Lateral patellar dislocation

Case contributed by Amr Farouk
Diagnosis certain


35 years old female patient with history of knee trauma couple of days ago.

Patient Data

Age: 35 years old
Gender: Female

Complete disruption of medial patellar retinaculum with adjacent periligamentous edema and lateral displacement of patella.

Associated patchy areas of marrow edema is seen involving lateral femoral condyle and medial patellar surface, appearing of low signal on T1 and high signal on T2 and STIR weighted images.

An osteochondral ulcer is seen at the posterior patellar articular surface.

Mild amount of intra-articular synovial effusion is noted.

Case Discussion

The MR features of medial retinacular abnormalities (ranging from strain to complete disruption) with adjacent periligamentous edema and hemorrhage, lateral displacement of patella medial patellar contusion +/- corresponding lateral femoral condyle contusion as well as associated joint effusion are diagnostic of lateral patellar dislocation.

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