Medial meniscus anatomy—from basic science to treatment

Abstract

This paper focuses on the anatomical attachment of the medial meniscus. Detailed anatomical dissections have been performed and illustrated. Five zones can be distinguished in regard to the meniscus attachments anatomy: zone 1 (of the anterior root), zone 2 (anteromedial zone), zone 3 (the medial zone), zone 4 (the posterior zone) and the zone 5 (of the posterior root). The understanding of the meniscal anatomy is especially crucial for meniscus repair but also for correct fixation of the anterior and posterior horn of the medial meniscus.

Full text

1 23
Knee Surgery, Sports Traumatology,
Arthroscopy
ISSN 0942-2056
Knee Surg Sports Traumatol Arthrosc
DOI 10.1007/s00167-014-3476-5
Medial meniscus anatomy—from basic
science to treatment
Robert Śmigielski, Roland Becker,
Urszula Zdanowicz & Bogdan Ciszek

1 23
Your article is protected by copyright and
all rights are held exclusively by European
Society of Sports Traumatology, Knee
Surgery, Arthroscopy (ESSKA). This e-offprint
is for personal use only and shall not be self-
archived in electronic repositories. If you wish
to self-archive your article, please use the
accepted manuscript version for posting on
your own website. You may further deposit
the accepted manuscript version in any
repository, provided it is only made publicly
available 12 months after official publication
or later and provided acknowledgement is
given to the original source of publication
and a link is inserted to the published article
on Springer's website. The link must be
accompanied by the following text: "The final
publication is available at link.springer.com”.

1 3
Knee Surg Sports Traumatol Arthrosc
DOI 10.1007/s00167-014-3476-5
KNEE
Medial meniscus anatomy—from basic science to treatment
Robert S
´migielski · Roland Becker ·
Urszula Zdanowicz · Bogdan Ciszek
Received: 5 December 2014 / Accepted: 6 December 2014
© European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA) 2014
understand its importance and also improve the anatomi-
cal approach to its repair. There are many anatomical
studies about menisci. The current paper focuses on the
anatomy of the medial meniscus. This anatomical study
was performed with the specific intention of identifying
the meniscus insertions, which is of relevance to meniscus
surgery.
Gross anatomy
The medial meniscus forms almost a semicircular shape
and covers up to 50–60 % of the articular surface of
medial tibial plateau [4] (Fig. 1a, b). The width of the
medial meniscus is about 11 mm significantly bigger
at the posterior region and becomes gradually smaller
towards the anterior horn. During knee flexion, the main
loading occurs at the posterior region of the meniscus [2].
The posterior horn of the meniscus slides slightly over the
posterior rim of the tibial plateau during deep knee flex-
ion. This is the moment where significant stress occurs on
the posterior horn and should be avoided early on after
meniscus repair.
Five anatomical zones of the medial meniscus are distin-
guishable in regard to the meniscus anatomy: the anterior
root (zone 1); the anteromedial zone (zone 2a and 2b); the
medial zone (zone 3); the posterior zone (zone 4); and the
posterior root (zone 5) (Fig. 2). This zonal division is based
on different anatomical characteristics and is in contrast to
the previous descriptions.
Weiss et al. [17] divided the medial meniscus into five
equal parts, each one representing exactly one-fifth of the
length [17]. This was modified by Yagishita et al. [19] by
combining the anterior and anterior junctional zone into
one, resulting in four zones.
Abstract This paper focuses on the anatomical attach-
ment of the medial meniscus. Detailed anatomical dissec-
tions have been performed and illustrated. Five zones can
be distinguished in regard to the meniscus attachments
anatomy: zone 1 (of the anterior root), zone 2 (anterome-
dial zone), zone 3 (the medial zone), zone 4 (the posterior
zone) and the zone 5 (of the posterior root). The under-
standing of the meniscal anatomy is especially crucial for
meniscus repair but also for correct fixation of the anterior
and posterior horn of the medial meniscus.
Keywords Anatomy · Medial meniscus · Attachment
Introduction
The menisci have received increased attention during the
last two decades. Numerous clinical studies have proven
the importance of the menisci for joint protection and
prevention of early osteoarthritis [5, 15]. A better under-
standing of meniscus anatomy may help surgeons to
R. S
´migielski (*) · U. Zdanowicz
Orthopaedic and Sports Traumatology Department,
Carolina Medical Center, Pory 78, 02-757 Warsaw, Poland
e-mail: robert.smigielski@carolina.pl; rsmigielski@gmail.com
URL: http://www.carolina.pl
R. Becker
Department of Orthopaedic and Traumatology,
City Hospital Brandenburg, Brandenburg, Germany
B. Ciszek
Department of Descriptive and Clinical Anatomy,
Medical University of Warsaw, Warsaw, Poland
Author's personal copy

Knee Surg Sports Traumatol Arthrosc
1 3
Zone 1—anterior root
As Homo sapiens changed from occasional to habit-
ual bipedalism, the anatomy of the human menisci also
changed. In contrast to tetrapods, there are two tibial inser-
tions indicating the full extension phase during gate [16].
The anterior root of the medial meniscus is located proxi-
mal to the superior aspect of the medial edge of the medial
tibial tuberosity and proximal and medial to the centre of
the superior edge of the tibial tuberosity [9].
According to Berlet et al. [1], there are four insertion
patterns of the anterior root of the medial meniscus. Type
I, the most frequent (Fig. 3), has the insertion located in the
flat intercondylar region of the tibial plateau (also called by
Jacobsen the cristae area intercondylaris anterior). Type II
has a more medial insertion, closer to articular tibial sur-
face. Type III has a more anterior insertion, which is on the
downslope of tibia. Type IV shows no solid fixation, and
only coronal fibres control meniscus stability.
The insertion site of the anterior root includes supple-
mentary, lower density fibres. The mean total tibial attach-
ment area is about 110.4 mm2, but only 50 % belong to the
Fig. 1 a Anatomical dissection of proximal tibial articular surface
(plan view, femur removed). 1 medial meniscus; 2 lateral meniscus; 3
tibial attachment of anterior cruciate ligament; and 4 tibial attachment
of posterior cruciate ligament. b The medial meniscus covers up to
50–60 % of the articular surface of medial tibial condyle. ACL ante-
rior cruciate ligament, PCL posterior cruciate ligament, MTC medial
tibial condyle, LTC lateral tibial condyle, aMM anterior root of
medial meniscus, pMM posterior root of medial meniscus, aML ante-
rior root of lateral meniscus, pML posterior root of lateral meniscus
Fig. 2 Anatomical dissection showing five anatomical zones within
medial meniscus. ACL anterior cruciate ligament, tl transverse liga-
ment (anterior intermeniscal ligament), PT patellar tendon, PCL pos-
terior cruciate ligament, ML lateral meniscus, PoT Popliteus tendon,
hl Humphry ligament (anterior menisco-femoral ligament)
Fig. 3 Zone 1 of medial meniscus. Anatomical dissection showing
type 1 of anterior tibial attachment of medial meniscus (marked with
black arrows). ACL anterior cruciate ligament, aMM anterior root of
medial meniscus, aML anterior root of lateral meniscus
Author's personal copy

Knee Surg Sports Traumatol Arthrosc
1 3
central, prominent root fibres (mean 56.3 mm2), which are
the most dense [9].
Radiographic landmarks were identified in order to
describe the attachment of the anterior horn [7]. The follow-
ing measurements are used on antero-posterior radiographs:
• 2.8 mm distal to proximal joint line
• 3.1 mm medial to medial tibial eminence line
• 17 mm medial to lateral tibial eminence line
On the lateral radiographic view, the following measure-
ments were identified:
• 12.2 mm anterior to tibial long axis
• 19.3 mm proximal to champagne glass drop (CGD) line
• 4.8 mm posterior to anterior tibial plateau line [8]
Rainio et al. [12] describe atypical insertion sites of
anterior root to anterior cruciate ligament in 1 % of cases.
The absence or the hypermobility of the anterior root of the
medial meniscus is one of the major anomalies. However in
all cases, the oblique ligament was present connecting the
anterior horn of medial meniscus to the proximal area of
anterior cruciate ligament.
Zone 2—anteromedial zone
The anteromedial zone includes the anterior horn of medial
meniscus and finishes with the anterior border of the
medial collateral ligament. The zone can be further divided
into two sub-zones: anterior 2a (from anterior root to the
transverse ligament) and 2b (from transverse ligament to
anterior border of the medial collateral ligament (Fig. 2).
The meniscus of zone 2a, 2b, 3, 4 attaches to the tibia
by inferior periphery only, with menisco-tibial ligament
(also called coronary ligament) [9, 10]. Although described
in previous studies [13, the outer border of the medial
meniscus in zone 2 is not attached to the joint capsule. The
superior periphery of medial meniscus at zone 2a shows no
attachment to the surrounding tissues (Fig. 4). In zone 2b,
however, the most superior periphery of the meniscus is
attached to the synovial tissue (Fig. 5).
Zone 3—region of the medial collateral ligament
This is the only zone where the entire periphery of the
meniscus is attached to the joint capsule. The lower part
is attached via the coronary ligament (menisco-tibial liga-
ment) and the upper part with the menisco-femoral liga-
ment (Fig. 6). Cross sections of medial meniscus in zone
3 showed the attachment to the joint capsule (Fig. 7a, b).
In contrast to previous studies, which have reported a firm
attachment to the deep layer of the medial collateral liga-
ment [18], we could not confirmed that in current study.
Anatomical dissection as well as histology of specimens
Fig. 4 Anatomical dissection of anterior aspect of the left knee joint.
Within zone 2a superior edge of medial meniscus remains free and
has no connections to surrounding tissues (marked with arrows). MM
medial meniscus, ML lateral meniscus, MFC medial femoral condyle,
LFC lateral femoral condyle, ACL anterior cruciate ligament, PCL
posterior cruciate ligament, HP Hoffa pad
Fig. 5 Anatomical dissection of antero-medial aspect of the knee
joint. Within zone 2b outer and superior border of medial meniscus
is connected to synovial tissue (marked with arrows). MM medial
meniscus, MFC medial femoral condyle, ACL anterior cruciate liga-
ment
Author's personal copy

Knee Surg Sports Traumatol Arthrosc
1 3
showed only one layer of medial collateral ligament. The
meniscus was attached to the joint capsule, separated from
medial collateral ligament with loose connective tissue.
However, the so-called deep layer of the medial collateral
ligament might be a kind of reinforcement of the joint cap-
sule, analogous to what is described in the shoulder.
Zone 4—posterior horn
The superior part of the meniscus periphery in zone 4
does not attach to the capsule (Fig. 8a, d). The inferior
part, in contrast, attaches to the tibia via loose connec-
tive tissue, forming the menisco-tibial (coronary) liga-
ment. The menisco-tibial ligament attaches to the tibia
about 7–10 mm below the level of articular cartilage and
forms a posterior femoral recess in this zone [6] (Figs. 9,
10). There is a wide area of the superior periphery of
the posterior horn, which shows no attachment to the
capsule.
Zone 5—posterior root
The insertion site of the posterior root is located (Figs. 11,
12) 9.6 mm posterior and 0.7 mm lateral from medial apex
of the tibial eminence, 3.5 mm lateral to the articular carti-
lage inflection point of the medial tibial plateau and 8.2 mm
anterior to the most superior tibial attachment of posterior
cruciate ligament [8].
Fig. 6 Anatomical dissection at the level of zone 3 of medial menis-
cus (at the level of medial collateral ligament, MCL). At this point,
meniscus attaches fully to joint capsule (marked with white arrows).
MM medial meniscus, MTC medial tibial condyle
Fig. 7 Histology (light microscopy, H&E stain, original magnifica-
tion ×4) of cross section of medial meniscus, at the level of medial
collateral ligament (zone 3): macroscopic view (a) and microscopic
view (b). MCL medial collateral ligament, MM medial meniscus, JC
joint capsule, 1 loos connective tissue separating medial collateral
ligament from joint capsule, 2 blood vessels
Author's personal copy

Knee Surg Sports Traumatol Arthrosc
1 3
The radiographic landmarks of the tibial attachment in
the antero-posterior and lateral view are the following [7].
Anteroposterior view
• 4.8 mm proximal to the proximal joint line
• 2.3 mm lateral to medial tibial eminence line
• 12.7 mm medial to lateral tibial eminence line
Lateral view
• 24.1 mm posterior to tibial long axis
• 21.8 mm proximal to CGD line
• 18 mm anterior to posterior tibial plateau line [7]
Connections between medial and lateral meniscus
There are four different menisco-meniscal ligaments con-
necting the medial with the lateral meniscus [20]: the
medial oblique intermeniscal ligaments; the lateral oblique
intermeniscal ligaments; the anterior ligament (also called
Fig. 8 Anatomical dissection of zone 4 of medial meniscus (a).
Menisco-tibial (coronary) ligament is marked with white arrows
(b, c). Medial collateral ligament is marked with black arrows (b),
notice: the level of attachment of menisco-tibial (coronary) ligament
on the tibia. MM medial meniscus, MTC medial tibial condyle. His-
tology (d) (light microscopy, H&E stain, original magnification ×4)
of cross section of medial meniscus within zone 4. Menisco-tibial
(coronary) ligament is marked with white arrows. Notice: curved
shape (marked with yellow arrows) of superior edge of medial menis-
cus within this zone, with no attachments to surrounding tissues
Fig. 9 Anatomical dissection of posterior aspect of the left knee
joint. Posterior femoral recess is marked with black arrows. Notice:
free superior edge of posterior horn of medial meniscus. LFC lateral
femoral condyle, ML lateral meniscus, PT popliteal tendon, PCL pos-
terior cruciate ligament, MM medial meniscus, JC joint capsule, MFC
medial femoral condyle, 1 proximal attachment of lateral head of
gastrocnemius muscle, 2 distal attachment of ilio-tibial band, 3 distal
attachment of biceps tendon, 4 lateral collateral ligament, 5 proximal
attachment of medial head of gastrocnemius muscle, 6 distal attach-
ment of semimembranous tendon
Fig. 10 Anatomical dissection of left knee joint. Postero-medial fem-
oral recess is marked with yellow arrows. MCL medial collateral liga-
ment, MM medial meniscus, JC joint capsule, PCL posterior cruciate
ligament, ACL anterior cruciate ligament, magnification of postero-
medial femoral recess
Author's personal copy

Knee Surg Sports Traumatol Arthrosc
1 3
transverse ligament); and the posterior intermeniscal
ligament.
The transverse ligament (anterior intermeniscal or ante-
rior menisco-meniscal ligament) is present in 60–94 % of
all knees [1, 11]. In contrast, the posterior intermeniscal
ligament can be found in 1–4 % of cases only [3].
The medial oblique intermeniscal ligament, which is pre-
sent in 1 % of knees, takes its name from its anterior menis-
cal point of origin, begins from the central part of the anterior
root of medial meniscus and passes obliquely backwards to
the upper part of the posterior horn of the lateral meniscus.
Consequently, lateral intermeniscal ligaments, which are pre-
sent in 4 % of knees, extend from the anterior root of lateral
meniscus, passing between the cruciates and inserting into the
upper part of the posterior root of the medial meniscus.
Chan et al. [3] also described two cases of unilateral
menisco-meniscal ligament: lateral and medial. In those
cases, there was additional connection between anterior
and posterior horn of each meniscus. Both ligaments were
identified on MRI, and a unilateral medial menisco-menis-
cal ligament was also confirmed by arthroscopy.
Clinical relevance
Although meniscal surgery is one of the most frequent
procedures in orthopaedics, a more detailed understanding
of the menisci’s anatomy is likely required to improve the
success of repairs or replacements.
Dividing the medial meniscus into five anatomical
zones, as described here, has important implications for
meniscal treatment. In each zone, a different suturing tech-
nique is required for anatomical reconstruction.
Knowing the exact anatomy of zones 1 and 5—ante-
rior and posterior root—is important especially for menis-
cal transplantation. In order to anatomically suture ante-
rior and/or posterior root of medial meniscus, we need to
restore rigid bone fixation through transosseous suturing.
Differences of as little as 2–3 mm have a significant impact
on the meniscus function [14]. The insertion of the menis-
cus transplant more medially will cause significant extru-
sion and an increase in femorotibial loading. On the other
hand, the meniscus transplant becomes very vulnerable if
the insertion is too close to the tibial eminentia because of
overloading.
Considering the attachment of the medial meniscus in
zone 2a, the inferior vertical suture technique is recom-
mended in order to restore the menisco-tibial ligament. This
is slightly different in zone 2b, because of the attachment
Fig. 11 Anatomical dissection of proximal tibial articular surface
(plan view, femur removed). Tibial attachment of posterior root of
medial meniscus is marked with white arrows. PCL posterior cruciate
ligament, aMFL anterior menisco-femoral ligament (Humphry liga-
ment), pML posterior root of lateral meniscus, ACL anterior cruciate
ligament, aML anterior root of lateral meniscus, aMM anterior root of
medial meniscus, pMM posterior root of medial meniscus, TL trans-
verse ligament (anterior menisco-meniscal ligament), MCL medial
collateral ligament
Fig. 12 Magnification of anatomical dissection of posterior aspect
of the knee joint. Posterior root of medial meniscus is marked with
white arrows. 1 posterior cruciate ligament, 2 anterior menisco-fem-
oral ligament, 3 posterior root of lateral meniscus, 4 tibial attachment
of anterior cruciate ligament, 5 anterior root of lateral meniscus
Author's personal copy

Knee Surg Sports Traumatol Arthrosc
1 3
of the inferior and superior part of the meniscus periphery.
Zone 3 requires two vertical sutures from the anatomi-
cal point of view in order to restore both the menisco-tib-
ial (coronal) and menisco-femoral ligaments. However,
it might be a challenge to suture the meniscus to the joint
capsule (which some authors [17] also call the deep layer
of medial collateral ligament) alone, instead to the medial
collateral ligament (superficial layer). The solution would
be to use absorbable sutures that allow, in time, independ-
ent movement between medial collateral ligament and joint
capsule. Zone 4 seems to be the most controversial. Our
anatomical study showed only the attachment of the inferior
part of the meniscus periphery to tibia. At the same time,
this is the most challenging and technically difficult area
for meniscus repair. Many surgeons are satisfied suturing
this part of the meniscus to the posterior capsule, but it may
have a significant impact on the mobility of the postero-
medial corner. There is a wide space between outer surface
of zone 4 of medial meniscus and the joint capsule. Suturing
the meniscus to the joint capsule will close the recess and
subsequently impair the mobility of the medial meniscus,
which may significantly change the position of meniscus
during knee movement. For this reason, a more anatomi-
cally suture placement in zone 4 should be considered.
Acknowledgments The authors gratefully acknowledge Maciej
Pronicki, MD, PhD for providing histopathology examinations,
Maciej S
´miarowski (maciej.smiarowski@gmail.com) for taking all
photographs and Center for Medical Education (www.cemed.pl) for
its help.
References
1. Berlet GC, Fowler PJ (1998) The anterior horn of the medial
meniscus an anatomic study of its insertion. Am J Sports Med
Am Orthop Soc Sports Med 26:540–543
2. Becker R, Wirz D, Wolf C, Göpfert B, Nebelung W, Friederich
N (2005) Measurement of meniscofemoral contact pressure after
repair of bucket-handle tears with biodegradable implants. Arch
Orthop Trauma Surg 125(4):254–602
3. Chan CM, Goldblatt JP (2012) Unilateral meniscomeniscal liga-
ment. Orthopedics 35:e1815–e1817
4. Clark CR, Ogden JA (1983) Development of the menisci of the
human knee joint. Morphological changes and their potential role
in childhood meniscal injury. J Bone Joint Surg Am 65:538–547
5. Englund M (2008) The role of the meniscus in osteoarthritis gen-
esis. Rheum Dis Clin North Am 34:573–579
6. Fenn S, Datir A, Saifuddin A (2009) Synovial recesses of the
knee: MR imaging review of anatomical and pathological fea-
tures. Skelet Radiol 38:317–328
7. James EW, LaPrade CM, Ellman MB, Wijdicks CA, Engebretsen
L, LaPrade RF (2014) Radiographic identification of the anterior
and posterior root attachments of the medial and lateral menisci.
Am J Sports Med 42:2707–2714
8. Johannsen AM, Civitarese DM, Padalecki JR, Goldsmith MT,
Wijdicks CA, LaPrade RF (2012) Qualitative and quantitative
anatomic analysis of the posterior root attachments of the medial
and lateral menisci. Am J Sports Med 40:2342–2347
9. LaPrade CM, Ellman MB, Rasmussen MT, James EW, Wijdicks
CA, Engebretsen L, LaPrade RF (2014) Anatomy of the anterior
root attachments of the medial and lateral menisci: a quantitative
analysis. Am J Sports Med 42:2386–2392
10. Lougher L, Southgate CR, Holt MD (2003) Coronary liga-
ment rupture as a cause of medial knee pain. Arthroscopy
19:e157–e158
11. Masouros SD, McDermott ID, Amis AA, Bull AM (2008) Bio-
mechanics of the meniscus-meniscal ligament construct of the
knee. Knee Surg Sports Traumatol Arthrosc 16:1121–1132
12. Rainio P, Sarimo J, Rantanen J, Alanen J, Orava S (2002) Obser-
vation of anomalous insertion of the medial meniscus on the ante-
rior cruciate ligament. Arthrosc J Arthrosc Relat Surg 18:1–6
13. Rath E, Richmond JC (2000) The menisci: basic science and
advances in treatment. Br J Sports Med 34:252–257
14. Stärke C, Kopf S, Gröbel KH, Becker R (2010) The effect of a
nonanatomic repair of the meniscal horn attachment on meniscal
tension: a biomechanical study. Arthroscopy 26:358–365
15. Stein T, Mehling AP, Welsch F, von Eisenhart-Rothe R, Jäger A
(2010) Long-term outcome after arthroscopic meniscal repair
versus arthroscopic partial meniscectomy for traumatic meniscal
tears. Am J Sports Med 38:1542–1548
16. Tardieu C, Dupont JY (2001) The origin of femoral trochlear
dysplasia: comparative anatomy, evolution, and growth of the
patellofemoral joint. Rev Chir Orthop Reparatrice Appar Mot
87:373–383
17. Weiss CB, Lundberg M, Hamberg P, DeHaven KE, Gillquist J
(1989) Non-operative treatment of meniscal tears. J Bone Joint
Surg Am 71:811–822
18. Wymenga AB, Kats JJ, Kooloos J, Hillen B (2006) Surgical
anatomy of the medial collateral ligament and the posterome-
dial capsule of the knee. Knee Surg Sports Traumatol Arthrosc
14:229–234
19. Yagishita K, Muneta T, Ogiuchi T, Sekiya I, Shinomiya K (2004)
Healing potential of meniscal tears without repair in knees with
anterior cruciate ligament reconstruction. Am J Sports Med
32:1953–1961
20. Zivanović S (1974) Menisco-meniscal ligaments of the human
knee joint. Anat Anz 135:35–42
Author's personal copy