CAST-BRACING
FOR
FRACTURES
OF
A BIOMECHANICAL
BERNARD
F.
MEGGITF,
From
A study
was made
through
ofthe
distal
fracture
ofthe
a standardised
femur.
weight-bearing
the fracture
mechanics
test
A.
STUDY
JUETf,
J.
Hospital,
DEREK
SMITH
Cambridge
in a series
treated
ofpatients
incorporating
were
strain-gauges,
a simple
to record
axial loads through
used
ofhealing.
SHAFT
The cast-brace
carried
with
a cast-brace
force-plate
the
loads
for
on the floor
cast-brace
ofonly
and
itself
10 to 20 per
and
cent
of
antibuckling
hinged
tube. Patterns
of weight-bearing
recovery
itself
limited
loads to safe levels.
A measure
of the recovery
of strength
at the
and termed
the “fracture
load
index”.
Graphs
obtained
in this way
biomechanical
phases
of bony union which
correlated
well with the stages
of clinical
body
demonstrated
FEMORAL
CLINICAL
ofload-bearing
hinges
the phases
weight
and functioned
showed
that the fracture
fracture
was determined
DAVID
Addenbrooke’s
Knee
during
AND
THE
four
mainly
as an
The clinical
application
of these results
have led to improvements
in the design of braces
and the
use of a cylinder
cast-brace
for fractures
of the distal half of the femoral
shaft and of a new type of brace
with a hinge at the hip attached
to the thigh cast for fractures
ofthe
proximal
shaft. A simple
clinical
test is
healing.
by which
described
The
become
distal
long-leg
cast-brace
The
clinical
treatment
patient
and
of the
were
confirmed
and Lafollette
others.
There
of
been
possible
load
be
during
test”
delayed
the
The
Meggitt,
simultaneously
leg
using
brace
assess
present
until
the
on
on
the
from
could
full
distal
femoral
The
quadrilateral
the
at the
function
of weight-bearing
the
mechanics
of
of
in the
loading
upper
on
for
British
reprints
Editorial
should
Society
be
sent
to
of Bone
Mr
and
of
to develop
it
were
cast-braces
a new
design
shaft
of
and
to
METHODS
throughout
brim
at the
the
thigh
a pair
an elastic
By
devices.
pass
both
up
fractured
femur,
and
the
thigh
cast
and
the
load
series
with
consisted
a long-leg
of stable
metal
knee-support
load
fracture
Cast-brace
of
plaster
hinges.
and
one
steady
hinge.
At
moment
with
with
and
the
first,
the
thigh;
and
the
healing
was
of plaster
on
Fracture
load.
the
leg
Addenbrooke’s
University
type
measured
but
were
not
This
as an
the
also
results
(Figs
on
of detector
and
were
each
of
the
bending
compared
and
these
3).
the
floor
loads
the
1).
assess
loading
using
with
only.
simultaneously
circuit
shank
significant
principle
vertical
measured
through
in the
not
2 and
test;
thrust
vertical
to
cast-brace
(Fig.
to
the
hinges
a standard
axial
were
by
measured
knee
on the
positioned
produced
measured
were
during
incorporated
continued
was
the
load
axial
through
by subtraction
on a beam-bending
a portable
a strain-guage
The
using
displayed
hinge
and
a Wheatstone
digitally
and
also
an oscillograph.
This
load
was
estimated
during
Hospital,
of Cambridge,
measured
were
thrust
The
brace,
and
through
obtainable
the
knee
the
Hills
by subtracting
standard
Road,
Cambridge,
the
hinge
weight-bearing
Cambridge
CB2
load
from
test.
200,
England.
England.
B. F. Meggitt.
Joint
Surgery
a
open
This
layer
in
the
thigh.
transducer
stress
This
recorded
upper
then
axial
loads
across
cast-brace
leg were
was
designed
force-plate
total
to the
This
leg load.
bridge
up the
was
shear
high
force-plate
leg,
strain-gauges
measurements
Total
also
a cylinder
first
weight-bearing
lower
on the
load.
using
During
the
then
the
hinge
results
and
total
on
could
}
AND
used
stockinet,
Load-measuring
on the
and
design
to accommodate
over
loads
to provide
cast-brace
results
design
wool.
hinges,
to investigate,
the
the
fractures,
polythene
knee
applied
of load-bearing
were
biomechanical
improve
for fractures
of the proximal
femoral
a simple
clinical
test of bony
union.
transducer.
of the study
These
to
MATERIAL
to
patients
be used
recovery
fracture.
clinically
Cast-brace.
and
fracture
reports
results
the
the
10-second
“
paper
load
for
in cast-braces.
these
function
by which
B. F. Meggitt,
MA,
FRCS,
Consultant
Orthopaedic
Surgeon
D. A Juett,
PhD,
Senior
Medical
Physicist
J. D. Smith,
MA,
PhD,
Lecturer,
Department
of Engineering,
12
nonof the
a force-plate.
by the femoral
in the cast-brace
objectives
significance
secondly,
© 1981
applied
Broom
on
of fractures
femoral
in a prospec-
the
mounted
the
taken
theories
load-relieving
Requests
has
in relation
findings
a standardised
postponed
for
work
cast-brace
fractures.
on
load
.
union
evidence
capacity.
The
healing
of the
et al.
and
published
strain-guages
the
assessed
little
preliminary
to measure
total
was
shown,
clinical
value
and mechanical
A method
was described
subtraction,
and
knee
fractures
of Mooney
were
of the
femoral
using
standing
very
reported
tive study
of the
of the cast-brace.
cast-brace
at the
of
of combining
mobilisation
limb
function
(1 975)
the
advantages
with
early
fractured
has
healing
Ross
and
hinges
the
in further
reports
by Connolly,
Dehne
(1973),
Brown
and Preston
(1975)
and
biomechanical
was
with
to monitor
accepted
in the treatment
femoral
shaft
since
the work
(1970).
operative
the
it is possible
0301-620X181/00310012
$2.00
THE
JOURNAL
OF BONE
AND
JOINT
SURGERY
CAST-BRACING
FOR
FRACTURES
OF
THE
FEMORAL
Weight-bearing
allow
test.
repeated
during
the
used
a
ofa
fracture.
and
two
on
leg
during
support
each
1 0-second
with
Medial
hinge
load
hinge
load
(Fig.
was
limb
L
-
(pl+pm)
for
estimated
of
brace
application
this
read-out.
Fig.
1
Diagram
to show
the
calculation
of fracture
load
from
the
results
recorded
by the forceplate
and the transducers incorporated
in the
hinges.
load.
The
at
hinges
six
and
tests.
patient
body
each
from
The
The
results
gait
used
cast-brace
the
weight
average
of the
the
load,
the
to be
total
obtained,
three
test
and
to
the
fractures
The
rapidly
indirectly
zero.
test
within
was
(Fig.
and
was
compact
in limited
the
The
#{149}
was
from
closely
session
with
force-plate
1 0-second
correlated
after
digital
recordings
recordings
series.
undertaken
leg load
set
usually
same
of their
this
The
was
and
separate
from
load
This
components
force-plate
a
then
a
the
transducers
before
the
braced
when
other
by
recorded.
the
hinge
patient
for
which
registered
cast-brace.
and
were
at the
for
obtained
subtracted
highest
healing
test
were
indicated
were
1 0-second
the
testing
also
thrust
When
the
was
to be held
hinges
loaded
consistent
recorded
standard
load
was
force-plate
of
the
as
were
transducers
on the
for
the
erect
recording
higher
of the
then
later
until
the
the
eliminated.
gauges
transducers
weight
loads
as
was
review
throughout
as
enabled
TOTAL LEG LOAD ( L)
on’
e
weighing
weight
load
weight
and
and
transferred
hinge
maximal
minimal
or crutches
the
of the plaster
by
hinge
and
with
and
A frame
weight
The
mid-stance
patients
weight
the
force-plate
A baseline
the
later
total
repeated
the
test
recordings
position.
two
stood
was
brace.
brace
patient
the
and
The
termed
limb.
strain
by using
cast-brace
established
and
A I 0-second
of the
known
developed
obtained,
variable
from
difficult
the
periods
the
very
obtained
initially
the
short
in a horizontal
therefore
proved
force-plate
vertically
and
method
this
phase
was
maximal
stance
the
4). By requiring
very
value
on
analysis
record
the
For
were
gait
to
to
at intervals
This
to balance.
the
results
hanging
was
was
patient
steadier
negative
=
the
from
possible
limb
F
through
simultaneously
was
(p1) Transducer
in its cast
necessary
loads
conventional
was
test’..
leg
obtained
1 0 seconds
(pm) Transducer
test
as possible
to help
then
simpler
was
of the
force-plates
limb.
standing
fractured
weight
allowed
Lateral
steady
the
much
At first
for the fractured
A
test
measurement
walk-way
time-consuming.
.‘
weight-bearing
comparable
healing
weight-bearing
crutch
A standard
and
with
13
SHAFT
fracture
the
five
or
used.
with
the
5) in three
therefore
force-plate
space.
The
load
were
-i---
T;
..
I
Ji!_2
Fig.
z-g.
rig.’.
Figure
2-Photograph
to show
the method
of incorporating
a transducer
in the hinges
of a cast-brace.
Figure
3-Radiograph
to illustrate
the
position
of the transducers
and hinges
in relation
to an oblique
fracture
of the lower shaft of the femur.
Figure
4-Photograph
of the experimental
equipment
being
used in the 1 0-second
standing
test. The patient
is taking
the maximal
tolerable
weight
on his fractured
leg while balancing
with
crutches.
The transducers
are connected
to the recording
equipment
by three
leads.
VOL.
63-B,
No.
1, 1981
14
B.
F.
MEGGITF,
D.
A.
JUETI’,
J.
D.
SMITH
kg
ii.,.
m=10.46±0.40
kg
9.09
6.82
2.27
0
10 sec
STANDING
TEST
11.&
m10.40±O.50
9.09
kg
6.82
14.56
2.27
0
WALKING
LOADS
Fig. 5
Recordings
taken
for one
:---I=:::::
patient
Male
at the
20 yrs
same
session,
to demonstrate
by a gait-analysis
*Femur
that
the 10-second
recording.
test
agree
with
those
provided
______
I
FOOT
which
........_.._-.--
:____±
-.-.
results
io
10 weeks
7O-._.....
gives
-
::
tBW75K9L
--
-
.
PLATE
t
/‘
-_I___- P
-ir
I
______
LP’
-
HINGE
GUAGES
2±?±E -.-.-
--
I±2PE
--
RECORDING
Body weight
Cast
brace
Mean
foot
Mean
hinge
weight
-
-
load
-
CALCULATING
75#{176}1’corrected
body
6.
example
of experimental
.-
-.
52. 8]
leg
recording
of the
force-plate
and
hinge
body
WL
69.0
46. 8
11.3-’Hinge
..Fracture
load
%BODY
weight
oJ
#{149}
67. 8%
load
load
-
load
Fig.
An
-
m’TTr
(KciJ
in brace
plate
.-
-
16.4%
11.3
35.5
51.5%
6
loads
weight.
with
the
calculation
THE
of fracture
load
as a percentage
JOURNAL
OF BONE
AND
of normal
JOINT
SURGERY
j#{149}
CAST-BRACING
all expressed
as a percentage
appropriate
correction
Patient
management.
two-thirds
of
could
reduction
femur,
with
and
tubercle
a
weight
weight
throughout
of the
patients
by
skeletal
Thomas’
traction
splint.
itself
fractures
any
were
using
a pin
was
through
FEMORAL
U
90
80
which
the
-
tibial
when
15
SHAFT
100
6).
manipulative
removed
THE
distal
injury
by
OF
after
(Fig.
of the
other
treated
Traction
FRACTURES
the study
cast-brace
with
uncomplicated
rehabilitation,
balanced
and
the
Twenty-two
the
interfere
ot body
for
FOR
70
.60
EAST
the
BRACE
OFF
fracture
not
had
reached
displaced
on
callus
formation.
hinges
incorporating
five
and
weeks
of the
test
hospital
were
four-week
carried
bearing
for
unsupported
brace
and
10
seconds
leg
were
then
then
allowed
were
achieved
stage
patient
maximal
and
could
at weekly
the
intervals
then
allowed
achieved.
were
it could
that
13
12
14
15
16
90
was
supported
for
18
ttt
80
the
of the
:
7#{176}
body
ON
weight
17
100
at
on
full
11
Fig. 7
weight-
removal
be shown
10
TU90 (Weeks)
flexion
tests
after
t
leg
taken
full
Further
I
to leave
on the
when
10
by
steady
of knee
removed
20
to
freed
weight
radiographs
immediately
until
then
measurement
30
kept
I 0-second
possible
was
out
first
was
and
be
carried
and
40
reached
hinges
the
cast-brace
usually
0P4
knee
was
The
tests
was
early
with
The
was
intervals
showed
applied
stage
but
patient
out.
The
then
be angulated
or a frame.
to take
two-week
intervals.
The
At this
Load-bearing
at
radiographs
This
fracture.
screws.
instructed
made
and
was
balancing
locking
in its cast-brace.
it could
cast-brace
by crutches
stable
was
and
in that
strain-guages.
after
until
standing
leg
supported
in extension
stage
examination
long
the
walk
removal
sticky”
clinical
A
to seven
stand
a
a
10 seconds.
50
CAST
BRAcE
OFF
40
RESULTS
Twenty-two
patients
with
fractures
of
the
distal
20
two-thirds
of the femoral
shaft were studied
throughout
their treatment.
Fifteen
of these
patients
united
soundly
without
complication.
Two
patients
suffered
delayed
union.
Five
cast-braces
patients
but also
Three
examples
are
patients
recovering
at different
levels
The
had special
adjustments
achieved
complete
bony
first
cast-brace
mid-shaft
brace-loading
presented
of
without
complication
in the femur.
patient
(Fig.
7) had
the
results
after
In the
fracture
of
second
the
1 00 per cent at
from 50 per cent
the
brace
at 1 5 weeks.
the indirectly
the directly
Figure
application
VOL.
63-B,
No.
on
the
and
reached
two
an oblique
(Fig.
8),
throughrising to
100
per
cent
Again
there
was little difference
between
calculated
fracture
load in the brace
and
measured
load out of the brace.
9 shows
the graph
from
the patient
who
I.
1981
11
12
13
14
15
Weeks)
8
100
80
of a
limb
from
10 to 17.5 per cent
53 per cent at seven weeks
removed,
10
Fig.
from
1 4 weeks.
The fracture
load increased
at 1 0 weeks
to 83 per cent at 14 weeks,
was
9
90
patient,
who had sustained
distal
third
of the
femur
brace-loading
varied
out. The leg load was
when
supported
8
fracture
was removed.
There
was little
difference
at 16
between
the unsupported
fracture
load measured
and the indirectly
calculated
load in the brace.
be
7
7190
70
weeks
after
he sustained
an oblique
fracture
of the femur.
The graph
shows
axial
of 1 0 to 20 per cent
of body
weight
could
6
5
7.5
Full body
weight
weeks
later.
.-.-....
to their
union.
ON
_80
a
CAST BRACE
throughout,
with a steady
increase
in the leg load from
36 per cent to full body
weight
by 16 weeks,
at which
time
the brace
was removed.
The
fracture
load
thus
increased
from 30 per cent at 7.5 weeks
to 50 per cent at
12 weeks,
and to 80 per cent
at 16 weeks
before
the
brace
weeks
directly
..
10
OFF
-40
lOrTEST LONDS:
20
LEG
-FRACTU80
10
.-.
*
a
s
N
1040
7
8
BRACE HINGES
LEGFRACTURE018 OF BRACE
9l0
Weeks)
Fig. 9
Graphs
showing
total leg-load,
brace-hinge
load,
and by subtraction,
the fracture
load in three
patients
who had sustained
fractures
of the
shaft
of the femur.
Clinical
details
concerning
the patients
and
a
discussion
of the results
are included
in the text.
achieved
the
most
rapid
healing.
The
fracture
was
oblique
and supracondylar.
Brace-loading
varied
between
5 and 1 0 per cent, with leg load increasing
from 50
per cent at five weeks
to full body weight
at eight weeks,
at which
stage
the brace
was removed.
Four
days later
the patient
could
stand
for 1 0 seconds
with
his full
weight
on
in some
discussed
The
the
limb.
of these
later.
results
There
fracture
from
is the
suggestion
load
curves
1 5 patients
without
of a plateau
and
this
will
complications
be
16
Table
B.
I. Results
in
1 5 patients
followed
F.
to full
MEGG!TT,
union
D.
in standard
A.
JUETr,
J.
D.
SMITH
cast-brace
Fracture
Patient
Cast-brace
Week
Age
Level
Type
in femur
Mid-third
of shaft
Lower-third
of shaft
Supra-condylar
are
given
in Table
and
achieved
Sex
Transverse
Oblique
Oblique
Comminuted
Comminuted
19
21
41
35
18
F
F
M
M
M
6
6
Transverse
Spiral
Oblique
Comminuted
Comminuted
20
25
19
29
18
Transverse
Oblique
Oblique
Condylar
Comminuted
25
34
68
65
69
in the
shaft showed
the “sticky”
of the
all
(years)
I. Fractures
third of the femoral
fractures
reached
application
of fracture
brace
100
middle
similar
callus
five
cent
leg-loading
to
100
per
cent
between
14
16
15
14
16
1 1-16
8-20
10-20
10-22
13-23
10.5
18
9.5
10.5
8.5
11
16
17
16
18
M
M
F
F
M
5
4.5
6
6
5.5
1 1
7-15
5-10
10-18
10-15
9-17
6.5
5.5
8
7
6.5
12
8
13
12
12.5
lower
2 1 -year-old
All
had
weeks
between
man
14
graph
until
for 10
range
and the
8.5 and
18 weeks.
shows
1 3 weeks,
the brace
the
the
brace
on
stressing.
77
per
pain
was
30
10
i
8
1#{212} il
9
12
13
14
15
16
17
1*
it
T1140I Weeks)
Fig.
10
patient,
weight.
bone
and 1 10 degrees
leaning
across
changing.
however,
could
and
the
and
nailing
1 2 is the
complete
and bone
graph
for
Figure
in the
1 1 is
the
cast
record
of
reaching
per cent
mechanical
during
at
of
the
no other
the series.
by 20
a
a large
advised
While
later,
In an
tuberosity
to
later the
with no
the patient
refracture
followed
a 72-year-old
produced
validity
weight-bearing
was
lady
who
sustained
a displaced
supracondylar
fracture.
The
shows
that at application
of the brace
seven
weeks
injury,
the fracture
load was 45 per cent but after
The
five supracondylar
fractures
showed
earlier
callus
stability
and bony
union
than the shaft
fractures
but the brace-loading
was similar
with a 7 to 1 8 per cent
range.
Two
patients
suffered
delay
in bony
union,
and
full
support
bony
union
grafting.
cent
fracture.
only
At operation,
the distal
fragment
was covered
muscle
and
only
end-to-side
healing
had
The weight-bearing
test had provided
a fairly
index
of the
mechanical
weakness
of the
load-bearing,
after
no pain
on the limb. One week
78 per cent body-loading
of knee flexion.
a bed one week
of
with
showed
patient
fracture
was
to achieve
On removal
united
on the knee at eight weeks
the
cent
at nine
weeks.
There
weeks
of
little
changed
occurred.
At
clinically
showing
mean
fracture-loads
and
mean
brace-loads±
1
standard
deviation
averaged
in 10 patients
with fracture
of the distal
shaft
of the femur.
Transverse
arrows
indicate
the range
of times
at
which
fracture
load-bearing
reached
50 per cent of body
weight
and
100 per cent of body
weight.
Graph
failed
fracture
was
recovery
Radiographs
mass
partial
weight
test showed
Figure
5
was
of body
fracture.
Rapid
intermedullary
20
4
a transverse
required
fracture
The
cent
occurred.
in fibrotic
occurred.
accurate
60
S
sustained
that
fracture-loading
after which
steady
2 1 weeks
take only
10-second
70
40
who
8.75
15
14.5
14
the mid-shaft
of the femur
in a high-speed
motor-cycle
accident.
The fracture
showed
little
callus
or stability
until the ninth
week,
when
the brace
was applied.
The
P40.68 FRACTURE LOADS #{149}
?4ANBRACELOADS
5,
of
weight
6.5
6
6
6.5
6
80
5#{176}
Week
100%
M
F
M
M
M
100
5,
Week
of
50%
weight
weight
6
5.5
7
posterolateral
90
as percentage
of body
16
16.5
18
17
15
seven
15 and
Load
10
9.5
11
10
9
and 16.5 weeks.
Figure
10 collates
the results
shaft fractures
in a single graph.
Axial brace-loads
from 8 to 22 per cent with a mean of 1 5 per cent
fracture
load improves
from 50 per cent between
1 1 weeks
of
removal
8-18
10-15
10-20
13-25
12-22
and
and
Week
14
15
16
14.5
14
behaviour.
phase
and
between
per
of
application
load as percentage
of body weight
60 per
26 weeks:
interference
The
load
slow
standing
patient
tests
attempt
three
for four
suffered
at 1 8 weeks
THE
weeks
pain
to seat
young
adult
JOURNAL
fell to 35 per
recovery
of
further
injury
to the healing
a delay
in bony
union,
thus
the load
test.
This
patient
the
during
cast
male
and
the
pain
after
her
tests
throughout
firmly
AND
100
had caused
fracture
and
confirming
had some
patients
OF BONE
graph
after
a fall
on
fall,
the
but
ischial
with
fractures
JOINT
SURGERY
CAST-BRACING
FOR
FRACTURES
OF
100
100
90
90
80
80
70
70
THE
FEMORAL
17
SHAFT
a
CAST
B
BRACE
.
OFF
60
60
B
10TEST LOADS;
5,
50
50
--TOTAL
40
S
a
S
30
CAST
BRACE
OFF
LEG LOAD
FRACTURE
.....8RACE HINGE
LEG FRACTURE LOAD
0117 OF BRACE.
40
30
20
20
#{149}
‘\
10
‘U
8
9
11
10
12
13
15
14
A
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
29
28
TINE ( Weeks)
) Weeks)
TIk
Fig. 11
Figure
1 1 -Graph
of the
padded
to
illustrate
1 2-Graph
Fig. 12
fracture
showing
loading
in one
patient
the effect
of a fall and
lower
femur
had their
cast-braces
polythene
brim was firmly
opposed
who
showed
further
injury
modified.
A
to the ischial
tuberosity
with the hip flexed
to 30 degrees.
A loose
below-knee
cast
with
a thick
lining
was
used.
Two
patients
showed
mean
cast-brace
loads of 52 and 63 per
cent at six weeks.
However,
they were unable
to extend
the hip fully because
of pain caused
by pressure
on the
tuberosity,
and
one
week.
ischial-bearing
brace loads
per
cent
the
thigh
had
to be
changed
within
A
third
patient
tolerated
a less
cast-brace.
Figure
13 shows
that
increased
from 25 per cent at six weeks
at 1 1 weeks
possible.
cast
The
when
fracture
1 00 per
cent
was
therefore
load
tight
castto 47
leg-loading
was
only
53 per
cent,
and out of the cast-brace
the directly
measured
load
on the leg was a little
less at 48 per cent.
The
fracture
was solid to clinical
examination
but pain was
experienced
on forced
bending.
further
casts
and
walked
with
maximal
comfortable
weight
on
recovery
followed
Tightening
patients
with
full
of the
thigh
10 weeks
after
The
patient
refused
crutches
taking
the
the limb.
A steady
weight-bearing
cast
at
was
fracture
tried
of the
1 7 weeks.
on two
lower
other
femoral
100
9#{176}
70
r
5,
10 TEST LOADS:
a
CAST
.
-
BRACE
.-.
OFF
20
.
.TOTAL LEG
FRACTURE
BRACE HINGES
LEG . FRACTURE
0111OF BRACE
7
0
9
10
11
TINS
12
13
14
15
16
(Weeks)
Fig. 13
Graph
to show
the increased
percentage
through
the cast hinges
in a 22-year-old
a cast modified
to allow weight-bearing
63-B,
No.
I.
1981
of body
weight
taken
man who had been given
on the ischial
tuberosity.
strip
cast
section
was
Loading
tests
no significant
and
sustained
cast-brace.
of the
split
cast
refracture.
was
vertically
17
Figure
removed
at the
from
back.
The
the
thigh
then
firmly
tightened
and
replastered.
before
and after
this adjustment
showed
difference
in either
patient.
DISCUSSION
Cast-brace
function.
section
per
of
the
cent
fracture,
loads
with
significant
thigh
which
controls
the
this
late
made
20
to
of the
to
take
higher
tuberosity,
cannot
The
be
but
obtained
brace
load
remains
possible
leg
It is therefore
load
the
steadily
fracture
loading.
The
produced
muscles,
varus
healing
ischial
section.
angulation
abductor
thigh
10
as a weight-relieving
be
maximal
healing.
the
of
the
in brace-loading
the
that
average
during
function
on
and
the
throughout
force
is lateral
adductor
and
show
an
difficulty
seating
by tightening
itself
not
with
increase
constant
increases
weight
does
It can
results
carries
body
and
caliper.
The
cast-brace
of the
main
deforming
by the recovering
as in the
known
complication
of
load-bearing
medial
hinge
more
plastic.
was generally
found
to be greater
in the
during
the period
when
the fracture
was
The
cast-brace
seems
to have
a bend-
functions
0
6
the
bowing
function
and thus
of the
fracture
fixation
are less because
free
fulcrum
10
5
and
of the
principle
in
to allow
during
traction.
safe
applies,
at
mainly
the muscles
the
knee.
as
an
with
the
upper
providing
and hinges
stresses
are balanced
and
The
cast-brace
“antibuckling
Axial
intermittent
walking.
The
thigh
cast
above
and
the shin
cast
below
medial
supports,
while
the lower
thigh
cast
give lateral
support
(Fig.
14). Anteroposterior
50
30
VOL.
A one-inch
front
three-point
540
callus-formation
application
shaft.
controlling
compression
80
-
deficient
after
the
there
is a
therefore
hinged
tube”.
Hydraulic
muscle-support
to the fracture
is unlikely
to
contribute
once telescoping
of the thigh has ceased.
The
elastic
lining and thigh cast may, however,
reduce
tissue
oedema
and allow
the muscle
pump
to contribute
to
vascular
thigh
cast
return.
The
adds
to the
quadrilateral
support
shape
surfaces
and
of
also
the
upper
provides
18
B.
improved
protection
against
of fracture
Mechanics
intact
femoral
torsion
repair.
shaft
during
Axial
F.
MEGGITF,
D.
of the
fracture.
forces
through
a 10-second
steady
standing
been
The
This
graphs
show
fracture
at a specific
time
maximal
load which can
load
steadily
fracture
repair,
recovery
increases
and
providing
of strength
for
is a mechanical
healing
measure
way”
or
tests patients
did
of “unsteadiness”,
“looseness”
Pain
.
not
complain
“weakness”,
is not
part
As callus becomes
allow
higher
but
of
of
more
safe
the
rigid,
limb-
loading
levels.
No
previous
report
can
be found
concerning
this mechanical
feedback
in human
fracture
repair
but it is suggested
that the signal
from
stressed
callus
is mediated
through
osseous
bio-electrical
potentials.
Fracture
middle
of
loads
of the
allows
Phase
a plateau
steeper
before
application
The first
of the cast-brace
steep
curve
of
.
2, the
plateau
weight-bearing
is Phase
phases
of
with
the
sequences
3 and
may
the
be
repair
early
may
recovery
final
called
mechanical
in the
slopes
10). Four mechanical
The
period
before
to full
These
show
with
7, 8, 9, and
identified.
rising
closely
repair
0
1
healing
curve
Phase
1 5).
1: 10
during
recovery
and after it (Figs
phases
can
be
of the
limb.
stability
termed
i
SMITH
mechanism
of inhibition.
the
mechano-receptors
a given
index
D.
During
their standing
pain
but of feelings
in healing,
there
is a
be taken
on the limb.
a physiological
in the
that
J.
“giving
of gait result
from
the load of
compression
load from contracting
are inhibited
after a shaft fracture,
they slowly
recover.
Muscle
loads
but the weight-bearing
loads
have
demonstrated.
JUETF,
the
test or at the mid-stance
body weight
plus the
muscles.
These
forces
but as repair
occurs
cannot
be measured
femoral
consistent
A.
steep
slope
Phase
4 (Fig.
recovery
clinical,
histological
observed
in the
be
is
correlate
and radiological
human
femoral
fracture.
L
M
$4
The
period
displaceable
$$
granulation
to illustrate
the
and the mechanism
The antibuckling
the
fracture
is
organisation
callus
.p,c
early
endochondral
ossification
Tfl-.\ JO
axial
recovery
during
the
and
and
1) is followed
and
calcification
resorption
mobile
of haematoma
(unstable-Phase
bendable
resulting
from
the
Phase
2). Vascular
rapid
increase
of the callus
of the calcified
corresponds
“plateau”
by
in strength
(plasticcallus
and
with
period,
slower
when
the
100
Fig. 14
Diagrams
the femur
forces.
the
tissue
“sticky”
..).c
when
during
deforming
forces
in fracture
of the shaft of
of three-point
pressure
in resisting
these
function
of the cast-brace
is evident.
90
0
z
80
70
=
60
C.,
This
mechanical
recovery
occurs
parallel
to
the
clinical
and
radiological
signs
of fracture
healing.
Fracture
load levels
of 25 to 35 per cent of body weight
are found
at the phase
of “sticky”
callus
from
five to
seven
weeks,
after the injury,
and this increases
to 100
per cent by 1 5 to 1 8 weeks
in keeping
with the observed
clinical
picture
of sound
union.
The
clinical
and
radiological
determination
of union
is empirical
but the
use of
measure
crude
the “fracture
of recovery
but
practical
load
index”
of strength.
healing
index
gave
a functional
The validity
of this
is confirmed
by results
the patients
with
delayed
union.
One
showed
a
decrease
in load index
after further
injury,
and in
the second
patient
the load index
remained
at 78 per
cent before
refracture
occurred
(Figs
1 1 and 12).
The fracture
itself controls
the safe load level in or
=
C.,
50
40
0
30
20
/
PHASE 1
,,
PHASE
2
5
6
8
10
n
1
MECHANICAL
2
3
4
Instability
7
9
PlastiCity
10
11
12
13
14
Elasticity
15
16
WEEKS
Rigidity
PHASES
CLINICAL
Mobile
Displaceable
PHASES
---
- .
Springy
-
Sticky
Bendable
Stable
--
Solid
Rigid
---
from
sharp
REPAIR
Haematoma
SEQUENCE
Granulation
RADIOGRAPHY
Flbrocartilage
Vascular
“Calcified
Calcified
Flecks
the cast-brace
site appears
system
and
receptor
through
during
progress
to
to exhibit
a biological
it is postulated
units
which
inhibit
the limb by inactivation
that
there
are
Osteonal
“Trabecular
Callus
Bone
Bone/
Dense Callus
Fluffy
out of
fracture
Resorption
Callus”
Dense Trabeculae
Fine
Trabeculae
union.
The
feedback
Fig.
mechano-
damaging
load-bearing
of muscles
and joints.
Diagrammatic
expressed
representation
of
15
the
four
as fracture
strength,
and related
and
radiological
phases
THE
JOURNAL
OF
phases
of
fracture
to the mechanical,
union
clinical
of recovery.
BONE
AND
JOINT
SURGERY
CAST-BRACING
FOR
FRACTURES
OF
THE
FEMORAL
The
standard
support
knee
cast-brace
to the
hinges
10 and
19
SHAFT
femoral
and
20 per
upper
cent
has
been
fracture
shin
cast
of body
shown
through
to provide
the
thigh
amounting
weight.
cast,
to between
The
ankle
and
foot
section
of the plaster
acts only as a static
support
for the
brace
above;
it immobilises
the foot, ankle
and calf and
adds to the weight.
Removal
of the lower
cast section
to
leave
a
free
ankle
function.
A modified
designed,
using
16).
A
adjustable
elastic
has
a suspension
at the back
used
!.
..
16
per
Photograph
of a patient
wearing
a
knee-hinge
cylinder-type
of castbrace.
The supporting
straps
from
a
waist
belt are seen
at the top of the
thigh
cast.
fracture
With
is springy
final
but cannot
remodelling
be bent
and
3).
osteonal
bone
solid
bony
union
is completed
(rigid-Phase
pattern
may not always
be discernable,
because
4). This
different
phases
time
may
large
occur
volume
The
criterion
breaking
experimental
of
at the
fracture
strength.
clinical
of
Little
work
union
(Laurin,
healing
has
fracture
healing.
strength
parallel
fracture
shown
to the
of the
based
can
been
done
It
the
on
the
and
four
hinge
of
stability
hinge
permits
the
collapse
Locking
been
VOL.
of the
screws
attained,
63-B,
No.
in
is less
1963;
that
of the
cylinder
the
slipping.
plaster
long-leg
knee-hinge
other
plaster
patients.
and
functional
quality
(Vaughan-Lane
Brace
design
knee-hinge
of
The
cast-brace
brace
fractures
of the
proximal
third
bony union
is well advanced
(1970)
stated that “fractures
femur
cannot
.
be
controlled
of the
bracing
fracture.
inadequate
femoral
support
shaft
(Fig. 17). Mooney
in the proximal
third
by
the
cast-brace”
.-.
.
the
__
human
functional
The
tube,
cast-brace
provides
in the early
plastic
is required
to
distal
for
important.
phase.
provide
are
fractures,
or
and
hinges
preventing
used
varus
while
later
in
application
The
lockable
walking
without
metal
fear
within
three
days.
to 50
casts.
A
with no
for most
fracture
1980).
femoral
provides
intro-
allowed
to 70
of the
lightweight
has
improved
the
femoral
and Meggitt
for
proximal
of the
in 1 978,
cast-brace
cylinder
The
combination
cylinder
design
the
brace
weight
callus.
of
of
knee,
especially
in the older
patient.
are removed
once
stable
balance
has
1. 1981
and
cast
with
and one of
and
of the
that
shaft
standing
usually
caused
(Fig.
load
index
increases
strength
in a healing
knee
middle
early
often
This
but
was
waist
biomechanical
fracture.
hinged
bending
at
the
cent
the
upper
in front
1976,
of Crystona
lightweight
of the weight
of the
the
better
brace”
APPLICATION
especially
fractures
in
Panjabi
mechanics
stability,
and strong
metal
polycentric
(Fig.
14).
This
is important
in
angulation
Roque
White,
is postulated
for distal
femoral
an antibuckling
pressure
be applied
been
used
to
plastic,
rigid
stiffness
by the fracture
ultimate
breaking
femoral
shaft.
to lateral
Medial
only
Sison
on
CLINICAL
Brace design
working
as
resistance
in a
is probably
and
has
unstable,
Clark,
Goodship
and Lanyon
1975).
Southwick
( 1 977) also described
stages
same
healing
This
fracture
models
stages
of healing:
four
identify
and
sites
of callus.
best
ultimate
in different
cast
from
for sitting.
since
provide
cylinder
per cent
compared
with conventional
plaster
long-leg
cast-brace
is used
for obese
patients
waist and flabby
thighs,
and the cylinder
brace
(elastic-Phase
of trabecular
would
system
to allow
clinically
plaster-of-Paris
Fig.
foot
“knee-hinge
waist
belt
supported
straps,
two of leather
been
duction
reduction
and
Radiograph
to
illustrate
the
inadequate
support
provided
by the standard
cast-brace
in patients
with
proximal
femoral
fractures.
The radiograph
was taken
within
one week
of the application
of the cast-brace,
six weeks
after
the fracture
had been
sustained.
The
for
until
et al.
of the
while
20
B.
F.
MEGGITr,
D.
A.
JUETF,
J.
D.
SMITH
‘4
Fig. 18
Diagram
to illustrate
principle
the deforming
of three-point
forces
fixation
in fracture
of the proximal
shaft
as provided
by the hip-hinge
of the femur
and
thigh-cast
brace.
to show
the
I
I,.;.
Fig. 19
Use of
fracture
Connolly
also
et al.
(1973)
commented
fracture
The
antibuckling
was applied
of the
concept
on
upper
that
the hip-hinge
of the femur.
and
Brown
the
difficulty
femoral
the
Fig. 20
thigh-cast
in a 5 1 -year-old
man
who had sustained
a subtrochanteric
Figure
19-Lateral
view of the patient
wearing
his cast-brace.
Figure
20-Anteroposterior
radiograph
of the same
patient.
and
Preston
of
(1975)
controlling
a
shaft.
cast-brace
functions
as
an
tube in resisting
the main deforming
forces
to fractures
of the upper
femoral
shaft.
The
main deforming
bending
moment
forces
of
at this
abductor
level stem from
and adductor
the lateral
muscles.
Resistance
to
three-point
fixation
port at the fracture
femur
below
and
hip
to
give
this
varus
above
force
necessitated
stability
(Fig.
the knee.
THE
The
JOURNAL
1 8).
For
hinges
OF
BONE
in
the
lever arm
extending
on
to
and lower
AND
the
sup-
for the distal
a hinge
at the
fractures
shaft, the distal
by a thigh cast
knee
on
lateral
site with medial
support
for the pelvis
above,
with
proximal
half of the femoral
the medial
side was provided
just
angulation
principle
JOINT
leg cast
SURGERY
CAST-BRACING
FOR
FRACTURES
OF
THE
a patient
has been
who
had
maintained
FEMORAL
Fig. 21
Anteroposterior
replacement.
were
mechanically
was
provided
pelvis
hinge
and
by a belt,
and flange
Fig. 22
lateral
radiographs
of
An acceptable
position
unnecessary.
by a rigid
Proximal
metal
band
lever
applied
level.
support
firmly
to the
and linked
to the thigh cast by a metal
placed
laterally
and in a position
of 20
degrees
of
abduction.
brace”
was
therefore
torsion-resisting
thigh
A
new
“hip-hinge
designed
cast
with
attached
of
weight
24
Crystona
lightweight
reduction
by
with
patients
femoral
undertaken.
fractures,
( Figs
plaster
30 per
fractures
cent.
of the
in
Early
same
metal
1 978,
but
practical
to a total
brace.
test
for
hip
use
in the
erect
crutches
much
with
scale
level
the
and
on blocks
to retain
weight
foot
the
(Fig.
balance,
as possible
of
normal
23).
the
to the
the
foot
While
patient
fractured
braced
using
slowly
of the
shaft
in the hip-hinge
thigh
cast
has
been
It has been
used on its own for traumatic
some
occurring
distal
to the prosthetic
hip
21 and
for
precarious
trochanteric
22),
and
on occasions
internal
region
and
as external
fixation
of
shaft
(Meggitt
Lane
1 980).
Application
reasonably
easy.
The edges
fractures
and
of the
thigh
of the Crystona
support
in the
Vaughanbrace
cast
was
were
protected
with felt and the hinge
axis was set at the level
of the tip of the greater
trochanter
in a position
of 20
degrees
abduction
at the hip. Varus
angulation
was not a
problem
fractures
Test
of
and bony
union
occurred
in all the traumatic
between
1 1 and 1 8 weeks.
union.
The
study
shows
that
there
is good
correlation
between
clinical
bearing
strength
of the healing
brace
carried
a constant
10
recovery
and
the loadlimb in a cast-brace.
The
to 20 per cent
of body
weight,
determined
VOL.
and
63-B,
No.
the
fracture
1. 1981
itself
the
safe
load
Fig. 23
A patient
undergoing
I 0-second
load-bearing
of bathroom
scales
limb
on
the simplified
test. The
use
is shown.
a
at the
a frame
or
transfers
as
leg and
of
half
fracture
supported
enabled
mobilisation
proximal
A crude
bathroom
quadrilateral
by a uniplanar
sustained
a fracture
distal
in a hip-hinge
thigh-cast
clinic was developed
to quantify
the mechanical
healing
of femoral
fractures
and to determine
the safe time for
removal
of the brace.
The test requires
the patient
to
stand
thigh-cast
a
hinge to a rigid pelvic
band.
An adjustable
waist belt and
shoulder
strap
suspension
were
provided
(Figs
19
and 20).
This hip-hinge
cast-brace
was used very rarely
with
conventional
plaster
of
Paris
as the
weight
and
subsequent
slipping
produced
problems.
The introduction
21
SHAFT
a steady
22
B.
standing
weight
rests and
recording
a
for
MEGGITF,
The
patient
highest
weight
load-bearing
is obtained.
D.
the test is repeated
until
a consistent
can be obtained.
From the known
body
“fracture
1 0 seconds
F.
index”
percentage
of body weight.
This
clinical
notes
at each
attendance
is
calculated
J.
D.
in the
Steady
100
70
transverse
the
per
removal.
refracture
10
were
8
9
10
TIH
11
12
13
14
15
16
17
(eks(
26
with
slow
to
and
per
At operation
at the fracture
show
of the
in
cent
for
hip-hinge
the
and
load
proximal
after
index
curves
thigh
for
shaft
brace.
two
who
Fracture
at six weeks
of fracture
nailing,
site,
thus
delayed
femoral
brace
application
at 1 1 weeks.
mechanical
leg-load
67
weakness
27
the
The
and
cent over three
weeks
when
when the patient
was going
fractures
treated
The
Fig. 24
removed.
brace
mechanical
stability
allowed
weight-loading
18
was
the
to 70 per
suddenly
the
Figures
7
in
a step using
crutches.
little
callus
was seen
patients
6
brace
cent
This rose
occurred
30
5
proved
index
and
85
50
0
which
united
was
explaining
recovery.
20
fracture
since
callus
to be
40
80
per cent reduction
occurred;
this
seven
days.
Figure
25 shows
a
stabilise.
A long-leg
brace
was applied
at 1 2 weeks
the
patient
refused
internal
fixation.
Little
developed
but at 1 9 weeks
the fracture
appeared
down
very
90
80
SMITH
only an eight
fully within
mid-shaft
a
increase
in this
index
provides
an
indication
of
satisfactory
healing.
When
full weight-bearing
is possible on the limb, the cast-brace
can be removed
with the
C
JUE1T,
removed
recovered
as
index is recorded
at the clinic.
A.
union
and
has
full
been
100
90
100
80
90
5,
70
80
60
5,
70
50
REFRACTURE
S
40
80
30
C
OFF
BRACE
40
20
4
80
10
BRACE
t
0
12
13 14 15 16
17
TIkt
18 19 20
Ieeeks
21 22 23
OFF
20
‘U
24 25 26 27
I
4
5
6
7
Fig. 25
9
7174
Graphs
of fracture-load
recordings
obtained
in
a fracture
clinic
using
bathroom
scales.
Figure
24 shows
the
uncomplicated
recovery
of a
1 9-year-old
man
whose
comminuted
shaft
fracture
was treated
in a cylinder-type
castbrace.
Figure
25 was obtained
from a 2 1 -yearold
man
who
had
sustained
a transverse
fracture.
His brace
was removed
too early
and
there
was
no full recovery
of fracture-load
strength.
Refracture
followed
at 22 weeks.
10
11
iT213
14 15
Ieeks)
Fig.
26
100
90
80
70
C
60
50
8040
3#{176}
knowledge
that
per cent
removal
the
true
fracture
of
body
weight.
of the brace
usually
load
Testing
shows
more
knee-hinge
accurate
load-bearing
subtraction
undertaken
cylinder
the
10-second
recorded
directly
brace
and
in.
the hip-hinge
in the
absence
Examples
The
of the use
load-bearing
of the
foot
the
10
5
thigh
section
of the simple
test
recovery
curve
are
for
of the
be
are
cast.
given.
a cylinder-
braced
fracture
of the iistal
femur
is shown
in Figure
24:
100 per cent load was achieved
at 14 weeks.
The brace
was left on for a further
two weeks,
and when
it was
7
8
9
10
Fig.
Graphs
from
recovery
femoral
thigh-cast
21-year-old
11
12
13 14
54-year-old
used
to monitor
clinical
27
recordings
made
during
from
fractures
of the
proximal
shaft
treated
with
the
hip-hinge
brace.
Figure
26-Graph
from
a
woman
whose
comminuted
frac-
ture healed
brace,
can
loads
6
TINR (eeeeksl
long-leg
load
20
after
of fall in
cent of body
weight
In patients
with the
steady
weight-bearing
as only
axial
force-plate
involved
80
one in apprehensive
recovery
to 100 per
weeks.
To obtain
a
index
of 20 per
at each
test.
than
immediately
this degree
the index and occasionally
a greater
patients.
Further
tests show
rapid
cent of body weight
in one to three
cast-brace,
may be
is greater
‘.
rapidly.
man
the
Figure
with
healing
27-Graph
a comminuted
of femoral
from a
fracture.
shaft
fractures
in
50 patients
in the fracture
clinic
at Addenbrooke’s
Hospital,
Cambridge,
from
1 977 to 1 980. It proved
to
be a practical
method
of assessment
of healing
of the
fracture
and gave an accurate
indication
of progress.
A
variety
of different
repair
curves
was obtained
but in
adults
for
all levels
THE
of shaft
JOURNAL
fracture
OF BONE
a 1 0-second
AND
JOINT
steady
SURGERY
CAST-BRACING
standing
test
showed
full weight-bearing
FOR
out
FRACTURES
of the brace
OF
THE
steady
23
SHAFT
load-bearing
to full body
or deficient
within
for the
an increase
This
organised
research
fund of the East Anglian
Health
Authority.
the Instrument
Workshop
technicians
for making
the precision
transducers,
Department
of Addenbrooke’s
Hospital,
Cambridge,
for the illustrations.
supported
by a grant
from
a locally
are grateful
to Mr R. V. Faben
and
Medical
Photography
and Illustration
is an indication
of delayed
danger
of refracture.
weight
by 20 weeks.
The test provides
an indication
timing
of brace
removal.
Failure
to show
work
was
The authors
Beard
and the
safe
in
FEMORAL
bony
20 weeks,
union
and
with
a
to Mr L. F.
REFERENCES
Brown
PE, Preston
Clark EA, Goodshlp
ET.
Connolly
143
E, LafoHette
Laurin
Meggitt
iF, Dehne
fractures.
Ambulatory
treatment
Lanyon LE. Locomotor
AE,
B. Closed
of femoral
shaft
fractures
with
bone strain as the stimulus
reduction
and
early
cast-brace
ambulation
J Bone Joint Surg [Am] 1973;S5-A:1581-99.
CA, Sison V, Roque N. Mechanical
investigation
of experimental
BF, Broom ND, Ross PM. Hinged walking plaster for fractures
BF, Vaughan-Lane
T. Hip hinge
thigh brace
for early
mobilisation
fractures.
around
Meggitt
In press.
Mooney
V, Nickel
1 970;52-A:
Vaughan-Lane
VOL.
R. Cast-brace
treatment
treatment
of femoral
Can J Surg 1963;6:2l8-28.
the knee. J Bone Joint Surg
of proximal
for fractures
femoral
shaft
of the distal
fractures.
1975;245:57P.
fractures.
[Br]
Part
II: Results
No.
in
1975;57-B:393.
Prosthet
part of the femur.
mt l980;4(3).
Orthot
J Bone
Joint
Surg
BF. New
casting
material
and improved
functional
design
stages
of fracture
for lower
femoral
fracture
bracing.
Prosthet
Orthot
In press.
AA III, Panjabi
63-B,
JP Jr, Snelson
in the
[Am]
1 563-78.
T, Meggitt
1980;4:(3).
White
VL, Harvey
J Trauma
1975;15:860-8.
mechanicaladaptability.J
Physiol(Lond)
a cast-brace.
for bone’s
1. 1981
MM,
Southwick
WO.
The four biomechanical
repair.
J Bone
Joint
Surg
[Am]
1977;59-A:188-92.
In: