WEIGHT-BEARING
A. S.
AREAS
GREENWALD,
CLEVELAND,
D.
From
The
been
transmission
investigated
because
of forces
by many
of the
W.
the
through
UNITED
the
area
whereas
on
the
in
the
within
femoral
elderly,
Centre,
surfaces
AMERICA,
of the
and
and
the
head
femoral
Trueta
there
human
(1953)
were
hip
joint
has
speculated
defined
that
pressure
to
show
these
areas
were made
by Goodfellow
the joint
and using
a dye transfer
technique.
the roof
of the acetabulum,
and presumably
a
1
orientation
head,
OF
JOINT
Oxford
Schajowicz
FIG.
subject,
STATES
articulating
Attempts
compressing
area on
HIP
ENGLAND
Orthopaedic
The joint
corresponding
HUMAN
OXFORD,
Harrison,
arrangement
surfaces.
by manually
a triangular
THE
OHIo,
HAYNES,
NuJfield
workers.
trabecular
areas
on the articular
and Bullough
(1968)
They
concluded
that
IN
were
apparatus.
not
weight-bearing
involved
of
all
the
in weight-bearing
articular
surfaces
in the
often
young
became
complete.
Dynamic
in vivo measurements
of the forces
Rydell
(1966)
and Paul (1967).
Rydell
measured
with
an instrumented
Austin
Moore
prosthesis.
estimate
of
the
measurements
VOL.
54 B, NO.
forces
of
1,
the
FEBRUARY
involved,
forces
1972
they
acting
cannot
on
be
the
acting
on the hip joint
have been made
by
the forces
acting
directly
through
the hip
Although
his results
gave a quantitative
related
normal
to
intact
the
normal
hip
joint
intact
with
joint.
a
Indirect
force
plate,
157
158
A.
cinematography,
S.
GREENWALD
anthropometric
AND
measurements
I).
W.
and
HAYNES
electromyography
were
(bc.
cit.).
He calculated
the resultant
forces
transmitted
through
stance
and swing phases
of normal
walking.
With the information
it would
be possible
to simulate
these forces
in an in vitro experiment
bearing
areas
such
hip joint.
the
of
The
purpose
of this
Human
at -20
communication
adult
degrees
tissue
was
hip joints
Celsius
were
obtained
until
used.
leaving
the
removed
AND
Paul
is to report
the
results
of
METHODS
at necropsy
The
specimens
joint
capsule
and
stored
in sealed
to
thus
drawn
tight.
was flexed
joint
held
was
made
in
margin
of the
felt
fine-tip
femoral
pen
was
in respect
disarticulated.
was
drawn
on
the
along
the
margin
of
the
ties.
from
also
the
and
position
machine
comprised
a known
load
to
a hydraulic
be
ram
applied
for
the
attached
strain
instruments
for measuring
aligned
in the frame
in the desired
position
bag was pulled
over the joint
and secured
mounting
7 1 was
soaking
plates
circulated
through
for
which
ten
to
minutes
other
was
mounted
to be marked
1).
were
mounting
pins
and
and
plates
placed
solution
to
with
in
a loading
to allow
joints
measured
application
were
and
were
two fresh
not frozen
(Greenwald
of loads
than
into
the
an
which
allowed
the
in the various
positions
(Fig.
the applied
for testing
(Fig. 4).
Ringer’s
fifteen
positions
joint
apparatus
specifically
any
specimens
erosion
of the walking
cycle
head
and
acetabulum
and
were
abnormali-
tested.
orientation
frame.
surfaces
In addition
which
were
study.
obtain
neutral,
FIG.
or
specimens
To
joint
cadaveric
for
surgical
drawn
at
marking
position.
and the joint
for
fibrillation
accepted
were
articular
macroscopically
Forty-nine
free
line was
original,
in its neutral
was removed
The
examined
With
and the femoral
head.
subsequently
used
to
the joint
capsule
The
adduction.
a line
both the acetabulum
These
lines
were
relocate
neutral
and
A further
across
the
angles
position
in this position
an incision
the capsule
along
the free
acetabular
labrum.
With
a
surface
acetabulum.
this
10 degrees
abduction
the
right
From
an estimated
that
a position
of rotation,
2
loading
bags
thawed
for the experiment
and the
intact.
The joint
was put into an extended
position,
the anterior
capsular
ligaments
being
The joint
polythene
were
the joint
the
pH
by
joint
during
the
derived
from Paul’s
study
to determine
the weight-
experiments.
MATERIALS
soft
made
hip
the
and
The femoral
attached
to
methacrylate
frame
designed
to be placed
in
1969, 1970).
a dynamometer
The
with
forces
(Figs.
2 and 3). The joint
was
by using the ink markings.
A polythene
Inlet and outlet
tubes
were attached
to
maintained
allow
for
at 37 degrees
Celsius
temperature
adjustments
and
and
of cartilage.
THE
JOURNAL
OF BONE
AND
JOINT
SURGERY
WEIGHT-BEARING
The
appropriate
AREAS
physiological
load
IN
was
THE
HUMAN
applied
to
HIP
the
159
JOINT
joint
hip
and
measured.
bath of Ringer’s
solution
was replaced
by a circulating
dye solution
in Ringer’s
solution
at 37 degrees
Celsius
and pH 7 1 staining
the
of 0 1 per
non-contact
dye
solution.
was
drained
removed
one
away
from
the
and
joint.
the
The
joint
washed
again
with
staining
and
unloading
loading,
Ringer’s
sequence
The
cent Safranin
areas.
The
The
lasted
load
was
approximately
minute.
HIP
JOINT
LOADING
Fio.
Diagram
The
joint
frame.
bag
A grid
a rubber
band.
the femoral
head
and
in the
detached
mesh
and
square
used
to obtain
the joint
gauze
the
contact
disarticulated
was
placed
to record
the contact
effect of load reduction
loading
and
over
the
frame
and
aligned
areas.
on the
to
size
the
of the
same
examination.
The
contact
6 and
their
areas
areas
outlined
measured
on the mesh
with
removed
femoral
head
on to both
were taken
contact
areas,
orientation.
staining
sequence
was followed
to obtain
the contact
pattern
On completion
of the experiments
the femoral
head and
the mounting
plates
and placed
in 10 per cent neutral
formalin
7) and
areas.
The periphery
of the contact
zone was traced
with a fine-tipped
felt pen (Fig. 5). Photographs
femoral
head
To study the
placed
was
of fine
of apparatus
FRAME
3
grid
from
the
and
secured
loading
with
the mesh grid and
of the acetabulum
the joint
The
same
was
again
loading
and
under
a lighter
load.
acetabulum
were removed
from
for radiological
and histological
were
traced
on to polar
graphs
(Figs.
a planimeter.
RESULTS
The
contact
acetabulum
on
maps
is involved
the
articular
the femur
superior
inferior
surface
demonstrate
that
in weight-bearing
of
the
with
femoral
head
to the acetabulum
during
the walking
and posterior
aspects
of the femoral
and
perifoveal
regions
normal
(Figs.
always
remains
loads
8 and
and
its
9).
the
entire
This
position
VOL.
ligament
54 B,
NO.
of the
I,
FEBRUARY
femoral
1972
head
and
the
area
determined
by
surface
of the
is reproduced
the
attitude
of
cycle.
head.
The contact
area includes
the anterior,
A band
of articular
cartilage
on the
a non-contact
area.
The peripheral
areas
of
the articular
surfaces
are brought
into contact
only at the extreme
limits
In the intact
joint
the band
of articular
cartilage
on the inferior
surface
does not make
contact
with a corresponding
hyaline
cartilage
surface.
by the
articular
contact
adjacent
soft
tissue
of the
of the walking
cycle.
of the femoral
head
it is covered
instead
fossa.
The
peripheral
160
A.
S. GREENWALD
AND
FIG.
The
joint
components
aligned
grid
used
to record
W.
HAYNES
4
mounted
into the loading
to the ink markings.
FIG.
Mesh
D.
the contact
frame
and
5
areas
on the femoral
THE
JOURNAL
head.
OF
BONE
AND
JOINT
SURGERY
WEIGHT-BEARING
areas
which
make
make
contact
With
occasional
with
the
reduced
AREAS
contact
are
(25
per
cent
the existing
full contact
area.
of the femoral
head are not
within
surface
.
THE
seldom
fibrocartilaginous
loads
IN
HUMAN
HIP
involved
161
JOINT
in weight-bearing
tissue
of the
labrum.
of body
weight
and
less)
partial
they
contact
The dome
of the acetabulum
included
in these
partial
contact
a#{149}
#{149}
.
as
usually
areas
occur
and the corresponding
areas
(Figs.
10 to
13).
.
!#{149}
.
1
#{149}1
L
F’
.
.c#{149}.
,_,,tt
FIG.
Figure
6-Contact
areas.
Figure
‘
7
U
6
FIG.
areas
outlined
7-The
same
FIG.
on the
contact
mesh
areas
grid.
The
as in Figure
green
regions
6, traced
on
8
7
denote
the partial
to a polar
graph.
FIG.
contact
9
The contact
areas obtained
from a normal
51-year-old
right male femoral
head (Fig. 8) and acetabulum
(Fig. 9) in the neutral
position
under load of 1 6 times the body weight.
The contact
areas remain
unstained.
These
from
reduced
aged
The
2677
the
area
square
54 B,
L
occur
during
partial
of full
centimetres)
femoral
VOL.
loads
subjects
contact
contact
and
head.
NO.
1, FEBRUARY
1972
the
areas
ranged
covered
swing
could
phase
not
between
approximately
22l9
of the
be
walking
cycle.
In many
specimens
obtained.
and
70
3368
square
centimetres
per cent of the articular
(average
surface
of
I 62
A.
Radiological
and
or compression
contact
between
the
same
dye
has
joint
now
ANI)
examination
There
was
cadaveric
and
in Figures
8 and
I).
did
W.
not
no difference
the
surgical
HAYNES
reveal
any
in the
as shown
stained
the
leaving
contact
damage
relative
FIG.
superior
areas
9 under
surfaces
of
on the anterior
due
size
to
or position
freezing
of the
specimens.
12
FIG.
The
GREENWALI)
histological
of the joints.
areas
S.
a reduced
load
of 02
the femoral
head
(Fig.
(Fig.
12) and posterior
13
times
the body
10) and
surfaces
weight.
acetabulum
(Fig.
13).
The
(Fig.
1 I),
DISCUSSION
The
results
indicate
the
that
acetabulum
during
the
stance
During
part of the swing
phase
only the anterior
size of the contact
area is dependent
on load.
The
degrees
of load
during
the
walking
acetabulum
is subjected
varies
Because
of rotational
movement
subjected
to
a similar
change
areas
dome
in
load
size
walking
of
the
cycle
contact
and posterior
biomechanical
the
entire
area
The
change
in the
forces
articular
is independent
surfaces
are
mechanism
is the subject
of current
investigations.
of the acetabulum
is subjected
to rapidly
cycle.
from
there
the
the
of load.
and the
the weight-bearing
suggest
that the
and
of
of
transfer
across
The results
is weight-bearing
phase
surface
to which
this
loaded,
of load
fluctuating
part
of
the
the unloaded
condition
to maximum
weight-bearing.
is no single area on the femoral
head which
is constantly
bearing.
Goodfellow
and
TI-IF
JOURNAL
Bullough
GE
(1968)
BONE
AND
and
JOINT
Byers,
SURGERY
WEIGHT-BEARING
Contepomi
and Farkas
dome
of the acetabulum.
cartilage
(1970)
The
study
Schajowicz
and
closely
to
also
the
provides
( 1953).
contact
areas
to
examined
the heads
early
they
concluded
cartilage.
that the absence
Byers,
Contepomi
which
related.
The
in
contact
it
seems
they
classified
HUMAN
HIP
is so far
in
for
they
the
occurring
in load
this
investigation
that
pressure
Farkas
may
(bc.
in
lesions
occur
or age
and
the
“non-pressure
cent
of the
cause,
cartilage
the
of
Harrison,
correspond
areas”
femoral
heads
areas.
In 26 per cent of
non-pressure
areas.
They
to the
similar
related
non-contact
by
areas”
71 per
be deleterious
observed
within
frequently
in
the presence
propounded
as “pressure
cit.)
as “non-progressive”
and
unresolved.
theory
designated
reported
163
JOINT
were present
in non-pressure
changes
in both pressure
and
ofjoint
and
non-progressive
and
areas
maintenance
areas
of
of hyaline
degenerative
“progressive”
and
or disease
the progressive
lesions
areas.
that,
that
inevitable
abnormal
forces
which
They
degenerative
changes
recorded
degenerative
but
support
areas
areas.
THE
interest
detected
non-contact
If it is accepted
of
The
IN
cartilage
degeneration
between
the change
quantitative
Trueta
correspond
change
recorded
relationship
is of considerable
degeneration
This
AREAS
cartilage.
and
whatever
their
in contact
In
so disintegrate
areas
non-contact
areas
at a slower
Whether
weight-bearing
cartilage
remains
unanswered.
mechanical
lesions
forces
damaged
are
will
lead
cartilage
followed
by
to accelerated
may
be
fibrillation,
destruction
protected
from
such
rate.
is itself
a causal
factor
in the
initial
degeneration
of
hyaline
SUMMARY
I.
A specially
designed
the
weight-bearing
2.
Under
loading
areas
loads
and
apparatus
in fifty-one
positions
and
normal
typical
dyeing
adult
of
the
technique
have
been
used
to demonstrate
the
entire
hip joints.
stance
phase
of
walking
articular
surface
of the acetabulum
is involved
in weight-bearing.
This contact
area is reproduced
the femoral
head,
and its position
determined
by the attitude
of the femur
to the acetabulum.
3. With
loads
typical
of the swing
phase,
the dome
of the acetabulum
and corresponding
areas on the femoral
head are not involved
in weight-bearing.
4. The results
are compared
with the conclusions
of previous
significance
with regard
to joint
degeneration
is discussed.
We wish
discussions.
to thank
the
Arthritis
and
Rheumatism
Council
for financial
investigators
support
and
and
Dr
C. G.
their
Woods
on
possible
for
helpful
REFERENCES
P. D.,
BYERS,
the
CONTEPOMI,
Rheumatic
Diseases,
J. W., and
C. A., and
29, 15.
FARKAS,
T. A. (1970):
A Post
Mortem
Study
of the
Hip
Joint.
A,znals
of
P. G. (1968): Studies
on Age Changes
in the Human
Hip Joint.
Journal
222.
GREENWALD,
A. S. (1969): Orthopaedic
Engineering.
Zenith,
3, 4.
GREENWALD,
A. S. (1970): The Transmission
of Forces
through
Animal
Joints.
Oxford:
D.Phil.
Thesis.
HARRISON,
M. H. M., SCHAJOWICZ,
F., and TRUETA,
J. (1953): Osteoarthritis
ofthe
Hip: A Study ofthe
Nature
and Evolution
of the Disease.
Journal
of Bone and Joint
Surgery,
35-B,
598.
PAUL,
J. P. (1967):
Forces
Transmitted
by Joints
in the
Human
Body.
The Proceedings
of the I,istitution
of
GOODFELLOW,
of Bone
and
Mechanical
RYDELL,
54 B,
ofBone
NO.
BULLOUGH,
Surgery,
Engineers,
N. (1966):
Functio,,
VOL.
Joint
50-B,
181(3J),
Intravital
andJoints,
1, FEBRUARY
8.
Measurements
p. 52.
1972
of Forces
Edited
by F.
Acting
G.
Evans.
on the Hip-Joint.
Berlin:
Springer
In Studies
Verlag.
on the
Anatomy
and