Bridging the Gap: A Unified Mathematical Model for Standardising Glenoid Bone Loss Measurement

Alexander Gallant; Quinten Mortier ; A Karelse; Alexander Van Tongel

Abstract

Background: A major factor in recurrent traumatic anterior shoulder instability is glenoid bone loss, often caused by bony Bankart lesions. Accurate quantification of glenoid bone loss is essential for determining appropriate treatment. Numerous measurement indexes have been proposed, but variability in methodologies complicates comparisons across studies and clinical decision-making.Purpose: To develop a conversion table to allow comparison between different indexes.Methods: This study identified 11 commonly used glenoid bone loss indexes from the literature. These indexes measure bone loss using different parameters, including linear measurements, surface area calculations, and ratios derived from 2D CT images or 3D reconstructions. A conversion table was developed to establish correlations between these indexes using Sugaya’s method as the reference.Results: Mathematical relationships between bone loss expressed as a percentage of glenoid width, surface area, and chord length were derived using basic formulas for circular segments. This demonstrated that linear measurement-based indexes tend to overestimate bone loss compared to surface area-based methods. A conversion table was created to facilitate direct comparisons between the different indexes.Conclusion: The proposed conversion table enables the conversion of glenoid bone loss values between different measurement methods. This tool enhances data conversion across studies, improves the accuracy of bone loss evaluation, and aids in clinical decision-making. Converting measurements will reduce discrepancies between linear and surface area-based methods, ultimately benefiting surgical planning and treatment selection.What this study adds: The authors feel this study adds the tools to allow both better understanding of the different aspects of glenoid bone loss and conversion of values between existing indexes.Potential impacts on research, practice or policy: The results of this study enhance data conversion across studies, improves the accuracy of bone loss evaluation, and aids in clinical decision-making.Study Design: Retrospective imaging and mathematical modelling study using 3D CT reconstructionsLevel of Evidence: IVKeywords: Glenoid Bone Loss, Shoulder Instability, Latarjet, Index, Quantification, Conversion Tablehttps://doi.org/10.70885/hmsj.2026.02.003

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