MRI-based anthropometric measurements of proximal humerus in Thai population

Abstract

Objective : The objective of this project was to analyze the exact anatomical data collected from magnetic resonance imaging of Thai patients’ shoulders and to compare their anatomical data with previous studies. Dimensions provided from this study can be used to assist implant manufacturers to evaluate the current and future designs.

Setting : Department of Orthopaedics, Faculty of Medicine, Chulalongkorn University

Research design : Descriptive study

Patients : Sixty-four shoulders / 58 patients who recieved MRI of the shoulder at Prachacheun Imaging Center from January 2008 – December 2008.

Methods : All anatomical data of the proximal humerus measured in 3D reconstruction of the MRI of patient shoulders. We used CATIA to measure all parameters and minimize the human errors by using a computer to calculate a 3D model

Results : The mean of total diameters of the articular was 36.64 ± 4.44 mm. The mean of the male and female shoulders were 40.83 ± 1.36 mm, 33.57 ± 2.76 mm respectively. Therefore, the difference between genders was significant. The mean articular thickness of the total subjects was 15.48 ± 2.38 mm, i.e., the mean of the male; 16.83 ± 2.05 mm; and the mean of the female; 14.50 ± 2.13 mm. The difference of articular thickness between genders was also significant. The mean neck-shaft angle of all subjects was 137.71 ± 6.43 mm. Separately, the mean of the male and female subjects were 138.80 ± 4.86 mm, 136.92 ± 7.32 mm, respectively. The mean medial offset of all subjects was 5.43 ± 1.51 mm. It is explained that the mean of the male and female subjects were 5.29 ± 1.81 mm, 5.53 ± 1.26 mm, respectively. The mean posterior offset of all subjects was 1.15 ± 0.94 mm. We discovered the means of male and female subjects were 1.27 ± 0.80 mm, 1.06 ± 1.04 mm, respectively. The mean of all retroversion angles was 13.99 ± 16.17 mm. The means of the male and female subjects were 10.21 ± 16.16 mm, 16.76 ± 15.82 mm, respectively. Subsequently, the difference of neck-shaft angle, medial offset, posterior offset and retroversion angle between genders were not significant

Conclusion : All data of this study when we compared to the previous in western population, we found significant difference in the diameter of the articular, neck-shaft angle, medial offset and posterior offset. This finding showed that an implant component suitable for using in western populations may not be compatible to the Thai population. The results of the project could provide fundamental data for the future design of shoulder prostheses suitable for the Thai population.