Popliteomeniscal Fascicles: Anatomic Considerations Using MR ...

Fig. 1—Drawing shows superolateral view
of posterolateral corner of knee with femur
and superficial fibular attachments removed.
Arrangement between popliteus muscle (8)
and tendon (9) (cut proximally and reflected)
and anteroinferior (11) and posterosuperior (10)
popliteomeniscal fascicles is apparent. Inferolateral
portion of anteroinferior popliteomeniscal fascicle
(11) forms common fibular styloid attachment
with anterior arm of popliteofibular ligament
(6). 1 = anterior cruciate ligament, 2 = posterior
cruciate ligament, 3 = lateral meniscus, 4 = anterior
meniscofemoral ligament of Humphry, 5 = posterior
meniscofemoral ligament of Wrisberg, 7 = posterior
arm of popliteofibular ligament, 12 = fibula. (Reprinted
with permission from Stäubli HU, Birrer S. The
popliteus tendon and its fascicles at the popliteal
hiatus: gross anatomy and functional arthroscopic
evaluation with and without anterior cruciate
ligament deficiency. Arthroscopy 1990; 6:209–220 [3])
the popliteomeniscal fascicles can be symptomatic
and manifest as localized posterolateral
pain and locking of the knee joint [8, 10,
11]. Some authors [11] have referred to this
disorder as hypermobile lateral meniscus and
describe specific clinical examination techniques
that can help in the diagnosis.
Although there is debate about the number
of popliteomeniscal fascicles, most studies
have described at least two: an anteroinferior
fascicle and a posterosuperior fascicle [3, 7,
12, 13]. The anteroinferior popliteomeniscal
fascicle originates from the lateral aspect of
the body of the lateral meniscus, courses in
an inferoposterior direction to form the floor
of the popliteal hiatus, and then blends with
the musculotendinous portion of the popli-
MR Arthrography of Popliteomeniscal Fascicles
teus muscle. The lateral portion of the anteroinferior
popliteomeniscal fascicle takes
an inferoposterior course and fuses with the
popliteofibular ligament to form a conjoined
attachment at the fibular styloid process. The
origin of the posterosuperior popliteomeniscal
fascicle is the posterosuperior margin of
the posterior horn of the lateral meniscus
medial to the popliteus tendon. This fascicle
forms the roof of the popliteal hiatus.
The posterosuperior popliteomeniscal fascicle
has a posterior course and attaches to the
posterior joint capsule, which fuses with the
musculotendinous portion of the popliteus
tendon (Fig. 1).
The presence of a third popliteomeniscal
fascicle, known as the posteroinferior popliteomeniscal
fascicle, is controversial. This
fascicle is reported to be located medial to
the popliteal hiatus [11, 14–16]. Last [17] in
1950 described a broad and robust aponeurotic
extension from the medial aspect of the
musculotendinous region of the popliteus
muscle that had a prominent attachment to
the inferior margin of the posterior horn of
the lateral meniscus. Terry and LaPrade [15]
and Ullrich et al. [16] also described the medial
aponeurotic extension and designated
the attachment to the inferior margin of the
posterior horn of the lateral meniscus the
posteroinferior popliteomeniscal fascicle.
This fascicle passes upward from the medial
aponeurosis of the popliteus muscle and inserts
on the inferior margin of the posterior
horn of the lateral meniscus near the origin
of the posterior meniscofemoral ligament of
Wrisberg. Feipel et al. [14] found the posteroinferior
popliteomeniscal fascicle present in
17% of 42 dissections of embalmed knee
specimens. Most other reports of the posteroinferior
popliteomeniscal fascicle do not
state its frequency.
The medial aponeurosis of the popliteus
musculotendinous region has been reported
to have additional medial attachments to the
inferolateral aspect of the posterior cruciate
ligament, the posterior capsule, and an
infero lateral connection with the oblique
popliteal ligament [14, 16]. A variant of the
posterior meniscofemoral ligament of Wrisberg
has been reported in which the origin is
the medial aponeurosis of the popliteus musculotendinous
region rather than the posterior
horn of the lateral meniscus [14].
This study was performed to examine the
normal MR arthrographic imaging anatomy
of the popliteomeniscal fascicles with specific
reference to the number of popliteomeniscal
fascicles, the thickness and course of the fascicles,
and the presence of other posterior attachments
from the medial aponeurosis of the
popliteus musculotendinous region.
Materials and Methods
After institutional review board approval was
obtained, 10 fresh unembalmed frozen cadaveric
knee specimens were obtained from the
department of anatomy donor program at our
institution. Specimens were from five men and
five women whose average age at death was 85
years (range, 73–93 years).
MR Arthrography
Before MRI, specimens were allowed to thaw
to room temperature for 24 hours, after which
arthrography was performed under fluoroscopic
guidance. Approximately 55–60 mL of a solution
containing 1 mL of gadopentetate dimeglumine
(Magnevist, Bayer Schering Pharma) diluted in
250 mL of equal parts saline solution and iohexol
(Omnipaque 350, GE Healthcare) was injected
into each knee joint via a lateral suprapatellar
approach with an 18-gauge needle. T1-weighted
spin-echo imaging was performed on a 1.5-T
MRI system (Signa LX Horizon, software version
8.3, GE Healthcare) with a quadrature knee coil
in the orthogonal sagittal, axial, and coronal
planes. The following MRI parameters were used:
TR/TE, 900/22; bandwidth, 16 kHz; matrix size,
512 × 256; field of view, 12 × 12 cm; slice
thickness, 2.5-mm; interslice gap, 0.5 mm; single
acquisition; imaging time, approximately 5
minutes for each sequence.
Specimen Sectioning and Photography
After MRI, the knee specimens were placed in a
freezer (Forma Bio-Freezer, Forma Scientific) and
deep frozen to −40°C. The frozen knee specimens
were sectioned with a band saw into 3-mm slices
in the sagittal (n = 4), axial (n = 3), and coronal
(n = 3) planes. After debris was rinsed from the
surface of the specimens, the sections were
thawed, floodlit, and photographed with a digital
camera (Coolpix 990, Nikon).
Image Interpretation
MR arthrographic images and specimen
photographs were simultaneously reviewed by two
musculoskeletal radiologists working in consensus.
Identification and location of the anteroinferior,
posterosuperior, and postero inferior popliteomeniscal
fascicles and the medial aponeurosis with
its medial attachments were based on gross
anatomic descriptions obtained from the literature
[3, 12, 14–16]. The number of popliteomeniscal
fascicles visualized and their location on MR
AJR:190, February 2008 443