Anat Cell Biol.  2021 Sep;54(3):297-303. 10.5115/acb.21.013.

A cadaveric study investigating the anatomy of the medial orbital wall

• Hester KM
• Rahimi OB
• Fry CL
• Nation HL

• KMID: 2521018
• DOI: http://doi.org/10.5115/acb.21.013

Abstract

The purpose of this study is to investigate the applicability of the current surgical guideline, known as ‘24-12-6’ surgical guideline, in the Hispanic and European populations. This guideline is used during numerous orbital surgeries and states that the distance between the anterior lacrimal crest (ALC) to the anterior ethmoidal foramen (AEF) (24 mm), the AEF to the posterior ethmoidal foramen (PEF) (12 mm), and the PEF to the optic canal (OC) (6 mm) follows a Rule of Halves. Previous studies suggest this surgical guideline is not applicable for all ethnicities; however, to our knowledge, no data has been published regarding the accuracy of this guideline pertaining to the Hispanic population. An experimental study was performed on 79 orbits (52 cadavers) donated to the Human Anatomy Program at UT Health San Antonio. The ALC, AEF, posterior ethmoidal foramen, and OC were identified; the orbit was enucleated and all remaining soft tissue removed. The distance between each landmark was recorded using a digital caliper. For all cadavers studied, the distances between the ALC, AEF, posterior ethmoidal foramen, and OC were 24.76 mm, 13.89 mm, and 7.61 mm, respectively. Thus, the ‘24-12-6’ surgical guideline was not applicable to the sample studied. Based on ethnicity data, these relationships were also not true for the European or the Hispanic populations. Therefore, significant anatomical variations exist in the current surgical guideline. Clinicians may need to adjust their methodology during surgical procedures in order to optimize patient care.

Keyword

Medial orbital wall; Orbit anatomy; 24-12-6 mm surgical guideline; Rule of halves

Figure

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  Fig. 1 Surgical guideline measurements. The current surgical guideline approximates the distances between the ALC, AEF, PEF, and OC. Right orbit. AEF, anterior ethmoidal foramen; ALC, anterior lacrimal crest; OC, optic canal; PEF, posterior ethmoidal foramen.

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  Fig. 2 Medial orbital wall Measurements Based on Populations. There was a statistically significant difference in medial orbital wall measurements between European and Hispanic samples when compared to the accepted surgical guideline. There was no statically significant difference in medial orbital wall measurements between ethnicities. AEF, anterior ethmoidal foramen; ALC, anterior lacrimal crest; OC, optic canal; PEF, posterior ethmoidal foramen.

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  Fig. 3 ALC-AEF measurements between sex and side of the body. While there was no statistically significant difference in ALC-AEF measurements between male and female samples (A), there was a statistically significant difference between the left and right sides of the face (B). AEF, anterior ethmoidal foramen; ALC, anterior lacrimal crest; F, female; L, left; M, male; R, right.

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  Fig. 4 AEF-PEF measurements between sex and side of the body. While there was no statistically significant difference in AEF-PEF measurements between left and right sides of the face (A), there was a statistically significant difference between male and female samples (B). AEF, anterior ethmoidal foramen; F, female; L, left; M, male; PEF, posterior ethmoidal foramen; R, right.

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  Fig. 5 PEF-OC measurements between sex and side of the body. There was no statistically significant difference in PEF-OC measurements between left and right sides of the face or between male and female samples. F, female; L, left; M, male; OC, optic canal; PEF, posterior ethmoidal foramen; R, right.

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  Fig. 6 Recommended surgical guideline. Based on the data from the Hispanic and European populations, the recommended surgical guideline between the ALC, AEF, PEF, and OC is 24.8-13.9-7.6 mm, respectively. Left orbit. AEF, anterior ethmoidal foramen; ALC, anterior lacrimal crest; OC, optic canal; PEF, posterior ethmoidal foramen.

Reference

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