Anatomic Determinants of Sacral Dysmorphism and Implications for Safe Iliosacral Screw Placement

Kaiser, Scott P.; Gardner, Michael J.; Liu, Joseph K.; Routt, Milton L; Morshed, Saam

doi:10.2106/jbjs.m.00895

Cited by 102 publications

(125 citation statements)

References 34 publications

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“…With wider use of screw fixations in different positions in the posterior pelvic ring (iliosacral or transsacral), several morphologic variations were described and the terms ''dysplastic sacrum'' and ''sacral dysmorphism'' were introduced, however, there is lack of consensus regarding their definitions [2,4,7,22,29]. Routt et al [29] described five qualitative radiographic signs for sacral dysplasia based on pelvic-outlet and true lateral views, whereas quantitative parameters were described by others [17,22]. Kaiser et al [17] developed a sacral dysmorphic score based on coronal and axial angulation of the upper sacral segment.…”

Section: Discussionmentioning

confidence: 99%

“…Routt et al [29] described five qualitative radiographic signs for sacral dysplasia based on pelvic-outlet and true lateral views, whereas quantitative parameters were described by others [17,22]. Kaiser et al [17] developed a sacral dysmorphic score based on coronal and axial angulation of the upper sacral segment. Mendel et al [22] reported the lateral sacral triangle configuration in the lateral view.…”

Section: Discussionmentioning

confidence: 99%

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Transsacral Osseous Corridor Anatomy Is More Amenable To Screw Insertion In Males: A Biomorphometric Analysis of 280 Pelves

Gras

Gottschling

Schröder

et al. 2016

Clinical Orthopaedics &Amp; Related Research

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Background Percutaneous iliosacral screw placement is the standard procedure for fixation of posterior pelvic ring lesions, although a transsacral screw path is being used more frequently in recent years owing to increased fracture-fixation strength and better ability to fix central and bilateral sacral fractures. However, biomorphometric data for the osseous corridors are limited. Because placement of these screws in a safe and effective manner is crucial to using transsacral screws, we sought to address precise sacral anatomy in more detail to look for anatomic variation in the general population. Questions/purposes We asked: (1) What proportion of healthy pelvis specimens have no transsacral corridor at the level of the S1 vertebra owing to sacral dysmorphism? (2) If there is no safe diameter for screw placement in the transsacral S1 corridor, is an increased and thus safe diameter of the transsacral S2 corridor expected? (3) Are there sex-specific differences in sacral anatomy and are these correlated with known anthropometric parameters? Methods CT scans of pelves of 280 healthy patients acquired exclusively for medical indications such as polytrauma (20%), CT angiography (70%), and other reasons (10%), were segmented manually. Using an advanced CT-based image analysis system, the mean shape of all segmented pelves was generated and functioned as a template. On this template, the cylindric transsacral osseous corridor at the level of the S1 and S2 vertebrae was determined manually. Each pelvis then was registered to the template using a free-form registration algorithm to measure the maximum screw corridor diameters on each specimen semiautomatically. Results Thirty of 280 pelves (11%) had no transsacral S1 corridor owing to sacral dysmorphism. The average of maximum cylindrical diameters of the S1 corridor for the remaining 250 pelves was 12.8 mm (95% CI, 12.1-13.5 mm). A transverse corridor for S2 was found in 279 of 280 pelves, with an average of maximum cylindrical diameter of 11.6 mm (95% CI, 11.3-11.9 mm). Decreasing

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Transsacral Osseous Corridor Anatomy Is More Amenable To Screw Insertion In Males: A Biomorphometric Analysis of 280 Pelves

Gras

Gottschling

Schröder

et al. 2016

Clinical Orthopaedics &Amp; Related Research

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“…Furthermore, all signs were also found in their non‐dysmorphic cluster, but with lower prevalence of 14–46%. Interestingly, the Kappa values for the interobserver reliability range between 0.36–0.59 (fair to moderate according to Landis & Koch) . Both topics were not addressed in our study.…”

Section: Discussionmentioning

confidence: 68%

“…The awareness of anatomical variations in the posterior pelvic ring in recent years is based on the complications of percutaneous screw fixation use. No common definition (“dysplastic sacrum,” “sacral dysmorphism,” or “upper sacral segment dysplasia”) and standardized determination of these variations is present in the literature …”

Section: Discussionmentioning

confidence: 99%

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Recommendations for iliosacral screw placement in dysmorphic sacrum based on modified in‐out‐in corridors

Wendt

Gottschling

Schröder

et al. 2019

Journal Orthopaedic Research

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(1) Can iliosacral osseous corridor diameters in sacral dysmorphism be enlarged by in‐out‐in screw placement at the posterior iliosacral recessus? (2) Are lumbosacral transitional vertebra (LSTV) the anatomical cause for sacral dysmorphism? (3) Are there sex‐specific differences in sacral dysmorphism? 594 multislice CT scans were screened for sacral dysmorphism and 55 data‐sets selected. Each pelvis was segmented manually and cylindrical iliosacral corridors (on the level of S1 and S2 vertebra) were semi‐automatically determined. Corridor trajectories, −diameters and −lengths were measured. LSTV (Castellvi‐type IIIb and IV) were found in 3 of 55 pelves and these lumbosacral variations are therefore not the anatomical basis for sacral dysmorphism. The prevalence of transsacral osseous corridors with diameters of <7.5 mm in axial CT images correlates with qualitative and quantitative criteria of sacral dysmorphism. Enlarging the osseous corridor diameters by penetration of the posterior iliosacral recessus increase the safe corridor diameters (females versus males) by 26% versus 15% at the level of S1‐ and 50% versus 48% at the level of S2‐vertebra. Sex‐specific differences for both corridors (osseous and in‐out‐in) were only found for the osseous corridor diameters at the level of S1 vertebra, being smaller in females (females versus males: 13.3 ± 3.6 mm versus 15.5 ± 3.8 mm, p = 0.04). Dysmorphic sacra can be reliably detected on standard axial CT slice images. Modified in‐out‐in corridors on the level of S1‐vertebra allow screw placement in all patients, but is still demanding compared to non‐dysmorphic sacra, due to the oblique corridor axis. Recommendations for intraoperative orientation for oblique screw placement are defined. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res

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Critical dimensions of trans‐sacral corridors assessed by 3D CT models: Relevance for implant positioning in fractures of the sacrum

Wagner

Kamer

Sawaguchi

et al. 2017

Journal Orthopaedic Research

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Trans-sacral implants can be used alternatively to sacro-iliac screws in the treatment of osteoporosis-associated fragility fractures of the pelvis and the sacrum. We investigated trans-sacral corridor dimensions, the number of individuals amenable to trans-sacral fixation, as well as the osseous boundaries and shape of the S1 corridor. 3D models were reconstructed from pelvic CT scans from 92 Europeans and 64 Japanese. A corridor of <12 mm was considered critical for trans-sacral implant positioning, and <8 mm as impossible. A statistical model of trans-sacral corridor S1 was computed. The limiting cranio-caudal diameter was 11.6 mm (±5.4) for S1 and 14 mm (±2.4) for S2. Trans-sacral implant positioning was critical in 52% of cases for S1, and in 21% for S2. The S1 corridor was impossible in 26%, with no impossible corridor in S2. Antero-superiorly, the S1 corridor was limited not only by the sacrum but in 40% by the iliac fossa. The statistical model demonstrated a consistent oval shape of the trans-section of corridor S1. Considering the variable in size and shape of trans-sacral corridors in S1, a thorough anatomical knowledge and preoperative planning are mandatory using trans-sacral implants. In critical cases, S2 is a veritable alternative. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2577-2584, 2017.

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Anatomic Determinants of Sacral Dysmorphism and Implications for Safe Iliosacral Screw Placement

Abstract: Background: Upper sacral segment dysplasia increases the risk of cortical perforation during iliosacral screw insertion.

Cited by 102 publications

References 34 publications

Transsacral Osseous Corridor Anatomy Is More Amenable To Screw Insertion In Males: A Biomorphometric Analysis of 280 Pelves

Transsacral Osseous Corridor Anatomy Is More Amenable To Screw Insertion In Males: A Biomorphometric Analysis of 280 Pelves

Recommendations for iliosacral screw placement in dysmorphic sacrum based on modified in‐out‐in corridors

Critical dimensions of trans‐sacral corridors assessed by 3D CT models: Relevance for implant positioning in fractures of the sacrum

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