Transcript magnetic resonance imaging of cystic knee lesions m. gongi, w

- Cystic lesions around the knee are a diverse
group of entities, frequently encountered during
routine MRI of the knee.
- These lesions may produce overlapping clinical
features, rendering the clinical diagnosis difficult.
- MRI is the technique of choice in characterizing
lesions around the knee: to confirm the cystic nature
of the lesion, to evaluate the anatomical relationship
to the joint and surrounding tissues, and to identify
associated intra-articular disorders.
The purpose of this study is to review the MRI
aspects of some cystic knee lesions.
- We retrospectively report 11 cases of cystic
knee lesions collected in the radiology
department of Fattouma Bourguiba Hospital of
Monastir over a period of 5 years.
- All patients were explored by MRI (1.5 Tesla)
for knee pain.
- The most common lesion was Baker cyst, also
termed popliteal cyst (5 cases).
- Meniscal cysts were found in 3 cases .
- A cyst of the ilio-tibial band was found in one
case.
- Mucoid degeneration of the anterior cruciate
ligament was diagnosed in 2 cases.
1 - Popliteal (Baker’s) Cysts :
Popliteal cysts are lined with synovium and result
from extrusion of joint fluid into the gastrocnemiosemimembranosus bursa through a weak portion
of the postermedial capsule of the knee between
the medial head of the gastrocnemius muscle and
the semimembrannosus muscle.
- Size :
The cyst can vary in size from quite small to very
large.
- Age :
It’s rare in chidren.
- Presentation :
-asymptomatic +++
-painful popliteal swelling ,
-knee effusion,
-clicking of the knee,
-buckling of the knee ..
- Complications :
- break : table of pseudo-thrombophlebitis,
- vascular or nerve compression,
- synovial diseases : osteochondromatosis ..
On MR images, popliteal cysts usually appear as
well-defined fluid collections.
The presence of hemorrhage or debris within the
cyst is not rare.
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SM
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2 - Meniscal Cysts
- Meniscal cysts characteristically are located
at the joint line on the medial or lateral side of the
knee and invariably are associated with an underlying
horizontal meniscal tear.
They are formed by extrusion of joint fluid, into the
adjacent tissues, through this meniscal tear which
leads directly into the cyst.
-Presentation :
They are manifested by knee pain, locking and a
mass adjacent to the joint line.
-On MR images, lateral meniscal cysts appear as welldefined rounded cysts located adjacent to a
meniscal tear.
Medial meniscal cysts tend to be larger and dissect
away from the site of the tear .
The meniscal tear is usually horizontal and extensive.
3 - Mucoïd degeneration of the
anterior cruciate ligament :
- The lesion presents with knee pain and restriction of
flexion.
- The pathogenesis is unclear.
- It’s suspected in a patient with a physically intact
ligament and no obvious trauma history.
- The lesion may manifest as an elongated cyst
along the long axis of the ACL, or as an enlarged
ACL.
- Discrete intraosseous ganglia are observed in
77% of the cases with mucoid degeneration of the
ACL.
These ganglia consist of myxoid material and
have generally no identifiable communication with
the articular surface or joint cavity.-
The MR-findings of mucoid degeneration of the ACL
include:
- an ill-defined ACL,
- an increased ligamentous girth,
- a normal orientation of the ligament,
- and an increased signal intensity on all sequences
interspersed among visible intact ACL fibers.
ACL
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4 - Cyst of the ilio-tibial band :
Iliotibial band friction syndrome (ITBFS) is a common
cause of lateral knee pain that is often related to
intense physical activity, as occurs in long-distance
runners, cyclists...
Clinical examination :
tenderness over the lateral femoral epicondyle and
reproducible pain during flexion and extension of the
knee.
On MRI findings, there is a cyst located adjacent to
Iliotibial band.
ITB
ITB
a
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- A wide variety of cystic lesions may be
encountered in the soft tissues and bones during
routine MR imaging of the knee.
- The ability of MR to visualize internal derangements
of the knee and abnormalities of the surrounding
soft tissues makes this technique ideally suited to the
evaluation of these cystic lesions.
- MR diagnosis is also needed to avoid unnecessary
arthroscopy and to guide specific therapy.