MRI has become the mainstay for confirming the diagnosis of PCL rupture. It is also used to assess other ligaments, articular cartilage (the joint lining), and menisci (cartilage that sits in between the tibia and femur). The image shows a normal PCL, the curved black band (highlighted by the white arrows).
This is an MRI scan of a 33-year-old male who was injured whilst playing football. He was able to continue playing however over the next month developed recurrent instability episodes (his knee was giving out). The MRI scan shows a ruptured PCL. The blue arrows show what is left of the PCL. The red arrows are where the PCL should be.