knee red dot

8/12/2019 Knee Red Dot

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Anatomy

Image Evaluation

Fractures and Pathology

Pitfalls and Variants

Images

Case Study


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Made up of 3 bones - femur,the tibia and the patella

2 ligaments - medial and

lateral collateral ligaments,(stabilize the knee from side-

to-side), ACL and PCL

(stabilize the knee from front-to-back)

AP Knee


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Lateral Knee


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Skyline View

Source: Wikiradiography


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Ligament Origin Insertion Function

Medial CollateralLigament (MCL)

Medial Epicondyleof Femur Superior Tibia

The MCL protects the medialside from a valgus force.

Lateral CollateralLigament (LCL)

Lateral Epicondyleof Femur Head of Fibula

The LCL protects the lateralside from a varus force

Anterior CruciateLigament (ACL)

Lateral Condyle ofFemur

Tibia Plateau (anteriorintercondylar area)

The ACL prevents anteriordisplacement of the tibia

relative to the femur.

Posterior CruciateLigament (PCL)

Medial Condyle ofFemur

Tibia Plateau (posteriorintercondylar area)

The PCL prevents posteriordisplacment of the tibia

relative to the femur.

Arcuate Ligament Lateral Epicondyle &Condyle of Femur Medial Fibular headStrengthens the joint capsule

posteriorlaterally.

Oblique PoplitealLigament Medial Tibial

Condyle Lateral Femoral Condlye

A recurrent expansion of thetendon of the

semimembranosus thatreinforces the joint capsule

posteriorly.

Patellar Ligament Apex of the Patella Tibial Tuberosity

A very strong, thick fibrousband that helps maintain

alignment of the patella and

the way it articulates on thesurface of the femur.


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A bursa is a fluid-filled structure that is present betweenthe skin and tendon or tendon and bone to reducefriction between adjacent moving structures.


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Methode 1:

The lateral

condylopatellar

sulcus(arrowed) @ lateralfemoral notch,

distinguishes the lateral

femoral condyle from the

medial femoral condyle.


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Methode 2:

The most reliable method

for identifying the medial

condyle is to locate therounded bony tubercle

(black arrow) known as

the adductor tubercle.


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On AP, a

perpendicular linedrawn at the mostlateral margin offemoral condyle

should not havemore than 5 mm ofthe lateral margin oftibia condyle outside

of it


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>5mm

Tibia plateaufracture


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1. Lateral split.

2. Split with depression.

3. Pure lateral depression.

4. Pure medial depression.

5. Bicondylar.

6. Split extends tometadiaphyseal region


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The patellar tilt angle is

formed by a line drawn

across the anterior limits of

the femoral condyle and aline connecting the apex of

the patellar articular surface

(lateral)+ve angle = normal

00 or ve angle = abnormal


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Alta Baja


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Alternative to Insall-Salvati ratioA horizontal line at the level of the tibial

plateau is drawn. Perpendicular to this

line vertically and a measurement ( B)

made of the distance between thehorizontal line and the inferior aspect of

the patellar articular surface. A second

measurement ( A) is made along the

patellar articular surface.B/ A is a measure of patellar height

Normal value = ratio of 0.8.

Patella alta = ratio >1.0


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Identified by significant patella alta blurring of the posterior

margin of the patellartendon in to Hoffas fat

pad

presence of an avulsionfracture


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This patient has had an unknown injury to the knee causing

rupture of the quadriceps femoris tendon. Note the unusual low position and forward tilting of the patella. The quadriceps tendon which is usually visualised contrasted

by the suprapatellar fat body is not demonstrated(arrow)


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Lines drawn along the lateral patellar facet and the

anterior margins of the femoral trochlea.

The lateral patellofemoral angle should be open laterally.


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Line BD should be equal or medial to the bisector line BD.

If it is lateral (as in this case), patellar subluxation can be

confirmed.


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Yellow = Hoffa's fat pad

[largest]

Blue = Posterior

suprapatellar fat pad

Red = Anterior

suprapatellar fat pad


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If suprapatellarpouch (bursa)> 5mm jointeffusion

Normal appearance


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Appears as well-defined rounded homogeneous soft tissue density

within the suprapatella recess.

Will displace the quadraceps tendon and patella anteriorly.

Can result from inflammation, infection or trauma and may be an

exudate, transudate, blood or fat.


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A particular type of effusion that occurs inintra-articular fracture.

A fat-fluid level is seen due to marrow fat

leaking into the joint space via the fracture.


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(a) Transverse (usually in

central or distal third of

the patella)

(b) Vertical

(c) Marginal

(d) Comminuted

(e) Osteochondral

(f) Sleeve


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Transverse fracture Vertical fracture


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Marginal fracture fracture of edge of thepatella, do not extend acrosspatella

Comminuted fracture


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Osteochondral fracture: An immediate fracture around the point of contact, separating a single

fragment that includes articular cartilage, subchondral bone, and

supporting trabecular bone.


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Sleeve fracture Chondral or osteochondral avulsion injury at the inferior pole of the patella. Occur in the pediatric population, typically between 8 - 12 years old. Result from sudden and forceful contraction of quadriceps.


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(A)An avulsion fracture between ligament and bone and

(B) An osteochondral fracture between the articular cartilages;

(C)Following patellar relocation, the osteochondral fragment

resulting from the fracture is located between the lateral facet of

the patella and the lateral femoral condyle.


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- Fracture at the superior pole of the patella


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May involve one or both condyles.

Usually associated with high impaction.

Usually associated soft tissue injury due to disruption

of ligamentous attachments.

Mechanism of injury: axial loading with varus/

valgus force


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Type A: extra-articular fracture

Type B: partial articular fracture

Type C: complete articular fracture


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Often associates with soft tissue injury

Caused by varus/valgus load with/without axial

load

Frequency :

lateral (60%)> bicondylar (25%)> medial(15%)

Partial or complete ligamentous ruptures occur in

about 15-45% & meniscal lesions in about 5-37% of

all tibia plateau fracture.

http://www.wheelessonline.com/ortho/tibial_plateau_fractures
http://www.wheelessonline.com/ortho/tibial_plateau_fractureshttp://www.wheelessonline.com/ortho/tibial_plateau_fractures


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1. Lateral split.2. Split with depression.3. Pure lateral

depression.4. Pure medialdepression.5. Bicondylar.6. Split extends tometadiaphyseal region


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60% of plateau fractureinvolve lateral plateau.

This probably is result ofvalgus alignment of lowerextremity and fact thatmost injuring forces aredirected laterally tomedially.


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Segond fracture

Reverse Segond fracture

Anterior cruciate ligament avulsion fracture

Posterior cruciate ligament avulsion fracture

Arcuate complex avulsion fracture

Biceps femoris avulsion fracturePellegrini Stieda disease (MCL tear)

http://radiopaedia.org/articles/avulsion-fractures-of-the-knee
http://radiopaedia.org/articles/avulsion-fractures-of-the-kneehttp://radiopaedia.org/articles/avulsion-fractures-of-the-kneehttp://radiopaedia.org/articles/avulsion-fractures-of-the-kneehttp://radiopaedia.org/articles/avulsion-fractures-of-the-kneehttp://radiopaedia.org/articles/avulsion-fractures-of-the-kneehttp://radiopaedia.org/articles/avulsion-fractures-of-the-kneehttp://radiopaedia.org/articles/avulsion-fractures-of-the-kneehttp://radiopaedia.org/articles/avulsion-fractures-of-the-kneehttp://radiopaedia.org/articles/avulsion-fractures-of-the-kneehttp://radiopaedia.org/articles/avulsion-fractures-of-the-knee


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Avulsion fracture of the

lateral tibial plateau

75% associated with

disruption of ACL

Occurs as a result of internal

rotation and varus stress

http://radiopaedia.org/articles/segond-fracture
http://radiopaedia.org/articles/segond-fracturehttp://radiopaedia.org/articles/segond-fracturehttp://radiopaedia.org/articles/segond-fracturehttp://radiopaedia.org/articles/segond-fracture


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Involves a fragment similar to that of the Segondfracture except that it is located on the medial

aspect of the proximal tibia.

Represents an avulsion of the deep capsular

component of the medial collateral ligament

Mechanism of injury: external rotation and a valgus

stress applied to the knee


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http://radiopaedia.org/cases/diagram-classification-of-acl-avulsion-fractures-1

Type 1 - minimally/non-displaced fragment

Type 2 - anteriorelevation of the fragment

Type 3 - completeseparation of thefragment. 3b - Involvesthe majority of theeminence.

Type 4 - comminutedavulsion or a rotation ofthe fragment.
http://radiopaedia.org/cases/diagram-classification-of-acl-avulsion-fractures-1http://radiopaedia.org/cases/diagram-classification-of-acl-avulsion-fractures-1http://radiopaedia.org/cases/diagram-classification-of-acl-avulsion-fractures-1http://radiopaedia.org/cases/diagram-classification-of-acl-avulsion-fractures-1http://radiopaedia.org/cases/diagram-classification-of-acl-avulsion-fractures-1http://radiopaedia.org/cases/diagram-classification-of-acl-avulsion-fractures-1http://radiopaedia.org/cases/diagram-classification-of-acl-avulsion-fractures-1http://radiopaedia.org/cases/diagram-classification-of-acl-avulsion-fractures-1http://radiopaedia.org/cases/diagram-classification-of-acl-avulsion-fractures-1http://radiopaedia.org/cases/diagram-classification-of-acl-avulsion-fractures-1http://radiopaedia.org/cases/diagram-classification-of-acl-avulsion-fractures-1http://radiopaedia.org/cases/diagram-classification-of-acl-avulsion-fractures-1http://radiopaedia.org/cases/diagram-classification-of-acl-avulsion-fractures-1http://radiopaedia.org/cases/diagram-classification-of-acl-avulsion-fractures-1


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Most common in children between ages of8-14 years

Usually result from avulsions of anterior

intercondylar eminence from pull of ACL

Caused by hyperflexion of the knee with

tibial internal rotation, or hyperextension ofthe knee.


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White arrow - capsular

avulsion fracture,

termed a Segond #.

Segond # are highlyassociated with ACL

tears.

Black arrow - avulsion #

of the tibial spines,

indicates ACL injury.


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Fracture of the posterior tibia

eminence

Less common

Caused by sudden

hyperextension of the knee or

a violent posterior

displacement of the tibiawhile the knee is in flexion.


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The arcuate sign describes an avulsed bone fragment relatedto the insertion of the arcuate complex at the fibular styloidprocess.

The avulsed bone fragment appears as an elliptic piece of bonearising from the fibular styloid process with its long axis orientedhorizontally on the AP knee


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Difficult to distinguish an avulsion fracture of the fibular head fromthat of the arcuate sign

Compare to appearance of arcuate sign, avulsion fracture ofthe biceps femoris tendon appears simply as an irregular bone

fragment arising from the fibular head


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Uncommon

Calcification of MLC may occur after

MLC tear, known as Pellegrini Stieda

disease


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Post traumatic ossification in or near the medial collateral ligament near

the margin of the medial femoral condyle


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Chronic avulsion injury related to

repetitive microtrauma and traction on

the tibial tubercle by the patellar tendon

Always occurs in adolescent athletes

performing activities that require jumping& kicking

X-ray: reveal fragmentation anterior to

the tibial tubercle, soft-tissue swelling, and

obliteration of the inferior angle of the

infrapatellar fat pad

Mainly a clinical diagnosis rather than a

radiographic one


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Osteochondrosis involving the apex of

patella

Usually seen in active adolescents between

10-14 years old

Calcification and ossification seen at inferiorpole of patella

X ray: small bony fragments adjacent to the

distal surface of patella with overlying soft

tissue swelling

Further evaluation with MRI is necessary to

distinguish this from patella sleeve fracture

http://www.pedsradiology.com/Historyanswer.aspx?qid=140&fid=1
http://www.pedsradiology.com/Historyanswer.aspx?qid=140&fid=1http://www.pedsradiology.com/Historyanswer.aspx?qid=140&fid=1


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Sub-articular, post traumaticnecrosis

Result of aseptic separation of an

osteochondral fragment withgradual fragmentation of the

articular surface

Commonly caused by direct blow

85% seen at medial condyle, 15%

at lateral condyle

http://radiopaedia.org/articles/osteochondritis_dissecans
http://radiopaedia.org/articles/osteochondritis_dissecanshttp://radiopaedia.org/articles/osteochondritis_dissecans


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An uncommon disease in which there is metaplasia

of the synovial lining of joints, bursae or tendons

into cartilaginous nodules

The nodules may detach and become loosebodies in the joint

As the loose bodies receive their nourishment from

the synovial fluid, they may continue to grow eventhough floating in the joint

http://www.learningradiology.com/archives06/COW%20209-Synovial%20Chondromatosis/synchondromatosiscorrect.htm
http://www.learningradiology.com/archives06/COW%20209-Synovial%20Chondromatosis/synchondromatosiscorrect.htmhttp://www.learningradiology.com/archives06/COW%20209-Synovial%20Chondromatosis/synchondromatosiscorrect.htmhttp://www.learningradiology.com/archives06/COW%20209-Synovial%20Chondromatosis/synchondromatosiscorrect.htmhttp://www.learningradiology.com/archives06/COW%20209-Synovial%20Chondromatosis/synchondromatosiscorrect.htmhttp://www.learningradiology.com/archives06/COW%20209-Synovial%20Chondromatosis/synchondromatosiscorrect.htm


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Multiple exostoses / osteochondromas whicharise from the metaphyseal region and point

away from the joint.

Usually asymptomatic, but can become large

and may fracture.

May become malignant, particularly if located

axially rather than from a long bone.


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Most common benign tumour in pediatric

A benign lytic lesion often seen at the distal femur

and proximal tibia.

Large fibrous cortical defect (>2cm) located within

the diametaphyseal region of a long bone.

Appears as metaphyseal eccentric "bubbly" lyticlesion surrounded by sclerotic rim.

http://radiopaedia.org/articles/non-ossifying_fibroma
http://radiopaedia.org/articles/non-ossifying_fibromahttp://radiopaedia.org/articles/non-ossifying_fibromahttp://radiopaedia.org/articles/non-ossifying_fibromahttp://radiopaedia.org/articles/non-ossifying_fibroma


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The fragment margins appearsmooth

The fragment will not fit back(like a broken biscuit) to makea normal smooth contouredpatella

Differential diagnosis:

Sinding-Larsen-Johanssondisease

patellar sleeve fracture

osteochondral fracture.


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Bipartite patella Tripartite patella


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Os Cyamella(Embedded in thepopliteus tendon)

Adjacent to Fibular Head


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Meniscal Ossicles(occur usually in the

medial aspect)


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An accentuated groove for thepatellar tendon

Differential diagnosis: erosion


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The epiphyseal region of the tibial head forms a beak-shaped

process that extends downward anteriorly over the tibia at itsdistal end.

There is an isolated ossification center which forms the tuberosity. DDx: Osgood-Schlatter disease


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May be mistaken as avulsion fracture of the tibial tuberosity

or Osgood Schlatter disease


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An old injury (or injuries) to

the medial collateral

ligament (MCL).

A form of myosotis

ossificans soft tissue

calcification.

Located within the

superior attachment ofthe medial collateral

ligament

Mimics #


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1. pedestrian struck by car head injury ? left humerus fracture


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1. pedestrian struck by car head injury ? left humerus fracture


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Mildly displaced fractures of the (L) distal femur, lateral tibial condyle of the(L) proximal tibia and (L) proximal fibula are seen. A sizeable (L) suprapatellar

effusion is noted, associated with soft tissue swelling.


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2. No clinical diagnosis


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Fracture, (L) patella. Bony density along the medial tibial plateau isnoted, with lucency in the medial tibial spine, suspicious for anotherfracture. A (L) suprapatellar joint effusion is noted, along with soft tissue

swelling of the (L) knee.

3.


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There is a minimally depressed (0.2 cm) fractureof the medial tibial plateau with condensationof the trabeculae extending from the

metaphyseal region to the intercondylar region.Non-depressed fracture of the medial tibialplateau extending to its articular surface is alsopresent.ConclusionSchatzker Type V fracture

4. rt knee pain and swelling


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4. rt knee pain and swelling


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Prominent anterior tibial tubercle is commonly seen in patient with OsgoodSchlatter's disease.No evident cortical break or fracture line seen.There is obliteration of the suprapatellar fat space suggestive of joint space

effusion.

6. JUMPED AND LANDED IN FULL EXTENSION ON LEFT LL, NOW WITH LEFT KNEEPAIN AND SWELLING


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6. JUMPED AND LANDED IN FULL EXTENSION ON LEFT LL, NOW WITH LEFT KNEEPAIN AND SWELLING


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Lateral tibial plateau fracture suspected. Repeat AP view suggested.A joint effusion/ haemoarthrosis associated.


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7. left knee pain with bruised


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7. left knee pain with bruised


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(L) suprapatellar effusion is noted.No fracture or dislocation is seen; the lucency across the lateral aspect of the

patella which appears well corticated is likely related to a bipartite patella.

8. left shin pain after fell into drain


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9. Right knee pain


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Cortical irregularity seen at the anterior aspect of the intercondylareminence suggests an avulsion fracture at the tibial insertion of the anterior

cruciate ligament. A small joint effusion is demonstrated.


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10. slipped and fel into drain. rt knee pain, limited rom


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There is suggestion of a fluid--fluid level seen in the supra-patellar pouch andthis may represent a lipo-haemarthrosis.

11. left knee


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11. left knee


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A radiolucent cortical lesion measuring 2.7 x 1.8cm in posterolateralmetaphyseal region of distal tibia, associated with narrow zone oftransition and sclerotic margin, likely to represent fibrous cortical defect(FCD).

12. laceration rt knee


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12. laceration rt knee


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No opaque foreign body or bony injury seen.Lucencies in the suprapatellar pouch and tibiofemoral joint are suspiciousfor intra-articular air from penetrating injury.


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-1.0x 0.4cm recent subchondral # w submeniscal chondral fissure of lat tibialplateau.- Mild chondromalacia noted at posterior aspect of lateral femoral condyle &inf patellar surface.


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Report: No fracture or dislocation is detected .


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# of the medialtibial plateau


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knee red dot

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