Appropriate Position of the Forearm for the Measurement of BMD

Han, Man Seok; Kwon, Soon Tae; Yang, Seoung Oh; Juhng, Seon Kwan

Abstract

OBJECTIVES
The aim of this study was to evaluate the appropriate position of the forearm for measuring the BMD (Bone Mineral Density). MATERIAL & METHODS: CT scanning was performed in 21 men to determine the appropriate position for the forearm. Twenty one healthy volunteers who were without any history of operations, anomalies or trauma were enrolled. CT scanning was used to evaluate the cross sectional structures and the rotation angle on the horizontal plane of the distal radius. The rotation angle was measured by the m-view program on the PACS monitor. The DXA was used for measuring 20 dried radii of cadaveric specimens in pronation and supination with 3degrees, 5degrees, 7degrees and 10degrees of rotation respectively, including a neutral position (0degrees) to evaluate the changes of BMD according to the rotation.
RESULTS
The mean rotation angle of the distal radius on the CT scan was 7degrees of supination (76%, n=16), 3.3degrees of pronation (15%, n=3), and 0degrees at the neutral position (9%, n=2), respectively. The total average rotation angle in the 21 people was 5.2degrees of supination. In the cadaveric study, the BMD of the distal radius was different according to the rotational angles. The lowest BMD was obtained in 1.4degrees of pronation.
CONCLUSION
In the case of the measuring of the BMD in the forearm in a neutral position, the rotational angle of the distal radius is close to supination. Therefore, pronation is needed for the constant measurement of BMD in the forearm. We recommend measuring the lowest BMD of the distal radius at about five degrees of pronation.