Core Radiology MSK Flashcards
H shaped vertebra are due to AVN of the endplates which is present in both Gaucher’s and Sickle cell. How can you differentiate?
Gaucher = hepatosplenomegaly
Sickle cell = Autosplenectomy
Gaucher = Erlenmeyer flask deformity (metaphyseal flaring)
Diffuse sclerosis of the bones with rugger jersey spine, what’s the diagnosis?
Osteopetrosis
What’s hereditary hyperphosphasia and how is the radiological features different from Paget’s disease?
Child Paget’s with trabecular and cortical thickening, bowing of the legs and osteopenia
HOWEVER there is epiphyseal sparing
Another name for lincon log vertebra?
H shaped vertebra
Case with marrow expansion, what’s your top differential?
How does marrow expansion look like in the
Hand
Skull
Facial bones
Long bones
Thalassemia
Hand: widening and squaring of the phalanx and metacarpals
Skull: hair on end
Facial bones: Obliteration of the sinuses > rodent face
Long bone: Erlenmeyer flask deformity (metaphyseal flaring)
What does myelofibrosis look like?
Demo: Old patient
Radiograph: diffusely sclerotic bones
Other findings: anemia and splenomegaly
What are the types of stress fractures?
Fatigue and Insufficiency
Insufficiency = bone is insufficient but stress is normal (bone abnormal, stress normal)
Fatigue = bone is fatigued from repetitive stress however bone is normal (bone normal, stress abnormal)
What is a pathological fracture?
Normal stress on bone weakened by underlying lesion/Pagets/Infection
Which sequence is best used to avoid magic angle phenomenon when visualizing the patellar tendon?
T2
What is the MRI presentation of tenosynovitis and what is a common pitfall?
Fluid tracking around the tendon circumferentially
Pitfall; biceps tendon with fluid tracking.
What are the causes of tenosynovitis?
Repetitive motion or surrounding inflammation (infection/inflammatory arthritis)
What is the MRI presentation of tendinosis and what is it’s other name?
Tendinosis = Myxoid degeneration
MRI: Intermediate intrasubstance signal, with normal or enlarged tendon.
NOTE: if fluid signal is seen then it’s NOT tendinosis, it’s a partial tear.
MRI presentation of partial tear vs complete tendon tear?
Both fluid signal
Partial: thinning/thickening of the tendon but incomplete disruption of the fibers.
Complete tear: retraction of the tendon
What is Jones fracture?
Fracture of the metaphyseal-diaphyseal 5th metatarsal.
What’s Friberg infarction and what is the age demographic?
Demo: young women in heels
Avascular necrosis of the second metatarsal
What’s the tendon involved in sesamoid fracture?
Flexor hallucis brevis
What does the Lisfranc ligament connect?
Medial cuniform to the second metatarsal base
Other name of navicular necrosis and what’s the demographic?
Child boy = Kohler
Adult female = Weiss
What’s the lover’s fracture? And what do you recommend if seen?
Calcaneal fracture due to high impact trauma
Associated with lumbar spine fracture, aortic/renal injury so we recommend lumbar and abdominal imaging.
What’s important to comment on after diagnosing a calcaneal fracture?
Subtalar extension because this allows us to use the Essex-Lopresti classification
What’s the most important talus fracture and why?
Talar neck fracture as it predisposes to osteonecrosis
What is this sign and why is it important?
Hawkin sign; subchondral lucent band visualized 6-8 weeks after tarsal bone fracture which indicates blood supply to the dome and no avascular necrosis (good prognosis)
What is this sign and what does it indicate?
C sign
Osseous talocalcaneal coalition
Talar beak sign (in all coalition)
What is this sign and what does it indicate?
Anteater sign
Osseous calcaneonavicular coalition
Talar beak sign (in all coalition)
What are the types of tarsal coalition and where are they located?
What is helpful sign?
Osseous, cartilagenous, ligamentous
Located:
Talocalceneal
Calcaneonavicular
What are the lateral ankle ligaments and which is most commonly injured?
1- Anterior talofibular (most common)
2- Posterior talofibular
3- Calcaneofibular (2nd most common)
Which muscle connects to the base of the 5th metatarsal?
Peroneus brevis
Where does peroneus longus attach?
Curves under the foot and attaches to the medial cuniform
What makes up the medial ankle ligaments?
Deltoid complex and spring ligament complex
What is the deltoid complex compromised of?
1- anterior tibiotalar
2- posterior tibiotalar
3- tibiocalcaneal
4- tibionavicular
Contents of the tarsal tunnel anterior to posterior
Tom, Dick and Harry
Posterior Tibial tendon
Flexor Digitorum longus tendon
Flexor Hallucis longus tendon
Posterior tibial artery and nerve
Danis-Weber classification
(Depends on the level of fibular fracture and resultant syndesmotic injury. )
Weber A; distal fibular fracture with intact syndesmosis
Weber B; more proximal trnassyndesmotic fracture
Weber C; high fibular fracture above the level of the syndesmosis however associated with total syndesmotic rupture and ankle mortise instability.
If you see a medial malleolar fracture or widening of the ankle mortise what’s the next step?
Take a radiograph of the proximal fibula for associated Maisonneuve fracture
What is this fracture called?
Pilon fracture; comminuted vertically oriented fracture of the distal tibia likely due to axial loading.
What is the special name for this fracture and what does it involve?
Triplane fracture:
Vertical epiphyseal fracture
Horizontal physis fracture
Oblique metaphyseal fracture
What’s the special name of this fracture and what does it involve?
Tillaux fracture:
Salter Harris 3 of the lateral tibial epiphysis in adolescents
How do you suspect achilles tendon injury on plain radiograph?
Increase soft tissue in the Kagar fat pad
Notching of the soft tissue
What’s the differential diagnosis of achilles tendon injury on radiograph?
Accessory soleus muscle; soft tissue mass in Kager fat pad
Haglund disease (retrocalcaneal bursitis)
What is recommended in all knee dislocations and why?
What’s the most common knee dislocation
Anterior is most common.
CT angiography is recommended for all knee dislocations because even if the distal pulses are intact there is a high risk of popliteal artery injury.
What is the finding?
dorsal defect of patella usually located in the superiolateral aspect
Which fractures are more stable, medial or lateral?
Lateral tibial plateau fractures are more stable than medial.
Lateral = lemme goooo
If there is injury to the meniscal root what do you look for and what can it mimic?
Look for meniscal extrusion
but don’t confuse it for the meniscofemoral ligament
What is the red zone of the meniscus?
Peripheral third of the meniscus is relatively vascular called the red zone in which injuries may heal spontaneously
How do you differentiate meniscus degeneration from tear?
Degeneration; high signal but not fluid signal and does not extend into the articular surface.
Tear; fluid signal that extends into the articular surface
Where are horizontal tears usually located and how does this make sense?
Posterior horn of the medial meniscus likely due to degenerative changes and less likely due to trauma.
Note: Osteoarthritis is asymmetrical with predominant involvement of the medial compartment
What is a vertical or longitudinal tear?
Tear the follows the curve of the meniscus
What is the most sensitive finding for detecting a bucket handle tear?
Absent bow tie sign
What are the signs seen in bucket handle tear?
Double delta; fragment displaced anteriorly
Double PCL; fragment displaced centrally into the intercondylar notch (most common) this only applies to the medial meniscus
What is this sign?
Double delta sign which indicates anterior displacement of the bucket handle tear fragment.
Radial tear/transverse tear
Extends from the free edge of the meniscus to the periphery occurring through the body
What is the sign of radial tear and what is this tear associated with?
Ghost meniscus occurring through the horn usually adjacent to the intercondylar notch.
Associated with meniscal extrusion
What is a meniscal cyst and why is it important to be mentioned?
Extension of joint fluid through meniscal tear
Importance: Can cause symptoms even after meniscus is resected and sometimes cannot be seen arthroscopically.
Define a discoid meniscus and how is it detected on MR?
Meniscus extending to the central tibial plateau
Exact measurement: meniscus body measurement more than 1.5 cm
MR: Bow tie appearance 3 slices or more (4mm thick)
Which meniscus is commonly involved in discoid meniscus and what is the presenting history?
Lateral meniscus
Hx: Locking/clicking of the knee in an adolescent.
Anterior cruciate ligament attachment and insertion
Arises: femoral intercondylar notch Attaches: anterior tibial plateau lateral to the tibial spine
Which attachment is stronger within the ACL and what is the clinical significance?
Tibial attachment is stronger causing more tears from the femoral end.
ACL tear on MRI
frank discontinuity of ligament fibers or abnormal course and signal
ACL tears are associated with two entities, name them.
Medial meniscal and MCL tears ( O’Donoghue’s triad aka unhappy triad)
Segond fracture; avlusion fracture of the lateral plateau.
What are the secondary findings in ACL tears?
Contusion pattern: lateral femoral condyle and posterolateral tibial plateau
Buckling of the PCL
What is Segond fracture associated with and what’s the next step?
1- ACL tear
2- Iliotibial band syndrome
Next step MRI because of the previous assocations.
The iliotibial band inserts at
Gerdy tubercle of the tibia
Posterior cruciate ligament arises and inserts
Arises: femoral intercondylar notch
Inserts: posterior tibial plateau.
PCL tear appearance on MRI
Increased laxity of the PCL with or without abnormal high signal intensity
Medial collateral ligament arises and attaches to
Why is it not visualized by arthroscopy?
Arises: Posterior aspect of the medical femoral condyle
Attaches: Medial tibial metaphysics
Not visualized by arthroscopy because it’s extrasynovial
Grades of MCL tear
Grade 1; Sprain; high signal of the soft tissue with normal signal ligament
Grade 2; severe sprain/partial tear; high signal/ partial disruption of the MCL fibers.
Grade 3; Complete disruption of the MCL
The lateral collateral ligament is compromised of many structures, 3 of which are visualized by MRI. Name them.
anterior to posterior;
1- Biceps femoris
2- LCL
3- Iliotibial band
The biceps and LCL attach on the lateral fibular head. The iliotibial band attaches to the Gerdys tubercle.
Clinically: anterolateral knee pain in a runner. DDx
IT band syndrome; fluid surrounding the iliotibial band
Lateral meniscus tear
The quadriceps originate from ________ except _________ it originates from _________
Femur
except: rectus femoris
from : AIIS
Define patella alta and patella baja
Alta; abnormally high patella, > 1.2
Baja; abnormally low patella, < 0.8
What is Jumper’s knee?
Patellar tendinosis = Jumper’s knee = thickening of the patellar tendon
History of loss of knee extension, what’s your differential diagnosis and how do you distinguish between the two?
Quadriceps tendon tear = Patella baja
Patellar tendon injury = Patella alta
What are the findings and diagnosis?
Bone marrow contusions; lateral femoral condyle and medial patellar facet with tearing of the medial retinaculum
Diagnosis: Patellar dislocation relocation
Define Osgood-Schlatter disease and the MRI findings.
Osteochondrosis of the tibial tubercle due to repetitive microtrauma in adolescent.
MRI:
1- increase signal of distal patellar tendon
2- marrow edema in the tibial tubercle
3- edema within Hoffa’s pad
What are the types of cartilage injury?
surface irregularity, fissuring, delamination
What’s the distribution of Osteochondrosis Dissecans
1- knee (lateral medial condyle)
2- ankle(posteriomedial or anteriorlateral talar dome)
3- elbow
What’s an unstable fragment in osteochondrosis dissecans and what is the complication?
Unstable fragment, lesion not attached to bone causing secondary osteoarthritis.
MRI finding of unstable osteochonrosis dissecans
Curvilinear high signal intensity on fluid sensitive sequence interposed between the fragment and underlying bone.
If pigmented villonodular synovitis is seen outside the knee joint it is termed
Giant cell tumor of tendon sheath
Whats the most common site for pigmented villonodular synovitis, the radiographic and MRI findings
Knee
Radiograph; knee effusion, soft tissue mass posterior to knee
MRI; hemosidernin deposit; dark signal on T1 and T2, with blooming on gradient echo sequences.
Describe the findings and diagnosis.
Overgrowth of intracapsular synovial fatty tissue, causing lobulated and globular intra-articular fatty masses.
Lipoma arborescens
Where is a Baker cyst located and what is an alternative diagnosis.
Located between the semimembranosus tendon and medial head of the gastrocnemius muscle. (Baker’s M&M)
DDx popliteal aneurysm.
Tennis leg
Tear of the plantaris tendon or medial head of the gastrocnemius
The center of the acetabulum that is not covered by cartilage is called
Pulvinar
Findings and diagnosis
PD; FAT SAT
Structure mostly the plantaris tendon. Note the abnormal signal within the medial head of gastrocnemius
Dx: Ruptured plantaris - tennis leg
Which muscles attach to the greater trochanter?
Gluteus medius, minimus
Obturator internus and externus Piriformis
Which muscle attaches to Lesser trochanter?
Note: Fracture in the lesser trochanter is always pathological until proven otherwise.
Ilipsoas
What is an easy way to establish whether or not there is a fracture to the anterior or posterior column of the acetabulum?
Iliopectinal and ilioischial lines disruption
Which acetabular column is commonly fractured?
Posterior
Name the intracapsular and extracapsular femoral fractures and why is it important
Femoral head and neck fractures = intracapsular, complications include femoral head osteonecrosis
Intertrochanteric and subtrochanteric = extracapsular, direct injury, rarely cause osteonecrosis.
Types of femoral neck fracture
Subcapital (most common)
Transcervical
Basicervical
Technical factors to adjust when patient with metallic prosthesis undergoes MRI
1- Decreasing the field strength
2- Fast spin echo sequences instead of gre
3- Increasing the receiver bandwidth, which will increase the noise, so we need to increase the number of acquisitions.
4- Artifacts can be directed in the superior-inferiro plane so the region
5- Decrease voxel size by decreasing slice thickness and increasing matrix size.
Indications of hip MRI
Occult traumatic fracture since radiographs are insensitive for detection of nondisplaced femoral neck fracture.
Occult stress fracture
Stress fractures; either fatigue or insufficiency fractures
Radiographs insensitive for detection of hip stress fractures, if present looks like a band sclerosis.
Classic location for femoral stress fractures
Inferomedial femoral neck
Less commonly superior femoral head fractures can mimic avascular necrosis, how to differentiate on MRI
AVN smooth and concave to articular surface, insufficiency fracture irregular low intensity fracture line convex to the articular surface.
If there is a stress fracture in an atypical location, what can be a clue during history taking
Bisphosphanate use
Arterial supply to the femoral neck
Medial femoral circumflex artery
Non traumatic causes of AVN
1- Red cell abnormalities
2- Abnormality of marrow packing (Gaucher)
secondary effects of meds (steroids)
alcohol
immunosuppression which tend to be bilateral.
Diving (Cassion’s disease)
Most common site for AVN?
Proximal femur and proximal humerus
Ficat staging for AVN
Stage 1; normal radiograph with signs of AVN on MRI
Stage 2; cystic and sclerotic changes
Stage 3; loss of normal spherical shape due to collapse of the subchondral bone. Subchondral lucent line = cresent sign.
Stage 4; Flattening of the femoral head and secondary osteoarthritis. Tx joint replacement.
What is this sign?
Subchondral lucent line = cresent sign which indicates avascular necrosis. Unlike Hawkin’s sign in the talar dome, it’s a lucent line within the talar dome if present decreases the likelihood of developing AVN.
Describe the findings
and what is it pathognomonic for?
Geographic subchondral lesion outlined by a serpentine low signal rim on T1 and on T2, two intensities are seen
Double line sign
Diagnosis: AVN
Transient bone marrow edema/ transient osteoporosis of the hip
MRI finding and demographic
Note: It’s a diganosis of exclusion
Demo: severe hip pain, young, middle aged adult, men, pregnancy
MRI: T1, diffuse low signal, high signal on T2 with signal extending from the femoral head into the neck.
Hip labral injury
Most common cause
Predisposing factor
Best diagnostic study
Most common location
MCC: chronic repetitive trauma rather than acute
Predisposing factor: Femoracetbaular morphological changes i.e DDH and femoral acetabular impingement
Best diagnostic study: MRI arthrogram
Most common location: anteriosuperior
Femoroacetabular impingement types
How do we make the diagnosis?
Cam
Pincer- type
Mixed
You need clinical symptoms for diagnosis (controversial topic)
Cam impingement
Causes
Demographic
Treatment
Many causes examples
1- Legg-calve-perth
2- DDH, slipped capital femoral epiphysis
Demo; young athletic males
Treatment: osteoplasty
Name the deformity and diagnosis
Pistol grip deformity
Dx: Cam impingement
Chance fracture/ Seat belt fracture definition
Flexion distraction injury, horizonal splitting of the vertebra beginning posteriorly in the spinous process/lamina
What are the measurements for craniocervical dissociation and ligamentous laxity
More than 12 mm BD interval; craniocervical dissociation
More than 2.5 mm AD interval adults and more than 5 in pediatrics ; ligamentous laxity
Define a Jefferson’s fracture
Which view on xray is helpful and what can you appreciate?
symmetrical fractures of the anterior and posterior arches of c1
Due to axial loading to the vertex
Open mouth- odontoid view = lateral masses are displaced laterally.
What are the 3 types of odontoid injury?
How does this fracture come about?
1 = tip of the dens
2= base of the dens (unstable)
3 = base of the dens extending into the vertebral body (stable/unstable)
Flexion injury
Hangman’s fracture definition
What’s characteristic on lateral radiograph?
Hyperextension causing traumatic spondylolysis of C2 = bilateral fractures through the pedicles of C2
Characteristic radiograph finding: disruption of the spinolaminar line.
Burst fracture
Compression fracture w/ retropulsion
Flexion teardrop
Avulsed bony fragment from anterior inferior aspect (anterior longitudinal ligament avulsion) with posterior displacement of the vertebrae into the spinal cord
What’s the most severe cervical spine injury and why
flexion tear drop due to it’s complication;
Anterior cord syndrome = complete paralysis and loss of pain and temp, dorsal column is intact
Extension teardrop fracture
It’s a stable fracture
usually at C2-C3 with an
anterior inferior avulsion fragment
No subluxation
Spinolaminar line not affected.
Clay Shoveler’s fracture
Displaced avulsion fracture of the spinous process
Lower cervical spine
Bilateral interfacetal dislocation (locked facet)
- Hyperflexion injury
- Complete disruption of all spinal ligaments
- Anterior dislocation of the affected vertebrae
Sign: naked facet sign (axial)
Perched facet: less severe variation (subluxation but not displacement)
Is a unilateral facet dislocation stable or unstable?
stable
Grisel syndrome
Non-traumatic rotatory subluxation C1-c2 caused by inflammatory mass i.e pharyngitis or retropharyngeal abscess.
Most common glenohumeral dislocation
Best seen on
Anterior GH dislocation where it’s displaced anterior inferiorly.
Best seen on axillary view
Define Hill sachs and Bankart
Hill sachs = compression fracture of posterolateral aspect of humeral head
Bankart = injury to the anterior-inferior rim of glenoid usually cartilaginous
What are the two signs seen in posterior shoulder dislocation
Light bulb sign = fixed internal rotation
Trough sign = compression fracture of the antero- medial humral head (reverse hill sach)
What happens in inferior shoulder dislocation?
- Rotator cuff injury
- Greater tuberosity fracture
- Injury to the axillary n + a
The subacromial and subdeltoid bursae normally communicate with each other and not the with the glenohumeral joint. IF you inject contrast into the glenohumeral joint and it extends into the subacromial/subdeltoid bursae, what does that indicate?
Complete tear
Type 3 and 4 acromion and clinical significance
Type 3; hooked undersurface
Type 4; convex undersurface
Significance; lead to rotator cuff tears
Os acromial
Persistent accessory ossification center of the acromion in patinets above 25 y
MRI findings with edema in this area suggests that it’s the cause of the patient’s shoulder pain.
Rotator cuff tendon insertion
Greater tuberosity; supraspinatus, infraspinatus, teres minor
Lesser tuberosity; subscapularis
Tendinosis/Tendiopathy
MRI finding and differential diagnosis
(Mxyoid degeneration of tendon)
MRI: diffuse/focal thickening with intermediate signal intensity on T1/T2
DDx: Magic angle artifact, may stimulate tendinosis/ partial tear, look for the T2
What is the footprint of the shoulder?
Site of attachment of tendons at the greater tuberosity
Most commonly injured rotator cuff tendons from most to least
Most commonly injured; supraspinatus, next infrapspinatus, least affected teres minor
Partial thickness tear MRI finding
MRI: abnormal signal intensity of the muscle/tendon but not extending through it’s entire thickness AND fluid signal.