PCL avulsion fracture

Case contributed by Dr Matt Skalski

Presentation

Status post motor vehicle accident

Patient Data

Age: 20 years
Gender: Female
X-ray

There is a lucent line traversing the posterior tibial eminence with cortical disruption and mild offset of the fragment. A small suprapatellar effusion is noted. 

X-ray

The fracture is outlined.

CT

There is minimal offset of the fragment with a small comminuted fragment medially. This amount of offset indicates a type 1 PCL avulsion fracture.

Diagram

The diagrams demonstrate the grade and mechanism of the injury. 

Case Discussion

There is an avulsion fracture of the PCL (type 1) at its insertion on the posterior tibial eminence, most likely secondary to an impact of the tibia on the car's dash. This mechanism makes sense because this fracture involves the non accelerating leg, which is typically flexed in position while driving, creating a good bio-mechanical scenario for shearing the tibia posterior relative to the femur in a frontal impact situation. 

This case is courtesy of Eric White, MD, who generously shared it with me. 

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Case information

rID: 23862
Published: 14th Jul 2013
Last edited: 22nd Dec 2019
Inclusion in quiz mode: Included