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Mandibular slope: a reproducible and simple measure of horizontal gaze

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Abstract

Study design

This study is a single-center retrospective radiographic review.

Objectives

The objective of this study is to evaluate a novel measurement parameter, mandibular slope (MS), as a measure of horizontal gaze.

Introduction

Assessment of sagittal spinal alignment is essential in the evaluation of spinal deformity patients. Ability to achieve a horizontal gaze, a parameter of sagittal alignment, is needed for the performance of daily activities. Standard measures of horizontal gaze, including the gold-standard chin–brow to vertical angle (CBVA) and the surrogate measures McGregor’s line (McGS) and Chamberlain’s line (CS), require high-quality imaging, precise head positioning, and reliance on difficult to view visual landmarks. A novel measurement parameter, MS, utilizing the caudal margin of the mandible on standard lateral spine radiographs is proposed.

Methods

90 radiographs from spine deformity patients with or without spinal implants from a single center were evaluated. Three spine surgery fellows independently measured CBVA, McGS, CS, and MS at two timepoints at least one week apart to assess accuracy and reliability. MS was measured as the angle created by the inferior edge of the mandibular body and the horizontal. Formulas for calculating CBVA based on the above parameters were derived and compared to the actual CBVA.

Results

Mean age was 49.7 years, 76 females and 14 males. CBVA correlated with CS, McGS, and MS, r = 0.85, 0.81, and 0.80, respectively (p < 0.001). Standard error between real CBVA and calculated CBVA using CS (0.4 ± 4.79) and McGS (0.4 ± 3.9) was higher than that calculated using MS (− 0.2 ± 4.3). ICC demonstrated the highest inter-observer reliability with MS (0.999). MS had the highest intra-observer reliabilities 0.975, 0.981, and 0.988 (p < 0.001); CS and McGS also demonstrated high intra-observer reliability.

Conclusions

MS is a promising measure of horizontal gaze that correlates highly with CBVA, has excellent intra- and inter-observer reliability with CBVA, and is easily measured using standard lateral spine radiographs.

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Funding

No research funding was received.

Author information

Authors and Affiliations

  1. Nicklaus Children’s Hospital, Miami, FL, USA

    Stephen George, Subaraman Ramchandran & Thomas Errico

  2. New York University Langone Medical Center, New York, NY, USA

    Matthew Spiegel, Themistocles Protopsaltis & Aaron J. Buckland

  3. Montefiore Medical Center, Bronx, NY, USA

    Jaime A. Gomez

  4. Hospital for Special Surgery, New York, NY, USA

    Renaud Lafage & Virginie Lafage

  5. Icahn School of Medicine, Mount Sinai Hospital, 5 E 98th St., 4th Floor, New York, NY, USA

    Baron Lonner

Authors
  1. Stephen George
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  2. Matthew Spiegel
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  3. Themistocles Protopsaltis
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  4. Aaron J. Buckland
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  5. Jaime A. Gomez
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  6. Subaraman Ramchandran
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  7. Renaud Lafage
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  8. Virginie Lafage
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  9. Thomas Errico
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  10. Baron Lonner
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Corresponding author

Correspondence to Baron Lonner.

Ethics declarations

Conflict of interest

Dr. Buckland reports personal fees from Nuvasive, personal fees from Stryker K2M, personal fees from Medtronic, personal fees from EOS Imaging, outside the submitted work. Dr. Errico reports personal fees from Stryker/K2M, personal fees from Altus, from null, outside the submitted work. Dr. Lafage reports other from Nemaris, outside the submitted work. Dr. Lafage reports personal fees from NuVasive Inc., other from International Spine Society Group, personal fees from Globus Medical, Inc., personal fees from The Permanente Medical Group, other from European Spine Journal, personal fees from DePuy Synthes Spine, outside the submitted work. Dr. Lonner reports grants and non-financial support from Grant from Depuy Synthes to Setting Scoliosis Straight Foundation in Support of the Harms Study Group's research, personal fees, non-financial support and other from Depuy Synthes, personal fees and other from Zimmer Biomet, personal fees and non-financial support from Apifix, other from Paradigm Spine, other from Spine Search, other from SRS Spine Deformity Journal, outside the submitted work. Dr. Protopsaltis reports personal fees from Globus, personal fees from Stryker K2M, personal fees from Medicrea, personal fees from Altus, personal fees from Innovasis, outside the submitted work. The other co-authors have no disclosures.

Ethical approval

This study was approved by the Institutional Review Board at Mount Sinai Beth Israel.

Informed consent to participate/publication

Informed consent for this study was not required as this was a retrospective radiographic review. Institutional Review Board approval was granted for this waiver of consent. Consent for publication for this study was not required as this was a retrospective radiographic review. Institutional Review Board approval was granted for this waiver of consent.

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George, S., Spiegel, M., Protopsaltis, T. et al. Mandibular slope: a reproducible and simple measure of horizontal gaze. Spine Deform 8, 893–899 (2020). https://doi.org/10.1007/s43390-020-00137-x

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  • DOI: https://doi.org/10.1007/s43390-020-00137-x

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