Executive Summary SIBA
For the purpose of the study, a compact desk-top µCT providing a nominal
isotropic resolution of 14 µm was used. Two groups of seven trabecular bone
specimens were measured from pre-menopausal and post-menopausal women
respectively. A novel algorithm was developed to simulate age-related bone loss
for the specimens in the first group. The algorithm, also referred to as
simulated bone atrophy (SIBA), describes a truly three-dimensional approach and
is based directly on cellular bone remodeling. Bone resorption is controlled by
osteoclastic penetration depth and bone formation is governed by the efficiency
level of the osteoblasts. The simulation itself describes an interative process
with a cellular remodeling cycle of 197 days. The activation frequency is
controlable and can be adjusted for the different phases of pre-, peri- and
post-menopause. Until the onset of menopause, set to be at the age of 50,
osteoblastic and osteoclastic activities are in balance; the structure remains
almost constant. After the onset of menopause an inbalance in the cell
activities is modeled resulting in a net bone loss. The doubling of the
activation frequency in peri-menopause causes a pronouced loss in that period.
By applying SIBA to the specimens from group one, it was possible to predict
age-related architectural changes and to "age-match" these specimens with those
from group two. Using advanced animation tools and quantitative bone
morphometry, the changes in bone architecture associated with the bone loss were
monitored over an average observation time of 43 years till the age of 80 years.
Ralph Müller · ESB'98 · Toulouse · 2-8 July 1998