Amilcare
Gentili,
MD
Anterior
Cruciate
Indirect
Signs
PURPOSE:
L. Seeger,
#{149}
Leanne
MD
Lawrence
Yao,
#{149}
Ligament
at MR Imaging’
Huy
M. Do,
#{149}
MD
Tear:
To establish
the sensitivof indirect
signs at
resonance
(MR) imaging
of
cruciate
ligament
(ACL) tear.
‘. \.
ity and specificity
magnetic
anterior
MD
MATERIALS
AND METHODS:
MR
images
of the knees
of 89 consecutive
patients
(54 with torn and 35 with
normal
ACLs) were reviewed.
The indirect
signs were as
follows
(first percentage
is sensitivity; the second,
specificity):
angle between
lateral
tibial plateau
and ACL
less than 45#{176}
(90%, 97%); angle between
Blumenstaat
line and ACL
more than 15#{176}
(89%, 100%); bone conRESULTS:
tusions
100%);
in lateral
compartment
(54%,
position
of posterior
cruciate
ligament
(PCL) line (52%, 91%); PCL
angle less than 107#{176}
(52%, 94%); PCL
bowing
ratio more than 0.39 (34%,
100%);
posterior
displacement
of lateral meniscus
more than 3.5 mm
(44%, 94%); anterior
displacement
of
tibia
more
than
7 mm (41%,
91%); and
lateral femoral
sulcus
deeper
than 1.5
mm (19%, 100%).
CONCLUSION:
Because
the specificity is high, the presence
of indirect
signs corroborates
the diagnosis
of
ACL tear. Because
the sensitivity
is
low, the absence
of these signs does
not exclude
the diagnosis
of ACL
tear.
a.
b.
Figure
1.
The ACL angle
is measured
between
the anterior
surface
of the ACL and a reference line parallel
to the midlateral
tibial plateau.
The reference
line is drawn
on an image
through
the midlateral
tibial plateau
and reported
on the image
showing
the ACL. (a) Sagittal
(2,100/90)
MR image
shows
ACL angle
of 55#{176}
(ANI 55) measured
in a 55-year-old
man with an
intact
ACL at arthroscopy.
(b) Sagittal
(2,000/80)
MR image
shows
ACL angle
of 19#{176}
(AN3 19)
measured
between
the anterior
surface
of the ACL and a reference
line parallel
to the lateral
tibial plateau
in a 35-year-old
man with
an ACL tear at arthroscopy.
M
resonance
(MR) imaghas been
reported
to be
accurate
in helping
make
the diagnosis of complete
anterior
cruciate
ligament
(ACL)
tear. In most
reports
the
ing
diagnosis
Radiology
1994;
From
ences,
the
193:835-840
Department
University
of Radiological
of California
Los
Angeles
SciCen-
ter for the Health
Sciences
(AC., L.L.S., L.Y.,
H.M.D.),
and the Department
of Radiology
(W114),
West Los Angeles
Veterans
Administration Medical
Center,
Wilshire
and Sawtelle
Blvds, Los Angeles,
CA 90073 (AC.).
From the
1993
RSNA
scientific
assembly.
28, 1994; revision
requested
received
July 19; accepted
print
requests
to AC.
RSNA,
1994
Received
April
june 23; revision
July 25. Address
re-
of
sagittal
ACL
include
focal
Index terms:
Knee, ligaments.
menisci,
and
cartilage,
4526.4857
#{149}
Knee, MR. 4526.1214
Ligaments,
injuries,
4526.4857
#{149}
Ligaments,
MR.
4526.1214
AGNETIC
within
ACL
images
(1,2).
tears
that
Direct
signs
wavy
contour
or diffuse
high
the substance
T2-weighted
images,
of the
tinuity
imaging
ACL
is accurate,
is based
show
on
a disrupted
of ACL
tear
(3,4).
lack
of con-
Although
false-positive
MR
and
false-negative
diagnoses
have
been
reported
(5). T2-weighted
images;
oblique
sagittal,
coronal,
and axial
images;
and gradient-echo
images
have
been
obtained
to improve
mesults
(6).
The
use of secondary
(indirect)
of ACL team has been
advocated
to improve
accuracy.
Numerous
mdirect signs
have
been
described.
These
include
orientation
of the ACL (6,7),
bone
contusions
and osteochondral
fractures
(7-1 1), posterior
cruciate
signs
(13),
(PCL)
PCL
line
bowing
eral femomal
drawer
sign
nor displacement
cus (13). The
was
to compare
specificity
of
(7,12),
PCL
(3,13,14),
angle
deep
lat-
sulcus
(7,15,16),
anterior
(7,14,17-19),
and posteof the lateral
menispurpose
of this study
the sensitivity
and
indirect
signs
of ACL
tear.
of the ACL,
signal
intensity
of the ACL on
and
ligament
MATERIALS
AND
METHODS
We performed
a retrospective
review
of
the images
of 89 consecutively
evaluated
patients
who
underwent
MR imaging
of
the knee
followed
by arthroscopy.
The
mean
age
months
of the
(range,
patients
16-75)
patients
were
men
Arthroscopy
was
thopedic
surgeons.
geons
who
performed
Abbreviations:
ment,
PCL
specialized
72 of the
=
ACL
posterior
was
30 years
years).
11
Sixty-two
and
27 were
women.
performed
by 14 orTwo
orthopedic
surin sports
89 procedures
anterior
cruciate
=
medicine
(81%).
cruciate
ligament.
liga-
1
a.
,.
Figure
2.
The
femur
and
ACL-Blumensaat
the distal
portion
superiorly
and
age shows
ACL-Blumensaat
copy.
a positive
(b) Sagittal
old man
line
is measured
when
questionnaires
tients
before
apex
points
inferiorly.
line angle of -7#{176}
in a 55-year-old
MR image
shows
ACU-Blumensaat
MR
patients
had a torn
normal
ACL. Of the 54
complete
and five were
the patient
charts
and of
administered
images
were
to the paobtained
showed
that 33 ACL tears (28 complete
and five partial)
were acute (less than I
month
old), nine were subacute
(between
1 and 3 months
old), and 13 were chronic
the
than
knee
has a negative
the
3 months
was
old). MR imaging
performed
(Signa,
GE Medical
Wis, or Magneton,
with
Systems,
Siemens,
noted.
On T2-weighted
tusions
graphic
unit
that
on either
proton-density-
pect
The
demonstrated
1500-2500/20,
=
70-90)
Ti-weighted
multiecho
scopic
MR imaging
clinical
were
mary
signs
history,
signs
were
all
on the hard
and
nine
considered.
depicted
of low
had
tensity
a focal
within
ment
on T2-weighted
cross
this
of the
if it
band
proton-
images.
The
if it had a wavy
high
substance
images,
ACL
con-
signal
of the
in-
liga-
or lacked
continuity.
The
sured
orientation
in two
different
of the ACL
ways:
was
(a) with
meare-
spect to the lateral
tibial plateau
(the ACL
angle)
(Fig 1) and (h) with respect
to the
Blumensaat
line (Fig 2).
836
MR image
ACL tear
measured
of a
at
arthrosbetween
a
#{149}
Radiology
con-
areas
of low
contusions
tibial
sig-
and osteo-
The
plateau.
of the
PCL
Schweitzer
image
was
was
the
margin
line
used
as de-
of the
in relation
as an indirect
selected
distal
that
best
portion
the
of the
medullary
PCL
cavity
line
cross
the
medullary
of the
did
of the
cavity
The
proxi-
not
distal
negative
PCL line
of the
distal
5 cm
of the femur.
The PCL angle was the angle measured
between
a line through
the center
of the
proximal
and a line through
the distal portion of the PCL (Fig 3) (13).
The PCL bowing
ratio was the ratio between
the distance
of the anterior
surface
of the PCL and a line connecting
the most
anterior
points
of attachment
of the PCL
on the femur
and tibia divided
by the dis-
tance between
the most anterior
points
of
attachment
of the PCL on the femur
and
the tibia (14).
Posterior
displacement
of the lateral
meniscus
was
measured
Sagittal
tibia.
The
first
corner
line
passes
of the
through
lateral
tibial
the
poste-
plateau,
and
the second
line is tangent
to the most
postenor aspect
of the posterior
horn
of the lateral
meniscus.
The posterior
displacement
of the
lateral
meniscus
is 6 mm.
to the pos-
portion
PCL and
extended
proximally.
was considered
positive
if the
extension
4.
of the
tangent
linear
(2,000/80)
MR image
of a
man with ACL tear at arthrosposterior
displacement
of the lateral meniscus
is measured
as the distance
(arrow)
between
two lines parallel
to the
Figure
35-year-old
copy.
The
nor
et al (12)
femur
;T;#{149}.:T-;T-
bone;
femur.
This sign was considered
if the proximal
extension
of the
did
Pri-
linear
on either
or diffuse
the
mal
different
indirect
P values
for group
intensity
densityor T2-weighted
was considered
torn
tour,
distal
sign
initial
copy.
as a continuous
signal
coro-
measure-
comparison
were based
on results
unpaired
f test.
The ACL was considered
normal
was
tenor
Because
study
made
or
by
to the distal
or
obtained.
retrospecof the arthro-
interpretations.
a retrospective
ments
(2,000/80)
line through
the center
of the proximal
portion of the PCL and a line though
the center
of the distal
portion
of the PCL is 96#{176}.
or TI-weighted
PCL. A line was drawn
ob-
or 70-90)
also were
was reviewed
knowledge
findings,
were
(400-500/20-30)
(1,500-2,500/20
nal acquisitions
Each study
tively without
was
time
lateral
position
sign.
sagittal
(repetition
bone
subcortical
were
Bone
of the
msec/echo
time
man angle
with
PCL
of geohigh
signal
chondral
fractures
were considered
posifive for ACL tear if they were present
in
the lateral
femoral
condyle
above
the lateral femoral
sulcus
or in the posterior
as-
multiecho
all patients
involved
contusions
tion.
acquisitions
as areas
nonlinear
intensity
nal intensity.
Milwaukee,
Erlangen,
images,
were
defined
or reticular,
images,
of
a I.5-T
presence
and location
of bone conand osteochondral
fractures
were
scribed
tamed.
(a) Sagittal
(2,100/20)
MR imman with
intact
ACL at arthrosline angle
of +32#{176}
in a 35-year-
The
tusions
Germany)
with a dedicated
extremity
coil.
The knee was positioned
in full extension
with approximately
15#{176}
of external
rotaFor
surface of the
the apex points
Sagittal
35-year-oldThe
copy.
ACL tear at arthroscopy.
At arthroscopy,
54
ACL and 35 had a
ACL teams, 49 were
partial.
Review
of
(more
the posterior
value when
between
of the ACL. The angle
value
(2,000/30)
with
angle
Figure 3.
as displacement
of
ment
line
(anterior
tangent
drawer
sign)
to the posterior
cortex
of the lateral
parallel
The
sured
to the long
axis of the tibia
(5).
depth
of the lateral
sulcus
was meaaccording
to the method
of Warren
et al (15)
drawn
served
and
the sulcus
this
femoral
Cobby
tangent
as the
was
condyle
et al (16).
to the
reference,
articular
and
measured
and
A line
the
surface
depth
of
perpendicular
to
line.
RESULTS
The
without
mean
ACL
mean
ACL angle
for patients
an ACL tear was 55.6#{176}.
The
ACL angle
for patients
with
an
tear
was
a significantly
29.9#{176}
(P < .001). Theme
cant
difference
between
angle
in acute
the posterior
horn of the lateral
meniscus
behind
the most posterior
margin
of the
chronic
tears
only
minimal
tibial plateau (Fig 4).
We measured
anterior
the
tibial displace-
by drawing
a
margin
of the
an
ACL
ACL
teams and
(Table
overlap
angle
tear
that
1). There
in the
between
and
smaller
was no signifithe ACL
patients
in
was
value
patients
with
December
of
with
a nor-
1994
C/)
a)
16
ci 14
20
(I)
C,)
15
10
10
0
08
.0
E
E4
zo
zo
0
10
20
30
40
50
60
70
-20
80
0
Angle
AOL
20
40
ACL-Blumensaat
60
Line
80
Angle
6.
5.
12
U)
0)
C,)
a)
N
10
C/)
08
20
15
10
a)
a)4
.0
E
:
zo
zo
80
60
100
PCL
120
Angle
140
00:20.40.60.811.2
160
PCL
7.
Ratio
Bowing
8.
Figures
5-8.
(5) Frequency
distribution
of ACL angle.
There
is good
separation
between
patients
with a normal
ACL (black
line) and patients
with
a torn ACL (gray
line).
(6) Frequency
distribution
of ACL-Blumensaat
line angle.
There
is good
separation
between
patients
with
a normal ACL (black
line) and patients
with a torn ACL (gray
line).
(7) Frequency
distribution
of PCL angle.
Overlap
is seen between
patients
with a
normal
ACL (black
line) and patients
with
a torn ACL (gray
line).
(8) Frequency
distribution
of PCL bowing
ratio.
Overlap
is seen between
patients
with
a normal
Table 1
Comparison
ACL
(black
between
line)
Acute
and
patients
and Chronic
Acute ACL
Sign
with
a torn
ACL
(gray
line).
the lateral
femoral
femoral
sulcus
had
ACL Tear
Chronic
ACL
Tears
Tears
(mean)
(mean)
and
presence
a specificity
of 100%. The
of bone contusions
in the
51%
Sensitivity
for
Acute ACL
P
Tears
Sensitivity
for
Chronic
ACL Tears
(%)
Value
posterior
plateau
(%)
aspect
of the
had a sensitivity
specificity
ACL
angle
ACU-Blumensaat
line
30.7#{176}
26.6#{176}
NA
NA
angle
Bone contusion
PCL line
PCL angle
PCL bowing
ratio
Posterior
displacement
of
lateral meniscus
(mm)
Anterior
drawer
=
5). When
less
than
45#{176}
was
used
the sensitivity
sign was 91
97%.
When
NS
an
as
=
0.419
of
a cutoff
of the
presence
% and the specificthe cutoff
angle
than
40#{176},
the sensitivity
decreased
to 89% and the specificity
increased
to 100%.
The mean
angle
between
the ACL
and the Blumensaat
line for patients
without
an ACL tear was -1.6#{176}.The
mean
ACL-Blumensaat
line angle
for
was
less
patients
with
an ACL tear was a significantly
greater
25.8#{176}
(P < .001).
There
was no significant
difference
r_1
-
condyle
sensitivity
was
< .001
< .05
was
with
100%.
acute
Among
the 33 patients
ACL teams, the sensitivity
was
76%.
.001
30
< .001
27
76
61
25
76
84
42
T..__._l____
in
18
was
150
91%
When
was
creased
creased
The
used,
and
a cutoff
the
the
specificity
sensitivity
to 89% and the
to 100%.
presence
of bone
than
despecificity
contusions
58%
plateau
or the
considered,
the
and the specificity
PCL line sign had a senand a specificity
of
91%. The sensitivity
was 76% for
chronic
teams and was 45% for acute
tears.
The mean
PCL angle
for patients
without
an ACL tear was 123#{176}.
The
was
more
tibial
were
A positive
7
angle
the
either
a
contu-
femoral
NS
86%.
bone
sions
between
the ACL-Blumensaat
line
angle
in acute
tears
and
that in
chronic
teams (Table
1). Theme
was
only
minimal
overlap
in the value
of
the ACL-Blumensaat
line angle
between
patients
with
an ACL tear and
patients
with
a normal
ACL (Fig 6).
When
an angle
more
than
9#{176}
was
used
as the
cutoff
value,
the sensitivity
When
100
not significant.
angle
100%.
100
sitivity
not applicable,
(Fig
was
5.1
8.7
0.827
ACL
ity
2.1
5.4
of
lateral
tibial
of 51% and
87
87
76
45
42
12
NS
NS
NA
NA
femoiral
mal
value,
of this
0.24
(mm)
Depth
of lateral
sulcus
(mm)
Note-NA
109#{176}
27.2#{176}
27#{176}
NA
NA
95#{176}
0.29
condyle
above
the
a sensitivity
of
inin
of
51
U/()
mean
PCL angle
for patients
ACL tear was a significantly
106#{176}
(p
overlap
<
between
and
.001).
There
in the value
patients
patients
7). When
the
than 107#{176},
the
the specificity
angle was less
with an
smaller
was,
however,
of the
with
an
PCL
ACL
with a normal
ACL (Fig
cutoff angle was less
sensitivity
was 52% and
94%. When
the cutoff
than 100#{176},
the sensitiv-
ity
decreased
to 37%
ity
increased
to 100%.
The PCL
was significantly
in acute tears
ent from that
The
patients
angle
team
and
in chronic
mean
PCL
without
bowing
an ACL
the
tears
specificangle
differ-
(Table
1).
ratio
for
tear was
R1in1ntv
#{149}
i7
-10
U)
14
Cl)
a)
a)
U)
U)
U)
U)
-5
0
5
10
Anterior
Drawer
15
20
12
10
08
0
6
‘-6
a)
.04
.4
zo
zo
2
-4
-2
2
0
6
4
Displacement
Posterior
8
10
12
LM (mm.)
(mm.)
Sign
10.
9.
Figures
9-11.
lateral meniscus
ACL
(black
(9) Frequency
(LM).
line)
and
distribution
Overlap
patients
is seen
with
of posterior
between
a torn
ACL
displacement
patients
(gray
with
line).
of
a normal
(10)
Cl)
Fre-
quency
patients
distribution
of anterior
drawer
sign. Overlap
is seen between
with a normal
ACL (black line) and patients
with a torn ACL
(gray
line).
(11) Frequency
distribution
oflateral
femoral
sulcus depth.
Overlap
is seen between
patients
with a normal
ACL (black line) and
patients
with
a torn
ACL
(gray
25
20
0
9-
0
a)
.0
line).
ES
:,
zo
0.19.
The
mean
PCL
bowing
ratio
for
patients
with an ACL tear was a significantly
larger
0.26 (P < .001). There
was overlap
in the value of the PCL
bowing
ratio between
patients
with
an ACL tear and patients
with a normal ACL (Fig 8). When
a ratio of more
than 0.39 was considered
abnormal,
the sensitivity
was 34% and the specificity was 100%
The PCL bowing
matio in acute tears was significantly
different
from that in chronic
tears
(Table
1).
The mean
posterior
displacement
of
the lateral
meniscus
for patients
without an ACL tear was 0.54 mm. The
mean
posterior
displacement
of the
lateral
meniscus
for patients
with an
ACL tear was a significantly
greater
3.05 mm (P < .001). There
was overlap in the posterior
displacement
of
the lateral
meniscus
between
patients
with an ACL tear and patients
with a
normal
ACL (Fig 9). When
more than
.
3.5 mm
of posterior
displacement
of
the lateral
meniscus
was considered
abnormal,
the sensitivity
was 44%
and the specificity
94% When
greater
than 5 mm of posterior
displacement
of the lateral
meniscus
was used as
the cutoff value,
the sensitivity
decreased
to 20% and the specificity
increased
to 100%. The PCL bowing
ratio in acute tears was significantly
different
from that in chronic
tears
(Table
1).
The mean
anterior
displacement
of
the tibia (anterior
drawer
sign) for
patients
with an intact ACL was 2.17
mm. The mean
anterior
displacement
of the tibia for patients
with an ACL
tear was a significantly
larger
6.18 mm
.
(P
<
.001).
There
was
overlap
in the
value of the anterior
displacement
of
the tibia between
patients
with an
ACL tear and patients
with a normal
838
#{149}
Radiology
Depth
Lateral
Femoral
Sulcus
(mm)
11.
ACL (Fig
of anterior
was
10). When
more than 5 mm
displacement
of the tibia
considered
abnormal,
the
sensi-
tivity was 63% and the specificity
80%. When
the cutoff value
was more
than 7 mm, the sensitivity
decreased
to 41% and the specificity
increased
to
91%. The anterior
displacement
of the
tibia in acute tears was significantly
different
from that in chronic
teams
(Table
1).
The mean
depth
of the lateral
femoral
sulcus
for patients
without
an ACL tear was 0.35 mm. The mean
depth
of the lateral
femoral
sulcus
for
patients
with an ACL team was a significantly
greater
0.74 mm (P < .02).
There
was overlap
in the value of
depth
of the lateral
femomal
sulcus
between
patients
with an ACL tear
and patients
with a normal
ACL (Fig
11); most patients
had a sulcus
less
than 1 mm deep.
When
a depth
of the
lateral
femomal
sulcus
more than 1
mm was considered
abnormal,
the
sensitivity
94%. When
was 30%
a depth
and the specificity
more
than
1.5
mm was used as the cutoff value,
the
sensitivity
decreased
to 19% and the
specificity
increased
to 100%. The
depth
of the lateral
femomal
sulcus
in
acute tears was not significantly
different from that in chronic
tears (Table
1).
Direct
signs of ACL tear had a sensitivity
97%.
of 93%
Theme
were
and
a specificity
one
and four false-negative
the one false-positive
secondary
signs were
of
false-positive
diagnoses.
In
diagnosis,
all
negative;
the
apparent
due
four
disruption
to a partial
false-negative
of the
ACL
volume
effect.
diagnoses,
was
Of the
three
were
partial
tears
and one was a complete
tear.
Of the three
false-negative
partial
tears,
a bone
contusion
was
present
in the lateral
femoral
condyle
in one patient;
otherwise,
the indirect
signs
were
all negative.
The patient
with
the false-negative
diagnosis
who
had a complete
team had a positive
ACL angle,
ACL-Blumensaat
angle,
posterior
displacement
line
of the
lateral
drawer
meniscus,
and
anterior
sign.
DISCUSSION
The MR imaging
diagnosis
of ACL
tear is usually
based
on direct
signs
of
tear. These
signs
include
a wavy
contour of the ACL,
focal or diffuse
high
signal
intensity
within
the substance
of the ACL on T2-weighted
images,
discontinuity
of the ACL,
or a combi-
nation
of these signs. These
direct
signs are usually
sufficient
for an accurate
diagnosis.
High
specificity
have been
these primary
signs.
sensitivity
reported
Only two
and
for
pa-
tients
in our series
had positive
mdirect signs
and negative
direct
signs.
Several
indirect
signs
of ACL tear
have
been
reported
in the literature
(Table
2).
A normal
ACL is taut when
the
angle
between
the femur
and the amticulam
surface
of the lateral
tibial
plateau
is approximately
55#{176}
(M. Shapiro,
oral
communication,
1994).
When
December
the
1994
cus,
Table
Indirect
2
Signs
of ACL Tear: Review
of the Literature
No.
Reference
Sign
ACL
Tibial
bone contusion
Femoral bone contusion
Bonecontusion
Bone contusion
Bone injury
to tibia or femur
Bone injury
< 4 wk earlier
Bone injury
< 3 wk earlier
Bone injury
Bone injury
< 6 wk earlier
PCL line
PCLline
PCL bowing
PCL bowing
PCL curvature
> 0.39#{176}
PCLangle
< 105#{176}
ACL parallel
to Blumensaat
line
Posterior
displacement
of
7
7
13
14
9
8
10
11
11
7
12
7
18
14
13
7
13
lateral
14
Posterior
lateral
7
Anterior
17
18
18
19
15
16
16
No.
Tear
without
ACL
43
43
39
50
32
Sensitivity
Tear
60
60
29
53
NDA
100
Specificity
NDA
NDA
NDA
60
59
60
29
40.5*
375*
48*
44
975*
failure
98.5*
97*
increased
the tibia
sign
Anterior
drawer
Anteriordrawer
Anterior
drawer
Anterior
drawer
Lateral
femoral
mmdeep
Lateral
femoral
mm deep
Lateral
femoral
sign
>
> 7 mm
> 5 mm
sulcus
>
1.5
sulcus
>
1
sulcus
>
1.5
mmdeep
100
50
53
44
96
39
29
73*
82.5*
43
60
79*
86*
39
29
56*
98.5*
no data available.
of scores of two independent
failure
of the
of secondary
of
knee.
restraints
anterior
in patients
and
can
This
allows
displacement
with
chronic
of
tears
50
43
10
53
60
52
44
60
96
88
60
29
100
58
100
93
60
21
29
91
38
86
100
153
47
10
98
41
62
29
97
41
62
12
tear
is due
to impacted
fracture,
to a Hill-Sachs
lesion
of the
humerus.
This impaction
occurs
when
the tibia becomes
displaced
anteriorly
and the lateral
femoral
sulcus
pushes
against
the posterior
rim of the tibial
plateau.
This is the same
mechanism
that causes
bone
contusions
in the
region
of the femomal
sulcus
and postemolateral
tibial
plateau.
similar
99
In conclusion,
tear
100
can
mary
Note.-NDA
* Average
restraints
PCL
acute
tears
Posterior
displacement
of the lateral meniscus
is a sign of anterior
displacement
of the tibia.
When
the tibia
becomes
displaced
anteriorly,
the latemal meniscus
remains
with
the femur,
resulting
in posterior
displacement
of
the posterior
horn
of the lateral
meniscus
with
respect
to the tibia
(13).
The increased
depth
of the lateral
femoral
sulcus
in patients
with
an
NDA
NDA
NDA
85.5*
94
90*
ACL
5mm
and
with
ACL
(20).
100
of
drawer
by delayed
secondary
56
85
48
71
66*
86
58*
17
sign,
be explained
(%)
96
NDA
drawer
patients
chronic
(%)
100
200
75
98
47
43
22
43
60
meniscus
displacement
meniscus
with
anterior
line between
patients
with
observers.
nosis.
on
alone,
signs
indirect
=
the diagnosis
be made
signs
the
but
the
of pri-
presence
corroborates
Except
of ACL
basis
the
for ACL
angle
of
diag-
and
ACL-
Blumensaat
line angle,
because
mdirect signs
have
a low sensitivity,
the
absence
of such
signs
does
not exdude
the diagnosis
of ACL tear.
#{149}
tibia
and
ACL
is parallel
femur
are
at this
angle,
to the posterior
the
with
injuries
that occurred
more
than
6 weeks
earlier
(11).
When
the ACL is deficient,
the
may
become
displaced
anteriorly.
This
anterior
displacement
of the
patients
sur-
face of the femoral
notch
(7). When
torn,
the ACL assumes
a more
horizontal
orientation.
In our experience,
the change
in orientation
of the ACL
is one
of the best indirect
signs
of an
ACL
tear;
a high
Bone
caused
tibia
it has
a high
specificity.
contusions
by anterior
at the
time
sensitivity
may
nor
and
be
drawer
of tear
likely
of the
directly
This
sign.
specificity
tivity
are most
subluxation
measured
(91%),
is only
41%
when
sign
edema,
mi-
In our
is
have
a high
specificity
but only
a moderate
crofractume.
usually
not
abnormalities
Pathologic
available
resolve
In one
described
case
(10), a biopsy
preparation
performed
of a tunnel
struction
the
of
ACL
correlation
because
these
spontaneously.
by Rosen
subjective
52%).
and
has
experience
Positioning
MR unit
of
demonstrated
edema
and hemorrhage
in the bone
marrow.
Bone
contusions
are seen
immediately
after
injury.
As reported
by Graf
et al (11), they
are not seen
a high
the
sensi-
a low
plane
three
the
patient
in
the
5.
6.
displacement
of the
lateral
menis-
162:547-551.
CT, Wirth
cruciate
MR
imaging
7.
compared
CR, Czajka
ligament
with
copy and clinical
tests. Radiology
861-864.
Remer
EM, Fizgerald
SW, Friedman
Rogers
LF,
tenor
cruciate
Hendrix
RW,
ligament
and
pattern
Schafer
injury:
of injury.
arthros-
1988;
166:
H,
MF.
An-
MR imaging
Radio-
Craphics
1992; 12:901-915.
Vahey
TN, Broome
DR, Kayes
KJ, Shelbourne
KD.
Acute and chronic
tears of
the anterior
cruciate
ligament:
differential
features
at MR imaging.
Radiology
1991;
181 :251-253.
Fitzgerald
SW, Remer
EM, Friedman
H,
Rogers
of the sagittal
difference
in the value of
PCL bowing
ratio, poste-
Radiology
diagnosis
(91%-100%)
sensitivity
(34%-
selection
1987;
Lee jK, Yao L, Phelps
J, Lozman
J#{149}
Anterior
tears:
signs
can affect
the degree
of bowing
of the PCL.
Even
a mild
genu
recurvatum
deformity
may
make
the PCL appear
bowed.
The
nor
3.
4.
sensitivity
Beltran
J, Noto
AM, Mosure
JC, Weiss KL,
Zuelzer
W, Christoforidis
A].
The knee:
surface-coil
MR imaging
at 1.5 T. Radiology
1986; 159:747-751.
Reicher
MA, Hartzman
S, Basset
LW, Mandelbaum
B, Duckwiler
C, Cold RH.
MR
imaging
of the knee. I. Traumatic
disorders.
is
of imaging
significant
PCL angle,
in
and
these
2.
7 mm
for ACL tear (17%)
(5). The PCL line,
PCL angle,
and PCL bowing
ratio
have
been
introduced
to make
assessment
of PCL bowing
less subjective.
et al
at the time
for recon-
tibia
has
least
1.
ante-
displacement
of the tibia
PCL bowing
is an indirect
of anterior
displacement
of the
The assessment
of bowing
is
tibia.
possibly
at
the
of anterior
present.
of the ACL
and
sign
although
accompanied
by impaction
of the
middle
portion
of the lateral
femoral
condyle
against
the posterior
portion
of the lateral
tibial
plateau
(8). The
signal-intensity
abnormalities
of bone
contusions
are
probably
due to
hemorrhage,
as
References
tibia
LF,
Hendrix
RW,
Schafer
MF.
MR
evaluation
of the anterior
cruciate
ligament:
value of sagittal
images
with coronal
and axial images.
AJR 1993; 16t):1233-l237.
Robertson
PL, Schweitzer
ME, Bartolozzi
AR.
Anterior
cruciate
ligament
tears: MR
imaging
evaluation.
Radiology
1994;
193:
829-834.
8.
Kaplan
Brown
PA, Walker
CW, Kilcoyne
RF,
DE, Tusek
D, Dussault
RC.
Occult
fracture
patterns
of the knee associated
with anterior
cruciate
ligament
tears:
sessment
with MR imaging.
Radiology
9.
10.
11.
ment
as12.
injuries.
Am j Sports
Med 1993;
220-223.
Schweitzer
ME, Cervilla
V. Kursunoglu-
Brahme
Murphy
Bj, Smith
RL, UribeJW,
Janecki
Cj,
Hechtman
KS, Mangasarian
RA.
Bone
signal
abnormalities
in the posterolateral
tibia and lateral
femoral
condyle
in complete tears of the anterior
cruciate
ligament:
a specific
sign? Radiology
1992; 182:
221-224.
Rosen
MA, Jackson
DW, Berger
PE.
Occult lesions
documented
by magnetic
resonance
imaging
associated
with anterior
cruciate
ligament
ruptures.
Arthroscopy
1991; 7:45-51.
Craf BK, Cook DA, De Smet AA, Keene
jS.
indirect
sign of anterior
cruciate
ligament
injury.
Clin Imaging
1992; 16:43-48.
McCauley
TR, Moses
M, Kier R, Lynch
JK,
Barton
W, joki P.
MR diagnosis
of tears
of anterior
cruciate
ligament
of the knee:
importance
of ancillary
findings.
AJR 1994;
162:115-119.
Tung GA, Davis
LM, Wiggins
ME, Fadale
PD.
Tears of the anterior
cruciate
ligament:
primary
and secondary
signs at MR
imaging.
Radiology
1993; 188:661-667.
Warren
RF, Kaplan
N, Bach BR.
The lateral notch sign of anterior
cruciate
ligament insufficiency.
Am j Knee Surg 1988;
‘Bone bruises”
aging
evaluation
on magnetic
of anterior
resonance
cruciate
14.
15.
imliga-
D.
Cobby
Mj,
The deep
The PCL line: an
Schweitzer
lateral
femoral
ME,
Resnick
notch:
sign of a torn anterior
cruciate
Radiology
1992; 184:855-858.
#{149}
Radiology
Chan
HK.
18.
19.
20.
WP, Fritz RC, Stoller
MR “anterior
drawer”
in the
diagnosis
DW, Cenant
sign: a useful
of complete
anterior
cruciate
ligament
tear (abstr).
Radiology
1991; 181:178-179.
Vahey
TN, Hunt JE, Shelbourne
KD.
Antenor
translocation
of the tibia at MR imaging: a secondary
sign of anterior
cruciate
ligament
tear. Radiology
1993; 187:817-819.
Chan
WP, Peterfy
C, Fritz RC, Cenant
HK.
MR diagnosis
of complete
tears of the antenor cruciate
ligament
of the knee:
importance of anterior
subluxation
of the tibia.
AIR 1994; 162:355-360.
Fetto jF, Marshallj.
The natural
history
and diagnosis
of anterior
cruciate
ligament
insufficiency.
Clin Orthop
1980; 147:29-38.
1:119-124.
16.
840
17.
sign
1992; 183:835-838.
13.
S, Resnick
21:
D.
an indirect
ligament.
flpcemhor
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