Posterior Sag Sign for PCL Tears Let's move on to the posterior cruciate ligament and how to assess injuries of it! The Posterior Sag Sign makes use of the fact that the tibia is translating posteriorly due to gravity in case of a torn PCL. Watch the test is carried out! According to a study by Rubinstein et al. (1994), the Posterior Sag Sign has a sensitivity of 79% and a specificity of 100%. | Physiotutors