Medical Imaging as a Bone Quality Determinant and Strength Indicator of the Femoral Neck - Biomedical Engineering Systems and Technologies - page 193

The biomechanical parameters were correlated with BMD using the Pearson corre-
lation coefficient (r) and a linear regression model.
30 experiments were conducted to determine both, compressive yield strength and
modulus of elasticity and associate these to the DXA determined T-scores. The T-
score compares the measured BMD to that of a young adult (at the age of 35) of the
same gender with peak bone mass, while considering statistical values.

3.2 Results

A correlation of characteristic and mean values (BMD and T-score) determined by
DXA measurements, to the corresponding mechanical properties (yield stress and
elastic modulus) of the examined specimens are reflected in figure 4. These values are
in good coherence with previously presented data [35, 36]. The offset in the deter-
mined values can be attributed to the different sampling sites and techniques of the
compared studies.

Fig. 4. Equivalent T-score values versus yield stress σy and elasticity modulus (p<0.001)

The introduced experimental investigation revealed a significant correlation of
BMD to the mechanical properties of the femoral neck. A strong enslavement of the
ultimate material strength to BMD (r=0.838) was found, while the correlation to elas-
tic modulus, calculated based on the linear elastic region of the determined stress-
strain curves [37], was weaker (r= 0.689).
A limitation however of the introduced process, is based on the assumption of the
material's isotropy and the determination of universal properties of a bone segment
comprising of both, cortical and cancellous tissue. This methodology was adopted, as
DXA measurements reflect a combined BMA encapturing both bone types by default
and thus the assumption of a compound material is beneficiary to the approach.