PCL avulsion fracture

Lateral radiograph of the knee (image 1) shows an avulsion fracture (arrow) of the posterior aspect of the tibia epiphysis and a large knee effusion (arrowhead). Sagittal CT image (image 2) shows the avulsion fragment (arrow). Sagittal T2 weighted MRI (image 3) highlights the avulsion fragment (arrow) and the large hemarthrosis (arrowhead). The proton density MRI (image 4) highlights that the avulsion fracture is connected to the posterior cruciate ligament (arrow). Posterior cruciate ligament avulsion fractures are uncommon. They typically occur after motor vehicle collision. However, it can also occur as a jumping injury where the individual lands on a plantarflexed foot with the knee in flexion.