Background: The loosening of the glenoid baseplate component is one of the most common complications after reverse total shoulder arthroplasty. The mismatch between size of baseplate and glenoid in Thai People may result in improper baseplate screw fixation and lead to early loosening of the glenoid component. Knowing of the glenoid size will guide the surgeon in placing or choosing the proper size glenoid baseplate to improve screw fixation strength.
Objective: Study the size of glenoid in Thai people and compare with previous studies.
Material and Method: The authors measured the glenoid size in anteroposterior and superoinferior directions, the data were recorded in term of mean and standard deviation. The present data were then compared with the previous glenoid studies to
identify the differences in size between Thai people and others.
Results: Among 160 patients with the mean age of 58.2+14.2 years, the overall glenoid size for the entire study group were 32.3+3.2 mm and 24.4+3.2 mm in superoinferior (SI) and anteroposterior (AP) directions, respectively. The male glenoid size were 35.6+2.6 mm and 26.7+2.5 mm in SI and AP directions, respectively. The female glenoid SI diameter were 31.0+1.9 mm and in AP diameter were 22.0+1.7 mm. The glenoid size in Thai people was significantly smaller than the glenoid size from previous studies in Caucasians.
Conclusion: The overall glenoid size in Thai people was significantly smaller than the previous studies in Caucasians. The female glenoid was also smaller than with the male. These findings alert surgeons to choose the proper glenoid baseplate design to avoid an overhang problem and improve screw fixation, especially in Thai female patients.

Keywords: Glenoid, Reverse total shoulder arthroplasty, Thai glenoid size