Meniscal Root pathology

1. Meniscus Meniscal Root Ligament Lesions, MRI of PMMRL tears
posterior horn of the medial meniscus PHMM

2. The meniscal roots are ligament-like structures that serve to anchor the
fibrocartilaginous menisci onto the tibial intercondylar fossa or intercondylar
eminence [1, 2].
The role of the meniscal root is paramount; it prevents the meniscus from
being extruded and allows the meniscus to generate hoop stress. This
enables the menisci to effectively transfer the load from the femur to the
tibia while protecting the articular cartilage of the knee from excessive load
[2].
Therefore, complete tearing of a meniscal root results in complete loss of
hoop stress, which is nearly functionally identical to that of total
meniscectomy [3] and a critical risk factor of early osteoarthritis of the
knee [4–6].
Read More: https://www.ajronline.org/doi/10.2214/AJR.14.12559?mobileUi=0

3. The “posterior medial meniscus root ligament (PMMRL)” attaches to the posterior
intercondylar fossa between the attachments of
• the posterior root of the lateral meniscus and
• posterior cruciate ligament [1].
Several recent reports have suggested that PMMRL tears are relatively
common, particularly in the middle-aged or elderly population, and may be a
cause of medial tibiofemoral osteoarthritis of the knee, which is the most common
source of total knee arthroplasty [7, 8].
MRI is the primary diagnostic tool for PMMRL tears and has been regarded as
both reliable and accurate for detection [4, 9].
Read More: https://www.ajronline.org/doi/10.2214/AJR.14.12559?mobileUi=0

7. D:??????Downloads?????? ?? IDMA - Diagnosis and treatment of rotatory knee instability2019.pdf
Fig. 2 A MRI of a medial
meniscus root tear in
conjunction with an ACL
tear.
The white arrows point
to the meniscus root as
it enters its insertion on
the tibia.
images (a and b), there
is fluid underneath the
root with no clear
attachment to the tibia.

8. D:??????Downloads?????? ?? IDMA - Diagnosis and treatment of rotatory knee instability2019.pdf
Fig. 2 A MRI of a medial
meniscus root tear in
conjunction with an ACL
tear.
The white arrows point
to the meniscus root as
it enters its insertion on
the tibia.
images (a and b), there
is fluid underneath the
root with no clear
attachment to the tibia.

9. D:??????Downloads?????? ?? IDMA - Diagnosis and treatment of rotatory knee instability2019.pdf
Fig. 2 A MRI of a medial
meniscus root tear in
conjunction with an ACL tear.
The white arrows point to the
meniscus root as it enters its
insertion on the tibia.
image (c) demonstrates no
clear attachment of the root to
the tibia
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10. tear extends to either the anterior or posterior meniscal root attachment to the
central tibial plateau.
They often tend to be radial tears extending into the meniscal root.
Epidemiology
According to one source, they are thought to account for ~10% of all arthroscopic
meniscectomies 5.
Pathology
While they can arise from a number of mechanisms, root tears are generally
thought to be chronic 5.
Associations
ACL tears are associated with posterior horn root tears of the lateral meniscus ref
https://radiopaedia.org/articles/meniscal-root-tear#:~:text=For%20root%20tears%20in%20general,demonstrate%20a%20meniscal%20ghost%20sign.

11. Classification
The LaPrade classification system of meniscal root tears has
become commonly used in arthroscopy, and there is evidence
that this system can be to some extent translated to MRI
assessment of these tears ref.
https://radiopaedia.org/articles/meniscal-root-tear#:~:text=For%20root%20tears%20in%20general,demonstrate%20a%20meniscal%20ghost%20sign.

12. Radiographic features MRI
Best assessed on T2 weighted sequences.
When it involves the posterior root, medial root tears are easier to diagnose than lateral
root tears.
On medial posterior root tears there is often 2:
• shortening or absence of the root on sagittal images
• vertical fluid cleft on coronal fluid-sensitive (T2) images
https://radiopaedia.org/articles/meniscal-root-tear#:~:text=For%20root%20tears%20in%20general,demonstrate%20a%20meniscal%20ghost%20sign.

13. Radiographic features MRI
On posterior root radial tears of the lateral meniscus, the appearance may be similar to
radial tears in other locations.
For root tears in general, sagittal imaging may demonstrate a
• meniscal ghost sign.
Other features include:
1. truncation sign on coronal images 4
2. features meniscal extrusion on coronal plane 4
https://radiopaedia.org/articles/meniscal-root-tear#:~:text=For%20root%20tears%20in%20general,demonstrate%20a%20meniscal%20ghost%20sign.

14. Meniscal root
tear
First study the
image on the left
and try to
recognize the
meniscal tear.
These tears often
go unnoticed.
Then continue with
the next images.
https://radiologyassistant.nl/musculo
skeletal/knee/meniscus-special-
cases#meniscal-root-tear

15. A radial tear is
present at the
posterior root
junction of the
medial meniscus
which extends
through the
entire thickness
of the meniscus
with a cleft of
fluid tracking
through the
defect (red
arrows).

16. A radial tear is
present at the
posterior root
junction of the
medial meniscus
which extends
through the
entire thickness
of the meniscus
with a cleft of
fluid tracking
through the
defect (red
arrows).

17. A radial tear is
present at the
posterior root
junction of the
medial meniscus
which extends
through the
entire thickness
of the meniscus
with a cleft of
fluid tracking
through the
defect (red
arrows).

18. A radial tear is
present at the
posterior root
junction of the
medial meniscus
which extends
through the
entire thickness
of the meniscus
with a cleft of
fluid tracking
through the
defect (red
arrows).

19. Meniscal root tears
are often associated
with extrusion of the
meniscus beyond
the margin of the
tibial plateau.
More than 3 mm
meniscus extrusion
is often associated
with tears involving
the meniscal root
(6).
In the case on the
left there is a
complete radial tear
separating the
posterior horn from
its root (red arrows).
There is also
minimal extrusion of
the meniscus (image
1/6).

20. Meniscal root tears
are often associated
with extrusion of the
meniscus beyond
the margin of the
tibial plateau.
More than 3 mm
meniscus extrusion
is often associated
with tears involving
the meniscal root
(6).
In the case on the
left there is a
complete radial tear
separating the
posterior horn from
its root (red arrows).
There is also
minimal extrusion of
the meniscus (image
1/6).

21. Meniscal root tears
are often associated
with extrusion of the
meniscus beyond
the margin of the
tibial plateau.
More than 3 mm
meniscus extrusion
is often associated
with tears involving
the meniscal root
(6).
In the case on the
left there is a
complete radial tear
separating the
posterior horn from
its root (red arrows).
There is also
minimal extrusion of
the meniscus (image
1/6).

22. Meniscal root tears
are often associated
with extrusion of the
meniscus beyond
the margin of the
tibial plateau.
More than 3 mm
meniscus extrusion
is often associated
with tears involving
the meniscal root
(6).
In the case on the
left there is a
complete radial tear
separating the
posterior horn from
its root (red arrows).
There is also
minimal extrusion of
the meniscus (image
1/6).

23. Meniscal root tears
are often associated
with extrusion of the
meniscus beyond
the margin of the
tibial plateau.
More than 3 mm
meniscus extrusion
is often associated
with tears involving
the meniscal root
(6).
In the case on the
left there is a
complete radial tear
separating the
posterior horn from
its root (red arrows).
There is also
minimal extrusion of
the meniscus (image
1/6).

24. Meniscal root tears
are often associated
with extrusion of the
meniscus beyond
the margin of the
tibial plateau.
More than 3 mm
meniscus extrusion
is often associated
with tears involving
the meniscal root
(6).
In the case on the
left there is a
complete radial tear
separating the
posterior horn from
its root (red arrows).
There is also
minimal extrusion of
the meniscus (image
1/6).

25. Here another
medial meniscal
root tear.
Notice that the
posterior horn
is not attached
to the tibia.
Instead there is
a gap (curved
arrow).
You can easily
overlook these
tears and think
that the
posterior horn
is normal.

26. Here another
medial meniscal
root tear.
Notice that the
posterior horn
is not attached
to the tibia.
Instead there is
a gap (curved
arrow).
You can easily
overlook these
tears and think
that the
posterior horn
is normal.

27. Here another
medial meniscal
root tear.
Notice that the
posterior horn
is not attached
to the tibia.
Instead there is
a gap (curved
arrow).
You can easily
overlook these
tears and think
that the
posterior horn
is normal.

28. Here another
medial meniscal
root tear.
Notice that the
posterior horn
is not attached
to the tibia.
Instead there is
a gap (curved
arrow).
You can easily
overlook these
tears and think
that the
posterior horn
is normal.

29. Here another
medial meniscal
root tear.
Notice that the
posterior horn
is not attached
to the tibia.
Instead there is
a gap (curved
arrow).
You can easily
overlook these
tears and think
that the
posterior horn
is normal.

30. Here another
medial meniscal
root tear.
Notice that the
posterior horn
is not attached
to the tibia.
Instead there is
a gap (curved
arrow).
You can easily
overlook these
tears and think
that the
posterior horn
is normal.

31. This is
another
typical
case of
a
medial
menisc
al root
tear.
Notice
that
there is
also a
lateral
discoid
menisc
us.

32. This is
another
typical
case of
a
medial
menisc
al root
tear.
Notice
that
there is
also a
lateral
discoid
menisc
us.

33. This is
another
typical
case of
a
medial
menisc
al root
tear.
Notice
that
there is
also a
lateral
discoid
menisc
us.

34. This is
another
typical
case of
a
medial
menisc
al root
tear.
Notice
that
there is
also a
lateral
discoid
menisc
us.

35. Clinical History: 53 year old female with 2-3 weeks of
knee pain and instability. Fat suppressed proton density
coronal and sagittal images are provided. What are the
findings? What is your diagnosis?
https://radsource.us/posterior-root-tear-of-the-medial-
meniscus/

36. Figure 1:Fat
suppressed
proton density
coronal and
sagittal
images

37. Figure 2:(2a)
A proton
density-
weighted
coronal image
demonstrates
fluid signal
extending
through the
posterior
meniscal root
medially
(arrow).
Extensive
degenerative
signal is
present within
the posterior
horn of the
meniscus. (2b)
A proton
density-
weighted
sagittal image
demonstrates
focal absence
of the posterior
meniscal root
with fluid
signal between
the posterior
cruciate
ligament and
the posterior
tibial eminence
(arrow).

38. 3
Figure 3:(3a) A proton density-weighted
sagittal image obtained at the level of the
PCL demonstrates a normal posterior medial
meniscal root - (arrows). Compare this
image with figure B, where fluid signal is
seen between the PCL and the tibial
eminence.

39. Figure 4:(4a) A proton density-
weighted coronal image obtained
at the level of the PCL insertion.
Notice that the posterior root of the
medial meniscus extends
horizontally to attach adjacent to
the PCL insertion (arrow).
Compare this image with figure A
where a fluid-filled gap is seen
between the PCL insertion and the
posterior horn of the medial
meniscus.

40. The meniscus is considered
“extruded” when it extends beyond the
margin of the tibia (figure
5a).1 Meniscal extrusions of greater
than 3mm are associated with tears of
the posterior meniscal
root.1,5 Meniscal extrusion is caused
by disruption of the collagen fibers
Figure 5:(5a) Figure 5a is from
another patient with a medial meniscal
root tear. As in the initial case, fluid
signal is seen within the posterior
meniscal root (arrow). The medial
meniscal body is extruded several
millimeters beyond the margin of the
tibial plateau (arrowheads). Such
meniscal extrusion is associated with
the development of osteoarthritis.

41. increased loading of the subchondral bone may lead to
insufficiency fracture (figure 6a). Yao, et. al. found
subchondral insufficiency fractures to have a predilection
for the medial joint compartment and to be associated
with meniscal tears, particularly radial tears and root
tears. They also found that the affected patients were
older
6Figure 6:
(6a) A coronal proton density-weighted image in another
patient with a meniscal root tear (not shown) demonstrates
crescentic low signal in the subchondral regions of both the
medial femoral condyle and the medial tibial plateau(arrows)
with extensive associated marrow edema. The appearance is
compatible with subchondral insufficiency fractures.
Notice that the medial meniscus is extruded several
millimeters beyond the margin of the tibia (arrowheads).