Avulsion fractures of the posterior cruciate ligament (PCL) are uncommon. On the basis of the site of damage of the PCL, hyperflexion, pretibial trauma, and hyperextension are proposed as mechanisms of PCL injuries. On the other hand, avulsion fractures of the tibial condyle are also rare. We report a PCL-mediated avulsion fracture of the lateral tibial condyle along with the tibial insertion of the PCL by extension-distraction force on the knee that has not been previously described in any study. This rare case may imply that application of an extension-distraction force to the PCL cause the avulsion fracture.