Bone mineral density measurement over the shoulder region

The purpose of this study was to (1). establish a method for measuring bone mineral density (BMD) over the shoulder region; (2). compare the relationship between shoulder BMD levels with hip BMD and body mass index (BMI); and (3). discuss the relevance of the shoulder scan as an early indicator of osteoporosis compared with hip scans, the latter representing a weight-bearing part of the skeleton. We developed a scanning procedure, including a shoulder fixation device, and determined the most appropriate software in order to establish a reference material with the highest possible precision. Duplicate scans of the dominant side shoulder on 80 healthy, non-osteoporotic Danish women revealed a coefficient of variation (CVSD) on BMD measurements of 1.7%, with no difference between young and old subjects. Shoulder BMD values were significantly lower than hip BMD values (P <0.00001). Both hip and shoulder values decreased with age (P <0.001). The difference between hip and shoulder BMD levels increased significantly with increased body mass index (BMI) (P <0.002). The positive relationship between the increased hip/shoulder BMD differential with BMI supports the conclusion that the shoulder is subject to the least relative influence of weight and stress loading because of migration of calcium to weight and stress-bearing areas. Since the effect of this migration could mask local osteoporotic bone loss, shoulder BMD measurement is likely to minimize false indicators of healthy bone in women with high BMI, and might therefore be a relevant early stage indicator of osteoporosis.