Download The "Unseen" Posterior Intermeniscal Ligament of the Knee

The "Unseen" Posterior Intermeniscal Ligament of the Knee
Poster No.:
P-0054
Congress:
ESSR 2016
Type:
Scientific Poster
Authors:
Z. Akkaya, R. Akmese, A. Gursoy Coruh, N. K. Altinbas, G. Sahin;
Ankara/TR
Keywords:
Congenital, Diagnostic procedure, MR, Musculoskeletal joint,
Extremities
DOI:
10.1594/essr2016/P-0054
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Page 1 of 12
Purpose
is to present and discuss the magnetic resonance imaging (MRI) findings of a case with
bilateral posterior intermeniscal ligaments of the knee.
Methods and Materials
A 41 -year old female patient with bilateral knee pain was evaluated by routine knee MRI
examinations at 1.5- T unit with a dedicated knee coil with 8 channels. A non-traumatic
patellar subluxation of the left knee, two years ago was mentioned in her relevant medical
history.
Results
No significant finding could be detected on anteroposterior and lateral radiographs of
both knees ( Fig. 1 on page 3 ).
On MRI of the left knee, aside from an osteochondral lesion of the medial femoral
condyle (Fig. 2 on page 3 ), which was confirmed arthrosopically as a grade IV lesion
(Fig. 3 on page 4 ) the posterior horn of medial meniscus showed increased signal
intensity and a relatively small volume than expected at posterior horn- root attachment.
Additionally a linear hypointense structure was noticed traversing from the posterior horn
of the medial meniscus to the posterior horn of the lateral meniscus just in front of the
posterior cruciate ligament (PCL) on sagittal (Fig. 4 on page 5), coronal ( Fig. 5 on
page 6 ) and axial images (Fig. 6 on page 6 ).
On initial evaluation, this structure was mistakenly diagnosed for a bucket handle tear
of the posterior horn of the medial meniscus which was smaller and hyperintense than
expected however, in arthroscopy, no bucket handle tear could be detected in the
posterior horn of the medial meniscus ( Fig. 7 on page 7 ).
The medial femoral condylar osteochondral lesion was treated by arthroscopic
debridment and microfracture technique. The follow up MRI 7 months later revealed
similar findings in the posterior horns of the menisci although a bucket handle tear had
been ruled out ( Fig. 8 on page 8 ).
Page 2 of 12
On closer examination of the contralateral knee MRI which was perfomed at another
session due to nonspecific knee pain, a similar but relatively thinner hypointens linear
structure, joining the posterior horns of both menisci was noticed (Fig 4- 5 and Fig. 9
on page 9 ). No anterior meniscofemoral ligament (ligament of Humphrey) could be
detected anterior to PCL, in its expected position.
Images for this section:
Fig. 1: Anteroposterior and lateral radiographs of right and left knees are unremarkable.
Page 3 of 12
Fig. 2: Consecutive fat- suppressed proton density (a-c) and T2- weighted (d-f) sagittal
images of the left knee demonstrate a focal osteochondral lesion (red arrows) at the
medial femoral condyle and grade II degenerative signal change in the posterior horn
of the medial meniscus (blue arrow). Also note the focal increased signal intensity and
relatively small volume of the posterior horn of medial meniscus in images (b) and (e).
Page 4 of 12
Fig. 3: Arthroscopic image of the cartilage defect (red arrows) at the medial femoral
condyle is shown.
Page 5 of 12
Fig. 4: Consecutive sagittal T2- weighted images (a-e) of the left knee, from medial
to lateral demonstrate the hypointense round structure (arrows) traversing from the
posterior horn of the medial meniscus to the lateral meniscus. The same structure in
front of PCL is shown in fat- suppressed proton density images (f-j). Also in retrospective
review, anomalous insertion of medial meniscus to ACL was suspected (green arrows),
however, this finding could not be confirmed with retrospective review of the arthoscopy
images. No apparent anterior meniscofemoral ligament is observed anterior to PCL.
Fig. 5: Coronal fat suppressed T2-weighted (a) and corresponding T1- weighted (b)
images of left and respective images of the right knee (c-d). Note the linear hypointense
structure (arrows) joining the posterior horns of medial and lateral menisci in both knees,
at the intercondylar eminencia of tibia.
Page 6 of 12
Fig. 6: Axial fat-suppressed proton density and T1- weighted images of left (a-b) and
right knees (c-d) depict the posterior intermeniscal ligaments (red arrows).
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Fig. 7: Aside from the osteochondral lesion at the medial femoral condyle (red arrow), the
posterior horn of the medial meniscus appears normal (blue arrow), ruling out a displaced
bucket -handle tear, in this arthroscopic image of the left knee.
Fig. 8: Consecutive sagittal fat- suppressed proton density images of the left knee 7
months after arthroscopic debridement and microfracture for the osteochondral lesion of
the medial femoral condyle is shown. The articular cartilage of the femoral condyle is
Page 8 of 12
thin and irregular and there is slight subchondral bone marrow edema- like signal change
(brown arrows).The medial meniscus (green arrows) demonstrates degenerative signal
changes and the posterior intermeniscal ligament (red arrows) continues to the lateral
meniscus (blue arrow) anterior to PCL.
Fig. 9: Consecutive sagittal gradient echo images of right (a-f) and left knee (g-l). Note
the degenerative signal changes in the medial menisci (green arrows). The posterior
intermeniscal ligament (red arrows) is somewhat thinner on the right side (red arrows in hk) however, in both knees, this structure is in direct continuation with the lateral meniscus
(blue arrow).
Page 9 of 12
Conclusion
With the advances in imaging technologies, some of the anatomical structures, which are
detailly studied in cadaveric studies in previous decades are now becoming less obscure
for the radiologists. As a result, it is becomig more important for the radiologists to be
familiar with anatomical variations and malformations.
Posterior intermeniscal ligament, which is mentioned in the anatomy literature to have a
prevalance of 2% of all knees, is described as a thin fibrous band passing between the
posterior horns of medial and lateral menisci in front of PCL (1,2).
Although anterior intermeniscal (transverse meniscal ligament) has been extensively
described in both anatomy and radiology literature, to the best of our knowledge, the
imaging findings of its posterior counterpart has not been depicted very clearly (1-5).
As in this case it can be a diagnostic pitfall for radiologists and be a cause of pseudotear
of the posterior horn of medial meniscus. Practically, to exlude a tear, directly following
the continuity of the ligament between the posterior horns of the two menisci may help
the radiologist just as with anterior intermeniscal ligament. As this ligament takes over
the place and probably some of the function of anterior meniscofemoral ligament, the
absence of an anterior meniscofemoral ligament in front of PCL may also be another sign.
Various morphological abnormalities or variations of menisci and ligaments associated
with menisci have been reported, including the complete, incomplete discoid menisci, the
Wrisberg type meniscus, a ring shaped meniscus, anomalous meniscal bands, double
layered meniscus or anomalous insertion of medial meniscus to anterior cruciate ligament
(ACL), oblique meniscomeniscal ligaments. They are reported to be more frequent in the
Asain populations and in the lateral menisci and in most cases have been associated
with diagnostic pitfalls for radiologists, simulating displaced meniscal tears. (2,6-13).
The increased intensity and relatively small posterior horns of the medial menisci of both
knees, just near their posterior root attachments were note-worthy and at the time of
initial assessment confusing findings which in our case lead to the false diagnosis of a
displaced bucket handle tear. However, in addition to the uniform, even continuity of the
fibrous structure, namely the posterior intermeniscal ligament, the bilateral, symmetric
appearance of relatively small posterior horns of medial menisci, which may show
degenerative signal changes may alert the radiologist of a pseudotear.
Page 10 of 12
References
1) Zivanovi# S. Menisco-meniscal ligaments of the human knee. Anat Anz.
1974;135:35-42.
2) Simão MN, Nogueira-Barbosa MH. Magnetic resonance imaging in the assessment
of meniscal anatomic variants and of the perimeniscal ligamentous anatomy: potential
interpretation pitfalls. Radiol Bras. 2011;44:117-122.
3) Aydingoz U, Kaya A, Atay OA, Ozturk MH, Doral MN. MR imaging of the
anterior intermeniscal ligament: classification according to insertion sites. Eur Radiol
2002;12:824-9.
4) Muhle MN, Thompson WO, Sciulli R, Pedowitz R, Ahn JM et al. Transverse ligament
and its effect on meniscal motion. Correlation of kinematic MR imaging and anatomic
sections. Invest Radiol. 1999;34:558-65.
5) de Abreu MR, Chung CB, Trudell D, Resnick D. Anterior transverse ligament of
the knee: MR imaging and anatomic study using clinical and cadaveric material with
emphasis on its contribution to meniscal tears. Clin Imaging 2007;31:194-201.
6) Watanabe M, Takeda S, Ikeuchi H. Atlas of arthroscopy. Tokyo:Igaku-Shoin:1978.
7) Tyler P, Datir A, Saifuddin A. Magnetic resonance imaging of anatomical variations in
the knee: Part 2:miscellanous. Skeletal Radiol. 2010;39:1175-86.
8)Tyler P, Datir A, Saifuddin A. Magnetic resonance imaging of anatomical variations in
the knee: Part 1:ligamentous and musculotendinous.Skeletal Radiol. 2010;39:1161-73.
9) Cha JG, Min KD, Han JK, Hong HS, Park SJ et al. Anomalous insertion of the
medial meniscus into the anterior cruciate ligament: the MR appearance. Br J Radiol.
2008;81:20-4.
10) Kim YG, Ihn JC, Park SK, Kyung HS. An arthroscopic analysis of lateral meniscal
variants and a comparison with MRI findings. Knee Surg Sports Traumatol Arthrosc.
2006;14:20-6.
11)Atay OA, Aydingoz U, Doral MN, Tetik O, Leblebicioglu G. Symptomatic ring- shaped
lateral meniscus: magnetic resonance imaging and arthroscopy. Knee Surg Sports
Traumatol Arthrosc. 2002;10:280-3.
12) Fujikawa A, Amma H, Ukegawa Y, Tamura T, Naoi Y. MR imaging of meniscal
malformations of the knee mimicking displaced bucket-handle tear. Skeletal Radiol.
2002;31:292-5.
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13) Chan CM, Goldblatt JP. Unilateral meniscomeniscal ligament. Orthopedics.
2012;35:1815-17.
Personal Information
Zehra Akkaya, MD
Department of Radiology, Ankara University Faculty of Medicine
Ankara- Turkey
Ramazan Akmese, MD
Department of Orthopedics and Traumatology, Ankara University Faculty of Medicine
Ankara- Turkey
Aysegul Gursoy Coruh, MD
Department of Radiology, Ankara University Faculty of Medicine
Ankara- Turkey
Namik Kemal Altinbas, MD
Department of Radiology, Ankara University Faculty of Medicine
Ankara- Turkey
Gulden Sahin, MD, Professor of Radiology
Department of Radiology, Ankara University Faculty of Medicine
Ankara- Turkey
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