ANNULAR
TEARS IN
AND
THE
DISC
LUMBAR
A POST-MORTEM
0. L. OSTI,
From
SPINE
STUDY
OF
B. VERNON-ROBERTS,
the University
ofAdelaide, and
Royal
DEGENERATION
135
DISCS
R. MOORE,
the Institute Adelaide
R. D. FRASER
ofMedical
Hospital,
and
South
Veterinary
Science
Australia
We studied 135 lumbar discs from 27 spines removed post-mortem from subjects of an average age of 31.5 years. Defects of the annulus fibrosus were classified as peripheral, circumferential or radiating; the nucleus pulposus as normal, moderately or severely degenerate. Peripheral tears were more frequent in the anterior annulus, except in the L5-S1 disc. Circumferential tears were equally disfributed between the anterior and the posterior annulus. Almost all the radiating tears were in the posterior annulus, and closely related to the presence of severe nuclear degeneration. Histology suggested that peripheral tears were due to trauma rather than biochemical degradation, and that they developed independently of nuclear degeneration. The association of peripheral annular lesions with low back pain is uncertain but our study suggests that they may have a role in the pathogenesis of discogemc pain. The degenerating dehydration and
also
the formation
Schmorl and
human intervertebral fraying of the nucleus
and
many
features
of tears
Junghanns
authors
(1932)
have
of these
within
since
tears
the annulus
gave
the first
reported
(Friberg
and
Hirsch
1953 ; Vernon-Roberts 1987). Annular tears
the
of low
pathogenesis
and
biochemical their
uncertain. mental
pain,
(Osti,
of
the
human
;
an active
disc
observations and the possible
1990),
annular
those who
experirole of
from
but
the
defects
unknown.
is
Injuries
Royal
Terrace,
Adelaide,
5000,
Adelaide Australia.
Hospital,
B. Vernon-Roberts,
Registrar
North
PhD,
FRCPath,
of Adelaide,
Adelaide,
South
R. Moore,
MSc,
Hospital
Scientist
Senior
Institute of Medical and South Australia, Australia. Correspondence
©
should
Veterinary be sent
South
Australia
Professor of Pathology Australia 5000, Australia.
Science,
to Dr 0.
Frome
Road,
L. Osti.
1992 British Editorial Society ofBone and 0301 -620X/92/5402 $2.00 JBoneJoint SurgfBr) 1992; 74-B :678-82.
678
Unit
FRCPA,
University
had
Joint
Surgery
Adelaide,
AND
adult
relative of
the
METHODS
in Adelaide,
metabolic
as a result
subjects
all five lumbar between 1987 and
population
with
died
Freshly and
then
skeletal
disorders,
of trauma.
The
135 discs
between
excised
lumbar
17 and
discs 1989,
excluding
or
aged
fixed
including
50 years
and
spines
in formalsaline.
or were
(average
the
posterior
separated
and
daily
arch
disc
six
parasagittal
was
examined
disc,
with
decalcified.
radiographs
its
slices then
intact at
tears.
defined
as discrete
fibrosus,
parallel
its
a
Peripheral tears
were
was
completion
into
checked
each
cut
Each
into slice
microscope
wax
were
and
for histology.
classified
into
circumferential tears,
inter-
was
thickness.
dissecting
processed
end-plates
end-plates
of uniform
Morphological classification Annular tears. Annular defects types : peripheral or rim lesions, tric) and radial (Fig. 1). Peripheral
complexes
apophysealjoints
adjacent
under
photographed,
radiographed
its adjacent
Decalcification and
with
were
Individualjoint
the intervertebral
vertebral
ofSpinal
and study
31.5).
by 0. L. Osti, MD, PhD, Orthopaedic R. D. Fraser, MD, FRACS, Head
a cadaver
study examined spines collected,
affected
remain
of the annulus in accelerating of the other components of the of
in
spine.
from
stress
types
characteristics
defects
MATERIAL
Hirsch
relationship
mechanical
various
lumbar
their
Fraser
the
annular
prospective each of27
but
and
analysed
of
Our from
with
lesions changes
have
and Pine 1977; may be related to intervertebral
Vernon-Roberts
incidence
1950
of the
Recent pathological studies have highlighted
fibrosus.
We incidence
descriptions
degradation
association
discrete peripheral the degenerative
disc
back
shows and
the morphological
and Schajowicz Vernon-Roberts to the
disc pulposus,
or
of the outer
and
adjacent
to one
THE
JOURNAL
OF BONE
rim
layers
lesions,
were
of the annulus
or both AND
three
(concen-
JOINT
end-plates SURGERY
ANNULAR
TEARS
AND
PERIPHERAL (Rim lesions)
Fig.
(Fig.
2). These
of tears
of the annulus
disc associated portion
were
of a 50-year-old man. with highly vascular of the disc from the
frequently
accompanied
annular
No. 5, SEPTEMBER
sometimes
of cystic tissue annulus
by ingrowth
layers of the annulus. Rim lesions generally to circumferential tears, seen as separation
74-B,
tissue,
An area granulation posterior
lamellae. 1992
The
extending
adjacent
into
bony
679
SPINE
RADIATING
fibrosus
(see
text).
The L4-L5 intervertebral osteophyte formation related to disorganisation with an old rim lesion
3
disc of a 46-year-old man. There is advanced at the anterior edge of the upper vertebral body, ofthe bony rim. This appearance is consistent (arrow) ( x 5).
Fig.
the middle gave origin
VOL.
LUMBAR
4
granulation
individual
THE
Fig.
of vascular
of the
IN
2
disc of a 39-year-old woman. There is a rim anterior edge of the upper vertebra, with early and bone marrow replacement by granulation
Fig. The L3-L4 intervertebral degeneration (arrow) separates the central fibrosus(x 6).
DEGENERATION
CIRCUMFERENTIAL (Concentric)
Classification
The L2-L3 intervertebral lesion (arrow) at the osteophyte formation tissue ( x 5).
DISC
5
The L4-L5 intervertebral disc of a 50-year-old man, showing a radial cleft extending to the outer layers of the anterior annulus (arrow). This is associated with multiple concentric clefts and extends into a rim lesion. Marrow replacement with granulation tissue is seen in relation totherimlesion(x 5).
rim sometimes showed granulation tissue, and with these lesions (Fig.
replacement osteophytes 3).
Circumferential
tears.
These
were
annular
in both
the
anterior
defects
of the marrow by were often associated the and
most the
common posterior
0. L. OSTI,
680
B. VERNON-ROBERTS,
The L5-Sl intervertebral disc of a 47-year-old woman. There are multiple clefts extending towards the periphery ofthe posterior annulus, with displacement of disc tissue posteriorly producing infolding of the inner layers of the anterior annulus. A cleft parallel to the end-plate of the lower vertebra extends to the outer annulus fibrosus deep to the posterior longitudinal ligament (arrow) ( x 5).
Fig.
R. MOORE,
R. D. FRASER
Fig. The L4-L5 intervertebral clefts with tears radiating fibrosus. Typical infolding shown (arrow) ( x 5).
7
disc of a 44-year-old towards the periphery of the inner layers
8a
Fig.
man. There are multiple ofthe posterior annulus of the annulus fibrosus is
8b
Morphological classification of the appearance pulposus (see text). a) Grade I. Normal disc showing clear demarcation nucleus pulposus and the annulus fibrosus. There clefts. b) Grade II. Mild to moderate degeneration. c) Grade III. Severe degeneration. Fig.
annulus
(Fig.
4). Especially
annulus,
they
were
ingrowth
and
cystic
advanced
radiated
from
of the annulus plate
(Fig.
the
in the
sometimes
and
in a plane
pulposus
parallel in
layers
which
forming
commonly expression
bowing separated
vascular
clefts
to the outer
or oblique there
of the
demarcation between ruptures were associated This displacement
with
were
to be a typical
degeneration,
5). In discs
outer
associated
degeneration,
nucleus
nucleus
between the are no obvious
8c
seen in relation to rim lesions. Radial tears. These appeared
of more
of
was
which lamellae
to the endstill
some
contralateral ment (Fig.
substance rim
lesions
of
annulus and nucleus, radiating with nuclear displacement. was accompanied by outward
the annular by the cleft,
lamellae where these were and by inward folding of the
inner annulus, 6). Some radiating
ofthe close
outer
annulus
to the
THE
towards the site of displaceruptures ran into the mid-
(Fig.
end-plate.
JOURNAL
7), and extended The
OF BONE
AND
outer
JOINT
into
peripheral
SURGERY
ANNULAR
portion
of such
granulation
Nucleus
may
become
at various
pulposus
morphological three grades (Fig.
a tear
tissue
stages
degeneration.
appearance according
TEARS
AND
DISC
vascularised
DEGENERATION
with
of maturity.
We
also
the
pulposus into appearance
Grade
There was clear demarcation and the concentric lamellar
I.’ normal.
the nucleus
pulposus
of the annulus fibrosus. The cut surface was bulging, with a gel or watery consistency creamy nucleus
colour. There were no clefts into the annular substance.
Grade
II.’ moderate
nucleus
and
was
of the and
less
extending
from
the
of the nucleus was flatter and more solid. Its was slightly darker, and early clefts were seen to
extend
towards
the outer
areas
pigmentation
was
to the outer
common
of the disc.
and
extensive
clefts
35 years
of the
had
radial
circumferential discs which
Peripheral
except and
at the L5-S1 five
posterior
rim
Circumferential
and
level
tears
posterior
parts
where
there
were
four
disc,
anterior
lesions.
were seen ofthe annulus
equally in the anterior at the four upper levels,
18 L5-S1
years
of age
with
no significant
the findings those
in nine
difference
over
in the
incidence
older
age
group,
Table I. The incidence pulposus in I 35 discs
correlating of annular (see text)
with tears
the
Number
Level LltoL2
P 7
27
C
R
P
C
11
1
0
10
of the
at the
very
the
annulus
preceded
the
Table II. Incidence of discs tears by age of subject Under (n=90)
showing
35 years
45
1
L3toL4
27
9
9
1
2
12
5
19
7
1
L4toL5
27
12
12
0
3
13
6
15
11
1
L5toSl
27
4
7
2
5
18
13
9
13
5
Morgan
and
King
association ility and
between low back
“incomplete
radial
segments and the upperlumbar
(50%)
annular pain,
annular
35 to 50 years (n=45)
Total
ar degen eration
important
pulposus.
7
9
Ghormley
more
of
in the nucleus
10
1
to
fibrosus
a plane parallel seen specifically
Coventry,
LStoSl
III
relation
annulus
fissuring
of
17
1992
disc.
7
3
74-B, No. 5, SEPTEMBER
of the
12
13
VOL.
periphery
body along This was
L4toL5
3
R, radial
of the vertebral to the end-plates.
recognised
in
of the
7
0
C, circumferential;
described,
separation
7
12
lesions);
also
They
occur independently in the anterior and
L3toL4
6
(rim
They
disc.
could defects
of radiating greater in the
27
P, peripheral
of the
of peripheral
7
of
only two of all the had grade III nuclear
6
II
degener-
evidence
during the third of concentric
was
L2toL3
*
nuclear
showed
and Kernohan (1945a,b) considered that decade of life the typical appearance
of the nucleus
19
part
formation,
35
presence
I
6
central
regins.
changes
Grad e R
severe
four
7
and degeneration
Posterior
with
and
L2toL3
There
Nude Anterior
tears,
6
35 years.
and circumferential tears, but the incidence ruptures in the posterior annulus was much
discs
9
under
of the annular subjects
II).
nine
LltoL2
in 18 subjects
half
and Junghanns (1971) considered that the of clefts extending from the nucleus pulposus annulus was related to the desiccation and
discs.
We compared
in about
from
DISCUSSION
but at the L5-S1 level there were 18 circumferential tears posteriorly and only seven anteriorly. Radial tears were almost exclusively seen in the posterior annulus and in almost half of the L5-Sl discs. Nuclear degeneration was seen in eight L1-L2 discs as against
seen
nuclear
(2.2%)
degeneration.
from the rim and adjacent
I and II. in the anterior
of 45 discs
severe
of 90 discs
defects. By contrast, showed peripheral tears
osteophyte
in Tables frequent
Seven
showed
two
old (Table
Seven
fraying
annulus.
are summarised tears were more
group
that clefts within the annulus of the nucleus as concentric
reached
RESULTS results
pulposus.
older
the younger age group, but definite was found in 33 of the 45 discs from
posterior
Our
681
nucleus
the
as against
Schmorl appearance into the
There was no distinction fibrosus. The cut surface consistency. Yellow-brown
SPINE
subjects under 35 years of age. No annular defects were
ation
surface colour
Grade III.’ severe degeneration. between nucleus and annulus was flattened and of friable
of the
degeneration
over
nucleus a milky
The distinction between well defined, and the cut
degeneration.
annulus
between structure
LUMBAR
from
discs from pathology
8):
THE
degeneration (15.6%)
classified
of the nucleus to its macroscopic
IN
33 (73%)
(1957)
drew
attention
to
the
tears, radiographic instabobserving the presence of
posterior
tears”
of “anterior concentric spine. Vernon-Roberts
in the
lower
lumbar
fissures or slits” in and Pine (1977),
reviewing over 300 lumbar spine post-mortems, confirmed that radiating annular tears were extensions of clefts from the nucleus pulposus, and also observed circumferential tears within the layers ofthe annulus and rim
lesions
near
the
attachment
of the
annulus
to the
682
0. L. OSTI,
peripheral vertebral body. and histological characteristics from
1 17 spines
but they T12 and
frequently with
were
studied L4-L5
major
tears of
reported
anterior
of the annulus.
fibrocartilaginous
tissue. that lesions
sometimes rim
with
pulposus
and
are most
lesions
On the histological
frequent
these
tears
may
parts
ofthe
intervertebraljoint
precede
characteristics
of rim
either
periphery.
The
considered of internal the inner
and
in the lower Discrete tears in otherwise
degenerative make
sagittally
lumbar
in other
The
histological that
they
are
of such
annular directed
towards
the
ruptures
was
that
annular
subsequently the nucleus
lesions
Ourobservations annulus regarded
started
coalescing pulposus.
indicate
may develop as separate
in
to
that tears
independently. entities from
the
extend
tears
The in
inner
formation
relatively
zone
of
young
of
these
the
discrete
discs
has
been
experimentally by Nachemson (1963, High intradiscal pressures would produce the tensile strain in the outer layers of the annulus.
1965).
The relevance development oflow
of peripheral annular lesions back pain remains uncertain,
common observation lation tissue formation defects of the annulus suggests
more
that
these
likely
(1988)
showed
provocation presence annulus
may
produce
Yoshizawa
that
the
outer
annulus
This
and
is the
is
Bogduk
only
part
of
disc with a demonstrable nerve supply. comes from the observation that pain
fibrosus
is closely to the outer
(Adams,
We
fibrosus
Dolan
suggest
and
related lamellae
Hutton
that defects the dehydration
precede
the nucleus pulposus stress. These outer the a part
symptoms.
et al (1980)
at discography of tears extending
accelerate and play
to the but the
of vascular ingrowth and granuin association with peripheral (Hirsch and Schajowicz 1953)
tears
since
the intervertebral More confirmation
to the of the
1986).
of the peripheral and fraying
of
and arelikely to be due to mechanical annular tears may influence and
degeneration in producing
of the intervertebral discogenic pain.
disc,
The authors acknowledge financial support of the Adelaide Bone and Joint Research Foundation and the National Health and Medical Research Council of Australia. We also thank Ms Christine Corke for typing the manuscript and Mr Dale Caville for the preparation of photographic material.
outer
inwards
ofthe
a degenerating
disc.
peripheral
annulus that were
from
Conclusions.
degradation
laterally
radiation
spine
ofthe annulus normal discs;
it likely
or
outward
defects nucleus
changes
complex.
lesions
likely, pain.
annular of the
extend
demonstrated
by Galante (1967) to be due to a combination disc pressure and early degenerative failure of annulus. By contrast, Kirkaldy-Willis (1983)
proposed lamellae, towards
showed
R. D. FRASER
intervertebral
greatest
appearances
due to trauma, rather than the biochemical of disc tissue. Friberg and Hirsch (1950) suggested ruptures started in the inner layers and outwards,
associated
a traumatic aetiology was could be related to low back
and in the posterior annulus. fibrosus can, however, occur
that
(1984),
fibrovascular
Our study suggests that radiating closely associated with degeneration
are
Ball
slabs of the Ti 1rim lesions more
Most
repair
R. MOORE,
distribution rim lesions and
sagittal found
disc,
attempted
they considered and that these
frequency, of vertebral by Hilton
only central discs. They
in the
evidence
The
B. VERNON-ROBERTS,
Although none of the authors have received or will receive benefits for personal or professional use from a commercial party related directly or indirectly to the subject of this article, benefits have been or will be received but are directed solely to a research fund, foundation, educational institution, or other non-profit institution with which one or more of the authors is associated.
peripheral
They should be the radiating clefts
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THE
JOURNAL
OF BONE
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SURGERY
