Jenny Zhao MD, PRESENTER: Nothing to Disclose

Abstract: HTML Purpose: This study compares true longitudinal transmenopausal (TransM) changes with longitudinal postmenopausal osteoporotic (PostM) changes in three-dimensional (3D) trabecular (Tb) architecture. This may improve our ability to understand the pathophysiology of osteoporosis and other bone disorders, and to estimate bone biomechanical properties in terms of fracture resistance given that the mechanical competence of Tb bone is a function of its apparent density and 3D distribution. During aging and osteoporosis, Tb plates are perforated and connecting rods are dissolved, with a continuous shift from one structural type to the other, which cannot be evaluated by 2D histological sections. There is debate among histomorphometrists about whether Tb thinning, or rather Tb disappearance occurs with aging and/or menopause based on 2D sections using the parallel plate model. Methods and Materials: We examined 39 paired iliac crest bone biopsies (78 specimens). For 20 TransM women, the 1st biopsy was from normal, premenopausal women, mean age 49 (± SD, ± 3) years (yrs), and the 2nd biopsy from the same group of women, but 1 yr postmenopausal, occurring 5 (± 2) yrs) after the 1st biopsy. From 19 PostM women with osteoporotic vertebral fractures and the hip/lumbar BMD at least 1 SD below the mean value in normal young women, the 1st biopsy was taken at age 68 (± 7) yrs, 10 (± 9) yrs since menopause, while the 2nd was 19 (± 5) months later. The specimens were scanned using a Scanco micro CT with isotropic resolution of 17 µ. 3D Tb structural parameters were directly measured without stereological model assumption. Structure model index 0 represent an ideal plate structure and 3 represents rod structure. Results: There was a significant change between paired bone biopsies in 3D Tb bone volume fraction (TransM versus PostM, -4.0%/yr vs. -3.3%/yr), Tb number (-1.2%/yr vs. -0.1%/yr), Tb thickness (-2.7%/yr vs.-0.5%/yr), Tb separation (2.4%/yr vs. 0.5%/yr), structure model index (8.0%/yr vs. 4.6%/yr), degree of anisotropy (-0.6%/yr vs. -0.1%/yr), and connectivity density (-1.1%/yr vs. -9.2%/yr). The percentage change was greater in 3D Tb thickness than in Tb number and Tb separation. Conclusion: 3D Tb microstructure rapidly deteriorates in the iliac crest, which is more pronounced in TransM women than in PostM women with osteoporotic fracture, while loss in Tb connectivity density is much greater in PostM women than in TransM women. Tb thinning does occur and trabeculae dramatically shift from a plate-like structural type to a rod-like pattern, and become more isotropic.     (J.Z. received a grant from Eli Lilly and Company.)

Zhao MD, J, Micro CT Examination of Longitudinal Changes in 3D Iliac Trabecular Microarchitecture: Transmenopausal versus Postmenopausal.  Radiological Society of North America 2003 Scientific Assembly and Annual Meeting, November 30 - December 5, 2003 ,Chicago IL. http://archive.rsna.org/2003/3105602.html