STRUCTURAL
CHANGES Their
In
recent
pain
known
years
manner
it
degeneration.
the
pathological
which
in
Some
these
help
in
intervertebral
and
become
in
123
removed
and
the
intervertebral
posterior
discs
vertically.
Pieces
examination. the
anatomical,
these
changes
this
discs,
to
to correlate
the
the
The
vertebrae
exhibit part
all the gross of the
foramen
and
This
united
by
three
the
posterior
nerve
clinical
joints
is
about
the
of the
The
and to
then
histological
information
The
studied low
intervertebral
on
relationship in detail
back
disc are
joints
nerve
posterior
detail.
subjected
to obtain
been
articulations
is occasionally
in
out. then
pain
of
in order
syndrome.
CONSIDERATIONS
: the
the
was carried arches were
occur.
has
the
a preliminary
horizontally
were
that
spine
examining
examined first
possible
picture
of synovial to the
by After
dissection The neural
joints
been
of the
root of
of low little
to be learned
acquired
were
variations
posterior
features relation
relationship
causes clinicians,
necropsies.
divided
PHYSIOLOGICAL
The
is in close
indeed
intimate
were
it has
the
AND
anatomical
capsule
and
with
posteriorly.
common most
still
been
flava
situ
appearance
findings
are joints
has
routine
ligamenta in
pathological
radiographic
ANATOMICAL
zygapophysial
and
and
necropsy
has at
of investigation
physiological
of the by
much
problems
ligaments
method
and
excised
examination
of the
By
one
of the excised spine, a careful ligaments were inspected.
joints
after
CANADA
symptoms.
spines
radiograph of the cadaver and The supraspinous and interspinous
that
DISCS*
Sciatica
is acknowledged
occur,
these
lumbar
and
TORONTO,
clear fact
that
cause
Pain
MACNAB,
this
changes
INTERVERTEBRAL
Back
increasingly
understanding
discs
Low
IAN
Though
changes
LUMBAR
to
HARRIS
has
is disc
about
THE
Relationship
R. I.
back
IN
root
elsewhere
found
the
to the
nerve
The
the
by
is of
attachment
to
two and
anterior
intervertebral
capsule
roots
the
joints
body.
through
bound
to
and
synovial
in the
as it escapes
joints
anteriorly,
simple
adhesions.
great
clinical
significance.
The
detailed
bodies
is
of
subsequently
of
annulus
obliterated These scars
*
Paper
304
read
in
by
London,
is penetrated
nucleus
herniations
Dr Macnab July
the caudal
cartilage
plates
changes at
meeting
three
help
the
blended
and
the
vessels
passing
1929)
(Fig.
discs
the
of the
are
single
disc ; and the
When
growth
they act Up to the
vertebral
these
two
are
the
vertebrae.
from
2).
that a
annulus.
: they
to anchor
spongiosa
into
intervertebral
functions
vertebral
changes
body
vessels
are
interrupts the lamella of calcified cartilage. which may break down under stress, giving
material
may
characteristic
the combined
of the
blood
scar which weak areas vessels
pulposus
surfaces
the
degenerative
intimately
have
and
the
nucleus
(Bohmig
of nuclear
blood
its of
1) ; they
by
pulposus
and
nature
components
vertebral bodies (Fig. the nucleus pulposus
microscopic herniations to some of the structural
World,
and
they leave a striated represent structurally
to microscopic
main
plates,
cranial These
cartilage
and
disc the
three
cartilage the
cartilage.
the
eight,
the
are
hyaline
of the immature barrier” between
into
rise
: the
intervertebral
understanding
There
plales-On
of hyaline
zone as a age
unit
cartilage
plates
of the in
occur.
functional The
anatomy
importance
enter
into
the of an
the
disc ageing
of the Orthopaedic
vertebral
from disc.
the
bodies.
Through
spongiosa
and
Occasionally
Associations
large
of the
these
give
rise
amounts
English-speaking
1952. TIlE
JOURNAL
OF
BONE
AND
JOINT
SURGERY
STRUCTURAL
of
nuclear
material
loss
of nuclear
This The
;,uclt’zis
vater
to
a large
of a loose
a few
cells
plays an intercellular
through
nucleus hvgroscopic
extent
on
these
role
and
disc The
(Schmorl’s
irregularly feature
is a viscid
function
material nutrition ma play
disc. in
has
in the
‘hole
pulposus of which
of intercellular l)ut
With
a
meshes
amount
a high
as
nucleus
understood,
of the a part
It disc
the
large
is poorly
gel.
of the
arranged, is the
nodes).
joint.
Histologically
strands
the this
facilitating
ill
growing
30:-
1)ISCS l)lates
of the
1948).
A striking
intercellular
decreases
cartilage
properties.
fibrous
of the
the
mechanics
in the
physical
of fine
INTERVERTEBRAL
in
the
(Macnab
morphology.
function
important substance
with
pulposus
is very network
LUMBAR
defects
interferes
of variable
The
5u1)stanCe.
THE
IN
escape
pit/posits-The and
consists are
may substance
content
depends
CHANGES
it
prol)al)ly
increasing age the degenerative
initiatillg
the
changes. i’/ze
aiz;iulus
The
annulu5
is
fibrosus-There
consists
of
no
sharp
lamellae
of
dividing
coarse
line
collagen
between fibres
the
nucleus
running
;ul
ol)liqueh’
;Lllnulus.
between
the
p.
C
-!.
“
:::
.
.
.
;
. ‘
&
.
i.
\_..
-4
#{149},
I
8 ‘
N,%
;*
#{149}:
:‘
‘e4
.
.‘
:r:
kW’ 1
11G.
1-\Iicroscol)ic
Figure coluiiinar liiiibar
arrangenent vertebra of
vertebral in
l)Odies.
the
the
annulus
alid
the
fibres one
The
occurs
the
vertebral W’hen
l)On\’ the the
observation \‘OL.
36B,
13(4)
annulus margins, spinal
has NO.
2,
to which
they
are
form
ring
rise
MAY
1954
three
and
enters with are
the the
deeply the
the
statement
that
so
the
doing
sul)jected.
groups.
One
vertebral
a
firm
that
into
l)lte
by
fan
from
their
stream
about to
the
nucleus pulposus
three
alignment
year.
millimetres (Beadle
possesses
the
ligaments; ring
pulposus
of
to meet
sixteenth
l)one
to
attachment
spinal
peripheral
the
able fibres ol)liquelv
the
downwards
the
about
in
‘ ‘
longitudinal
hone the
out
curves
above
nucleus
of the
hi’aline
‘
chaliges
l)etter
the
at
anchorage the
attachment
the
body body
longitudinally
The
ful)res
are
fibres
group with
of the
hl)res
librosus
to blend vertebral
direction the
The into
annulus
imhedded disc
is divided to
vessels.
deeply
of the
outwards
fuses
column
given
into
giving
in a newborn child s1ioving the of a growing cpiphvsis. Figure 2 Fourth perforations of tln cartilage l)lat(’ for the
is of interest.
be folloved fibres
jasses
fibres this
plate
The
group
UJ)wards
turns
1)eripheral
by
2
plate
be shown
can
and
can
3).
and
one
it preselit,
cartilage
(Fig.
phtte
below;
group
this
hyaline
cells
cartilage from
stresses
of attachnient
cartilage
to the
are
cartilage
cells characteristic showing iianv passage of blood
dissection
that
the
direction
of the
careful
rotational to
vertel)ral
cartilage infant
newborn
layers
the
\Vithstalld
of
of the a
By
maiy
FI(;.
section
of
bone. \Vhen above
1931). protrudes. turgor.
The It
is
:30(5
R.
doubtful,
of
if this
however,
disc
is divided the
turgor
horizontally
nucleus
seen
the
on
vertical
I.
HARRIS
AND
is an inherent
property
nucleus
not
does
section
may
the
remaining
frozen
adjacent
vertebral
l)etweefl
them.
took
of
of
The
body
and
increase
the
in
part
compress
of
range
of
changes
that
coiled
spring,
are
pulling
nucleus
of
the
its
components,
seen
The
substance
by
herniation
equivalent
to
experimental
of by
they
consequent the
nucleus
the
spine can
no
into
through longer
give a trivial
resist
plate
by
of
cartilage. plate,
the
alignment
A spine
does no
not
Two
was
the
possible
nucleus
fixed
pulposus
vertebrae
elasticity
was
protrude.
movement of
rigidly
of
(Fig.
the
fibres
These
observations
disc of will
4).
of
to
posterior abnormal Similarly
the
unit
adversely
the
deformation
joints
may and
movements when of THE
on
posterior add
be
the
to
integrity
of
of the
cartilage
plate Desiccation
fibres
the
nucleus
by
the BONE
damage lose body AND
all
nuclear
ligaments.
annulus
a
resistance
movements
the
is
the
likened
resilient
the
to
OF
increased
in excessive
the
JOURNAL
direction,
an
Loss
in
result
and
one understand
can
others.
In it
displacement.
to
the
depends the
annulus.
in
annulus
nucleus. diameter
extension
such
easier
a defect
and
the in
permits
against on
through
nucleus
it
The
coupling
of
annulus
make plates
body
by and
the
vertical
movement
the
cartilage
react
of the
injury.
efficiently
the
vertebral
annulus,
rise
excessive
degeneration.
and
its
prevented degree
in
of
reduce
posteriorly
excessive
allows
stability the
an
displacement to
is
displaced
incision
of which
the
tends
deformation
annulus
bodies
to the
also
protrusion
experimentally.
the
resist
a small with
extirpation
damage can
of
vertebral to one
hyaline cartilage
that
to
and
is
limits
directions.
damage
the
contraction
the hyaline
nucleus
the
is to
pulposus This
through
pulposus.
an intervertebral that
unopposed
Protrusion
due
annulus
pulposus
in association the
tested
a manner
between
disc
to the
the
thaw.
is largely
the
segments
all
in
the
cartilage
been
the
annulus
nucleus
movement
to
annulus with
state
to
nucleus
nucleus The
the
has in such
diameter.
the
\Vhen
suggests
it. of the
horizontal
of
at
due
the cells.
allowed
pulposus
functions
division
removal
with
except
into
frozen
transfixed
nucleus
spine
Experimental
hypothesis
then
be
of the blended
be followed of the cartilage
the
nucleus. This
3
junction intimately
In
were
anteriorly.
and
This
compresses
its
displaced
can
level
main
the
fibres
was
the
weight of
flexion
are
spine
which
fibrosus
One
fibres
fibres. bodies
‘ ‘
the
longitudinally.
every
turgor
annulus
of the
The
at
place ‘ ‘
of
annulus
annulus divided
and
The
appearance
of the
protrude.
FIG.
The histological Notice how the and the direction
I. MACNAB
is
sustained
their
elasticity
weight JOINT
or SURGERY
by
(‘HANGES
STRUCTURAL
movement. in
If there
volume
of the
height.
This
is a uniform nucleus
will
loss
the
occur
IN
THE
LUMBAR
of elasticity
annulus
throughout
protrudes
whenever
the
the
around
patient
its
assumes
that
of fibrous the
a local
tissue
nucleus
loss
of elasticity,
replacement
.
The
I 945,
(Figs.
5 and
Piischel
1 930,
Beadle
inspissation into
of
destruction
of
the
disc
found
when so. called
associated in
the
disc
position.
It
loses
is
quite
through vertebrae. not bulge
hyalinisation
give
rise
or
to
a localised
a localised
area
herniation
of
the
of
6).
The
disc
can
the
degenerative
process
is a complex
be
summarised
with
increasing
with
this
metaplasia
be
properly in
of with
regarded
the
body.
found
in
of thirt’.
degeneration
increasing
there the
end
of the
are
annulus
second
become (Coventry
saving
that
it consists
conversion
of
brown
degeneration
into
decade.
nature
phe1omenon by
microscopic
To
denote
changes
the
the
sixth
normal
the
ground and
fibrocartilage,
herniation
of
is nothing distinguish
avoid
and
the
nuclear
ageing,
could
upon
be about
them the either
which
coml)arabie
intervertebral
specific
confusion showing
ageing
an decade
that
those of
as
However,
There “
age. to
structural
at or
it may
plate
DISCS
retrogressive
associated
cartilage
commonly
paper
development a
ageing
) but
I 931
INTERVERTEBRAL
spongiosa.
elsewhere
this
greatest
components,
in a man
with
retained
of
could
THE
Associated
hyaline
disc
“
its
the
vertebral
seen changes
degree
the
variations
changes
structural of
all
IN
changes
elements.
the
into
Such age
of
formed
hyalinisation substance
reaches
structural
evident
a gradual
substance
disc
onwards
increasingly of
upright
pins passing between these levels but does vertebrae.
area
ilijury
CHANGES
intervertebral
then
ci al.
from
or a decrease
and
pulposus. DEGENERATIVE
From
a localised
resulting
fibres
4
FIG.
Two vertebral bodies have been fixed by Roger-Anderson them in such a manner that no movement is possible Notice how the nucleus pulposus bulges at all other in the disc between the rigidly fixed
conceival)le
annulus
circumference an
307
I)ISCS
INTERVERTEBRAL
from
term
disc described the
be
changes
structural or
to
changes “
an
superimposed
the
a degenerate
degeneration
prematurely may
as pathological
the
“disc
with
presenting
will
be
exaggerated the
effects
of
injury. When normal voL.
the
structural
stresses 36
B,
xo.
aIld 2,
MAY
changes
strains 194
inflicted
of
age on
occur the
prematurely
unstable
segment
during
an
max’
damage
active the
period
of
disc
severely.
life,
N.
The
annulus
tears
show
may
may
occur
tears
(Figs.
HARRIS
running
anywhere
postero-laterally
I.
on 7 and
MACNAB
I.
concentrically
the
8).
ANI)
periphery,
or more but
Sometimes
they
commonly
they
are
are
section
of twenty. the annulus
The
radial
extrusion
or
of nuclear
5
intervertebral disc taken from a man pulposus is er gelatinous and the fibres of ill defined. l’he nucleus blends into the fibres
of
a lumbar
nucleus
fibrosus
an
The posteriorly
.-
FIG.
horizontal
radially. common
with
associated
‘cv’-.
.\
most
are
of
the
annulus.
A
.
FIG. Horizontal
section
thirty-five.
This
which
is
annulus
of
disc
relatively become
a
lumbar
shows
intervertebral
the
smaller
in
increasingly
prominent.
invariably
material.
Although
The
extravasated
into
the
spongiosa
The
posterior
these blood of the and
tears is derived vertebral postero-lateral
occur
ill
from
disc
characteristic size. It also
These
found
with
an
avascular
taken
from
inspissation shows how are
the
the
increasing
changes
a man of the nucleus, fibres of the that
are
age.
area
a concomitant
of
they
injury
are to
frequently
the
haemorrhagic.
cartilage
plate,
opening
body. tears
are
of
clinical THE
significance. JOURNAL
In OF
BONE
the
region
AND
JOINT
of such SURGERY
STRUCTURAL tears age
displacement group
of the
in which
character
and
CHANGES nucleus
these
tears
spontaneous
IN
THE
is resisted are
most
extrusion
LUMBAR solely
section
of a lumbar
by
frequently
the
However,
intervertebral
weak
found,
is unlikely.
FIG.
Horizontal
INTERVERTEBRAL
7 disc
showing
DISCS
posterior
the
nucleus
even
when
a posterior
ligament. has
the
tear
309
lost
In
its
nucleus
of the
the
gelatinous has
become
annulus.
p
8
FIG.
Horizontal
section
annulus.
Note
of the
a lumbar small
size
intervertebral of
the
disc nucleus
developed
inspissated and
and
extension
to extrusion
@f such
Deposits VOL.
36 B,
contains of the
NO.
many spine. a nucleus
of
calcium
2,
MAY
are 1954
formed
the
an dark
antero-lateral
tear
discoloration
of the
that
has
in it.
elements
in its
It is conceivable
that
unprotected
posteriorly.
occasionally
showing and
found
substance
a sudden in
prematurely
it is still unguarded aged
displaced
on
flexion
could
discs.
Such
flexion give deposits
rise
310 are
R.
seen
grallular The from
in 9).
the
nucleus
blood
grown disc
both (Fig.
of
a
pigments
through ma
annulus
and
in
in
degenerate deposited
defects
result
I. HARRIS
in
the
plate
(Figs. the
FIG.
9
repeated and tissue
the
injury
fragmentation
nucleus
is barely
surrounding
THE
The
EFFECTS
vertebral
is lipping
several
or
bodies-A osteophyte
of the
cavities
OF
DISC
the
at
the
(Fig.
represented
bottom
observed of
either
brownish
8).
nucleus
lumbar into the
occur
DEGENERATION
commonly formation
may being
be
or
discoloration from
Severe
(Fig.
amorphous
injury
10).
derived
vessels to
With
that a
have
degenerate
constant
and
disc pulposus.
10
second haemorrhage
disc
a
first lumbar intervertebral calcium in the nucleus
the
recognisable,
may
haemorrhages 7 and
into
FIG.
of
they
shows
of minute
haemorrhage
section a massive
MACNAB
and
commonly
section of the a deposit of amorphous
Horizontal showing
I.
nucleus
a result
cartilage
massive
Horizontal showing
the
disc as
AND
vertebral
intervertebral nucleus pulposus.
11).
The
by
of which
ON
radiological bodies. THE
can
a
disc
annulus
fibres
loose
shreds
few
be seen
the
pitted
SURROUNDING
shredded
of brownish cartilage
plate.
STRUCTURES
manifestation Although JOURNAL
are
of disc our
OF
BONE
degeneration
investigations AND
JOINT
lead SURGERY
STRUCTURAL us
to
suppose
clinical
that
significance
investigation
being
lies
chiefly
the
type
in
involved
LUMBAR
lipping
is related
lipping
is not
at present.
that
they
that
The
posterior
that
is
to
joints.
not has
are
damage
to the
say,
senile
changes
will
when
damage
severe
with
mechanics
probable the
occasioned
and
occur
by
degenerative
In
roll
Once
and
flexion
1)odies
of an
of osteophvtes
degeneration
effect
on
the
subject
importance
of disc
the
but
Stabilit\’
many
in the
disc
also of
becomes in the
behind
the
found
arc
the
vertebral
of the
axis on
is so
flexion
cranial
through
posterior
are 14 and
36B,
body.
NO.
joints
associated
with
15).
It is partly
2,
1954
taking
rocking the
joint
ball-bearing; and
place
The give
the
stead’
rise
vertebral
the
I)etween
movement.
adjacent
remains of the
an
disc
constant
of the
the
spinal
that
in
position; joints,
trauma
occasioned
of disc
variability shift
degeneration
posterior
the
of
to a rocking
the
axis
when by
rise these
degeneration position
OccasioI1all\
rise
giving
change
h’pothesis
of the
is occurring.
it gives
every
immediately The
with
antero-posterior
with
disc
nucleus.
presence The
of movement commonly
with
In
alters the
is Compatil)le
unpredictable.
permits
extension through
in front and
pulposus.
and
and
passes
immediately
more
repeated
axis
movement
it
but
a guide
of flexion
the
type
Sometimes and
axis
nucleus
that 13)
as
movement the
irregular
12 and
a spinal
irregular.
irregular
pronounced
acts joints
extension
the
of
joints.
disc showing marked are fragmented and there of the nucleus pulposus.
pulposus
the
over
person,
zvgapophysial
component
theposterior
it passes
is most of the
(Figs.
vertebral the
extension
rock
axis
is indicative
irregularity
1)odies
flexion
full
throughout
bodies
behaviour the
; in full
is progressive
fibres
that
In
posterior
11
substance
and
the
of a young
component.
lumbo-sacral
and
experiment
the
and
disc
.
the
excessive
by
disc
the
general1’
coincidental;
--
nucleus
occurred,
to
-
annulus
gel
of movement.
nucleus
position the
has uneven,
been
change
the
the
in
are
is partly
in
found
one
other
the
in the
incompressible
degeneration
It has
of
clefts
1)0th
of
discs
relationship
damage
derangement
The
extension
overthis
segments
VOL.
instances,
is the
intervertebral
are
severe
section
the This
changes
changes
are
(Figs.
in most
the
its
concomitantly
correspondingly
disintegration.
the
and
in
FIG.
the
that
:31 1
I)ISCS
problem
presence
joints.
structural
Horizontal
of
This
place
posterior
r-
that
degeneration
changes
severe
associated
altered
the
disc clear.
only
taken
joints-Degenerative
with However,
they
of
to all
It seems
denote
degeneration
at
INTERVERTEBRAL
segment.
associated
to
THE
of vertebral fact
disc
IN
osteophytic conducted
the
of
CHANGES
the
vertel)ral
or tilting
of movement it does
so, flexion
to very
severe
irregular
of
passes and
damage
movements
312
N.
that
initiates
The
instal)ilitV
fractures
the
degenerative with
articular
HARRIS
changes
associated
of the
I.
facets.
AN1)
which
some
of
The
I.
are
these
MACNAB
seen
in the
structural
frequency
with
posterior
changes which
joints in
such
the
(Macnab
disc
fractures
1950).
predisposes
are
found
to
suggests
p.
FIG. Figure
in
extension.
Figure
lip
articular
may
are facet
Disc
L.3
13-On
on
L.4.
The
fiexion
of
well
be
not
uncommon,
can
degeneration
be
radiograph the
spine
has
the
been
body
taken
of L.3
can
the
patient
forward
on
FIG.
sustained found
with
moves
14
of the spine taken in full extension facet rocks open when the spine
they
dorsal
13
FIG.
of
FIG.
l