Bone tissue composition varies across anatomic sites in the proximal femur and the iliac crest

Abstract

The extent to which bone tissue composition varies across anatomic sites in normal or pathologic tissue is largely unknown, although pathologic changes in bone tissue composition are typically assumed to occur throughout the skeleton. Our objective was to compare the composition of normal cortical and trabecular bone tissue across multiple anatomic sites. The composition of cadaveric bone tissue from three anatomic sites was analyzed using Fourier transform infrared imaging: iliac crest (IC), greater trochanter (GT), and subtrochanteric femur (ST). The mean mineral:matrix ratio was 20% greater in the subtrochanteric cortex than in the cortices of the iliac crest (p = 0.004) and the greater trochanter (p = 0.02). There were also trends toward 30% narrower crystallinity distributions in the subtrochanteric cortex than in the greater trochanter (p = 0.10) and 30% wider crystallinity distributions in the subtrochanteric trabeculae than in the greater trochanter (p = 0.054) and the iliac crest (p = 0.11). Thus, the average cortical tissue mineral content and the widths of the distributions of cortical crystal size/perfection differ at the subtrochanteric femur relative to the greater trochanter and the iliac crest. In particular, the cortex of the iliac crest has lower mineral content relative to that of the subtrochanteric femur and may have limited utility as a surrogate for subtrochanteric bone.

Figure 1

Representative FTIRI mineral:matrix ratio images and corresponding pixel histograms listed with mean and full width at half maximum (FWHM) values for the Gaussian curves fit to each distribution for cortical bone at the (a) iliac crest, (b) greater trochanter, and (c) subtrochanteric femur.

Figure 2

FTIR parameter distribution (a) means and (b) full widths at half maximum (FWHM) for cortical bone from each of the 10 donors. Values have been normalized to those at the iliac crest for each donor to facilitate visual comparison across sites. Missing bars indicate that the tissue type was not present in the biopsy.

Figure 3

FTIR parameter distribution (a) means and (b) full widths at half maximum (FWHM) for trabecular bone from each of the 10 donors. Values have been normalized to those at the iliac crest for each donor to facilitate visual comparison across sites. Missing bars indicate that the tissue type was not present in the biopsy.

Figure 4

FTIR parameter distribution (a) means and (b) full widths at half maximum averaged over the 10 donors for 3 anatomic sites: iliac crest (IC) greater trochanter (GT), and subtrochanteric femur (ST). Error bars indicate standard deviations. * p < 0.05 vs. IC, ** p < 0.05 vs. GT, ^ p < 0.1 vs. IC, ^^ p < 0.1 vs. GT. (Sample sizes for each tissue type and site: Cortical IC 10, ST 9, GT 9; Trabecular IC 9, GT 9, ST 3.)