It's easy to see the PCL tear from its tibial attachment in this case. However, noticing the layering in the effusion which signifies lipohaemoarthrosis is of paramount importance, because it means that there's an overlooked intra-articular fracture. The fracture in this case is actually an avulsed segment from the tibia at the PCL insertion, type III. Look again and you'll find the small low signal cortical portion attached to the PCL. Easy to miss, huh?
Also, never forget evaluating the peri-articular musculature. In this case, you'll find a heterogenous high T2 signal in the popliteus muscle, it was contused during the trauma. However its tendon remains intact, so it's not torn.