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Open Access
CC BY 4.0 · Arch Plast Surg 2023; 50(04): 370-376
DOI: 10.1055/a-2074-2092
Pediatric/Craniomaxillofacial/Head & Neck
Original Article

Mapping the Posterior Ledge and Optic Foramen in Orbital Floor Blowout Fractures

Yu Cong Wong 
1   Department of Surgery, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
,
Doreen S.L. Goh 
1   Department of Surgery, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
,
Celine S.Y. Yoong 
1   Department of Surgery, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
,
Cowan Ho 
1   Department of Surgery, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
,
Elijah Z. Cai 
2   Department of Surgery, Division of Plastic, Reconstructive and Aesthetic Surgery, National University Health Systems, Singapore
,
Angela Hing 
1   Department of Surgery, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
3   Department of Surgery, Yong Loo Lin School of Medicine, National University Health Systems, Singapore
,
Hanjing Lee 
2   Department of Surgery, Division of Plastic, Reconstructive and Aesthetic Surgery, National University Health Systems, Singapore
,
Vigneswaran Nallathamby 
4   Department of Surgery, Division of Plastic, Reconstructive and Aesthetic Surgery, Ng Teng Fong General Hospital, Singapore
,
Yan L. Yap 
2   Department of Surgery, Division of Plastic, Reconstructive and Aesthetic Surgery, National University Health Systems, Singapore
,
Jane Lim 
2   Department of Surgery, Division of Plastic, Reconstructive and Aesthetic Surgery, National University Health Systems, Singapore
,
Sundar Gangadhara 
5   Department of Ophthalmology, Division of Orbit and Oculofacial Surgery, National University Hospital, Singapore
,
Thiam C. Lim 
1   Department of Surgery, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
2   Department of Surgery, Division of Plastic, Reconstructive and Aesthetic Surgery, National University Health Systems, Singapore
3   Department of Surgery, Yong Loo Lin School of Medicine, National University Health Systems, Singapore
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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.

Keywords

orbital fractures - blowout fractures - optic nerve

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/)

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