Similarity analysis of bone mineral density measurements of femur sites using dendrogram

Bone mineral density (BMD) measurements are the gold standard by which osteoporosis is diagnosed. Dual Energy X-ray Absorptiometry (DEXA) is the most commonly used measuring technique to assess BMD at both the hip and spine. There are three sites within each hip, collectively called the femoral sites, which are assessed - the femoral neck site, the trochanteric site, and Ward's triangle. It is a known fact that the different areas of the femur are composed of different percentages of cancellous bone. The null hypothesis that we examine in this paper is that there is no difference between the mineralization states at all of these sites. To do so, we introduce and present a dendrogram-based methodology that (1) identifies valid clusters for any two given subsets of the six sites, (2) uses the valid clusters to examine the existence of associations between the two subsets, and (3) the existence of association, if any, is measured by the degree of similarity between the two subsets. The obtained results in this research effort partially reject the null hypothesis.