Abstract:
The development of mathematical simulation of adaptive bone remodelling aids the
prediction and the prevention of bone related pathological symptoms. This study is
aimed to aid the development of mathematical simulation by identifying a threshold CT
number to clearly differentiate the cortical and the trabecular regions from a clinical CT
image, developing an experimental protocol to create an atlas of structural and
mechanical properties and observing for possible relationships between the CT numbers
to the structural and mechanical properties of human knee bones. A series of
experimental protocols including clinical CT scanning, bone cube extraction and
compression tests and micro-CT scanning on the specimens was successfully developed.
The protocols were performed on five specimen groups of porcine tibia, porcine femur,
embalmed human femur, fresh human tibia and fresh human femur. This study
identified the threshold CT numbers for porcine (880), embalmed (664) and fresh (600)
knee bones. The porcine tibia and femur showed a correlation (R2 = 0.56) between the
CT numbers and the stiffness while fresh human tibia and femur showed three strong
linear correlations (0.59 ≤ R2
≤ 0.85) between the CT numbers and the stiffness. Some
correlations were observed between the major structural properties of interest (BV/TV,
Tb.Th and Tb.N) and the CT numbers in the porcine (0.4 ≤ R2
≤ 0.5) and the fresh
human knee bones (0.34 ≤ R2
≤ 0.5). No relationship was found between the CT
numbers and the mechanical and the structural properties in the embalmed bone. In
addition to this, no relationship between the stiffness and BV/TV was observed in all
specimen groups. The atlas of the stiffness, CT numbers and structural properties
indicated increase in the stiffness, CT numbers, BV/TV, Tb.Tb, Tb.N and BS/BV as the
location of trabecular gets closer to the cortical region. It also identified that the
direction of trabeculae alignment is not the only determinant of the direction of highest
stiffness. It is suggested to perform an experiment to identify the impact of
formalaldehyde on structural and mechanical properties of trabecular bone and to
develop a device that would measure compressive and shear strains without contacting
the bone samples directly to improve the results obtained in this study.