mri knee what to see - dr shekhar...
TRANSCRIPT
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