Dr. SHEKHAR SRIVASTAV Sr.Consultant – KNEE & SHOULDER

ARTHROSCOPY

MRI KNEE

WHAT TO SEE

MRI KNEE - WHAT TO SEE MRI is the most accurate and frequently used diagnostic tool for evaluation of internal derangement of knee.

MRI examination of knee consists of spin echo sequences obtained in sagittal, coronal and usually axial plane.

Sagittal cuts

most important

SAGITTAL CUTS

Cruciates

Meniscus

Cartilage

Extensor mechanism

CORONAL CUTS

Collaterals

Meniscus

Cartilage

AXIAL CUTS PATELLO-FEMORAL PROBLEMS

MRI Knee

Meniscus

ACL

PCL

Collateral ligaments

Patello femoral

Chondral defects

Misc.

Meniscus Normal anatomy

The normal meniscus shows uniform, low signal intensity (Black) Peripherally the meniscus have a bow- tie configuration

Centrally, the normal meniscus is composed of 2 separate triangular structures, the anterior horn and the posterior horn. The apices (free edges or inner margins) appear as sharp points of the triangle facing each other.

MRI grading system for

Meniscal Degeneration

GRADE 1 & 2 , NOT

SIGNIFICANT

GRADE 3 , SIGNIFICANT

MENISCUS TEAR

Types of Meniscal Tear

Three basic meniscal tear

Longitudinal

Radial

Horizontal

Longitudinal Tears

Longitudinal tears separate the meniscus into inner and outer fragments and occur parallel to the outer margin of the meniscus are perpendicular to the tibial plateau and propagate parallel to the circumferential axis of the meniscus

Radial tears ( Transverse

Tears) These are vertical tear

and propagate perpendicular to the main axis of the meniscus

Horizontal tear These tears are also called cleavage or fish- mouth tears

They divide the meniscal tear into a top ( superior) portion and a bottom ( inferior) portion

Most are degenerative, occurring in older patients with osteoarthritis.

Bucket- Handle Tears

These tears are displaced vertical longitudinal tears and usually involve the MM .

The separated central ( inner) fragment, when viewed axially, resembles the handle of a bucket The remaining larger peripheral portion of the meniscus resembles the bucket.

Typical locations of the displaced fragment include the intercondylar notch anterior and parallel to the PCL ( double PCL sign)

MRI criteria for

meniscal tears Two MRI criteria have been established for diagnosing meniscal tears.

Criteria 1 Criteria 1 is increased internal signal intensity in the meniscus

The abnormal signal intensity must be in contact with one articular surface, either the superior or interior surface or at the tip ( free edge) of the meniscus

Criteria 2 Criterion 2 is an abnormal meniscal shape

ACL The normal ACL appears on sagittal images as a solid band or as a striated band diverging slightly, ruler straight although mild sagging convex inferiorly can be present, especially with mild knee flexion.

The ACL shows low- to intermediate signal intensity , higher than that of the PCL.

ACL Tear – Primary Signs

– Secondary Signs

Primary signs of the ACL tear Disruption, increased signal intensity in the substance of the ACL on T2 weighted images, abrupt angulation or wavy

appearance and abnormal ACL axis. Nonvisualization or near nonvisualization with replacement be a cloud of focal edema and hemorrahage.

Secondary Signs of ACL Tear

Pivot - shift bone bruises and

osteochondral fracture

Anterior translocation of the tibia

Segond fracture

Anterior tibial spine fractures

Buckling of PCL

Pivot- Shift Bone Bruises

and Fractures

Secondary Signs of ACL Tear

Anterior Translocation of the Tibia

Avulsion fracture of the tibia at ACL insertion

Secondary Signs of ACL Tear

Segond

Fracture

Buckling

PCL

PCL

Major stabilizer of knee

Restrain against post. displacement Isolated –3%

Combined –97% – ACL injury - 65%

– MCL – 50%

– Medial Meniscus – 30%

– Posterior capsule and fibular collateral ligament

MRI Finding

Intrasubstantial tear

Partial tear

Complete tear

Avulsions

Collateral Ligaments Coronal images with anatomy defining and fluid-sensitive sequences demonstrate the

medial and lateral supporting structures optimally. Additional useful information can be gleaned from sagittal and axial images of

these structures

Chondral Defects

Degenerative

cartilage defects

Osteochondritis dissecans

Chondromalacia patellae

Osteochondritis Dissecans

Chondromalacia Patellae

Miscellaneous Meniscal cysts

Ganglion cyst

Discoid meniscus

Infections

PVNS

Extensor mechanism tear – Quadriceps tendon tear

– Patellar tendon tear

– Tibial tuberosity avulsion

Meniscal Cysts Ganglion Cysts

Discoid Meniscus

INFECTION

Tubercular

Hypointense Synovial

proliferation

Marrow Edema

Osteomyelitis

Abcess

Cortical erosion

Sinuses

PVNS Low signal changes

Synovial proliferation

Hemosiderin

deposition

Extensor Mechanism Tear

Quadriceps Tendon Tear

Patellar Tendon Tear

Tibial Tuberosity Avulsion

MRI – Very useful tool in hands of

Radiologists & Orthopedicians

Orthopedicians probably in a better position than Radiolologist

to read MRI

Visit www.delhiarthroscopy.com

Thank You

MCL Tear

Grade I Microscopic tear

Grade II Partial tear

Grade III Complete tear

LCL

LCL tear is seen as a

serpiginous or lax ligament

with discontinuous fibers (or

avulsed fibular head), often

without significant

thickening of the ligament.

LCL tears rarely are

isolated, and an LCL tear

becomes more likely as

associated PLC and

cruciate ligament injuries

increase in severity

Studies reported tt in diagnostic arthroscopy

51% (With use of MRI)

MRI accuracy in Meniscus & ACL Pathology > 90%

Difference in radiologist & arthroscopist opinion in

meniscal injury because

Different radiologist are at different level of the

learning curve and different arthroscopist have

different level of experience

Partial ACL Tear Partial tears of the ACL are common, accounting for 10-43% of all ACL tears

Direct signs may include focal angulation of the ACL or partial – thickness focal high signal intensity.

T2- weighted images allow more confident identification of abnormal focal high signal intensity in the ACL substance ( stoller, 1997).

MRI grading system for

Meniscal Degeneration

Grade I

Grade I is a nonarticular , focal or diffuse region of increased signal intensity within the substance of the meniscus .

Grade 2 Grade 2 is a horizontal , linear area of increased signal intensity within the substance of the meniscus that extends to but does not involve the articular surface.

.

Patients are usually asymptomatic

Meniscal Degeneration

Grade 3

Is a region of

abnormal signal

intensity within the

meniscus extending to

and communicating

with at least 1 articular

surface of the

meniscus Clinically Significant