抄録
The purpose of this study was to evaluate the humeral head retroversion in asymptomatic shoulder. We compared the differences between the dominant side and the non-dominant side, and sex differences. CT was done on 470 shoulders (235 healthy volunteers). 113 were males (mean, 30.4 years old) and 122 were females (mean, 30.0 years old). 104 males and 119 females were right-handed, and 9 males and 3 females were left-handed. We classified the materials into 4 groups according to the history of sports activities for two years or above in the growth period until 18 years old. We adopted our original measuring method utilizing Nobuhara's anatomical axis to draw the humeral head axis. The mean value of the humeral head retroversion on the dominant side of men was 37.7±10.4°, and 31.6±9.3° on the non-dominant side. Women's humeral head retroversion was 31.2±9.2° on the dominant side, and 25.9±10.2° on the non-dominant side. There were the significant differences between the dominant side and non-dominant side, or male and female as evaluated with the unpaired t-test (p<0.0001). The measurements of humeral head retroversion on the dominant side were larger than the non-dominant side regardless of sex in all groups classified based on sports career during a growth period. In addition, the measurements in males tended to be larger than females regardless of the dominant hand side with the sports classification. However, when the sex and the dominant hand side were the same, there were no significant differences in measurements of humeral head retroversion between the 4 groups. If there were some acquired elements except unilateral sports strain affecting the development of humeral torsion, it is possible that the differences of the measurements between the dominant side and non-dominant side, or male and female meant the differences of the degree of the exposure.
