POSTER ABSTRACTS - ISAKOS

specific portions of the swollen synovium
adjacent to the medial meniscus.
The patient went home on the same day of the
surgery. The extension disturbance improved to
full extension to 140 degrees two weeks after
surgery. Three months after the arthroscopy, he
had full range of motion, but with slight pain on
the medial side of the knee. However, an MRI
performed at this period revealed the same
abnormal signal on the medial meniscus.
DISCUSSION:
In 2001, Cothran et al, described the focal
abnormal signal of the meniscus on MRI in the
knees of patients who had acute trauma and
concluded that this signal could not be classified
within the criteria of the meniscal tear.
Furthermore, they found ACL tears in almost in all
their patients. However the arthroscopic findings
were not described in detail.
In our case, we found abnormal hypervascularity
of the synovium that surrounded the medial
meniscus and subsynovial ACL tear on
arthroscopy. As Cothran described, this is one of
the compressive forces exerted on the meniscus
that may be similar to the mechanism of the bone
contusion. However we did not observe changes
of the meniscal signal on the MRI as the patient’s
symptoms improved. We suggest that this
abnormal signal of the meniscus on the MRI of
the knee may reveal the hypervascularity of the
meniscus without meniscal tear as a result of
contusion associated with an ACL tear.
In 1999, we described the classification of
abnormalities of the meniscus in MRIs in patients
over 40 years of age. This case cannot be
classified into any of the groups in that
description. However it is similar to the group 4
abnormalities of the osteoarthritis in our
classification. This particular case is a 62-year old
man who hasn’t had symptoms of osteoarthritis.
Therefore the pathology of the abnormal signal in
this case is unknown over the long-term and it is
necessary to observe this case over a period to
further investigate the changing of the signal in
the MRI into reduction or production and how this
signal in MRI relates to acute trauma and
osteoarthritis in the elderly.
Takahiko Kiyama, Fukuoka, JAPAN
Toyonobu Yoshimura, Fukuoka, JAPAN
Keihan Cho, Fukuoka, JAPAN
Kazuhiko Saeki Fukuoka JAPAN
Takeshi Kanamiya Fukuoka JAPAN
Masatoshi Naito Fukuoka JAPAN
Fukuoka Rehabilitation Hospital, Fukuoka, JAPAN
[Purpose]Lateral discoid meniscus reportedly has
a high rate of occurrence in both knees. Clinically,
however, the opposing knee to that which has
been diagnosed with lateral discoid meniscus is
often found to be normal upon examination. In
this study we investigated the rate at which
discoid meniscus occurred in both knees.
[Materials and Methods]Of the 90 cases
diagnosed with lateral discoid meniscus in our
department, we studied 50 cases in which
diagnosis of the opposing knee was possible.
These 50 cases comprised 15 males and 35
females with ages ranging from 6 - 79 years (mean
49.4 years). Diagnoses were made by arthroscopic
examination or MRI. Discoid meniscus
morphology was classified using the Watanbe
classifications of normal type, incomplete type
and complete type. The Wrisberg type was
included in the incomplete type.
[Results]In 39 cases (78%) discoid meniscus
occurred simultaneously in both knees. In 30 of
these cases (60%) both knees were of the
complete type, 6 cases (10%) were a combination
of the complete type and the incomplete type, and
in 3 cases (8%) both knees were of the incomplete
type. In the remaining 11 cases (22%) one knee
was normal. The opposing knee was of the
complete type in 9 cases (18%) and the
incomplete type in 2 cases ( 4%).
[Discussion] With few reports of investigations,
the epidemiology of the occurrence of lateral
discoid meniscus in both knees is still unclear. A
high rate of occurrence in both knees (95%) in
cadavers has been reported, but the reliability is
low due to the small number of cases. The
number of cases in this study is sufficiently large
and therefore reliable. Our results suggest that in
20% of cases with lateral discoid meniscus the
opposing knee is normal.
E-poster #716
A Study of the Occurrence of Lateral Discoid
Meniscus in Both Knees
Michiya Hara, Fukuoka, JAPAN, Presenter
Hirofumi Hanada, Fukuoka, JAPAN
Seigen Mori, Fukuoka, JAPAN