Transient patellar dislocation

Case contributed by Sherif Shebl Kotkata


Twisting injury of the knee, with severe pain, and limitation of movement after trauma.

Patient Data

Age: 20 years
Gender: Male

The patella shows moderate bone marrow edema along its medial articular surface, that also shows mild angulation of its bone cortex, suggesting mild compression fracture with altered signal of the corresponding overlying retropatellar cartilage.  

Bone marrow edema is noted along the lateral aspect of the lateral femoral condyle, and minimally along the anteromedial aspect of the medial tibial plateau. 

The patellar attachment of the medial retinaculum shows increased girth with abnormal signal intensity, impressive of sprained or partially torn medial retinaculum.

Moderate knee joint effusion.

This distribution pattern of bone marrow edema added to the soft tissue injury, overall features are impressive of transient patellar dislocation injury.

Case Discussion

Bone marrow edema in almost contralateral articular bone surfaces of the patella and femur (medial and lateral articular surfaces) are alarming signs of transient patellar dislocation injury pattern.

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