Changes of interstitial bone thickness with age in men and women

Mean interstitial bone thickness has been estimated from mean trabecular thickness and mean wall thickness (It.Th = Tb.Th-2*W.Th) with varying results. Some authors found age-related changes of It.Th while others did not. We measured It. Width (It.Wi, 2D) directly, in cancellous iliac crest bone from 23 women aged 20-78 yrs. and 21 men aged 23-74 yrs. At grid-selected sites coupled measurements were done of Tb.Wi and It.Wi, together with W.Wi. It.Wi was defined as the distance between cement lines nearest to the surface at both sides of a trabecula. A thionine stain was used to visualize the cement lines. When the persons studied were divided into two age groups: 20-49 yrs (Group 1) and 50-79 yrs (Group 2) significant but opposite age-related trends were seen both in men and women. Group 1: Men: r = -.68; p < .02; n = 11; Women: r = -.68; p < .02; n = 11. Group 2: Men: r = .79; p < .01; n = 10. Women: r = .59; p < .05; n = 12 (r = coeff. of correlation). Men: It.Wi 63.3 microns (3rd decade [dec.]); 50.8 microns (6th dec.); 67.8 microns (8th dec.). Women: It.Wi 63.7 microns (3rd dec.); 48.3 microns (6th dec.); 63.8 microns (8th dec.). Measured It.Wi values appeared considerably larger than their calculated counterparts (mean delta: 35%). The decline of It.Wi is interpreted as a sign of negative bone balance at the BMU level, leading to thinning of trabeculae, the subsequent increase has to be the result of both declining resorption depth and disappearance of the thinner trabeculae.(ABSTRACT TRUNCATED AT 250 WORDS)