Normal popliteofibular ligament. Download

Transcript
POSTEROLATERAL CORNER
•  Complex anatomy and infrequent lessions but with
clinical relevance.
•  Their injuries are usually associated with rupture of one
or both cruciate ligaments. Particularly PCL (62%).
•  Mechanism of injury: Most common: direct blow to the
anteromedial proximal tibia, directed posterolaterally,
with the knee near full extension or a noncontact,
external rotation hyperextension injury.
•  The significance of a missed PCL injury can have
serious consequences such as chronic instability,
degenerative changes or predispose to failure of the
cruciate reconstruction.
Components of the PLC
•  Superficial layer
-Iliotibial band
-Biceps femoris tendon
-Lateral gastrocnemius tendon
o  Deepest layer
v  Fibular collateral ligament
v  Fabellofibular ligament (inconstantly)
v  Popliteal tendon-muscle unit: consist of
q  Popliteus muscle and tendon
q  Popliteofibular ligament
q  Arcuate ligament
q  Posterolateral joint capsule
Specific components that can be
identified on MRI
ü Fibular collateral ligament
ü Popliteal tendon muscle unit including
popliteofibular ligament
ü Biceps femoris tendon. Iliotibial band
ü Fabello fibular ligament
ü Arcuate and Segond Fractures
MRI protocols
•  We strongly suggest the application of 1.5 or 3
Tesla scanners.
•  We perform a routine knee protocol that includes
axial, sagital and coronal DP or T2 FAT SAT 3mm
sequences, a sagital DP, a coronal T1 WI 3mm,
sagital T2 FAT SAT WI 3mm and a axial STIR
3mm sequences.
•  We recommend performing coronal oblique
images in order to improve the examination
showing the arcuate and popliteofibular ligaments.
Anatomic illustration of posterolateral corner of the knee
demonstrating most of the components and their relation with other
structures.
Fibular collateral ligament
BICEPS FEMORIS TENDON
Normal FCL: Consecutive coronal FSE T1
weighted images
The lateral collateral ligament originates from
the lateral femoral epicondyle and extends
distally and posteriorly over an oblique
course to insert on the lateral aspect of the
fibular head, anterior and distal to the tip of
the fibular styloid process.
FIBULAR COLLATERAL
LIGAMENT
FIBULAR STYLOID
PROCESS
Sagital FSE T1 weighted image
Distally, fibular collateral ligament
often joins with biceps femoris tendon
Biceps Femoris Tendon
The long and short heads
of the biceps femoris
tendon typically join above
the knee and course distally
to insert predominantly into
the lateral aspect of the
fibular styloid
Normal BFT: Consecutive coronal
FSE T1 weighted images
Coronal fat-suppressed fast spin-echo T2-weighted images shows fluid
signal extending along the fibular collateral ligament and the biceps femoris
tendon consistent with slight injury
Coronal FS FSE T2–weighted MR image shows avulsion and
retraction of biceps femoris tendon (arrows).
Avulsion of biceps femoris
tendon. Coronal fatsuppressed T2-weighted
image shows distal tear of
this structure from fibular
head (arrow)
Avulsion of lateral collateral ligament and biceps
femoris tendon. Consecutive axial fat-suppressed T2weighted image show distal tear of both structures
from fibular head (arrow)
Avulsion of lateral collateral ligament and biceps
femoris tendon. Coronal FSE T1 weighted image and
sagital fat-suppressed T2-weighted image depict distal
tear of both structures from fibular head (arrows).
Popliteus muscle-tendon unit
The popliteus muscle is a major dynamic stabilizer of the lateral
knee and arises from the posterior medial tibia, extending superiorly
and laterally to form a tendon that continues into the joint through
the popliteal hiatus, deep in relation to the fabellofibular and arcuate
ligaments to insert onto the lateral surface of the femoral condyle. Popliteus muscle-tendon unit
POPLITEUS
TENDON
Normal popliteus muscle-tendon:
Consecutive axial FS FSE DP weighted images
POPLITEUS
MUSCLE
Popliteus injuries. Coronal fat-suppressed fast spin-echo
T2-weighted images depict fluid signal extending along
margins of popliteus muscle belly (arrow), consistent
with partial tear.
Popliteus injuries. Axial and sagital fatsuppressed fast spin-echo T2-weighted
images show edema at myotendinous
junction of popliteus (arrows), consistent
with partial tear in this region.
ASSOCIATE LESSIONS WITH
POPLITEUS MUSCLE-TENDON UNIT
Calcific tendinitis of popliteus muscle-tendon.
Coronal FS FSE T2 weighted image depicts small
areas of low-signal present within the popliteus
muslce and tendon that was suspected to be
calcification. Ganglion of the popliteus
tendon
Axial and coronal FS FSE
images of a knee show a
small cystic structure
(arrows) within and over
the anterior margin of the
popliteus tendon, reflecting
a ganglion cyst. Normal popliteofibular ligament. Coronal
T1-weighted image and anatomic
illustration depict this structure which
originates near the popliteus
musculotendinous junction and courses
laterally to attach to the medial aspect of
the fibular styloid process (arrow)
Popliteofibular ligament
Torn of popliteofibular ligament. Coronal fatsuppressed fast spin-echo T2-weighted image
shows avulsion of distal popliteofibular
ligament (arrow) from fibular styloid process.
Fabello fibular ligament
Normal fabello fibular ligament:
Coronal FSE T1 weighted image
shows this variably present ligament
which extends from the fabella to
the styloid process (arrow).
This ligament arises from the fabella, if a fabella is present,
or from the posterior aspect of the supracondylar process
of the femur to insert distally on the posterior and lateral
edges of the fibular styloid process, anterolateral to the
insertion of the popliteofibular ligament.
Lateral gastrocnemius tendon
PLANTARIS
BICEPS
FEMORIS
Is a superficial muscle which arises from the
supracondylar tubercle of the lateral condyle.
Then spreads out into an aponeurosis
Axial FS FSE DP images and coronal FSE T1
weighted image shows the lateral gastrocnemius
muscle-tendon which extends near the plantaris and
biceps femoris muscle-tendons (red arrows).
The iliotibial band is a combination of the
tendon of the tensor fascia lata and the deep and
superficial fibers of the gluteus major. Consists of
deep and superficial layers. The superficial layer
is the main tendinous component and inserts onto
Gerdy’s tubercle on the anterior lateral tibia.
The deep layer inserts on the distal femur.
Isolated tears of the iliotibial band are rare,
but these tears may occur in patients with injuries
to multiple ligaments of the knee.
Coronal FS FSE proton density and
FSE T1 weighted MR images
illustrate fluid signal extending along
margins of the superficial layers of
the iliotibial band (arrows) consist of
disruption of fibers (partial tear).
Arcuate ligament
Drawing of posterolateral corner of
the knee demonstrating the Y shaped
of the arcuate ligament which arises
from the fibular styloid and divides
into two limbs. The lateral extends
superiorly to merge with the posterior
capsule, whereas the medial limb
extends superomedially, over the
popliteus, to join fibers with the
oblique popliteal ligament
Arcuate ligament
Intact arcuate ligament .
Axial fat-suppressed fast spin-echo T2-weighted image at
level of joint line shows arcuate ligament with no signs of
injury
Torn arcuate ligament .
Axial fat-suppressed fast spin-echo T2-weighted image
shows tear of posterolateral joint capsule (arrows) at level of
joint, which is consistent with arcuate ligament tear.
Drawings of the fibula showing the
insertions of ligaments and tendons.
Popliteofibular ligament inserts in upper
facet of apex of fibular head, just medial
to insertions of fabellofibular and arcuate
ligaments.
Lateral collateral ligament and direct arm
of long head of biceps femoris tendon are
attached to lateral margin of fibular head.
Arcuate fracture
Coronal FSE T1
weighted image shows
a small fracture
(arrows) at the medial
aspect of the fibular
head.
The “arcuate” sign or fracture is an avulsion fracture of the fibular head and
styloid. Could be comprise the attachment of the lateral collateral ligament,
biceps femoris tendon and arcuate ligament complex.It is usually associated
with cruciate ligament injury (mostly PCL) The importance of this injury is that if it is not diagnosed acutely, posterolateral
instability could develop and may result in failed cruciate ligament
reconstruction
Sagital, coronal and axial FS FSE T2weighted MR images illustrates bone
bruises (arrows) at the level of the
medial aspect of the fibular head. In this
case there were not assocciate ligament
or tendon injuries.
Segond fracture
Segond fracture is an avulsion
fracture of the knee which
involves the lateral aspect of the
tibial plateau, and is particularly
frequently (75% of cases)
associated with disruption of
the anterior cruciate ligament.
However, there are additional
frequently encountered injuries.
Other assocciate injuries
include:
ü  Avulsion of the biceps femoris
tendon
ü  Avulsion of the fibular
collateral ligament
ü  Avulsion of the iliotibial band
ü  Medial or lateral meniscal tear
Segond fracture
Axial, sagital and coronal FS FSE T2-weighted MR and coronal
FSE T1 images illustrates bone bruises (arrows) at the level of
the lateral aspect of the tibia plateau in a 21-year-old woman with
acute posterolateral corner injury
Typically these injuries are seen in two settings:
Ø  falls
Ø  sports: especially skiing, basketball and baseball
Associate lessions with PLC
Injuries of posterior cruciate
ligament.
Sagital FSE T2 and sagital FS
FSE DP weighted images
show mid intrasubstance
increased signal present in the
PCL (arrow) compatible with
an interstitial partial tear.
Injury of anterior
cruciate ligament.
Sagital FSE T2
weighted image
depicts disruption of
fibers (arrow) in the
proximal and mid
ACL consistent with
complete tear.
Medial femoral
condyle contusion.
Axial FS FSE T2weighted image
shows increased
signal intensity
within bone marrow
of anterior aspect of
medial femoral.
condyle
SUMMARY
• 
The knowledge of the normal and abnormal MRI appearances of the
structures of the PLC of the knee as well as the patterns of injury will
help radiologist suggest the diagnosis of PLC injury even when is not
clinically suspected.
• 
Tears of 2 or more PLC components suggest the diagnosis of high
grade PLC injury and should direct the orthopedic to consider surgical
tratment (especially when fibular collateral ligament and the poplteus
musculotendinous unit including PFL and arcuate ligament are injuried).
• 
This diagnosis is utterly significant in the setting of combined injuries
(PCL-ACL). Furthermore, unrecognizes high grade PLC injuries may
lead to significant graft failures, instability and also osteoarthritis.
• 
Conversely, injury to only one of the PLC structures, depending on the
associated injuries can often be successfully treated nonsurgically.