MR KNEE ORTHOPAEDIC PERSPECTIVE

VIRTUAL ARTHROSCOPY

DR RITESH MAHAJAN MD MERCURY IMAGING INSTITUTE

SCO 172-173 SEC 9C CHANDIGARHMERCURY IMAGING CENTRE

SCO 16-17 SEC 20D CHANDIGARH

• MR KNEE – MAXIMALLY WRITTEN EXAMINATION

• 90 TO 95% - MENISCAL TEARS• 100% - CRUCIATE INJURIES

CRUCIATE

COLLATERAL

OSSEOUS

NORMAL MENISCUS

MENISCUS

• GRADE

KEEP THE HOLISTIC ALIVE

ATTEMPT TO PROGNOSTICATE DEFINE THE ETIOLOGY DIFFERENTIATE DEGENERATION & TRUE TEAR ANCILLIARY FINDINGS AWARE OF THE PITFALLS

MENISCAL SAVING- SUTURESDEBDRIDEMENT

TEAR DEGENERATION

BOW-TIE

• PRESENT • EXAGGERATED• ABSENT

CHILDRENELDERLYARTHRITICPOST INTERVENTION

DISKOID MENISCUS

5 mmx 3 4 mm x 3

BUCKET HANDLE

ABSENT BOW TIE SIGN

SIGNS……………..

DOUBLE BOWTIE DOUBLE PCL

MEDIALLY FLIPPED MENISCUS ANTERIORLY FLIPPED MENISCUS

PITFALLS

RADIAL IMAGING

NORMAL ACL

ACL

ACUTECHRONIC

ACL CYST

POSTERO-LATERAL CORNER INJURY

NORMAL PCL

PCL TEAR

NORMAL MCL

MCL

MENISCOCAPSULAR SEPARATION

NORMAL LCL

LCL

BEFORE ARTHROSCOPY…….

GOOD LOOK AT POSTERIOR HORN OF THE LATERAL MENISCUS

GOOD LOOK AT PERIPHERY OF THE MENSICI GOOD LOOK AT ANCILLIARY FINDINGS

POST INTERVENTION

ROUTINE MRHETEROGENOUS HOFFA’S FAT PAD - ARTHRFIBROSIS

ORIENTATION OF THETIBIAL GUTTER PARALLEL TO INTERCONDYLAR NOTCH MR ARTHROGRAM

NORMAL PATELLA

PATELLA

NORMOGRAMS

DYNAMIC PATELLAR TRACKING

KISSING CONTUSIONS LAX MEDIAL PATELLAR RETINACCULUM

ILIOTIBIAL BAND SYNDROME

BONE CONTUSION• APPPRECIATE• DIFFERENTIATE • PROGNOSTICATE

OSTEOCHONDRITIS DESSICANS

STABLE - UNSTABLE

OSTEOCHODRAL FRACTURE FRAGMENT

SPONTANEOUS OSTEONECROSIS OF KNEE

GEOGRAPHIC AREAS WITH NARROW ZONE OF THE TRANSITION. MEDIAL CONDYLE/

TIBIAL PLATEAU- WEIGHT BEARING AREAS INVOLVED.

POSITIVE CRESCENT SIGN APPRECIATED AS PARALLEL SUBCHONDRAL HYPERINTENSITY IN TIBIOFEMORAL

ARTICULATIONS.

GEOGRAPHIC DISTRIBUTION OF

THE LESIONS IN EITHER SIDE

FEMORAL CONDYLES AND TIBIAL PLATEAU

REGION

EITHER SIDE FEMORAL CONDYLES AND TIBIAL PLATEAU HAS LESIONS

HETEROGENOUS CONTENTS IN THE CORE OF THE LESIONS

CORROBORATIVE WITH ? HAEMORRHAGE

PRODUCTS ? NECROTIC DEBRIS.

EITHER SIDE FEMORAL CONDYLES

INVOLVED

TIBIAL GUTTER AND EITHER SIDE TIBIAL PLATEAU INVOLVED

BURSAE

PES ANSERINUS BURSITIS

BONE ISLAND

EXOSTOSIS

PVNS

ARTHRITIS

LOOSE BODY

MR - ARTHROSCOPY

• MEDIALLY FLIPPED MENISCUS• DISKOID CAN IMPAIR VISION• PERIPHERAL TEAR PRONE TO BE MISSED • POST ARTHROSCOPY PAIN

ANY BODY CAN HAVE THE FACTS,BUT HAVING AN OPINION IS AN ART&

MEDICINE IS AN ART

CASE REVIEW- ORTHOPAEDICS

25 Yr male with Acute Spontaneous onset of pain and

swelling both knee joints (since Feb 2010) – Recurrent symptoms

left knee.

MR PROTOCOL……….

• USE BODY COIL FIRST• USE SURFACE COIL NEXT• OBTAIN CORONAL OR SAGGITAL FIRST• AXIALS TO FOLLOW• DYNAMIC CONTRAST BETTER THEN

CONVENTIONAL

• CONVENTIONAL RADIOGRAPH

• RADIONUCLEIDE IMAGING

• MRI

• CONCEPT OF CAPSULE• CONCEPT OF COMPARTMENT

• INTRA CAPSULAR• EXTRA CAPSULAR• INTRA COMPARTMENT• EXTRA COMPATMENT

LET”S NOT SHY TO KEEP ANATOMICAL ATLAS CLOSE BYWHILE REPORTING

EDEMA ? TUMOR?

• FEATHERY APPEARANCE• INTER MUSCLE FASCIAL PLANE• FAT MARBELING OF MUSCLES• MASS EFFECT• NORMAL TEXTURE SIGN

CODMAN’S ANGLE

• INCONTINUOUS PERIOSTEAL REACTION• TUMOR: BLOOD:PUS

THIS CASECHEST SKIA GRAM ?

RADIOGRAPH OF LESION?(NON SPECIFIC)

EXTRA COMPARTMENTINTRA CAPSULAR

CENTRIFUGAL CODMANS ANGLE

LOBULATEDLOW SIGNAL/ MODERATE ENHANCEMENT

SEGOND’S FRACTURE

FRACTURES

OS GOOD SCHELTER’S DISEASE

Tears in the red zone of the meniscus may be treated with a variety of meniscus-preserving techniques (eg, suture repair); by contrast, tears in the white zone of the meniscus typically are treated by means of débridement (3,7). It also is important to identify a tear located in the red zone because the prognosis associated with such a tear is superior to that associated with tears in the white zone, regardless of whether white-zone tears are treated surgically (4–6).

Post Arthroscopy• Appreciate the entry ports • Anterior portal ( patellar tendon)

– Heterogenous hoffa’s fat pad• Recurrent – residual meniscal

pathology – consider MR arthrogram

• Symptomatic post arthroscopy – recurrent / residual pathology – Necrotic changes in the bones.

Meniscal morphology• Diskoid meniscus ( lateral

>Medial).• Diskoid meniscus – impairs

complete evaluation through single anterior appraocah

• Radial diametre > 12mm Diagnostic ( Sagittal 5mm thick scans – three section)

Meniscal ossicles/ calcification

• Mesenchymal differential• Hypointense intrasubstance

signal

• Cruciate and collateral ligamentous act synergistically to stabilize the joint.

G

ACL• Image in external rotation / oblique

image • Double echo • ACL TEAR – ancilliary findings • Anterior tibial subluxation > 5mm with

respect to fibula • Posterior dislocation to posterior horn of

tibia.• Kissing contusion – Posterolateral tibial

plateau , anterior and middle femoral condyle

• Chronic ACL tear – Slumping of distal fragment over tibial spine.

• Intact lateral segment and slumping medial fragment

Post ACL repair • MR – Both osseous and

intraarticular components seen

• ARTHROSCOPY – Limited to anterior graft surface.

PCL• GRADE ONE –

INTRALIGAMENTOUS HAEMORRHAGE / EDEMA

• GRADE TWO – PARTIAL TEAR• GRADE THREE –COMPLETE

TEAR• BONY CONTUSIONS –

LATERAL FEMORAL CONDYLE , ANTERIOR TIBIAL PLATEAU.

MCL• SUPERFEICIAL / DEEP PART - 8 TO

10CM LONG SPAN FRON MEDIAL FEMORAL EPICONDYLE TO MEDIAL TIBIAL METAPHYSIS.

• MCL DEEP TO PES ANSERINUS TENDON AND AWA FROM THE JOINT LINE.J

• O “DONOGHUE’S TRIAD- TEARS OF ACL /MCL/MEDIAL MENISCUS

• GRADE ONE – INTTRASUBSTANCE EDEMA/ HAEMORRHAGE

• GRADE TWO –PARTIAL TEAR• GRADE THREE – COMPLETE TEAR

LCL

• ILIOTIBIIAL BAND/ TENDON OF BICEPS FEMORIS/RETINACULUM / ARCUATE LIGAMENT.

• EXTENDS FROM LATERAL FEMORAL EPICONDYLE EXTENDS INFERIORLY & JOINS TENDON OF BICEPS FEMORIS TO FORM CONJOINT TENDON INSERTING ON FIBULAR HEAD.

• SEGOND FRACTURE – AVULSION FRACTURE OF LATERAL CAPSULE AT IT’S TIBIAL INSERTION SITE.

• ASSOCIATION WITH ACL TEAR

PATELLAR TENDON

• CHRONIC STREEE OVER INSERTION SITE – PAIN/ INFLAMMATORY REACTION IN REGION OF TIBIAL TUBEROSITY – OS GOOD-SCHLATTER DISEASE.I

• LOSS OF NORMAL TONE – DEGENERATION TENDNITIS

BONY INJURIES• TYPE I – MEDULLARY EDEMA –

IGNORED CAN LEAD TO IMPACTIO FRACTURES.

• TYPE 2 – CORTICAL BREAK/ INTERUPPTION . INDENTATION APPRECIATED IN THE ROUND , SMOOTH , CONTOUR OF THE ARTICULAR SURFACE OF THE BONE . INTRAARTICULAR FAT MAY BE APPRECIATED

• TYPE THREE – SUBCHONDRAL DEGENERATIVE SCLEROSIS.H

OSTEOCHONDRITIS DISSECANS• FRAGMENTATION OF THE CORTICAL

BONE • LATERAL ASPECT OF THE MEDIAL

FEMORAL CODYLE• USUALLY UNILATERAL , YOUNG

INDIVIDUALLS, LOOSE BODIES.• DISPLACED / NON DISPLACED

CORTICAL FRAGMENT • STABLE / UNSTABLE CORTICAL

FRAGMENT - >1CM SIZE, FLUID DEEP TO THE FRAGMENT, INCREASED BONY UPTAKE ON BONE SCAN. INTERUPPTED ARTICULAR CARTILAGE REPRESENT UNSTABLE FRAGMENT.

OSTEONECROSIS• SPONTANEOUS

OSTEONECROSIS • POST TRAUMATIC

OSTEONECROSIS• DOUBLE LINE SIGN ON T2W • OSTEOCYTE NUTRITION IS

COMPROMISED

CHONDROMALACIA• CARTILAGE AND MENISCI

INCRESE THE EFFECTIVE CONTACT BETWEEN THE ARTICULAR SURFACES

• CARTILAGE CAN TAKE UP 5 TIMES THAN THE NORMAL PRESSURE – ANY THING MORE THAN THAT CAN LEAD TO CHONDROMALACIA

MR GRADING OF CHONDROMALACIA

• 1- SURFACE INTACT ( FOCAL THICKENING/ MR SIGNAL CHANGE <10MM)

• 2-SURFACE FISSURE ( IRREGULAR SURFACE WITHOUT COMPLETE CARTILAGE LOSS >10MM<25MM)

• 3- EXPOSED BONE ( FULL THICKNESS LOSS OF CARTILAGE WITH JOINT FLUID CONTACTING BONE). ( >25MM)

•

PATELLAR MALTRACKING / MAL ALIGNMENT

• Any malalignment/ maltracking occur only during early 5 to 30 degrees of flexion.

• Kinematic imaging with or without load ( dynamic imaging).

• Patella alta ( inferior pole of the patella placed high in relation to the trochlear groove)

• Patella baja / infera (inferior pole of the patella is positioned below the trochlear groove).

Patellar shape ( wiberg)• Type 1 – Both lateral and

medial facet are equal and concave .

• Type 2 – Medial facet is smaller than the lateral facet .

• Type 3 – Medial facet is significantly small in comparison to the lateral facet.

Normal patellar alignment / tracking

• Ridge of the patella is placed in the centre of the trochlear goove all thorugh the flexion.

• Flexion movement – forces act on the patellofemoral joint. ( Retinaculum , quadriceps tendon )

• Extension – no forces act of the patella ( any deviation is pseudosubluxation)

• Excessive lateral patellar syndrome/ lateral patellar tilt .

• Medial subluxation of the patella ( patello adentro)

• Lateral to medial subluxation

•

Pictures• Patella alta / baja• Vastus lateralis• Patellar tracking• Forces around patella.

Periarticular fluid collections Bursae - Glide planes ( lubricating) • Semimemberanous – semitendinosus

bursae – popliteal / baker’s bursae.• Tendon of pes anserinus / superficial

MCL ( Pes anserinus bursae)• MCL and semimemberanous tendon• Semimemberanous and medial

epicondyle of the femur• Medial head of the gastrocnemius

and posteromedial capsule – often communicating with the joint space.

• Pes anserinus bursitis – fluid present medial to pes tendons ( sartorius / gracialis/ semitndinosis)

MASSES • OSTEOCHONDROMA - CARTILAGE CAP.

( <1CM)• OSTEOID OSTEOMA - CENTRAL NIDUS

WITH CALCIFIED LESION WITH PERILESIONAL EDEMA ( IF TRABECULAR) , PERILESIONAL SCLEROSIS ( IF CORTICAL).

• BONE ISLAND• ENCHONDROMA – MATRIX

CALCIFICATION• PVNS – MONOARTICULAR , MULTIFOCAL,

RARELY CALCIFIED. HAEMOSIDERIN STAIN OF SYNOVIUM

• SYNOVIAL CHONDROMATOSIS – METAPLASIA OF SYNOVIUM – CHONDRAL ISLANDS – LLOOSE BODIES

INFLAMMATION• PANNUS – ISOINTENSE TO

THE FLUID- CEMR HELPS TO DIFFERENTIATE THE PANNUS FRO JOINT FLUID.

SONK (Spontaneous osteonecrosis of the knee joint)

• Age =40 to 60 years of age.

• Unknown etiology • Steroid

Haemoglobinopathy Transplant Fracture.

• Medial femoral condyle – common

• Lateral femoral condyle –less frequent

• Both together – Rare.

• Cortical flattening• Subchondral cyst/

sclerosis.• Crescent sign –Linear cleft

immediately below and parallel to the involved cortex is visible ( representing subchondral fracture)

• Loose bodies - later stage.

SPONTANEOUS OSTEONECROSIS

• AGE = 40 to 60 years • Medial condyle wt bearing

surface1. Flattening - Present2. Collapse- Present3. Sequesteration- Present4. Loose body- Present5. Joint degeneration-Present

OSTEOCHODRITIS DISSECANS

• AGE < 20 yrs • Medial condyle non wt

bearing surface1. Flattening - absent2. Collapse- absent3. Sequesteration- Present4. Loose body- Present5. Joint degeneration-absent.

Lessons learnt......................

Corelation with conventional Radiographs important

Look for step defect ( lucency in the subcortical location) on radiographs especially in wt bearing areas.

Crescent sign and flattening of the Cortical contour appreciated on MR .