The Coraco-Gleno-Scapular line: A simple tool for assessing glenoid bone defects.

Background: The treatment decisions for shoulder instability often necessitate surgical intervention, with glenoid bone loss being a key factor. Currently, various techniques exist to identify glenoid bone loss, each with its own advantages and disadvantages. This study introduces the Coraco-Gleno-Scapular (CGS) line as a tool for assessing critical glenoid bone defects. The objective is to define the CGS line and evaluate its utility in guiding clinical decisions regarding bone loss, proposing that defects extending posterior to this line indicate critical bone involvement requiring surgical intervention.

Methods: The study analyzed 50 normal right shoulders from individuals aged 18-40 years. Using 3D en face views of the glenoid, the CGS line was defined from the anteroinferior base of the coracoid process, crossing the anterior glenoid, to the anteroinferior pole of the scapula. The best-fit circle area method and the glenoid index linear method were used to calculate the percentage of the bone area located anterior to the CGS line.

Results: The best fit circle area method revealed a mean glenoid surface area anterior to the CGS line of 22.19%, while the glenoid index linear method indicated a mean area of 27.2% anterior to the CGS line. Of the 50 shoulders, 14 had a glenoid surface area <20% anterior to the CGS line using the best-fit circle method, with no cases below 17.5%, while 36 individuals had a glenoid surface area >20%.

Conclusion: The Coraco-Gleno-Scapular line is a reliable and simple tool for assessing glenoid bone loss, providing valuable guidance in managing shoulder instability. Its ease of use makes it a promising candidate for standard application in clinical practice.

Level of evidence: Prospective observational study, Level III.