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DOI: 10.1055/a-2074-2092
Mapping the Posterior Ledge and Optic Foramen in Orbital Floor Blowout Fractures

Abstract
Background The posterior ledge (PL) is a vital structure that supports the implant posteriorly during orbital floor reconstruction. This study describes a technique for mapping the PL in relation to the infraorbital margin (IM) in patients with orbital floor blowout fractures. This study establishes the location of the optic foramen in relation to the PL.
Methods Facial computed tomography (FCT) scans of 67 consecutive patients with isolated orbital floor blowout fractures were analyzed using Osirix. Planes of reference for orbital fractures, a standardized technique for performing measurements on FCT, was used. Viewed coronally, the orbit was divided into seven equal sagittal slices (L1 laterally to L7 medially) with reference to the midorbital plane. The distances of PL from IM and location of optic foramen were determined.
Results The greatest distance to PL is found at L5 (median: 30.1 mm, range: 13.5–37.1 mm). The median and ranges for each slice are as follows: L1 (median: 0.0 mm, range: 0.0–19.9 mm), L2 (median: 0.0 mm, range: 0.0–21.5 mm), L3 (median: 15.8 mm, range: 0.0–31.7 mm), L4 (median: 26.1 mm, range: 0.0–34.0 mm), L5 (median: 30.1 mm, range: 13.5–37.1 mm), L6 (median: 29.0 mm, range: 0.0–36.3 mm), L7 (median: 20.8 mm, range: 0.0–39.2 mm). The median distance of the optic foramen from IM is 43.7 mm (range: 37.0– 49.1) at L7.
Conclusion Distance to PL from IM increases medially until the L5 before decreasing. A reference map of the PL in relation to the IM and optic foramen is generated. The optic foramen is located in close proximity to the PL at the medial orbital floor. This aids in preoperative planning and intraoperative dissection.
Authors' Contributions
Y.C.W., D.S.L.G., C.S.Y.Y., E.Z.C., and T.C.L. conceived the study, designed the study, conducted data collection, analyzed the data, and drafted the manuscript. C.H. aided in data conceptualization, participated in the design of the study, and aided in data collection. A.H. participated in the design of the study, collation of data, and aided in project administration, serving as the project coordinator. H.L., V.N., Y.L.Y., J.L., S.G. aided in project design and administration and participated in the review and edit of the manuscript. All authors read and approved the final manuscript.
Notes
This study was presented at the Plastic and Reconstructive Surgery (PRS) Korea 2019, South Korea (November 10, 2019) and 23rd Malaysian Association of Plastic, Aesthetic and Craniomaxillofacial Surgeons (MAPACS) Annual Scientific Congress 2019, Kuala Lumpur (April 13, 2019).
Ethical Approval
This study was conducted in accordance with the Declaration of Helsinki and approved by the National Healthcare Group Institutional Review Board, Singapore (DSRB No. 2019/00628). Waiver of informed consent in obtaining CT scans of patients was obtained, while CT scans in this manuscript were published with informed consent from patients.
Publikationsverlauf
Eingereicht: 11. Juni 2022
Angenommen: 07. Februar 2023
Accepted Manuscript online:
14. April 2023
Artikel online veröffentlicht:
02. August 2023
© 2023. The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution License, permitting unrestricted use, distribution, and reproduction so long as the original work is properly cited. (https://creativecommons.org/licenses/by/4.0/)
Thieme Medical Publishers, Inc.
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