Arthroscopic partial menisectomy followed by cyst decompression is currently recommended for treatment of a meniscal cyst. However, it is doubtful whether partial menisectomy should be performed on cysts communicating with the joint in cases without a meniscal tear on its surface since meniscal function will be sacrificed. In this report, a meniscal cyst arising from the posterior horn of the medial meniscus without meniscal tear on its surface was resected using an arthroscopic posterior trans-septal approach. A 59 year-old male presented to our hospital with popliteal pain when standing up after squatting down. Magnetic resonance imaging revealed a multilobulated meniscal cyst arising from the posterior horn of the medial meniscus extending to the posterior septum with a grade 2 meniscal tear by Mink's classification. The medial meniscus was intact on the surface on arthroscopic examination. The meniscal cyst and posterior septum were successfully resected using a posterior trans-septal approach without harming the meniscus. This is the first report on a meniscal cyst being resected using an arthroscopic posterior trans-septal approach with a 9-month follow-up period

A Lakdawala

AD Tasker

C Hulet

JH Ahn

JH Lonner

JH Yoo

JM Kim

JV Crues III

KH Lu

M Spina

RA Pedowitz

S Louisia

SE Campbell

TS Howe

English

PubMed

Tsuyoshi Ohishi

Eiji Torikai

Daisuke Suzuki

Tomohiro Banno

Yosuke Honda

Springer - Publisher Connector

CASE REPORT Open Access
Arthroscopic treatment of a medial meniscal cyst
using a posterior trans-septal approach: a case
report
Tsuyoshi Ohishi*, Eiji Torikai, Daisuke Suzuki, Tomohiro Banno, Yosuke Honda
Abstract
Arthroscopic partial menisectomy followed by cyst decompression is currently recommended for treatment of a
meniscal cyst. However, it is doubtful whether partial menisectomy should be performed on cysts communicating
with the joint in cases without a meniscal tear on its surface since meniscal function will be sacrificed. In this
report, a meniscal cyst arising from the posterior horn of the medial meniscus without meniscal tear on its surface
was resected using an arthroscopic posterior trans-septal approach. A 59 year-old male presented to our hospital
with popliteal pain when standing up after squatting down. Magnetic resonance imaging revealed a multilobu-
lated meniscal cyst arising from the posterior horn of the medial meniscus extending to the posterior septum with
a grade 2 meniscal tear by Mink’s classification. The medial meniscus was intact on the surface on arthroscopic
examination. The meniscal cyst and posterior septum were successfully resected using a posterior trans-septal
approach without harming the meniscus. This is the first report on a meniscal cyst being resected using an arthro-
scopic posterior trans-septal approach with a 9-month follow-up period.
Background
Recently, selective menisectomy followed by decompres-
sion of the cyst is commonly performed in arthroscopic
treatment of a meniscal cyst [1-3]. However, the surface
of the meniscus is intact in the case of a grade 2 menis-
cal tear judged by magnetic resonance imaging (MRI)
[4]. An operator might hesitate to perform partial resec-
tion of an intact meniscus in communication with a cyst
since meniscal function could be sacrificed. In this
paper, a meniscal cyst arising from the posterior horn of
the medial meniscus was resected under arthroscopy,
without menisectomy, using a posterior trans-septal
approach. This is the first report on resection of a
meniscal cyst using an arthroscopic posterior trans-
septal approach.
Case report
A 59-year-old jobless man presented at our hospital
with a 2-month history of transient right popliteal pain
when standing after squatting and while descending
stairs. He was 170 cm tall and 55 kg in body weight and
had not suffered from any antecedent trauma. Clinical
examination of the right knee revealed a full range of
motion without catching and locking episode. No swel-
ling, warmness, erythema, tenderness (including the
medial joint line) or hydrops was found around the
knee. There was no anterior, posterior or lateral instabil-
ity. He did not have pain during manual instability tests.
McMurray’s test reproduced pain but no click at the
medial joint line. No mass was palpable around the
knee. Standard radiographs showed no sign of osteoar-
thritis. An MRI revealed a grade 2 horizontal tear
according to Mink’s classification of the posterior seg-
ment of the medial meniscus [4] (Fig 1-A). A multilobu-
lated meniscal cyst arising from the posterior horn of
the medial meniscus to the posterior septum just behind
the posterior cruciate ligament (PCL) was also detected
(Fig 1-B, C). Communication tracts between horizontal
tear of the meniscus and the cyst were identified on the
MRI coronal plane (Fig 1-D).
Arthroscopic surgery was performed under spinal
anesthesia without a pneumotourniquet. The knee was
flexed at more than 90 degrees on the operating table
using a foot stopper. Anterior cruciate ligament, PCL
* Correspondence: t-ohishi@ken.ja-shizuoka.or.jp
Department of Orthopaedic Surgery, Enshu Hospital, Hamamatsu, Shizuoka,
Japan
Ohishi et al. Sports Medicine, Arthroscopy, Rehabilitation, Therapy & Technology 2010, 2:25
http://www.smarttjournal.com/content/2/1/25
© 2010 Ohishi et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons
Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in
any medium, provided the original work is properly cited.
and both lateral and medial meniscus were intact under
arthroscopic examination. The posteromedial compart-
ment was examined from the anterolateral portal
through an intercondylar space. The surface of the pos-
terior horn of the medial meniscus was intact and no
cyst-like lesion was found on the edge of the posterior
segment of the medial meniscus. Starting the procedure
for making a trans-septal portal, the posteromedial and
posterolateral portals were created according to the
approach reported by Ahn et al [5]. After making a pos-
terolateral portal, a rod with a sheath was inserted
through the posterolateral portal to the septum. Pushing
the sheath into the septum, the arthroscope was then
inserted into the posteromedial portal. While maintain-
ing the view of the medial side of a septum, a 1.5-3.0
mm Kirschner wire was pushed into the septum through
the sheath from the posterolateral portal and then the
septum was perforated. The Kirschner wire was pushed
2 or 3 times into the septum to enlarge the initial hole
so that the switching rod could easily pass through the
septum. Then, the switching rod was inserted from
the posterolateral portal to the posteromedial portal via
the trans-septal portal. Once the trans-septal portal was
created, the arthroscope and instruments are easily
interchangeable through the two posterior portals
according to the posterior “back and forth” approach
presented by Louisia et al [6]. Viewing from the
posteromedial portal, proliferated synovial tissues
expanding from the posterior horn of the medial menis-
cus to the posterior septum were found (Fig 2-A). The
cyst and posterior septum were resected by a punch and
a motorized shaver inserted from the posterolateral por-
tal while viewing from the posteromedial portal. When
the cyst ruptured, a clear mutinous fluid seeped from
the cyst cavity. A meniscal tear was not found although
the posterior edge of the medial meniscus was carefully
examined by a probe after cyst resection (Fig 2-B).
An MRI examination 9 months after the operation
revealed that the meniscal cyst had disappeared and
abnormal intensity inside the medial meniscus decreased
(Fig 3-A,B). The patient’s popliteal pain also disappeared
completely during the 9-month follow-up period.
Discussion
To our knowledge, this is the first report of a meniscal
cyst being resected without harming the meniscus using
a posterior trans-septal portal under arthroscopy.
Resection of a meniscal cyst involving the septum is
difficult by the intercondylar approach from two ante-
rior portals even with a posteromedial portal in addition
for managing the procedure. Although the use of a
70-degree arthroscope can help the visualization of the
posterior compartment, the whole area of the septum
cannot be visualized since the camera head of an
Figure 1 Sagittal images (A,B,C) and coronal image (D) of T2 weighted MRI. A horizontal meniscal tear is identified inside the meniscus in
Figure 1-A (a white arrow). A multilobulated cyst is located just behind the medial meniscus and the PCL (B, C). The cyst is in communication
with the meniscal tear on Figure 1-D (white arrows). Note that the horizontal meniscal tear has not extended to the tibial or femoral surface.
Ohishi et al. Sports Medicine, Arthroscopy, Rehabilitation, Therapy & Technology 2010, 2:25
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Page 2 of 5
arthroscope is too near the septum from an anterior
intercondylar approach. Although the septum can be
viewed clearly from the posteromedial portal, it is cum-
bersome to manage the instruments to excise the cyst
from anterior portals or from an additional high poster-
omedial portal. In our case, a posterior trans-septal
approach was employed for the resection of the menis-
cal cyst as this approach allows an operator to identify
the posterior edge of the medial meniscus, the septum
and PCL and to treat the lesions involving those struc-
tures easily. A trans-septal approach was initially
reported by Kim et al. in 1996 [7]. This technique is
quite useful for accessing the posterior compartment of
the knee, however the operator should bear in mind the
risk of popliteal neurovascular injury when making a
trans-septal portal. We have modified previously
reported techniques to make a safe trans-septal portal.
To avoid neurovascular complications, we always perfo-
rate the septum with a sheathed Kirschner wire in the
lateral to medial direction while monitoring the tip of
the Kirschner wire from the posteromedial portal since
the popliteal neurovascular bundle is placed just poster-
ior and lateral to the septum. We have used this
approach for access to the posterior lesion in 95 knee
cases and there have been no neurovascular complica-
tions from this procedure.
To date, articles on arthroscopic posterior trans-septal
approaches for PCL reconstruction, suture of posterior
horn of the medial meniscus or posterior capsules and
excision of a ganglion cyst derived from the septum
have been reported [8-12]. We have also used this pos-
terior trans-septal approach to perform synovectomy of
the posterior capsule, resection of the posterior horn of
the medial meniscus, resection of PCL ganglion, and
resection of free bodies in the posterior cavity. Although
this technique allows us to manage lesions in the poster-
ior cavity easily, it can be applied only when the lesion
in the posterior cavity is difficult to access from the
Figure 2 Arthroscopic view from the posteromenial portal. A probe is inserted via the trans-septal portal from the posterolateral portal (A).
Proliferative synovial tissue (arrow heads) arising from the posterior horn of the medial meniscus (MM) expands to the septum. Resection of
synovial tissue, cyst and posterior septum was completed (B). Posterior cruciate ligament (PCL) and lateral femoral condyle (LC) can be seen. MC:
medial femoral condyle.
Figure 3 Sagittal image of T2 weighted MRI examined 9 months after the operation. The meniscal cyst has completely disappeared (A).
Note that grade 2 signal intensity inside the meniscus decreased compared with abnormal signal intensity shown in Fig 1-A (B).
Ohishi et al. Sports Medicine, Arthroscopy, Rehabilitation, Therapy & Technology 2010, 2:25
http://www.smarttjournal.com/content/2/1/25
Page 3 of 5
anterior intercondylar approach even with an additional
posteromedial portal. An operator should always bear in
mind that a neurovascular bundle is just behind the
septum.
For the treatment of a meniscal cyst, previous reports
recommended either a partial menisectomy with cyst
decompression under arthroscopy or open cystectomy
with a repair of the meniscus capsular attachment [3].
Almost all meniscal cysts are accompanied by some
meniscal tear, including grade 2 lesions judged by MRI,
although it is not obvious on the surface of the menis-
cus. In such cases as ours, an open cystectomy is recom-
mended according to the therapeutic options for
meniscal cysts [3]. However, substantial damages in the
surrounding soft tissue, especially damage to the poster-
ior capsule, at the popliteal fossa could be unavoidable
by an open procedure since the lesion is deep under the
skin and is not palpable on the skin. Recently, all arthro-
scopic procedures for selective menisectomy with cyst
decompression or cyst drainage with suture of the torn
meniscus were reported to preserve or restore a menis-
cal function [1,13,14]. Howe et al. demonstrated the
excellent results for a long follow-up period by creating
a small channel at the capsule adjacent to the cyst for
decompression of the cyst into the joint without harm-
ing of the healthy meniscus [15]. The principle of our
method in this case is almost same as Howe’s one in
terms of equalizing pressure between the meniscus and
joint cavity by excising the cyst so as not to allow joint
fluid re-enter to the torn meniscus through the commu-
nication tract.
Since MRI has become routinely available, more medial
meniscal cysts, including asymptomatic ones, can be
detected by MRI [16]. According to Campbell et al, 72
out of 109 meniscal cysts (66%) were located in the med-
ial compartment and 53 of these medial meniscal cysts
(74%) arose from the posterior horn of the medial menis-
cus [17]. Such evidence would indicate that meniscal
cysts like our case are not rare and will increasingly be
found. Popliteal pain in our patient might not be caused
by a grade 2 meniscal tear but by impingement of the
meniscal cyst between the posterior femoral condyle and
posterior edge of the tibia since the patient felt pain after
squatting down. A symptomatic meniscal cyst with an
asymptomatic grade 2 meniscal tear should be treated by
arthroscopic procedure without harming the meniscus.
Recurrence of meniscal cysts has been reported
although long-term results of selective partial menisect-
omy with cyst decompression were satisfactory in pre-
vious papers [1,18]. Hulet et al. reported 11 out of 105
lateral meniscal cysts recurred after arthroscopic partial
menisectomy followed by cyst decompression with
an average 5-year follow-up [18]. They concluded that
the reason for recurrence was mainly attributed to
inadequate menisectomy performed so as not to damage
the healthy part of the meniscus. Very few papers
reported on the long-term results of meniscal cysts that
were excised without managing the torn meniscus
under arthroscopy [15]. Our case needs to be followed
for a long period since menisectomy was not performed
at all so as to completely preserve meniscal function.
Conclusions
A posterior trans-septal approach is useful for resection
of a meniscal cyst arising from the posterior horn of the
medial meniscus, especially in the case where the lesion
involves the posterior septum.
Consent
Written informed consent was obtained from the patient
for publication of this case report and any accompany-
ing image. A copy of the written consent is available for
review by the Editor-in-Chief of this journal.
Authors’ contributions
TO and ET carried out the surgical treatment and DS, TB and YH discussed
the results and commented on the manuscript. All authors have read and
approved the final manuscript.
Competing interests
The authors declare that they have no competing interests.
Received: 12 May 2010 Accepted: 12 October 2010
Published: 12 October 2010
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Cite this article as: Ohishi et al.: Arthroscopic treatment of a medial
meniscal cyst using a posterior trans-septal approach: a case report.
Sports Medicine, Arthroscopy, Rehabilitation, Therapy & Technology 2010 2:25.
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Arthroscopic treatment of a medial meniscal cyst using a posterior trans-septal approach: a case report

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Abstract Arthroscopic partial menisectomy followed by cyst decompression is currently recommended for treatment of a meniscal cyst. However, it is doubtful whether partial menisectomy should be performed on cysts communicating with the joint in cases without a meniscal tear on its surface since meniscal function will be sacrificed. In this report, a meniscal cyst arising from the posterior horn of the medial meniscus without meniscal tear on its surface was resected using an arthroscopic posterior trans-septal approach. A 59 year-old male presented to our hospital with popliteal pain when standing up after squatting down. Magnetic resonance imaging revealed a multilobulated meniscal cyst arising from the posterior horn of the medial meniscus extending to the posterior septum with a grade 2 meniscal tear by Mink's classification. The medial meniscus was intact on the surface on arthroscopic examination. The meniscal cyst and posterior septum were successfully resected using a posterior trans-septal approach without harming the meniscus. This is the first report on a meniscal cyst being resected using an arthroscopic posterior trans-septal approach with a 9-month follow-up period.</p

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Arthroscopic treatment of a medial meniscal cyst using a posterior trans-septal approach: a case report

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