ORIGINAL RESEARCH MORPHOLOGICAL STUDY OF THE MENISCI OF ...

ORIGINAL RESEARCH

MORPHOLOGICAL STUDY OF THE MENISCI OF THE KNEE JOINT IN ADULT
CADAVERS OF THE SOUTH INDIAN POPULATION

B.V. Murlimanju1, Narga Nair2, Shakuntala Pai2, Mangala Pai1, Chethan P1, Chandni Gupta2

1Manipal University, Anatomy, Mangalore, Hindistan 2Manipal University, Anatomy, Manipal,
Hindistan

ABSTRACT

Objective: To estimate the incidence of different shapes of the medial and lateral meniscus and the
incidence of discoid meniscus in the South Indian population.
Methods: The study included 108 menisci from 54 adult cadaveric knee joints which were preserved in 10%
formaldehyde solution. After the dissection procedure, the morphological variants of the shapes of menisci
were macroscopically noted and classified. The medial meniscus was subgrouped as crescent-shaped, sided
U-shaped, sided V-shaped, sickle-shaped and C-shaped. The lateral meniscus was subgrouped as crescent-
shaped, C-shaped and discoid-shaped.
Results and Conclusion: From our observations, 50% of the medial menisci were cresent- shaped, 38.9%
were sided V-shaped and 11.1% were sided U-shaped. The percentages of the different types of lateral
menisci were 61.1%, C-shaped and 38.9%, crescent-shaped. No discoid medial or lateral meniscus (0%) was
observed in the study.

Keywords: Knee, Lateral meniscus, Medial meniscus, Shape, Side

GÜNEY HİNDİSTANLI YETİŞKİN KADAVRA POPÜLASYONUNDA DİZ EKLEMİ
MENİSKÜSLERİNİN MORFOLOJİK DEĞERLENDİRİLMESİ

ÖZET

Amaç: Güney Hindistan popülasyonunda, medial ve lateral menisküs şekil farkı ve diskoid menisküs
görülme oranının tahmin edilmesi.
Yöntem: Çalışmada, %10 formaldehid solüsyonunda korunmuş olan, 54 yetişkin kadavra dizinden elde
edilmiş 108 adet menisküs kullanılmıştır. Diseksiyon prosedüründen sonra çıkarılan menisküslerin
şekillerindeki morfolojik varyasyonlar makroskopik olarak incelenip sınıflandırılmıştır. Medial menisküs
için, hilal biçimli, kenarlı U biçimi, kenarlı V biçimi, orak biçimi ve C biçimi alt gruplama yapılmıştır.
Lateral menisküs için ise hilal biçimi, C biçimi ve diskoid biçimi alt gruplaması yapılmıştır.
Bulgular ve Sonuç: Yaptığımız gözlemler sonucu, medial menisküslerin % 50’si hilal biçimli, %38,9’u
kenarlı V biçimli, %11.1’i kenarlı U biçimli bulunmuş; lateral menisküs şekillerindeki yüzdeler ise %61.1 C
biçimli, %38.9 hilal biçimli bulunmuştur. Çalışmada diskoid yapıda lateral veya medial menisküs’e
rastlanmamıştır.

Anahtar Kelimeler: Diz, Lateral menisküs, Medial menisküs, Kenar, Şekil

İletişim Bilgileri: Marmara Medical Journal 2010;23(2);270-275
B.V. Murlimanju, M.D.
Manipal University, Anatomy, Mangalore, Hindistan
e-mail: [email protected]

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Marmara Medical Journal 2010;23(2); 270-275
B.V. Murlimanju, et al.
Morphological study of the menisci of the knee joint in adult cadavers of the South Indian population

INTRODUCTION Among them, 37 were right-sided and 17 left-
The menisci are two crescentic lamellae, sided isolated lower limbs. All specimens
which serve to deepen the surfaces of the were preserved in 10% formaldehyde
articular fossae of the head of the tibia for solution. After the dissection of the skin and
reception of the condyles of the femur1-3. The muscles, the approaches to the menisci were
anatomical abnormalities and variations of the performed, opening anteriorly by a
intraarticular structures of the knee joint have longitudinal incision on each side of the joint
recently become significant because of new capsule, cutting the patellar ligament and the
techniques such as arthroscopy, computed collateral ligaments transversely. In order to
tomography and magnetic resonance imaging. expose the menisci clearly, the joint capsule
Also the investigation of these variants is and the intra-articular ligaments were cut, and
important in order to define the the condyles were circumferentially detached
morphological features for clinical diagnosis from their soft tissue attachments and
and surgical procedures4. The frequency and removed, exposing the tibial plateau. All
severity of knee injuries in organized and dissections were performed in a systematic
recreational sports industry are well- fashion and the data were recorded on a
documented. In American football, the knee is standardized collection sheet.
the most commonly injured joint. Stocker et
al in 1997 reported that meniscal injuries Morphological variants of the shapes of the
accounted for 12% of all football knee menisci were macroscopically noted and
injuries in a recent high school injury survey5. classified. The medial meniscus (MM) was
sub-grouped as sickle shaped, sided U-
The meniscus has several roles that contribute shaped, sided V-shaped, crescent-shaped and
to the successful function of the knee. Injuries C-shaped. The lateral meniscus (LM) was
to the meniscus are common in work, sports sub-grouped as crescent (semilunar)-shaped,
and everyday activities, and can be disabling. C-shaped and discoid-shaped (Fig.1). When
In meniscus allograft transplantation, it has the meniscus covers the tibial plateau
been stated that providing a meniscal allograft circularly, the meniscus is said to be a discoid
that matches the size and shape of the type. Menisci, which had thin anterior and
meniscus to the recipient’s knee is the posterior horns and thin bodies, were defined
responsibility of the tissue bank providing the as crescent (semilunar)- types. Menisci, which
graft6. In both anatomical and orthopedic had thin anterior, posterior horns and thick
literature, attention to the form of the menisci bodies, were defined as sickle-shaped types.
of the knee joint has been directed for the Menicsi which resembled sided U, sided V
most part to the occurrence of a discoid type and C were named as sided U, sided V and C
of lateral meniscus. No attempt has been shaped respectively.
made, heretofore, to classify the menisci of
the knee joint according to their shapes or to RESULTS
consider possible racial or sexual differences7. From our observations, four morphological
In the present study, the objectives were to types of the shape of menisci were
estimate the incidence of different shapes of determined. 50% of the medial menisci
medial and lateral meniscus and also to (MMs) were crescent-shaped, 38.9% were
estimate the incidence of discoid meniscus in sided V- shaped and 11.1% were sided U-
the South Indian population. shaped (Table I, Figs.2, 3, 4). The percentages
of the lateral menisci types (LMs) were
MATERIAL AND METHOD 61.1% C-shaped and 38.9% crescent-shaped
Human adult knee joints, available in the (Table II, Figs 5, 6). Discoid medial or lateral
anatomy laboratory, were used for the present menisci were not observed in the present
study. The study included 108 menisci from study (0%).
54 knee joints of the South Indian population.

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Marmara Medical Journal 2010;23(2); 270-275
B.V. Murlimanju, et al.
Morphological study of the menisci of the knee joint in the adult cadavers of the South Indian population

Table I: Showing the incidence of different shapes of medial meniscus (n = 54).

Shape Total no. & Percentage
Crescentic 27 (50 %)

Sided V 21 (38.9 %)
Sided U 6 (11.1 %)

Discoid nil (0%)

Fig 1: Diagram showing the various shapes of the Fig 2: Left tibial plateau showing crescent-shaped
menisci (source of classification - Kale A et al4, medial meniscus, observed in 50% of the specimens
2006) a. Crescent-shaped, b. Sickle-shaped, c. C- (M – medial meniscus, L – lateral meniscus, A –
shaped, d. sided U-shaped, e. sided V- shaped, f. Anterior, P – Posterior)
incomplete discoid, g. complete discoid. (A-anterior
& P-posterior)

Fig 3: Right tibial plateau showing sided V-shaped Fig 4: Right tibial plateau showing sided U-shaped
medial meniscus, observed in 38.9% of the medial meniscus, observed in 11.1% of the
specimens (M – medial meniscus, L – lateral specimens (M – medial meniscus, L – lateral
meniscus, A – Anterior, P – Posterior) meniscus, A – Anterior, P – Posterior)

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Marmara Medical Journal 2010;23(2); 270-275
B.V. Murlimanju, et al.
Morphological study of the menisci of the knee joint in adult cadavers of the South Indian population

Fig 5: Left tibial plateau showing crescent-shaped Fig 6: Right tibial plateau showing C-shaped lateral
lateral meniscus, observed in 61.1% of the specimens meniscus, observed in 38.9% of the specimens (M –
(M – medial meniscus, L – lateral meniscus, A – medial meniscus, L – lateral meniscus, A – Anterior, P
Anterior, P – Posterior) – Posterior)

Table II: Showing the incidence of different shapes of lateral meniscus (n = 54).

Shape Total no. & Percentage
C shaped
Crescentic 33 (61.1 %)
Discoid 21 (38.9 %)
nil (0%)

DISCUSSION contrast, C.M. Charles7 classified the menisci,
In primates, Parsons noted that the MM both on the basis of the relative size of the
always has a crescentic shape but that the LM anterior and posterior cornua and also on the
may have either a crescent or a disc shape8. degree of curvature. It has been reported that
Vallois9 confirmed this observation and the LM has a crescentic shape12. In 1889,
studied the whole morphology of the knee Young13 described a discoid lateral meniscus
joint in primates. Since then, numerous papers in a cadaver specimen. Discoid meniscus is an
on the variations of human knee menisci have atavistic anomaly in which the meniscus of
been published, revealing fundamental the knee, predominantly the LM, is discoid
elements10. Fick & Rudolph11 described the rather than semilunar in shape10,14. Additional
MM as a half, two thirds or three-fourths anomalies of the meniscal shape have been
ellipse and stated that the lateral could be classified as hypoplasia or hyperplasia. The
compared to an almost complete circle. In meniscal hyperplasia or discoid menisci have

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Marmara Medical Journal 2010;23(2); 270-275
B.V. Murlimanju, et al.
Morphological study of the menisci of the knee joint in adult cadavers of the South Indian population

been the object of many studies, because they development28-30. The meniscus arises from
are frequently the source of symptoms15,16. the eccentric portion of the articular interzone
The vast majority of discoid menisci are during the O’Rahilly stage 22, however until
lateral; the discoid medial meniscus is week 9 of development, the menisci are not
extremely rare10,17. Rare cases of it have been easily distinguishable31. On the other hand,
reported by the researchers as case reports during embryologic development, the blood
10,17-19. This fact was mentioned in the supply of the meniscus enters from the
research of Kelly and Green20 as the discoid periphery and extends throughout the entire
meniscus was most likely a congenital width. However, by the ninth month of life,
deviation and usually occurred laterally. the central third will be avascular and by
Moreover, it was reported that the discoid adulthood, only the peripheral one third will
shape resulted in a greater coverage of the receive any blood supply32. At 9 week’s
tibia and was usually associated with development, they are already perfectly
increased thickness of the meniscus that formed. From that point on, the menisci grow
might lead to abnormal shearing forces across at the same rate as the rest of the intra-
the knee joint20. articular structures, without undergoing any
macroscopic structural changes30 and assume
The reported incidence of discoid meniscus the normal adult relationships with the rest of
has ranged from 0.4 to 17% with the vast the knee by the 14th week20,33. The differences
majority occurring on the lateral side of the in the shape of the meniscus may be due to
knee21,22. The most common congenital the mesenchymal differentiation or to the
abnormality of the meniscus in man is a development of the vasculature early in
discoid meniscus with a frequency of 1.5- embryonic life.
4.6% for the lateral23 and 0.3% for the medial
one24. Cadaver studies have reported the In the present study, four morphological types
prevalence of lateral discoid menisci to be of the shape of menisci were determined and
between 0 and 7%25-27, whereas arthroscopic there was no discoid medial or lateral
studies have demonstrated ranges from 0.4 to meniscus (0%) observed. The present study
16.6%20. But racial differences do exist recorded the incidence of discoid meniscus as
among the incidence rates. Kale A et al4 0%, from the South Indian population. This is
studied 22 fetal knee joints, reporting that a very low incidence rate. The study included
73% of the cadavers they studied had the a low number of specimens and needs to be
same shape of meniscus on each side. In their researched further with a large sample size. In
study, they also did not determine any discoid contrast, from a study conducted by P.S. Rao
medial meniscus. According to their and S.K.Rao34 in South India, based on 3,167
observations, 18.18% of the MMs were knee arthroscopies done between the years
crescent-shaped, 22.72% of the MMs were 1993 & 2004, 177 (5.59%) discoid lateral
sided V-shaped, 9.09% of the MMs were menisci were encountered. In conclusion, our
sided U-shaped, 36.36% of the MMs were results show that, in the majority of the
sickle-shaped and 13.63% of the MMs were specimens (50%) the MM was crescentic in
C- shaped. In the same study, 13.63% of the form and the most common shape of the LM
LMs were crescent-shaped, 9.09% of the LMs was ‘C’ shape (61.1%). The discoid medial or
were C-shaped and 77.27% of the LMs were lateral meniscus was not observed in our
discoid-shaped. Among the discoid shaped, series. We believe that our study will provide
54.54% of the LMs were incomplete discoid support to the meniscal anatomy, concerning
and 22.72% were completely discoid. The the surgical procedures and arthroscopy of the
variations of the shape of the menisci were knee joint. The study has provided additional
explained by the embryological meniscal information on different shapes of the medial
development10,23. The meniscus arises from and lateral meniscus with contribution to a
the differentiation of mesenchymal tissue better delineation of meniscal anatomy and
within the limb bud and becomes a clearly implications in regard to allograft meniscus
defined structure by the eighth week of fetal transplantation.

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Morphological study of the menisci of the knee joint in adult cadavers of the South Indian population

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