Measurement of Hip Geometry-Technical Background.

Conventional dual-energy X-ray absorptiometry images display a digital projection of the inorganic mineral mass in a scanned region. Bone mineral density software generates an average of the pixels within one or more regions. Although not used in the conventional analysis, the images also contain dimensional information limited to the plane of the image. The hip structure analysis method and that of the similar GE, Madison, WI, algorithm Advanced Hip Analysis use both the dimensional information and the mineral mass data to compute the types of dimensional properties (i.e., geometry) that are used to evaluate mechanical strength in engineering analyses. This article describes the hip structure analysis method and a somewhat cruder geometry approximation that does not require a reanalysis of the image. Limitations of the methods are discussed.