Whole Bone Modeling Using Bone Mineral data or Bones Are Not Amorphous blobs Thomas j. Beck, Sc D The Johns Hopkins university School of medicine
Whole Bone Modeling Using Bone Whole Bone Modeling Using Bone Mineral Data Mineral Data or Bones Are Not Amorphous Blobs Bones Are Not Amorphous Blobs Thomas J. Beck, Sc.D. Thomas J. Beck, Sc.D. The Johns Hopkins University The Johns Hopkins University School of Medicine School of Medicine
The Fundamental problem a Bones get less dense as we age d Old people with low density bones fracture easily a Space-flight rapidly causes bones to get less dense a Does space flight produce the same effects on bone as aging
The Fundamental problem The Fundamental problem Bones get less dense as we age Bones get less dense as we age Old people with low density bones Old people with low density bones fracture easily fracture easily Space -flight rapidly causes bones to flight rapidly causes bones to get less dense get less dense Does space flight produce the same Does space flight produce the same effects on bone as aging? effects on bone as aging?
The human Femur toona Head Bone loss causes L668 troche ntenrocnanmteric fragility of proximal (upper)end of femur Fractures are major cause of death(indirect) and Medial disability in elderly Patellar surface Adductor epicondyle ucon Concern that space-flight Vesa rainny might have similar Literal n consequences Ia) Anterior surface (b) Posterior surface
The Human Femur The Human Femur Bone loss causes Bone loss causes fragility of proximal fragility of proximal (upper) end of femur (upper) end of femur Fractures are major cause Fractures are major cause of death (indirect) and of death (indirect) and disability in elderly disability in elderly Concern that space Concern that space -flight might have similar might have similar consequences consequences
Bone dynamics a Bone is a dynamic tissue and is constantly being absorbed and rebuilt throughout life. a Because bones get less dense with age physicians interpret this as an imbalance between resorption and formation. a Old people with low density bones fracture easily so it is assumed that bone density is a measure of likelihood of fracture
Bone Dynamics Bone Dynamics Bone is a dynamic tissue and is constantly Bone is a dynamic tissue and is constantly being absorbed and rebuilt throughout life. being absorbed and rebuilt throughout life. Because bones get less dense with age Because bones get less dense with age physicians interpret this as an imbalance physicians interpret this as an imbalance between between resorption resorption and formation. and formation. Old people with low density bones fracture Old people with low density bones fracture easily so it is assumed that bone density is a easily so it is assumed that bone density is a measure of likelihood of fracture. measure of likelihood of fracture
Current bone Measurements DXA Scan Image of Hi Digital image with all soft tissues subtracted and only bone mineral present Pixel values represent areal mass in g/cm Areal mass is averaged over part of region containing bone (femoral neck region shown) Result approximates volumetric density and is called bone mineral density (BMD)
Current Bone “Density”Measurements Current Bone “Density”Measurements DXA Scan Image of Hip DXA Scan Image of Hip •Digital image with all soft tissues subtracted and only bone mineral present • Pixel values represent areal mass in g/cm2 •Areal mass is averaged over part of region containing bone (femoral neck region shown) •Result approximates volumetric density and is called bone mineral density (BMD)