Patellar dislocation with trochlear dysplasia

Case contributed by Dr Ahmed Abdrabou

Presentation

Knee injury during football game 2 days ago

Patient Data

Age: 18 years old
Gender: Male

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)

Case Discussion

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.

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