Objective: Glenoid defect is an important factor of consideration in determining appropriate surgical treatment for anterior shoulder instability, so precise assessment is necessary. The glenoid fossa bare spot has been reported to be a useful landmark during arthroscopic examination, although there are some controversies. The objective of the present study is to determine whether the bare spot is located in the center of the glenoid and thus the extent to which it can be used as a landmark.

Materials and Methods: The distance from the center of the bare spot to the anterior, posterior, superior, and inferior rim of the glenoid were measured in 40 male and 26 female specimens.

Results: The average glenoid length was 36.1 mm superoinferiorly and 27.2 mm anteroposteriorly. However, both the vertical and horizontal length of the glenoid was significantly smaller in females than in males (p-value <0.01). The average anterior and posterior glenoid length was 13.2 mm in females versus 13.5 mm. The anterior glenoid length was significantly shorter than the posterior length in females (p-value = 0.02), but there was no significant difference in males (p-value = 0.22).

Conclusion: The anterior glenoid length is shorter than the posterior in females. The posterior glenoid length may be a useful reference in evaluating bone loss of the anterior glenoid rim in
males, but may not be useful in females.

Keywords: Anterior glenoid defect, Bare spot, Arthroscopic evaluation