34 y.o. with knee pain

50 y.o with knee pain

20y.o. with knee pain

MRI of the KneeNancy M. Major

Technique• Extremity coil• Extension / 5-10º external rotation• Short TE images

– menisci, PCL• Sagittal, axial, coronal T2WI (FSE, GRE)

– edema, fluid collections, ligaments, tendons, cartilage

Knee MRI• Menisci

• Ligaments

• Patella dislocation

• Cartilage

• Bursae

Menisci• Dense fibrocartilage• Medial

– tightly attached to MCL and tibia

• Lateral– loosely attached to

tibia– superior and

inferior fascicles

Medial Lateral

Normal Meniscus

• Low signal• Body segments• PHMM to AHMM

– 30-50% larger– 10-30% higher

• PHLM=AHLM

Bucket handle tear

Flap tear

Body Segments• Too few

– Bucket-handle tear•displaced fragment•double PCL sign

– Small•symmetric medial & lateral

– Mortar & pestle (OA)

Body Segments• Too many

– Discoid meniscus (lateral 3%)

– Large meniscus

Discoid meniscusDiscoid meniscus

Meniscal Tears• Knee pain• Traumatic or degenerative• Types

– oblique– radial– flap– bucket-handle

Meniscal Tears

• Sensitivity decreased with ACL tear

– Examine periphery

– Examine PHLM

Meniscus Pitfalls

• Transverse ligament

• Popliteus tendon

• Meniscofemoral ligaments

Transverse ligament

Popliteus tendon

Meniscofemoralligament

Meniscal cysts

• Intrameniscal (“swollen meniscus”)

• Parameniscal

• “Horizontal cleavage tear”

Intrameniscal cyst

Parameniscal cyst

ACL

• Linear low signal

• Contusion patterns– posterolateral tibia

and LFC

Pivot Shift Phenomenon

Near 100% assoc with ACL tear(Except adolescents)

Contra-coup Contusion

Medial Lateral

ACL

• ACL cyst– “drumstick”

appearance

– incidence 1%

Arthrofibrosis : Cyclops

• Low signal

• Uncommonly torn, often not

repaired

• Evaluate on short TE images

PCL

PCL

PCL tearT2 PD

PCL Tears

Rodriguez, et al. submitted ARRS 2005

32 arthro proven tearsAll increased signal TIWI32/32 thickened (> 7mm)32/32 no increased signal T298/100 (98%) nml < 7mm

•••••

• Low signal T2WI

• Adheres to MM

• Valgus stress

MCL

• Grade 1-fluid signal in ST medial to ligament

• Grade 2-high signal in and around ligament

• Grade 3-complete rupture

Collateral LigamentsMCL

• Meniscocapsular separation

– meniscus separated from attachment

to joint capsule

– fluid signal between meniscus and

capsule

MCL

LCL• Components

– Iliotibial band– Fibular collateral ligament– Biceps femoris tendon

• Less commonly injured than MCL– posterolateral corner injury

Anatomy diagram LCL

Iliotibial band

Coronal ITB

Fibular collateral ligament

Sagittal fib coll and biceps fem

Biceps femoris

Posterolateral Corner

• Lateral collateral ligament• Arcuate ligament• Popliteus tendon• Capsule• Additional small ligaments

(popliteofibular ligament)

Vinson EN, Helms CA. Journ Knee Surg 2005; 18:151-6

Patellar Dislocation• Lateral

• Medial retinaculum / VMO

• Cartilage defect

• Anterior LFC contusion

Patella dislocation

Cartilage

• Focal defects

• Loose bodies

Cartilage Delamination

Kendall et al. AJR 2005

• Characteristic MR appearance• Cartilage-bone interface (tidemark) • Poor prognosis• Requires extensive debridement• Common at arthroscopy

OCL Stability

• Fluid signal encircling fragment

• High signal in bone

• High signal in fragment

September

January

January 05

1 yr later

June

September, after microfracture

Bursae• Pes anserinus• Semimembranosis/tibial collateral

ligament (SMTCL)• Tibial collateral ligament• Baker’s cyst (not a true bursa)• Tib-fib

Baker’s cyst

SMTCL bursa

Summary• Menisci (evaluate body segments!)• Ligaments (ACL cyst,PCL short TE)• Patella dislocation• Cartilage (look for delamination)• Bursae (SMTCL)