{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,1]],"date-time":"2026-07-01T04:39:39Z","timestamp":1782880779354,"version":"3.54.5"},"reference-count":17,"publisher":"Journal of Neurosurgery Publishing Group (JNSPG)","issue":"2","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2024,8,1]]},"abstract":"<jats:sec>\n<jats:title>OBJECTIVE<\/jats:title>\n<jats:p>Expandable transforaminal lumbar interbody fusion (TLIF) cages were designed to address the limitations of static cages. Bilateral cage insertion can potentially enhance stability, fusion rates, and segmental lordosis. However, the benefits of unilateral versus bilateral expandable cages with varying sizes in TLIF remain unclear. This study used a validated finite element spine model to compare the biomechanical properties of L5\u2013S1 TLIF by using differently sized expandable cages inserted unilaterally or bilaterally.<\/jats:p>\n<\/jats:sec>\n<jats:sec>\n<jats:title>METHODS<\/jats:title>\n<jats:p>A finite element model of X-PAC expandable lumbar cages was created and used at the L5\u2013S1 level. This model had cage dimensions of 9 mm in height, 15\u00b0 in lordosis, and varying widths and lengths. Various placements (unilateral vs bilateral) and sizes were examined under pure moment loading to evaluate range of motion, adjacent-segment motion, and endplate stress.<\/jats:p>\n<\/jats:sec>\n<jats:sec>\n<jats:title>RESULTS<\/jats:title>\n<jats:p>Stability at the L5\u2013S1 level decreased when smaller cages were used in both the unilateral and bilateral cage models. In the unilateral model, cage 1 (the smallest cage) resulted in 47.9% more motion at the L5\u2013S1 level compared to cage 5 (the largest cage) in flexion, as well as 64.8% more motion in extension. Similarly, in the bilateral TLIF model, bilateral cage 1 led to 49.4% more motion at the L5\u2013S1 level in flexion and 73.4% more motion in extension compared to bilateral cage 5. Unilateral insertion of cage 5 provided superior stability in flexion and surpassed cages 1\u20133 in extension when compared to cages inserted either unilaterally or bilaterally. Reduced motion at L5\u2013S1 correlated with increased adjacent-segment motion at L4\u20135. Bilateral TLIF resulted in greater adjacent-segment motion compared to unilateral TLIF with the same-size cages. Inferior endplates experienced higher stress during flexion and extension than superior endplates, with this difference being more pronounced in the bilateral model. In bilateral cage placement, stress differences ranged from 46.3% to 60.0%, while they ranged from 1.1% to 9.6% in unilateral cages. Qualitative analysis revealed increased focal stress in unilateral cages versus bilateral cages.<\/jats:p>\n<\/jats:sec>\n<jats:sec>\n<jats:title>CONCLUSIONS<\/jats:title>\n<jats:p>The authors\u2019 study shows that using a large unilateral TLIF cage may offer better stability than the bilateral insertion of smaller cages. While large bilateral cages increase adjacent-segment motion, they also provide a uniform stress distribution on the endplates. These findings deepen our understanding of the biomechanics of the available expandable TLIF cages.<\/jats:p>\n<\/jats:sec>","DOI":"10.3171\/2024.2.spine231116","type":"journal-article","created":{"date-parts":[[2024,5,25]],"date-time":"2024-05-25T01:44:21Z","timestamp":1716601461000},"page":"209-215","source":"Crossref","is-referenced-by-count":6,"title":["Do expandable cage size and number of cages matter in transforaminal lumbar interbody fusion at L5\u2013S1? A comparative biomechanical analysis using finite element modeling"],"prefix":"10.3171","volume":"41","author":[{"given":"Mohamad","family":"Bakhaidar","sequence":"first","affiliation":[{"name":"Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, Wisconsin;"},{"name":"Division of Neurosurgery, Department of Surgery, Faculty of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia; and"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Balaji","family":"Harinathan","sequence":"additional","affiliation":[{"name":"Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, Wisconsin;"},{"name":"School of Mechanical Engineering, Vellore Institute of Technology, Chennai, India"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Karthik","family":"Banurekha Devaraj","sequence":"additional","affiliation":[{"name":"Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, Wisconsin;"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Narayan","family":"Yoganandan","sequence":"additional","affiliation":[{"name":"Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, Wisconsin;"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Saman","family":"Shabani","sequence":"additional","affiliation":[{"name":"Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, Wisconsin;"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1754","reference":[{"issue":"2","key":"b1","series-title":"Curr Rev Musculoskelet Med","first-page":"118","article-title":"Comparison of low back fusion techniques: transforaminal lumbar interbody fusion (TLIF) or posterior lumbar interbody fusion (PLIF) approaches","volume":"2","author":"Cole CD","year":"2009","unstructured":"Cole CD, McCall TD, Schmidt MH, Dailey AT. 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J Orthop Surg Res. 2022;17(1):325."}],"container-title":["Journal of Neurosurgery: Spine"],"original-title":[],"link":[{"URL":"https:\/\/thejns.org\/view\/journals\/j-neurosurg-spine\/41\/2\/article-p209.xml","content-type":"text\/html","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/thejns.org\/downloadpdf\/journals\/j-neurosurg-spine\/41\/2\/article-p209.xml","content-type":"text\/html","content-version":"vor","intended-application":"syndication"},{"URL":"https:\/\/thejns.org\/downloadpdf\/journals\/j-neurosurg-spine\/41\/2\/article-p209.xml","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2024,12,6]],"date-time":"2024-12-06T13:19:30Z","timestamp":1733491170000},"score":1,"resource":{"primary":{"URL":"https:\/\/thejns.org\/view\/journals\/j-neurosurg-spine\/41\/2\/article-p209.xml"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2024,8,1]]},"references-count":17,"journal-issue":{"issue":"2"},"URL":"https:\/\/doi.org\/10.3171\/2024.2.spine231116","relation":{},"ISSN":["1547-5654"],"issn-type":[{"value":"1547-5654","type":"print"}],"subject":[],"published":{"date-parts":[[2024,8,1]]}}}