The human sacrum and safe approaches for screw placement

Arman, Candan; Naderi, Sait; Kiray, Amac; Aksu, Funda; Yılmaz, Hakan; Tetik, Süleyman; Korman, Esin

doi:10.1016/j.jocn.2008.07.081

Cited by 41 publications

(53 citation statements)

References 9 publications

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“…Safe zone size analyses to date have primarily focused on an oblique safe zone corridor pertinent to unilateral iliosacral screws in the upper sacral segment and have reported the safe zone size in the second sacral segment in dysmorphic sacra to be capacious . Conflitti et al manually measured on their PACS the safe zone for unilateral iliosacral screws in 24 dysmorphic sacra and found the average width of the first sacral segment to be 13.2 mm and the second sacral segment to be 15.2 mm, noting that in the second sacral segment iliosacral screws could be placed transversely to end in the contralateral ilium whereas they had to be placed obliquely in the first segment .…”

Section: Discussionmentioning

confidence: 99%

“…Transsacral screws have become a popular method of fixation of the posterior pelvis as they can be placed percutaneously, avoiding posterior dissection and potential wound complications, with minimal blood loss and with the patient supine or prone . Transsacral screws are technically challenging in that they span both foraminal regions of the sacrum within an intraosseous corridor that is dependent on sacral morphology . With advances in the technique of fluoroscopically guided percutaneous screw placement and anatomic understanding of the sacrum and surrounding neurovascular structures, there has been a low incidence of neurovascular injury …”

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confidence: 99%

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Transsacral screw safe zone size by sacral segmentation variations

Lee

Rosenbaum

Martusiewicz

et al. 2014

Journal Orthopaedic Research

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Variations in sacral segmentation may preclude safe placement of transsacral screws for posterior pelvis fixation. We developed a novel automated 3D technique to determine the safe zone size for transsacral screws in the upper two sacral segments in 526 adult pelvis computed tomography scans. Safe zone sizes were then compared by gender and sacral segmentation variations (number of neuroforamen and the presence/absence of lumbosacral transitional vertebrae, AELSTV). Ten millimeters was used as the safety threshold for a large screw. 3 (0.6%), 366 (70%), and 157 (30%) sacra had 3, 4, or 5 neuroforamen, respectively. Eighty-eight (17%) were þLSTV. Safe zone size depended on gender, number of neuroforamen in ÀLSTV sacra and presence of LSTV (p < 0.001) but not on the uni-or bilateral nature of the LSTV. 17% of ÀLSTV sacra were below the safety threshold in S1, 27% in S2, whereas 3% of þLSTV sacra were below in S1, 74% in S2. Of ÀLSTV sacra that cannot take an S1 screw safely, 77% can do so in S2, leaving only 4% of sacra that cannot accommodate a screw safely in either upper segment. The results demonstrate a predictable pattern of safe zone size based on gender and sacral segmentation variations. Keywords: lumbosacral transitional vertebrae; sacral dysmorphism; sacral safe zone; sacral segmentation; transsacral screw Transsacral screws have become a popular method of fixation of the posterior pelvis as they can be placed percutaneously, avoiding posterior dissection and potential wound complications, with minimal blood loss and with the patient supine or prone. 1,2 Transsacral screws are technically challenging in that they span both foraminal regions of the sacrum within an intraosseous corridor that is dependent on sacral morphology. [3][4][5][6][7][8][9][10][11][12] With advances in the technique of fluoroscopically guided percutaneous screw placement and anatomic understanding of the sacrum and surrounding neurovascular structures, there has been a low incidence of neurovascular injury. 3,[13][14][15][16][17] The lumbosacral junction is the most variable portion of the spine with variations in sacral segmentation, thought to be related to its load-related fusion, seen in both number of segments, typically four to six, and lumbosacral transitional vertebrae (LSTV) defined as either sacralization of the lowest lumbar segment or lumbarization of the upper sacral segment. [18][19][20][21][22] LSTV are estimated to be present in 4-30% of the population and have been described since at least the early 20th century. [23][24][25] Castellvi et al. identified four types based on morphology in their classification system for LSTV. 24,25 Type I includes unilateral (Ia) or bilateral (Ib) dysplastic transverse processes; type II, incomplete unilateral (IIa) or bilateral (IIb) lumbarization/sacralization with an enlarged transverse process that has a diarthrodial joint between itself and the sacrum; type III, unilateral (IIIa) or bilateral (IIIb) lumbarization/ sacralization with complete osseous fusion of the tran...

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Transsacral screw safe zone size by sacral segmentation variations

Lee

Rosenbaum

Martusiewicz

et al. 2014

Journal Orthopaedic Research

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“…By contrast, several authors have recommended that placement of S1 pedicle screws in a central position should be avoided because of the risk this placement carries of damage to the iliac vessels, the sympathetic chain, and the lumbosacral trunk, which are all close to the sacrum [19][20][21][22][23][24]. Therefore, from both biomechanical and anatomical points of view, it is recommended that S1 pedicle screws should be inserted inwardly with an acceptable angle reported as about 30°to 40°, almost the same as that of the S1 facet angle [27][28][29][30][31]. However, in general, S1 pedicle screws are inserted from a medial entry point with an outward angle, because of the prominent dorsal overhang of the posterior iliac crest and paravertebral muscle mass [30,[32][33][34][35].…”

Section: Discussionmentioning

confidence: 99%

L5 spinal nerve injury caused by misplacement of outwardly-inserted S1 pedicle screws

Inoue

Ozawa

et al. 2012

Eur Spine J

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“…After revision by coauthors, for the purpose of the study, two publications were selected, upon their consent, as comprising the appropriate set of data for analysis. The first one published by Arman et al in 2009 deals with sacral anatomy, focusing on spine surgery application [18]. The second one published by Richards et al (‘Bone density and cortical thickness in normal, osteopenic, and osteoporotic sacra’) gives the crucial data for quality of bone across the sacrum in both normal, osteopenic and osteoporotic bone [19].…”

Section: Methodsmentioning

confidence: 99%

Evidence-based support for S1 transpedicular screw entry point modification

Kubaszewski

Nowakowski

Kaczmarczyk

2014

Journal of Orthopaedic Surgery and Research

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BackgroundIn the literature, ‘below and lateral to the superior S1 facet’ is defined as the basic technique for screw introduction. Until a recently published modification, no analysis for alternative starting point has been proposed nor evaluated, although some surgeons claim to use some modifications. In this study, we analyse the data from anatomical and radiological studies for optimal starting point in transpedicular S1 screw placement.MethodsA Medline search for key word combination: sacrum, anatomy, pedicle, screws and bone density resulted in 26 publications relevant to the topic. After a review of literature, two articles were chosen, as those including the appropriate set of data. The data retrieved from the articles is used for the analysis. The spatial relation of S1 facet, pedicles and vertebral body with cortical thickness and bone density in normal, osteopenic and osteoporotic sacrum is analysed.ResultsPresented data advocates for more medial placement of the screws due to higher bone density and lower bone loss in osteoporosis. Medial shift of the starting point does not increase the risk of spinal canal perforation. Osteoarthritic changes within the facet can augment the posterior supporting point for screw. The facet angular orientation is similar to convergent screw trajectory.ConclusionsModified technique for S1 screw placement takes advantage of latest anatomical and clinical data. In our opinion, technique modification improves the reproducibility and may increase stability and the screws within the posterior cortex of the S1 vertebra. Further biomechanical and clinical study should be performed to prove its superiority to classical technique.

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The human sacrum and safe approaches for screw placement

Cited by 41 publications

References 9 publications

Transsacral screw safe zone size by sacral segmentation variations

Transsacral screw safe zone size by sacral segmentation variations

L5 spinal nerve injury caused by misplacement of outwardly-inserted S1 pedicle screws

Evidence-based support for S1 transpedicular screw entry point modification

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