Methodological principles for fractal analysis of trabecular bone

A standardized methodology for the fractal analysis of histological section s of trabecular bone has been established. A modified box counting method has been developed for use on a PC-based ima ge analyser. The effect of image analyser settings, magnification, image or ientation and threshold levels was determined. Also, the range of scale ove r which trabecular bone is effectively fractal was determined and a method formulated to calculate objectively more than one fractal dimension from th e modified Richardson plot. The results show that magnification, image orientation and threshold settin gs have little effect on the estimate of fractal dimension. Trabecular bone has a lower limit below which it is not fractal (lambda < 25 mu m) and the upper limit is 4250 mu m. There are three distinct fractal dimensions for trabecular bone (sectional fractals), with magnitudes greater than 1.0 and less than 2.0. It has been shown that trabecular bone is effectively fractal over a define d range of scale. Also, within this range, there is more than one fractal d imension, describing spatial structural entities. Fractal analysis is a mod el-independent method for describing a complex multifaceted structure, whic h can be adapted for the study of other biological systems. This may be at the cell, tissue or organ level and complements conventional histomorphomet ric and stereological techniques.