Is the Bare Spot reliable for the bone loss measurement?

Area of Science:

• Orthopedic Surgery
• Anatomy
• Biomechanics

Background:

• Assessing bone loss in anterior shoulder instability is crucial for surgical planning.
• The Bare Spot (BS) is a proposed anatomical landmark for intra-operative glenoid bone defect evaluation.
• Reliability of the BS for defining bone loss requires validation.

Purpose of the Study:

• To evaluate the reliability of the Bare Spot (BS) as an anatomical landmark for intra-operative definition of bone loss in anterior shoulder instability.

Main Methods:

• Measurements of distances from the BS to glenoid margins (anterior, posterior, inferior) were taken.
• Both arthroscopic visualization and open surgical approaches were utilized in 20 shoulders.
• Comparison of measurements between arthroscopic and open methods assessed reliability.

Main Results:

• The BS did not consistently align with the glenoid center; BS-P distance exceeded BS-A distance (p < 0.05).
• The BS was located approximately 40% closer to the anterior glenoid margin.
• A correction factor (BS-A × 1.25 / BS-P = 1) was proposed to account for anterior positioning.

Conclusions:

• The BS is positioned 40% of the joint diameter from the anterior glenoid margin, necessitating a correction factor for accurate use.
• The BS can serve as a valuable landmark in shoulder instability surgery when its anterior bias is considered.
• Arthroscopy demonstrated reliability for obtaining accurate bone measurements within the shoulder joint.