{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,17]],"date-time":"2026-09-17T16:51:04Z","timestamp":1789663864612,"version":"4.0.1"},"reference-count":19,"publisher":"Journal of Neurosurgery Publishing Group (JNSPG)","issue":"4","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2021,4]]},"abstract":"<jats:sec>\n<jats:title>OBJECTIVE<\/jats:title>\n<jats:p>Pelvic incidence (PI) is a commonly utilized spinopelvic parameter in the evaluation and treatment of patients with spinal deformity and is believed to be a fixed parameter. However, a fixed PI assumes that there is no motion across the sacroiliac (SI) joint, which has been disputed in recent literature. The objective of this study was to determine if patients with SI joint vacuum sign have a change in PI between the supine and standing positions.<\/jats:p>\n<\/jats:sec>\n<jats:sec>\n<jats:title>METHODS<\/jats:title>\n<jats:p>A retrospective chart review identified patients with a standing radiograph, supine radiograph, and CT scan encompassing the SI joints within a 6-month period. Patients were grouped according to their SI joints having either no vacuum sign, unilateral vacuum sign, or bilateral vacuum sign. PI was measured by two independent reviewers.<\/jats:p>\n<\/jats:sec>\n<jats:sec>\n<jats:title>RESULTS<\/jats:title>\n<jats:p>Seventy-three patients were identified with an average age of 66 years and a BMI of 30 kg\/m<jats:sup>2<\/jats:sup>. Patients with bilateral SI joint vacuum sign (n = 27) had an average absolute change in PI of 7.2\u00b0 (p &lt; 0.0001) between the standing and supine positions compared to patients with unilateral SI joint vacuum sign (n = 20) who had a change of 5.2\u00b0 (p = 0.0008), and patients without an SI joint vacuum sign (n = 26) who experienced a change of 4.1\u00b0 (p = 0.74). ANOVA with post hoc Tukey test showed a statistically significant difference in the change in PI between patients with the bilateral SI joint vacuum sign and those without an SI joint vacuum sign (p = 0.023). The intraclass correlation coefficient between the two reviewers was 0.97 for standing PI and 0.96 for supine PI (p &lt; 0.0001).<\/jats:p>\n<\/jats:sec>\n<jats:sec>\n<jats:title>CONCLUSIONS<\/jats:title>\n<jats:p>Patients with bilateral SI joint vacuum signs had a change in PI between the standing and supine positions, suggesting there may be increasing motion across the SI joint with significant joint degeneration.<\/jats:p>\n<\/jats:sec>","DOI":"10.3171\/2020.8.spine20742","type":"journal-article","created":{"date-parts":[[2021,1,15]],"date-time":"2021-01-15T07:20:31Z","timestamp":1610695231000},"page":"617-622","source":"Crossref","is-referenced-by-count":18,"title":["Change in pelvic incidence between the supine and standing positions in patients with bilateral sacroiliac joint vacuum signs"],"prefix":"10.3171","volume":"34","author":[{"given":"Anthony L.","family":"Mikula","sequence":"first","affiliation":[{"name":"Departments of Neurological Surgery 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Changes of pelvic incidence in surgically corrected adult sagittal deformity. \nEur Spine J. \n2016;\n25(\n11):\n3707\u2013\n3714.\n2628963410.1007\/s00586-015-4199-0"},{"issue":"9","key":"b15","series-title":"Eur Spine J","doi-asserted-by":"publisher","first-page":"2103","DOI":"10.1007\/s00586-019-06027-9","article-title":"Changes in pelvic anatomy after long corrective fusion using iliac screws for adult spinal deformity","volume":"28","author":"Oba \nH","year":"2019","unstructured":"Oba \nH\n, \n\nEbata \nS\n, \n\nTakahashi \nJ\n, \n\n \nChanges in pelvic anatomy after long corrective fusion using iliac screws for adult spinal deformity. \nEur Spine J. \n2019;\n28(\n9):\n2103\u2013\n2111.\n3122797010.1007\/s00586-019-06027-9"},{"issue":"1","key":"b16","series-title":"Eur Spine J","doi-asserted-by":"publisher","first-page":"138","DOI":"10.1007\/s00586-018-5738-2","article-title":"Long fusion to the pelvis with S2-alar-iliac screws can induce changes in pelvic incidence in adult spinal deformity patients: analysis of predictive factors in a retrospective cohort","volume":"28","author":"Tseng \nC","year":"2019","unstructured":"Tseng \nC\n, \n\nLiu \nZ\n, \n\nBao \nH\n, \n\n \nLong fusion to the pelvis with S2-alar-iliac screws can induce changes in pelvic incidence in adult spinal deformity patients: analysis of predictive factors in a retrospective cohort. \nEur Spine J. \n2019;\n28(\n1):\n138\u2013\n145.\n10.1007\/s00586-018-5738-2"},{"issue":"3","key":"b17","series-title":"Spine (Phila Pa 1976)","doi-asserted-by":"publisher","first-page":"195","DOI":"10.1097\/BRS.0000000000002775","article-title":"Loss of pelvic incidence correction after long fusion using iliac screws for adult spinal deformity: cause and effect on clinical outcome","volume":"44","author":"Oba \nH","year":"2019","unstructured":"Oba \nH\n, \n\nEbata \nS\n, \n\nTakahashi \nJ\n, \n\n \nLoss of pelvic incidence correction after long fusion using iliac screws for adult spinal deformity: cause and effect on clinical outcome. \nSpine (Phila Pa 1976). \n2019;\n44(\n3):\n195\u2013\n202.\n10.1097\/BRS.0000000000002775"},{"issue":"3","key":"b18","series-title":"Spine (Phila Pa 1976)","doi-asserted-by":"publisher","first-page":"E142","DOI":"10.1097\/BRS.0000000000001722","article-title":"Use of S2-alar-iliac screws associated with less complications than iliac screws in adult lumbosacropelvic fixation","volume":"42","author":"Elder \nBD","year":"2017","unstructured":"Elder \nBD\n, \n\nIshida \nW\n, \n\nLo \nSL\n, \n\n \nUse of S2-alar-iliac screws associated with less complications than iliac screws in adult lumbosacropelvic fixation. \nSpine (Phila Pa 1976). \n2017;\n42(\n3):\nE142\u2013\nE149.\n10.1097\/BRS.0000000000001722"},{"key":"b19","series-title":"World Neurosurg","doi-asserted-by":"publisher","first-page":"253","DOI":"10.1016\/j.wneu.2016.06.042","article-title":"S2-alar-iliac screws are associated with lower rate of symptomatic screw prominence than iliac screws: radiographic analysis of minimal distance from screw head to skin","volume":"93","author":"Ishida \nW","year":"2016","unstructured":"Ishida \nW\n, \n\nElder \nBD\n, \n\nHolmes \nC\n, \n\n \nS2-alar-iliac screws are associated with lower rate of symptomatic screw prominence than iliac screws: radiographic analysis of minimal distance from screw head to skin. \nWorld Neurosurg. \n2016;\n93:\n253\u2013\n260.\n2731930810.1016\/j.wneu.2016.06.042"}],"container-title":["Journal of Neurosurgery: Spine"],"original-title":[],"link":[{"URL":"https:\/\/thejns.org\/view\/journals\/j-neurosurg-spine\/34\/4\/article-p617.xml","content-type":"text\/html","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/thejns.org\/downloadpdf\/journals\/j-neurosurg-spine\/34\/4\/article-p617.xml","content-type":"text\/html","content-version":"vor","intended-application":"syndication"},{"URL":"https:\/\/thejns.org\/downloadpdf\/journals\/j-neurosurg-spine\/34\/4\/article-p617.xml","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,6,28]],"date-time":"2025-06-28T00:58:57Z","timestamp":1751072337000},"score":1,"resource":{"primary":{"URL":"https:\/\/thejns.org\/view\/journals\/j-neurosurg-spine\/34\/4\/article-p617.xml"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,4]]},"references-count":19,"journal-issue":{"issue":"4"},"URL":"https:\/\/doi.org\/10.3171\/2020.8.spine20742","relation":{},"ISSN":["1547-5654"],"issn-type":[{"value":"1547-5654","type":"print"}],"subject":[],"published":{"date-parts":[[2021,4]]}}}