Patella fracture simulating bipartite patella

Case contributed by Dr Andrew Dixon

Presentation

Fall on knee.

Patient Data

Age: 65
Gender: Female

Lucent line through the superolateral aspect of the patella on the AP projection. Possible subtle step in the patella subchondral bone plate on the lateral image. Small knee joint effusion. Background medial tibiofemoral compartment and patellofemoral joint osteoarthritis. 

CT confirms the lucent line in the superolateral patella on the plain radiograph to represent an acute non-displaced fracture. Small joint effusion. 

Case Discussion

This case is interesting as it is a bit of a double bluff. There is a lucent line through the superolateral patella an the AP plain film which is in the typical location for bipartite patella (an anatomical variant) which is often misinterpreted as a fracture by the inexperienced reader. This one is however a fracture though, as the line is very thin, much thinner than is seen in bipartite patella. Tricky!

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Case information

rID: 48364
Case created: 3rd Oct 2016
Last edited: 4th Oct 2016
Tag: rapids
Inclusion in quiz mode: Included

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