Introduction

Accurate evaluation of glenoid bone loss is essential for effective surgical management of shoulder instability. This study presents the Coraco-Gleno-Scapular (CGS) line as a novel tool for assessing significant glenoid bone defects, aiming to enhance clinical decision-making.

Methodology

We analyzed 50 normal right shoulders (ages 18-40) using 3D Computed Tomography (CT). The CGS line was established from the coracoid base to the antero-inferior glenoid pole. Two methods were used to quantify bone defects: the Best Fit Circle Area Method, which calculates the percentage of bone defect anterior to the CGS line, and the Glenoid Index Linear Method, which determines the defect percentage using a/b * 100, where a is the anterior glenoid width and b is the total glenoid width/diameter.

Results

Interobserver reliability, measured by intraclass correlation coefficients (ICC), demonstrated high agreement (ICC = 0.87, 95% CI: 0.70-0.93) between two orthopedic surgeons with six years of experience. The mean bone defect measured by the Best Fit Circle Area Method was 21% (range: 18-31%), while the Glenoid Index Linear Method indicated a mean defect of 24% (range: 20-32%). Fourteen shoulders had less than 20% bone defect using the Best Fit Circle Method, with none below 17.5%, suggesting no sub-critical bone loss. Thirty-six shoulders exhibited more than 20% bone defect.

Conclusion

The CGS line is an effective and user-friendly tool for evaluating glenoid bone loss, demonstrating potential for enhancing the management of shoulder instability. Its ease of use and high reliability support its further exploration and validation in clinical practice.