-page":"1","DOI":"10.1080\/16878507.2019.1693176","volume":"13","author":"MB Afifi","year":"2020","unstructured":"Afifi MB, Abdelrazek A, Deiab NA et al (2020) The effects of ct x-ray tube voltage and current variations on the relative electron density (red) and ct number conversion curves. 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