Posterior cruciate ligament and posterolateral corner deficiency results in a reverse pivot shift.

BACKGROUND: As measured via static stability tests, the PCL is the dominant restraint to posterior tibial translation while the posterolateral corner is the dominant restraint to external tibial rotation. However, these uniplanar static tests may not predict multiplanar instability. The reverse pivot shift is a dynamic examination maneuver that may identify complex knee instability. QUESTIONS/PURPOSES: In this cadaver study, we asked whether (1) isolated sectioning or (2) combined sectioning of the PCL and posterolateral corner increased the magnitude of the reverse pivot shift and (3) the magnitude of the reverse pivot shift correlated with static external rotation or posterior drawer testing.
METHODS: In Group I, we sectioned the PCL followed by structures of the posterolateral corner. In Group II, we sectioned the posterolateral corner structures before sectioning the PCL. We performed posterior drawer, external rotation tests, and mechanized reverse pivot shift for each specimen under each condition and measured translations via navigation.
RESULTS: Isolated sectioning of the PCL or posterolateral corner had no effect on the reverse pivot shift. Conversely, combined sectioning of the PCL and posterolateral corner structures increased the magnitude of the reverse pivot shift. The magnitude of the reverse pivot shift correlated with the posterior drawer and external rotation tests.
CONCLUSIONS: Combined sectioning of the PCL and posterolateral corner was required to cause an increase in the magnitude of the mechanized reverse pivot shift. The reverse pivot shift correlated with both static measures of stability. CLINICAL RELEVANCE: Combined injury to the PCL and posterolateral corner should be considered in the presence of a positive reverse pivot shift.