Skeletal Consequences of
Spaceflight
Thanks to Dr. Grant
Schaffner
Prof. Dava Newman
Prof. Dava Newman 16.423J/HST515J Space Biomedical Engineering and Life Support
2
Bone - Summary
Prof. Dava Newman 16.423J/HST515J Space Biomedical Engineering and Life Support
3
Skeletal Consequences of
Spaceflight
Background
ò
Early flights: very little idea of physiological changes to expect
big concerns: respiration, cardiovascular
bone probably wasn t a serious consideration
ò
What
has been learned in the pa
st 37 years of
human spaceflight
?
Prof. Dava Newman 16.423J/HST515J Space Biomedical Engineering and Life Support
4
Spaceflight
Bone Loss in Humans
F
l
i
ght
/
S
t
ud
y
Fi
n
d
i
n
g
R
ef
er
en
ces
G
e
m
i
ni
4
,
5
,
a
nd
7
4-
14 da
y
s
;
C
al
c
a
neus
and m
et
ac
ar
pal
bone
dens
i
t
y
l
os
s
es
o
f
2-
4%
f
or
5
as
t
r
on
aut
s
,
a
nd 9%
f
or
s
i
x
t
h
V
os
e
,
1
974
So
y
u
z
9
18 day
s
;
8-
1
0%
dec
r
eas
e i
n c
al
c
a
neus
d
ens
i
t
y
f
or
bot
h c
os
m
ona
ut
s
B
i
r
y
k
ov
and
K
r
as
ny
k
h
,
1970
Ap
o
l
l
o
1
7
12.
6 day
s
;
m
ean
C
a
l
o
s
s
of
0
.
2%
of
t
ot
al
body
and
m
ean P
hos
phor
us
l
os
s
of
0.
7%
of
t
ot
a
l
b
ody
t
hr
ou
gh
i
nc
r
eas
e
d ur
i
n
ar
y
and f
ec
al
ex
c
r
et
i
on
R
a
m
ba
ut
,
et
al
.
,
19
75
S
ky
l
ab
2
M
i
ssi
o
n
N
o
s
i
gni
f
i
c
ant
bo
ne m
i
ner
a
l
c
ont
ent
c
h
anges
i
n
ar
m
;
c
al
c
a
neus
l
os
s
r
e
t
ur
ned t
o nor
m
a
l
b
y
87t
h
day
pos
t
f
l
.
V
oge
l
&
W
hi
t
t
l
e,
1976
Long Te
r
m
F
ol
l
ow
-
U
p
of
S
k
y
l
a
b B
one
D
e
m
i
n.
S
t
a
t
i
s
t
i
ca
ll
y
s
i
g
n
if
ic
a
n
t
lo
s
s
o
f o
s
ca
lc
i
s
m
i
n
e
r
a
l
in
ni
n
e S
k
y
l
ab c
r
ew
m
em
ber
s
,
5
y
ear
s
af
t
er
f
l
i
ght
T
i
l
t
on,
et
al
.
,
1980
C
o
m
b
in
e
d
U.S
.
/
U.S
.
S
.
R
.
S
t
udy
of
Long Te
r
m
Fl
i
g
h
t
QC
T
o
f
s
p
i
n
e
;
U
p
t
o
8
m
o
n
t
h
s
;
N
o
l
o
s
s
i
n
v
e
r
te
b
r
a
l
bodi
es
,
but
8%
l
os
s
i
n
pos
t
er
i
or
el
em
ent
s
(
4%
l
os
s
i
n
v
ol
um
e of
at
t
ac
hed m
us
c
l
es
)
;
ex
er
c
i
s
e
c
ount
er
m
eas
ur
es
onl
y
par
t
i
al
l
y
s
u
c
c
e
s
s
f
ul
O
g
anov
,
et
al
.
,
1990
M
i
r
366-
D
ay
M
i
ssi
o
n
O
ne
c
os
m
onaut
a
v
er
aged
10%
l
os
s
of
t
r
abec
u
l
ar
bone f
r
om
L1
,
L2,
L3;
m
eas
ur
ed by
Q
C
T
G
r
i
gor
i
ev
,
et
al
.
,
1991
M
i
r
4
.
5
-
6
M
ont
h F
l
i
ght
s
Q
D
R
as
s
es
s
m
ent
of
B
M
D
;
t
ot
al
body
m
i
ner
al
l
os
s
e
s
av
er
aged 0.
4%
;
m
os
t
m
ar
k
e
d
l
oc
al
l
os
s
w
as
i
n
f
e
m
o
r
a
l
n
e
c
k
a
n
d gr
e
a
t
e
r
t
r
oc
ha
nt
e
r
-
-
up
t
o 1
4
%
O
g
anov
,
et
al
.
,
1992
M
i
r
1
a
nd 6
M
ont
h
F
l
i
ght
s
pQ
C
T
;
not
i
c
eabl
e l
os
s
of
t
r
abec
u
l
ar
an
d
c
or
t
i
c
al
bone
i
n
t
i
bi
a af
t
er
6
m
ont
hs
C
o
l
l
et
,
et
al
.
,
199
7
NAS
DA
S
t
u
d
y
o
f
2
NA
S
A
A
s
t
r
ona
ut
s
42
y
.
o.
f
e
m
al
e
and 32
y
.
o.
m
al
e;
s
hor
t
f
l
i
gh
t
;
negat
i
v
e
c
al
c
i
um
bal
anc
e;
3.
0%
l
os
s
of
B
M
D
i
n L2
-
4
M
i
y
a
m
o
to
,
e
t
a
l
.,
1
9
9
8
Prof. Dava Newman 16.423J/HST515J Space Biomedical Engineering and Life Support
5
Spaceflight
Bone Loss in Animals
F
l
i
ght
/
S
t
ud
y
Fi
n
d
i
n
g
R
ef
er
en
ces
C
o
sm
o
s 605
R
at
s
;
B
on
e f
or
m
at
i
on
r
educ
ed
i
n
m
e
t
aphy
s
es
of
l
ong
bones
Y
ago
dov
s
k
y
,
e
t
a
l
.
,
1976
C
o
sm
o
s 782
R
at
s
;
40%
r
educ
t
i
o
n i
n l
engt
h of
pr
i
m
ar
y
s
p
ongi
os
a
due
t
o
r
e
duc
ed f
or
m
a
t
i
on an
d i
nc
r
ea
s
ed r
es
or
pt
i
on
A
s
l
i
ng,
1
978
C
o
sm
o
s 782?
R
at
s
;
O
s
t
eobl
as
t
di
f
f
er
e
nt
i
at
i
on i
n
non-
w
ei
g
ht
-
b
ear
i
n
g
si
t
e
s
uppr
es
s
ed
dur
i
ng
w
ei
ght
l
es
s
ne
s
s
R
o
ber
t
s
,
1981
C
o
sm
o
s 936
R
at
s
;
30%
d
ec
r
ea
s
e i
n f
em
or
al
br
ea
k
i
ng
s
t
r
engt
h o
f
f
em
or
a
w
i
t
h
r
ec
ov
er
y
of
no
r
m
al
pr
oper
t
i
es
af
t
er
25d
S
pe
c
t
or
,
et
al
.
,
1983
C
o
sm
o
s 782 &
9
36
R
at
s
;
A
r
r
e
s
t
l
i
ne s
e
par
a
t
i
n
g bon
e f
or
m
ed
dur
i
ng
and
pos
t
-
s
p
ac
ef
l
i
ght
;
def
ec
t
i
v
e
and hy
pom
i
ne
r
al
i
z
ed bone
T
ur
ner
,
et
al
.
,
1985
R
at
T
ai
l
S
u
sp
en
si
o
n
,
1984
U
p t
o
15 day
s
;
C
al
c
i
um
c
ont
e
nt
:
t
i
bi
a
=
86.
2
+
/
-
2.
5
%
,
v
er
t
ebr
a =
75.
5 +
/
-
3.
5%
of
c
ont
r
o
l
G
l
obus
,
e
t
a
l
.
,
1984
C
o
sm
o
s 1514
P
r
i
m
at
es
;
5 d
ay
s
;
r
es
o
r
pt
i
on
i
nc
r
eas
ed du
r
i
ng f
l
i
ght
C
a
nn,
et
al
.
,
1986
C
o
sm
o
s 1667,
188
7,
2044
P
r
i
m
at
es
;
13 day
s
;
l
ow
er
m
i
ner
al
i
z
at
i
on r
a
t
e and
l
es
s
bone m
i
ner
al
i
z
ed;
l
ongi
t
udi
nal
gr
ow
t
h
s
l
ow
ed
C
a
nn,
et
al
.
,
1990
C
o
sm
o
s 1667
R
at
s
;
7d s
pac
ef
l
i
ght
v
s
7d t
a
i
l
-
s
us
pens
i
o
n;
l
os
s
of
t
r
abec
ul
ar
bon
e i
n pr
ox
t
i
bi
al
m
et
a
ph m
or
e ex
t
ens
i
v
e
in
f
l
ig
h
t
r
a
t
s
V
i
c
o,
et
al
.
,
1991
C
o
sm
o
s 2044
R
at
s
;
F
r
ac
t
ur
e
r
ep
ai
r
pr
oc
es
s
i
m
pai
r
ed du
r
i
ng f
l
i
ght
K
ap
l
ans
k
y
,
et
al
.
,
199
1
C
o
sm
o
s 2229
P
r
i
m
at
es
;
11.
5
day
s
;
t
endenc
y
t
ow
ar
d
dec
r
eas
ed
B
M
C
dur
i
ng f
l
i
ght
;
onl
y
par
t
i
al
r
ec
o
v
ey
1
m
ont
h
a
f
t
e
r
Z
er
at
h,
et
al
.
,
1996
R
at
T
ai
l
S
u
sp
en
si
o
n
,
1998
U
nl
oaded
bones
di
s
pl
a
y
r
e
duc
ed
os
t
eob
l
as
t
nu
m
be
r
,
gr
ow
t
h,
and m
i
ner
al
i
z
at
i
on
r
at
e
i
n
t
r
a
bec
ul
a
r
bone
M
o
r
ey
-
H
ol
t
on
and
G
l
obus
,
1
998
Prof. Dava Newman 16.423J/HST515J Space Biomedical Engineering and Life Support
6
Bedrest
/
Hypokinesia
Studies
Models for Weightlessness of
Spaceflight
S
t
udy
F
i
nding
Re
f
e
r
e
n
c
e
s
5-
36 W
eek
s B
ed
r
est
90 healt
h
y
y
oung m
en
;
5% los
s
of
c
a
lc
aneal m
i
ner
la
eac
h m
o
nt
h;
m
ec
han
ic
al and bioc
hem
i
c
al
c
ount
er
m
eas
ur
es
no
t
s
uc
c
es
s
f
ul
S
c
hneider
and
M
c
Donald,
198
4
120-
d
ay
B
e
d
r
est
M
i
ner
aliz
at
ion r
a
t
e
s
l
o
wed;
c
o
nt
r
a
dic
t
or
y
r
e
s
u
lt
s
dem
ons
t
r
at
e dif
f
ic
ult
i
es
of
bedr
es
t
as
s
pac
e a
nalog
V
i
c
o,
et
al.
,
198
7
17-
w
eek B
e
d
r
est
6 healt
hy
y
oung m
ale
s
;
6 m
ont
hs
of
r
eam
bula
t
ion;
B
M
D % c
h
an
g
e (
p
<
.
05)
:
f
emo
ra
l
n
eck (
F
N)
-
3.
6,
tr
o
c
h
a
n
t
e
r
(T
) -4
.
6
; %
/
w
e
e
k
(p
<
.
0
5
): F
N
-.
2
1
+/
- .
0
5
,
T
-
.
27 +
/
-
.
05;
Reamb
u
l
at
i
o
n
% re
co
very:
F
N 0
.
00 +
/
-
.
0
6
,
T
0
.
0
5
+/
- .
0
5
(p
r
o
x
.
fe
m
u
r
d
i
d
n
o
t r
e
c
o
v
e
r
w
e
l
l
)
Le
B
l
anc
,
et
al.
,
1990
3
7
0
-d
a
y
A
n
ti
o
r
th
o
s
ta
ti
c
Hyp
o
k
i
n
e
s
i
a
T
e
s
t
Highes
t
los
s
es
in f
oo
t
bones
;
r
em
edial m
eas
u
r
es
delay
os
t
e
opor
os
is
b
u
t
do not
c
o
m
p
let
e
ly
ex
c
l
u
d
e it
;
r
es
u
lt
s
o
bt
ained by
d
i
f
f
er
ent
m
et
h
ods
of
t
en c
on
f
lic
t
ing
Z
a
ic
hic
k
and M
o
r
u
k
o
v
,
19
98
Prof. Dava Newman 16.423J/HST515J Space Biomedical Engineering and Life Support
7
Summary of Findings
ò
Significant bone loss in weightlessness
ò
Calcium excretion increases negative balance
ò
Bone mineral density decreases
weight bearing areas: 1-2% per month
ò
Osteoblast
(builders) proliferation and activity
reduced, while osteoclasts
(consumers) appear to
be unaffected
ò
Fracture repair may be impaired
ò
Bone strength is reduced
Prof. Dava Newman 16.423J/HST515J Space Biomedical Engineering and Life Support
8
Research Questions
ò
What
is the rate of bone
loss in critical areas?
ò
How does this affect bon
e strength?
ò
What
is the risk of fracture?
duration of
spaceflight
activity, gravity level
bone
habitus
: body weight, etc.
ò
What
countermeasures are possible and
how
effective are they?
Prof. Dava Newman 16.423J/HST515J Space Biomedical Engineering and Life Support
9
Current Research
Justification
ò
Focus on critical weight bearing areas and regions of rapid bone loss (related du
e to remodeling)
lumbar spine
proximal femur (hip)
ò
Presently, bone strength estimated
from DXA
BMD (or BMC) correlation with failure load
Prof. Dava Newman 16.423J/HST515J Space Biomedical Engineering and Life Support
10
Current Research
6000
5000
Failure Load (N)
4000
3000
2000
r
2
= .71
y = 4,524x + 470
p < .001
1000
0
0
0.2
0.4
0.6
0.8
1
Neck BMD (gm/cm
2
)
ò
Neglects: specific loading condition, body
habitus
,
bone geometry, 3-D density distribution (DXA is 2-D)
ò
Does not exploit engineering theory
Prof. Dava Newman 16.423J/HST515J Space Biomedical Engineering and Life Support
11
Other Research Efforts
Curved Beam Model from DXA
(Beck & Ruff, 1996)
ò
Use algorithm to get section properties (A, I) from DXA scan
ò
Develop curved beam model with stress concentration due to curvature
ò
Apply loads and assess stress on medial and lateral edges to determine failure load
ò
Limitations: 2-D, beam theo
r
y
Prof. Dava Newman 16.423J/HST515J Space Biomedical Engineering and Life Support
12
Finite Element Analysis Approach
Collaboration with
Orthopaedic Biomechanics
Lab
(Oden &
Selvitell
i
)
QCT scans and
Stack
NIH Image
Extract
contours
contours
to define geometry
3-D Finite Element Model
Extract density distribution (trabecular
area)
Define elemen
t
material prope
rties
Prof. Dava Newman 16.423J/HST515J Space Biomedical Engineering and Life Support
13
QCT Slice
Prof. Dava Newman 16.423J/HST515J Space Biomedical Engineering and Life Support
14
Skeletal Representations
Prof. Dava Newman 16.423J/HST515J Space Biomedical Engineering and Life Support
15
Meshing
ò
Cut selected contours into subsect
ions to guide
meshing so that warped elements are
avoided and
mesh pattern aligns with density distribution
ò
Quadrilateral elements with 27 nodes per e
lement
Prof. Dava Newman 16.423J/HST515J Space Biomedical Engineering and Life Support
16
Assign Element Material Properties
ò
Use empirical modulus relationships to assign values based on density
ò
Human
trabecular
and cortical bone assumed
to
be transversely isotropic assign elastic constants for each elem
ent:
E,
E ,
ν
,
ν
, G, G .
Poisson s ratio assumed constant
(
ν
=
ν
= 0.3).
Source:
Selvi
tell
i
,
1997
Prof. Dava Newman 16.423J/HST515J Space Biomedical Engineering and Life Support
17
Apply Boundary Conditions
ò
Loads
joint contact
muscle forces?
ò
Constraints
Prof. Dava Newman 16.423J/HST515J Space Biomedical Engineering and Life Support
18
Convergence Study
231 Elem
.
1,344 Elem
.
4,960 Elem
.
2,625 Elem
.
Convergence Study - Average Displacement
0.134
0.1336
Displacement (mm)
0.1332 0.1328 0.1324
0.132
0
1000
2000
3000
4000
5000
Number of Elements
Prof. Dava Newman 16.423J/HST515J Space Biomedical Engineering and Life Support
19
Failure Analysis Algorithm
No
Yes
Update e,
s
FE Model
Increment
Displ
acement
Calcul
ate Strains
and Reacti
o
n
Forces
Calcul
ate
e
ma
x
(prin
)
Reduce Modul
us
End
Element Fail
ure?
Model
Fail
ure?
Yes
No
ABAQUS User Subroutine
Prof. Dava Newman 16.423J/HST515J Space Biomedical Engineering and Life Support
20
Preliminary Results
Astronaut Skeletal Modeling
I
Dynamic Model of Fall on Hip
II
Structural
Analysis of Femur