MSK Radiology Quizes by MZeba

Necrotizing Fascitis ⚡Clinical diagnosis ⚡Air in soft tissues in the absence of penetrating trauma:pathognomic ⚡MR:no deep soft tissue abnormality= excellent negative PV MZeba

Iliotibial Band (Friction) Syndrome 🦴Common in athletes, resulting in lateral knee pain due to chronic inflammation of fat near the iliotibial band. 🦴Similar pathology can occur over the greater trochanter. 🦴MRI: ➖For definitive diagnosis is unclear ➖To exclude other causes like meniscal tears or lateral collateral ligament injury. 🦴MRI Findings ➖Knee: Edema in soft tissues lateral to the lateral femoral condyle (low T1, high T2 signal). ➖Hip: Similar soft tissue changes; may show gluteus medius/minimus tendinopathy or tears, and bone marrow edema. ➖Other Signs: Cystic areas representing primary/adventitious bursae. ➖Chronic Findings: 1. IT band thickening. 2. Increased T2 signal intensity superficial to the IT band. 3. Soft tissue fibrosis. 4. Bony proliferation. 🦴DD for Lateral Knee Pain ➖Lateral meniscal tear ➖Lateral collateral ligament injury ➖Meniscal cyst MZeba (Source: Radiopedia)

Imaging of Orbital Blow-Out Fracture 🌀Plain Radiograph:   👁️Poor sensitivity   👁️Signs: 👓Black Eyebrow Sign (orbital emphysema), 💧Teardrop Sign (inferior fat herniation)   👁️Fluid in maxillary sinus or ethmoidal air cells may suggest fractures 🌀CT Scan:   👁️Preferred Modality: Thin-slice, bone algorithm   👁️Assess: Fracture location/extent, intra orbital hemorrhage, globe injury, muscle entrapment, fat prolapse   👁️Late Enophthalmos Indicators: ➖Fracture area ≥2 cm², ≥25-50% wall involvement. ➖ internal orbital buttress collapse ➖fat herniation ≥1.5 mL 🌀Treatment:   👁️Prioritize globe injury   👁️Conservative management for fractures without globe injury   👁️Surgery Indications: Significant enophthalmos, diplopia, muscle entrapment, large fractures   👁️Timing: Often semi-delayed to allow swelling reduction. (Source: Radiopedia) MZeba

Klippel-Feil Syndrome: Cervical vertebral fusion; diagnosed with fusion of two or more cervical vertebrae. 🌀 Associations: 🦴Shoulder deformity (Sprengel) 🦴Wildervanck, Duane syndromes 🦴Aortic arch anomalies 🦴Spinal scoliosis, disc herniation, cervical spondylosis 🦴Renal abnormalities 🌀Classic triad (short neck, low hairline, restricted neck motion) present in <50% of cases 🌀Classifications: 🦴Type I: Extensive cervical/thoracic fusion 🦴Type II: 2-3 vertebrae fusion with abnormalities 🦴Type III: Cervical fusion with thoracic/lumbar fusion 🌀 Imaging: 🦴Plain X-ray: Fused vertebrae, wasp-waist sign, hemivertebrae, scoliosis 🦴CT: Detailed fusion, canal stenosis 🦴MRI: Canal stenosis, cord compression, associated conditions (e.g., Chiari malformation) MZeba

Imaging of SCFE 🌀XR ➖Views: AP and Frog-Leg (bilateral for comparison) ➖Pre-Slip: Widened growth plate, irregular physeal edges ➖Acute Slip: Posteromedial slippage ➖Chronic Slip: Sclerotic physis, widened metaphysis (coxa magna) Key Signs: 🐸Frog-Leg View: Best for visualizing posterior and medial slip 🐸AP View: Klein’s Line misses epiphysis (Trethowan sign) 🐸Loss of Triangular Sign: Metaphysis displaced laterally 🐸Metaphyseal Blanch Sign: Increased density of proximal metaphysis 🌀USG: ➖Role: Assists in hip pain assessment; not a replacement for X-ray ➖Findings: May show hip effusion or malalignment 🌀Conditions that may predispose to SUFE include: ➖obesity: significant risk factor ➖hypothyroidism ➖hypopituitarism ➖hyperparathyroidism ➖renal osteodystrophy ➖radiation/chemotherapy (Radiopedia) MZeba

ACL Tears 🌀Associations: ➖O'Donoghue unhappy triad ➖Segond fracture ➖Posteromedial corner injury ➖Meniscocapsular separation 🌀XR ➖Deep lateral sulcus sign ➖Anterior tibial translocation sign ➖Segond fracture ➖Arcuate fracture ➖Joint effusion 🌀CT: ➖High specificity and sensitivity for ACL disruption ➖Characterizes avulsed 🦴 fragments. 🌀MRI: 🔥Primary Signs: ➖Swelling, increased T2 or fat-saturated PD signal ➖Fiber discontinuity ➖Abnormal ACL orientation (angle >15°) ➖Empty notch sign ➖Midsubstance tears (discontinuity or abnormal contour) ➖Isolated posterolateral bundle tear (gap sign, footprint sign) 🔥Secondary Signs: ➖Bone contusion in lateral femoral condyle and tibial plateau ➖7 mm anterior tibial translation ➖Uncovered posterior horn of lateral meniscus ➖Segond or arcuate fractures ➖Bowing of PCL ➖Medial or lateral collateral ligament injury ➖Deeper lateral femoral sulcus (>1.5 mm) (Source: Radiopedia) MZeba

Meniscal Root Tears: 🌀Occurrence: 1. Acute injury in younger patients 2. Degenerative process in older patients 🌀 Classification: LaPrade classification system is commonly used and can be partially applied to MRI 🌀 MRI Findings: 1. Medial Posterior Root Tears: Shortening or absence of the root on sagittal images Vertical fluid cleft on coronal T2-weighted images 2. Lateral Posterior Root Tears: Appearance similar to radial tears in other locations 3. General Features: Meniscal ghost sign on sagittal images Truncation sign and meniscal extrusion on coronal images (Source: Radiopedia) MZeba

OSTEOPOROSIS 🌀 Gold Standard: DEXA 🌀 CT: Osteoporotic vertebra have HU <95-110.

Slip Capital Femoral Epiphysis Grading: 📜 Graded based on the displacement of the epiphysis in relation to the metaphysis 1. Mild: lateral edge of the epiphysis is within the lateral third of the metaphysis 2. Moderate: lateral edge between the lateral 1/3…

Slip Capital Femoral Epiphysis Grading: 📜 Graded based on the displacement of the epiphysis in relation to the metaphysis 1. Mild: lateral edge of the epiphysis is within the lateral third of the metaphysis 2. Moderate: lateral edge between the lateral 1/3 and halfway point of the metaphysis 3. Severe: medial third (over the halfway point of the metaphysis) (Radiopedia)

Pyknodysostosis: --- Osteosclerosis with narrowed medullary cavities is the main generalised imaging finding. --- Long bone fractures are common. --- pyknodysostosis differs from osteopetrosis by: 1. Wormian bones; delayed closure of sutures and fontanels (prominently the anterior) 2. Obtuse mandibular angle. 3. Gracile clavicles that are hypoplastic at the lateral ends 4. Partial absence of the hyoid bone. 5. Hypoplasia or aplasia of the distal phalanges (Radiopedia + )

OCD --- The STIR sequence is helpful in the depiction of chondral lesions in the patellofemoral joint --- MRI features that aid in diagnosis include: 1. The location and extent of bone marrow edema. 2. The presence of a fracture line. 3. Hypointense area immediately subjacent to the subchondral bone plate. 4. Deformity of the subchondral bone plate https://pubs.rsna.org/doi/10.1148/rg.2018180044

Ankylosing Spondylitis and MRI -- MRI positivity requires visualization of areas of bone marrow edema on periarticular or subchondral bone in the sacroiliac joints on fat-suppressed T2/ STIR images or or contrast enhancement on fat-suppressed T1WI. -- In the absence of concomitant bone marrow edema, enthesitis, capsulitis, and synovitis, even when reflecting active inflammation, are insufficient findings for MRI positivity. -- No structural lesions, such as sclerosis, erosions, periarticular fat depositions, and bony bridges, have been selected as criteria for MRI positivity. (Source: https://www.ajronline.org/doi/full/10.2214/AJR.12.8858 )

Trimalleolar fractures: 1. A three-part fracture of the ankle. 2. The fractures involve the medial malleolus, the posterior aspect of the tibial plafond (referred to as the posterior malleolus) and the lateral malleolus. 3. Having three parts, this is a more unstable fracture and may be associated with ligamentous injury. 4. Sometimes CT is needed to get a better impression of the size of the fracture fragment of the posterior malleolus. 5. Articular steps >1 mm are also an indication for internal fixation (Radiopedia, RadAssistant)

Vertebral # Important Descriptors: 1. Wedge compression fracture: involvement of one endplate but not the posterior wall 2. Pincer or split fracture: involvement of both endplates but not the posterior wall 3. Burst fracture: involvement of one endplate (incomplete) or both endplates (complete) and the posterior wall. (Radiopedia)

Osteoporotic vs pathological # The following features favor the diagnosis of a benign compression fracture: 1. No bony destruction 2. Preserved normal fatty bone marrow T1WI signal 3. Low signal intensity band on T1WI and T2WI indicating a fracture line 4. Fluid sign 5. Retropulsion (not posterior bulging) of the posterosuperior cortex of the vertebral body 6. No epidural mass 7. Multiple compression fractures (Radiopedia)

Lunatomalacia: Lichtman classification -- Stage I: normal radiographs, ↑ T2 & ↓ T1 signal on MR -- Stage II: sclerotic ± lytic/cystic changes, no collapse -- Stage III: collapse -- Stage IV: collapse + radiocarpal or midcarpal OA (StatDx)

Monteggia #: Anterior, posterior, lateral, anterior + #both bones