Introducing the Modified Cobb Angle for Measuring Cervical Spine Curvature During Swallowing

Area of Science:

• Anatomy
• Biomechanics
• Swallowing Physiology

Background:

• Cervical spine curvature, measured by the C2-C7 Cobb angle, may influence swallowing.
• The C2-C4 modified Cobb angle (MCA) was developed for swallowing research due to visualization challenges of lower cervical vertebrae.
• Previous studies indicated suboptimal reliability and validity of the MCA, necessitating further investigation.

Purpose of the Study:

• To evaluate the measurement properties of the C2-C4 MCA and a revised C2-C4 MCA.
• To assess the reliability and validity of these measures in healthy participants during thin liquid bolus swallowing.
• To compare the revised MCA with established cervical spine curvature measurements.

Main Methods:

• Exploratory analysis of videofluoroscopic images from 35 healthy participants.
• Examination of inter- and intra-rater reliability and criterion validity of the C2-C4 MCA and revised C2-C4 MCA.
• Comparison with C0-C2, C2-C6, and C2-C7 Cobb angles at different swallowing phases using ICCs, Pearson correlations, and mixed model analysis.

Main Results:

• The C2-C4 revised-MCA demonstrated superior intra- and inter-rater reliability.
• Moderate positive correlation was observed between the C2-C4 revised-MCA and the C2-C6 Cobb angle, indicating criterion validity.
• No significant differences in the C2-C4 revised-MCA were found across swallowing frames, age, sex, or head extension.

Conclusions:

• The C2-C4 revised-MCA exhibits enhanced psychometric properties compared to the original MCA.
• This revised measure is a reliable and valid tool for assessing cervical spine curvature during swallowing.
• The findings support the utility of the C2-C4 revised-MCA in swallowing research and clinical applications.