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7/31/2019 Benedict Rogers - Biomechanical Analysis of Proximal Femoral Metastatic Lesions
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7/31/2019 Benedict Rogers - Biomechanical Analysis of Proximal Femoral Metastatic Lesions
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Introductionmetastatic pathological fractures
Up to 27% of all cancers
Variable histology
Osteolytic & osteoblastic mix
Affected by bisphosphonate Rx
(not uniform)
Unknown biomechanics
Variable stereology
Bone mineral density
Bone volume fraction
7/31/2019 Benedict Rogers - Biomechanical Analysis of Proximal Femoral Metastatic Lesions
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Aim
Quantify the comparative structural impactof..
Osteolytic lesions
Mixed osteolysis/osteoblastic lesions Bisphosphonate treatment
..on metastatic femoral lesions
Assess the reliability of clinical fracture risk
assessment.
7/31/2019 Benedict Rogers - Biomechanical Analysis of Proximal Femoral Metastatic Lesions
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7/31/2019 Benedict Rogers - Biomechanical Analysis of Proximal Femoral Metastatic Lesions
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Controls
MT-1 humanbreast cancer
genes
MT-1 humanbreast cancer
genes
Canine Ace-1prostate cancer
genes
Healthy
N=6
Osteolytic
lesions
N=8
+ systemic
bisphosphonates
Osteolytic lesions
N=9
Mixed osteolytic/osteoblastic
lesions, N=9
5-6 week old
Nude athymic rats
N=32
7/31/2019 Benedict Rogers - Biomechanical Analysis of Proximal Femoral Metastatic Lesions
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Stereology
CT imaging
Region of interest
600 slices distal physis
proximal CT slices per 0.01 mm
Each scan reconstructed
continuous tone (.ct) format greyscale bitmap (.bmp)
Amira Dev 5.2.2 imaging software
7/31/2019 Benedict Rogers - Biomechanical Analysis of Proximal Femoral Metastatic Lesions
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7/31/2019 Benedict Rogers - Biomechanical Analysis of Proximal Femoral Metastatic Lesions
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7/31/2019 Benedict Rogers - Biomechanical Analysis of Proximal Femoral Metastatic Lesions
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7/31/2019 Benedict Rogers - Biomechanical Analysis of Proximal Femoral Metastatic Lesions
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7/31/2019 Benedict Rogers - Biomechanical Analysis of Proximal Femoral Metastatic Lesions
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Cortical destruction
>2/31/3-2/3
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0.5
0.55
0.6
0.65
0.7
0.75
0.8
0.85
Osteolytic BP-Osteolytic Mixed Control
TMD
gHA/cm3
ResultsTissue Mineral Density
7/31/2019 Benedict Rogers - Biomechanical Analysis of Proximal Femoral Metastatic Lesions
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0.4
0.45
0.5
0.55
0.6
0.65
0.7
0.75
Osteolytic BP-Osteolytic Mixed Control
BV/TV
ResultsBone Volume Fraction, BV/TV
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0
20
40
60
80
100
120
140
160180
200
uc(MPa)
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
E
(GPa)
0
1
2
3
4
5
6
7
EA
(kN)
Ultimate Compressive Stress,
UC (Mpa)
Axial Rigidity,
EA, kN
Youngs Modulus,
E, GPa
ResultsMechanical Testing
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0
50
100
150
200
250
0.35 0.55 0.75 0.95
uc
(MPa)
TMD (gHA/cm3)
ResultsUC stress vs Tissue Mineral Density
R2=0.72
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7/31/2019 Benedict Rogers - Biomechanical Analysis of Proximal Femoral Metastatic Lesions
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7/31/2019 Benedict Rogers - Biomechanical Analysis of Proximal Femoral Metastatic Lesions
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7/31/2019 Benedict Rogers - Biomechanical Analysis of Proximal Femoral Metastatic Lesions
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Discussion
Bisphosphonate treatment increases
BV/TV by 19% (p
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Discussion
Mirels size correlates with bone volume fraction
Not with tissue mineral density
Ultimate compressive stress correlates Tissue mineral density
Not with bone volume
Mirels size does not correlate ultimate
compressive stress
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Discussion
CT improves
definition of cortical involvement
enhances reliability of Mirels score
Previous published inter-observer correlation
Size..0.48 0.56
Type.0.35 0.61
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7/31/2019 Benedict Rogers - Biomechanical Analysis of Proximal Femoral Metastatic Lesions
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Thank You