Patellar dislocation with trochlear dysplasia
Knee injury during football game 2 days ago
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Completely torn patellofemoral ligament and lateral patellar subluxation.
Bone marrow contusion exhibiting bright STIR signal seen at medial patellar facet and lateral femoral condyle which is characteristic of patellar dislocation.
Hemorrhagic joint effusion (note the high signal in T1WI)
Diagnosis: Acute patellar subluxation
When applying valgus stress on the patella the patellofemoral ligament is torn and the medial patellar facet hits the lateral femoral condyle resulting in characteristic marrow edema pattern.
- Elias DA, White LM, Fithian DC. Acute lateral patellar dislocation at MR imaging: injury patterns of medial patellar soft-tissue restraints and osteochondral injuries of the inferomedial patella. Radiology. 2002;225 (3): 736-43. Radiology (full text) - doi:10.1148/radiol.2253011578 - Pubmed citation
- Diederichs G, Issever AS, Scheffler S. MR imaging of patellar instability: injury patterns and assessment of risk factors. Radiographics. 2010;30 (4): 961-81. Radiographics (full text) - doi:10.1148/rg.304095755 - Pubmed citation
- Stoller D, Tirman P, Bredella M et-al. Diagnostic imaging. AMIRSYS. (2004) ISBN:0721629202. Read it at Google Books - Find it at Amazon