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Novel Approach towads Knee Injury Reporting- Correlating
Bone Marrow Edema Patterns & Soft Tissue Injuries
Poster No.:
C-0274
Congress:
ECR 2015
Type:
Educational Exhibit
Authors:
S. Devu, U. Matapathi, S. V. Muddana, S. Marda, S. Polineni, S.
Athne; Hyderabad/IN
Keywords:
Acute, Structured reporting, MR, Musculoskeletal joint
DOI:
10.1594/ecr2015/C-0274
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Learning objectives
1.To understand the dynamic anatomy of knee joint.
2.To characterise the pattern of contusions .
3.To characterise the soft tissue injuries.
4.To evaluate a pattern, correlating specific patterns of bone contusions and soft tissue .
Background
Knee joint is the largest and maximum weight-bearing joint in humans and is mobile hinge
joint which is second commonly injured joint after wrist and is most commonly imaged
joint.
The knee permits flexion and extension about a virtual transverse axis, as well as a slight
medial and lateral rotation about the axis of the lower leg in the flexed position. The centre
of the transverse axis of the extension/flexion movements is located where both collateral
ligaments and both cruciate ligaments intersect. This centre moves upward and backward
during flexion, while the distance between the centre and the articular surfaces of the
femur changes dynamically with the decreasing curvature of the femoral condyles. The
total range of motion is dependent on several parameters such as soft-tissue restraints,
active insufficiency, and hamstring tightness.
Anatomy in extended position:
With the knee extended both the lateral and medial collateral ligaments, as well as the
anterior part of the anterior cruciate ligament, are taut. During extension, the femoral
condyles glide into a position which causes the complete unfolding of the tibial collateral
ligament. During the last 10° of extension, an obligatory terminal rotation is triggered in
which the knee is rotated medially 5°. The final rotation is produced by a lateral rotation
of the tibia in the non-weight-bearing leg, and by a medial rotation of the femur in the
weight-bearing leg. This terminal rotation is made possible by the shape of the medial
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femoral condyle, assisted by contraction of the popliteus muscle and the iliotibial tract
and is caused by the stretching of the anterior cruciate ligament.
Anatomy in flexed position:
In the flexed position, the collateral ligaments and anterior cruciate ligaments are relaxed
while the posterior cruciate ligament is taut. Rotation is controlled by the twisted cruciate
ligaments; the two ligaments get twisted around each other during medial rotation of
the tibia - which reduces the amount of rotation possible - while they become unwound
during lateral rotation of the tibia. Because of the oblique position of the cruciate ligaments
at least a part of one of them is always tense and these ligaments control the joint as
the collateral ligaments are relaxed. Furthermore, the dorsal fibers of the tibial collateral
ligament become tensed during extreme medial rotation and the ligament also reduces
the lateral rotation to 45-60°.
The patellar ligament is the anterior ligament of the knee joint. It is the distal part of the
quadriceps tendon and attaches to the tibial tuberosity. The vastus medialis and lateralis
contribute to the patellar ligament medially and laterally through the medial and lateral
retinacula, which make up the joint capsule of the knee on either side of the patella. The
retinacula also maintain alignment of the patella relative to the patellar surface of the
femur.
The LCL extends from the lateral epicondyle of the femur to the lateral surface of the
fibular head. The LCL is separated from the lateral meniscus by the popliteus tendon.
The LCL also splits the tendon of the biceps femoris into 2 parts.
The MCL extends from the medial epicondyle of the femur to the medial condyle and
superior part of the medial surface of the tibia. The MCL is firmly attached to the medial
meniscus, which is why these are commonly torn at the same time in contact sports.
The oblique popliteal ligament and arcuate popliteal ligament reinforce the joint capsule
on the posterior aspect. The oblique popliteal ligament is a recurrent expansion of the
tendon of the semimembranosus, and it arises from the medial tibial condyle and passes
toward the lateral femoral condyle, where it blends in with the rest of the joint capsule.
The arcuate popliteal ligament arises from the posterior fibular head and passes over the
tendon of the popliteus and spreads over the posterior surface of the knee.
The ACL attaches posterior to the attachment of the medical meniscus on the anterior
intercondylar area of the tibia and passes superior, posterior, and lateral, where it
attaches to the posterior part of the medial side of the lateral condyle of the femur.
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The PCL arises from the posterior intercondylar area and passes on the medial side of the
ACL to attach to the anterior part of the lateral surface of the medial condyle of the femur.
The menisci are wedge shaped and attach at their ends to the intercondylar area of the
tibia. The medial meniscus is C shaped and firmly adheres to the deep surface of the MCL
medially, the ACL anteriorly, and the PCL posteriorly. Because of these attachments, the
medial meniscus is less mobile than the lateral meniscus.
Flexion is produced by the hamstring muscles, which consist of the semitendinosus,
semimembranosus, and long head of the biceps femoris along with the short head of
the biceps and, weakly, the gracilis, sartorius, gastrocnemius, and popliteus. The medial
rotators of the knee are the semitendinosus, semimembranosus, popliteus, gracilis, and
sartorius. The lateral rotator of the knee is the biceps femoris.
Images for this section:
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Fig. 8: Relaxed ACL in flexed position
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Fig. 9: Taut ACL in extension position
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Fig. 10: Relaxed PCL in extension position
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Fig. 11: Taut PCL in flexion position
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Fig. 12: Relaxed Collaterals in flexion position
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Fig. 13: Taut Collaterals in extension position
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Findings and procedure details
MR IMAGING PROTOCOL:
Patient Positioning :Supine with 10- 15 degree external rotation
Imaging Planes: An axial acquisition through the patello-femoral joint is used as initial
localiser for subsequent sagittal and coronal imaging.
Slice Thickness: 4mm sections are used for axial and coronal plane and 3 to 4 mm thick
sections are used for sagittal images
T2 contrast highlights ligamentous edema and haemorrhage in collateral ligaments in
coronal plane and cruciate ligaments in sagittal plane as demonstrated by FS PD FSE
sequence(TR of 3000 to 4000 msec and TE of 40 to 50 msec).
STIR(TR of 4000 msec, TE of 18 msec,TI of 140 msec,and an ETL of 4) and FS PD
FSE sequences are more sensitive than T2 or T2* weighted imaging for identification of
trabecular bone contusions and fractures.
A. PIVOT SHIFT PATTERN OF INJURY:
Most commonly identified pattern of injury in most of the hospitals,either associated with
sports or road traffic accidents associated with sudden deceleration and rotating for
change in direction.
Valgus load and rotational force in flexed position of knee with external rotation of tibia
or internal rotation of femur causes injury/rupture of ACL,
causing anterior subluxation of tibia resulting in impaction of posterior tibia and
posterolateral femoral condyles.
The resulting bone contusion pattern involves the posterior aspect of the lateral tibial
plateau and the mid-portion of the lateral femoral condyle near the condylo-patellar
sulcus. The exact location of the lateral femoral condyle injury depends on the degree
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of flexion of the knee at injury. Increasing degrees of flexion result in a more posteriorly
located bone bruise, whereas less flexion results in a more anteriorly located edema.
Soft-tissues injured with the pivot shift injury include anterior cruciate ligament,tears of
the posterior capsule and arcuate ligament, the posterior horn of the lateral or medial
meniscus , and the medial collateral ligament .
Representative case :Figures 1 and 2
B. CLIP INJURY:
Results from direct contact injury on lateral femoral condyle, with valgus force on medial
collateral ligament and avulsion force at its femoral attachment on medial femoral
condyle.
Seen in road traffic accidents,when hit on side by a vehicle,and in sports like American
football and Kabbadi(An Indian Originated Contact Sport).
Direct contact/hit to lateral femoral condyle with traction force at medial femoral condyle
causing injury of Medial collateral ligament.With increased flexion,injury to ACL and
medial meniscus do occurs.
Bone marrow edema is seen in the lateral femoral condyle (from the direct blow), area
of edema may be present in the medial femoral condyle (secondary to avulsive stress to
the MCL).Varying degrees of MCL injury are associated.
Representative case : Figure 3
C. HYPEREXTENSION INJURY:
Results from direct application of force on the anterior tibia while the foot is planted or
from an indirect force, such as a forceful kicking .
The most severe cases often result from direct injury (eg, a car bumper hitting the anterior
tibia of a pedestrian). During the brief moment of hyperextension, the anterior aspect
of the tibial plateau strikes the anterior aspect of the femoral condyle, resulting in the
"kissing" contusion pattern of bone injury .
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If a valgus force is also applied at hyperextension, the kissing contusions will be located
medially.
Direct force to anterior tibia when foot is planted; indirect force like with kicking causing
kissing contusions of tibia and femur and injury to ACL ,PCL, and posterior structures .In
cases of severe trauma neurovascular and gastrocnemius injury may be also seen.
During the brief moment of hyperextension, the anterior aspect of the tibial plateau strikes
the anterior aspect of the femoral condyle, resulting in the "kissing" contusion pattern of
bone injury. If a valgus force is also applied at hyperextension, the kissing contusions
will be located medially.
Depending on the amount of force applied, associated soft-tissue abnormalities may
include injury to either the ACL or PCL and a meniscal injury . If a substantial force
is applied, dislocation of the knee may occur , along with injury of the popliteal
neurovascular structures , complete disruption of the posterolateral complex, and,
possibly, gastrocnemius injury.
Representative case : Figures 4 and 5
D. DASHBOARD INJURY:
Results from direct impaction of tibia with a hard surface,as seen with direct striking of
tibia against the dashboard in automobile accident ,or fall on ground with tibia hitting
directly in a flexed position.
Direct force on tibia with knee in flexed position causes contusions in anterior tibia and
posterior patella and injury of PCL and posterior Capsule.
Tibia is forced posteriorly relative to the femur wherein the PCL which is taut in flexion
is prone for disruption.
Representative case : Figure 6
E. PATELLAR SUBLUXATION:
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Seen in young individuals with shallow trochlear groove,and can be associated with
repeated attacks and self correction.
Twisting motion of knee in flexion causes internal rotation of femur on fixed tibia with
qaudriceps contraction causing lateral patellar subluxation resulting in contusions at
anterolateral femoral condyle and inferomedial patella.
Representative case : Figure 7
F. UNCLASSIFIABLE INJURIES:
Pre-existing conditions such as osteoarthritis causing significant subchondral edema &
in sceanrios of very Subtle and severe trauma .
Images for this section:
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Fig. 1: CASE 1:HISTORY OF KNEE INJURY WHILE PLAYING FOOTBALL.
FINDINGS:SAGITTAL T2 FAT-SAT IMAGE SHOWS CONTUSIONS IN
POSTEROLATERAL TIBIAL CONYLE AND LATERAL ASPECT OF INTERCONDYLAR
SULCUS OF FEMUR.ALSO SEEN ARE VERTICAL TEAR OF POSTERIOR HORN OF
LATERAL MENISCUS AND GRADE-2 SPRAIN OF ARCUATE LIGAMENT
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Fig. 2: FINDINGS:SAGITTAL T2 FAT-SAT IMAGE SHOWS AVULSION OF ACL AT
ITS TIBIAL ATTACHMENT,INJURED POSTERIOR CAPSULE,COMPLEX TEAR OF
POSTERIOR HORN MEDIAL MENISCUS ,SIGNIFICANT EDEMA IN POSTERIOR
SOFT TISSUES
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Fig. 3: CASE 2:ROAD TRAFFIC ACCIDENT,HIT BY CAR FROM SIDE.
FINDINGS:CORONAL T2 FAT-SAT IMAGING SHOWS ILL DEFINED SUBCHONDRAL
EDEMA ON LATERAL FEMORAL CONDYLE,AND ON THE MEDIAL FEMORAL
CONDYLE AT THE LEVEL OF MCL ATTACHMENT.ALSO NOTED IS FLUID AROUND
THE INTACT MCL(GRADE-1 SPRAIN)
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Fig. 4: CASE 3:HISTORY OF KNEE INJURY WHILE PLAYING FOOTBALL.
FINDINGS:SAGITTAL T2 FAT-SAT IMAGE SHOWS EDEMA IN ANTERIOR ASPECT
OF FEMORAL CONDYLE AND TIBIAL TUBEROSITY.TORN ACL MIDBODY FIBRES
AND SIGNIFICANT INFLAMMATORY CHANGES IN POSTERIOR SOFT TISSUES
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Fig. 5: CASE 3B:CORONAL T2 FAT-SAT IMAGE SHOWS DEPRESSION FRACTURE
OF MEDIAL TIBIAL PLATEAU,AND SUBCHONDRAL EDEMA IN FEMORAL
CONDYLE,ALSO NOTED IS DISRUPTED MEDIAL COLLATERAL LIGAMENT.
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Fig. 6: CASE 4:HISTORY OF FALL FROM BIKE IN A ROAD TRAFFIC ACCIDENT.
FINDINGS:SAGITTAL T2 FAT-SAT IMAGE SHOWS SIGNIFICANT EDEMA IN THE
ANTERIOR TIBIA,COMPLETE AVULSION OF POSTERIOR CRUCIATE LIGAMENT
AT ITS TIBIAL ATTACHMENT,POSTERIOR CAPSULAR STRAIN AND SIGNIFICANT
INFLAMMATORY CHANGES IN POSTERIOR SOFT TISSUES
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Fig. 7: CASE 5:HISTORY OF KNEE PAIN SUDDENLY WHILE BENDING,WITH
SIMILAR PREVIOUS ATTACKS. FINDINGS:AXIAL T2 FAT-SAT IMAGE SHOWS
CONTUSIONS IN INFERIOMEDIAL PATELLA AND LATERAL FEMORAL
CONDYLE, SHALLOW TROCHLEAR GROOVE,OSTEOCHONDRAL FRACTURE IN
MEDIAL PATELLAR FACET,DISRUPTED MEDIAL RETINACULUM,INFLAMMATORY
CHANGES IN PREPATELLAR SOFT TISSUES
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Conclusion
Imaging of acute injuries around knee joint is best done with MR imaging,to characterise
involved bones and soft tissues.
Contusions and fracture patterns are like road maps towards associated soft tissue
injuries.
Pattern recognition can be used as a guidance for reporting ,increased accuracy and to
avoid missing of subtle injuries.
Personal information
References
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