Determining torsion angle of humerus head using MRI method.

BACKGROUND/AIM To measure the torsion angle of the humerus using images obtained via magnetic resonance imaging (MRI) in healthy volunteers and to evaluate outcomes with respect to sex and age groups. MATERIALS AND METHODS The study consisted of 36 healthy adults (18 males and 18 females aged between 20 and 68 years). The humeral torsion angle (HTA) was calculated using axial MRI images. Differences between results in terms of sex and age groups were evaluated with the Mann-Whitney U test. RESULTS The median HTA was 21.5 degrees (25th to 75th percentile: 7.8 degrees -28 degrees; range: -4 degrees to 36 degrees) in females, while it was 18.5 degrees (25th to 75th percentile: 7.5 degrees-32.3 degrees; range: 2 degrees to 41 degrees) in males. HTA median value was 19.5 degrees (25th to 75th percentile: 8.3 degrees-30.5 degrees; range: -4 degrees to 41 degrees) in all healthy volunteers. No significant differences were found between gender and age groups. CONCLUSION Considering intersocietal anatomic differences, our study may shed light on torsion angle for Turkey by determining mean torsion angle value. Moreover, this study indicated that HTA can be successfully measured using MRI. We think that our outcomes can be used as a reference for prosthesis design and shoulder joint prosthesis replacement. Moreover, we also think that this study will provide benefits in examining pathologies related to the shoulder joint, such as recurrent anterior dislocation syndrome.