mri of patellar disorders
DESCRIPTION
A short presentation on the practical issues related to the patellofemoral joint (subluxation, dislocation and incongruence) and chondromalaciaTRANSCRIPT
MRI of Patellar Disorders
Dr. Bhavin JankhariaJankharia Imaging
Patellar Disoders
PF Joint•How to diagnose acute subluxation / dislocation
and not to miss the diagnosis especially when the patella has reduced back
Patellar Disoders
PF Joint•How to diagnose acute subluxation / dislocation
and not to miss the diagnosis especially when the patella has reduced back
•How to evaluate PF incongruence
Patellar Disoders
PF Joint•How to diagnose acute subluxation / dislocation
and not to miss the diagnosis especially when the patella has reduced back
•How to evaluate PF incongruence•Chondromalacia
Acute Injury
PF Joint
Acute•Dislocation / subluxation•Retinaculum and medial patellofemoral ligament
tears•Chondral lesions
Marrow Edema Anterior Lateral Femoral Condyle
When marrow edema is seen in the anterior aspect of the lateral femoral condyle, our
antennae need to go up for the presence of an acute lateral patellar subluxation /
dislocation
Here the edema is straightforward….
….as are the associated lateral patellar tilt and subluxation (red arrow) and acute chondral defect (yellow arrow)
It is when the patella has reduced and the only positive finding is the marrow contusion (arrow)
that it becomes necessary to look at the patella and the medial patellofemoral ligament (MPFL), which is edematous, contused
and torn with subtle lateral patellar translation, best seen on the T2W axial MRI
A review of the anterior most STIR coronal images often will show marrow contusion of the medial patellar facet subjacent to
the attachment of the MPFL
The MPFL avulsion tear at the patellar attachment is along the inferior aspect (yellow arrow) with involvement of the whole MPFL up to the anterior femoral attachment of the medial collateral ligament (MCL) (blue arrow). Note the marrow contusion in the anterior LFC
(red arrow).
Sometimes, the MPFL injury may be a bony avulsion (red arrow)
The MPFL tear can also be at the femoral attachment (red arrow), in which case, often the anterior aspect of the femoral attachment of
the MCL (blue arrow) may be involved.
Chondral defects (red arrow) may occur due to the shear stress of the subluxation / dislocation and an effort should be made to look for
additional cartilage fragments (blue arrow)
PF Joint
Acute Subluxation / Dislocation•Marrow edema of the anterior LFC is a clue
PF Joint
Acute Subluxation / Dislocation•Marrow edema of the anterior LFC is a clue•If seen, look at the patellar marrow, cartilage, MPFL and congruence
Patellofemoral Incongruence
There are various parameters that we can use to assess PF
incongruence. They are listed in the next few slides
PF Joint
• Measurements–Patellar length
Chhabra et al. Skeletal Radiol (2011) 40:375 387
patellar tendon length / patellar bone long axis length greater than 1.3 usually
suggests patella alta
PF Joint
• Measurements–Patellar length–Translation
Chhabra et al. Skeletal Radiol (2011) 40:375 387
greater than 2 mm difference between the medial edges is considered significant
PF Joint
• Measurements–Patellar length–Translation–Abnormal tilt
Chhabra et al. Skeletal Radiol (2011) 40:375 387
Lateral patellar angle less than 8 degrees is significant. The angle
should open laterally.
PF Joint
• Measurements–Patellar length–Translation–Abnormal tilt–Trochlear sulcus depth
and lateral femoral condylar overgrowth
Chhabra et al. Skeletal Radiol (2011) 40:375 387
Trochlear depth of 3mm or less and trochlear angle greater than 145 degrees suggests trochear dysplasia / hypoplasia
PF Joint
• Measurements–Patellar length–Translation–Abnormal tilt–Trochlear sulcus depth
and lateral femoral condylar overgrowth
Lateral femoral condylar protrusion greater than 8 mm suggests overgrowth
PF Joint
• Measurements–Patellar length–Translation–Abnormal tilt–Trochlear sulcus depth
and lateral femoral condylar overgrowth
–Tibial tubercle - trochlear groove distance
Chhabra et al. Skeletal Radiol (2011) 40:375 387
Distance greater than 15mm suggests an abnormal TT-TG distance
PF Joint
• Measurements–Patellar length–Translation–Abnormal tilt–Trochlear sulcus depth
and lateral femoral condylar overgrowth
–Tibial tubercle - trochlear groove distance
Chhabra et al. Skeletal Radiol (2011) 40:375 387
PF Joint
• Measurements–Patellar length–Translation–Abnormal tilt–Trochlear sulcus depth and lateral femoral condylar
overgrowth –Tibial tubercle - trochlear groove distance–Superolateral Hoffa's fat pad signal, etc
Chhabra et al. Skeletal Radiol (2011) 40:375 387
Old PF Injury
In some patients with PF incongruence, a careful search often reveals evidence of old, perhaps undiagnosed lateral
patellar subluxation
This patient has PF incongruence with lateral patellar subluxation and abnormal tilt with a loose body (red arrow)
A careful review of the patient in the previous slide shows an old avulsion injury of the patellar attachment of the MPFL (red arrows)
Chondromalacia
Chondromalacia Patellae
• Cartilage softening, swelling, fibrillation in young patients
• Staging– Gd 1: softening,
swelling
Elias DA. Clin Radiol 2004; : 543
Chondromalacia Patellae
• Cartilage softening, swelling, fibrillation in young patients
• Staging– Gd 1: softening,
swelling– Gd 2: fragmentation,
fissuring upto 1.3mm
Elias DA. Clin Radiol 2004; : 543
Chondromalacia Patellae
• Cartilage softening, swelling, fibrillation in young patients
• Staging– Gd 1: softening, swelling– Gd 2: fragmentation,
fissuring upto 1.3mm– Gd 3: fissuring > 1.3mm
Elias DA. Clin Radiol 2004; : 543
Chondromalacia Patellae
• Cartilage softening, swelling, fibrillation in young patients
• Staging– Gd 1: softening, swelling– Gd 2: fragmentation,
fissuring upto 1.3mm– Gd 3: fissuring > 1.3mm
Elias DA. Clin Radiol 2004; : 543
Chondromalacia Patellae
• Cartilage softening, swelling, fibrillation in young patients
• Staging– Gd 1: softening, swelling– Gd 2: fragmentation,
fissuring upto 1.3mm– Gd 3: fissuring > 1.3mm– Gd 4: cartilage loss down
to subchondral bone
Elias DA. Clin Radiol 2004; : 543
Chondromalacia Patellae
• Cartilage softening, swelling, fibrillation in young patients
• Staging– Gd 1: softening, swelling– Gd 2: fragmentation,
fissuring upto 1.3mm– Gd 3: fissuring > 1.3mm– Gd 4: cartilage loss down
to subchondral bone
Elias DA. Clin Radiol 2004; : 543
While there is some correlation between PF incongruence and
acute lateral patellar subluxation, repetitive subluxation and
chondromalacia, each of these can exist without the other
Dynamic Imaging and Patellar Tracking
As a rule patellar tracking can be done clinically. The mere demonstration of a tracking abnormality on either static or
dynamic real-time images is usually not clinically relevant
Dynamic Imaging
• Patello-femoral joint– Tracking– Patellar subluxation and tilt– Passive, active, with our without loading
Patellar Disoders
PF Joint•How to diagnose acute subluxation / dislocation
and not to miss the diagnosis especially when the patella has reduced back
•How to evaluate PF incongruence•Chondromalacia
Thank You