Software for compartmental translation analysis and virtual three-dimensional visualization of the pivot shift phenomenon

Anterior cruciate ligament (ACL) injury may cause knee instability and may result in damage to the menisci and the articular cartilage. The pivot shift test is commonly used to identify rotational instability of the knee following injury to the ACL. The magnitude of lateral compartment translation correlates well with the grade of the pivot shift. However, commonly used navigation systems do not readily provide individualized compartmental translation. We aimed to develop software to (a) quantify individual medial and lateral compartmental translation in the knee during the pivot shift test, and (b) generate animated three-dimensional renderings of recorded pivot shift examinations. Twelve paired cadaveric knees were used to test the software. Three mechanized pivot shift tests were performed on each knee with the ACL intact and again after sectioning the ACL. Using the Pivot Shift Processor, we successfully analyzed the data recorded using the navigation system. After sectioning the ACL, there was a greater increase in tibiofemoral translation in the lateral compartment compared to the medial compartment. The Pivot Shift Visualizer successfully produced a 3D rendering of the knee joint and the recorded pivot shift maneuvers. This virtual representation of the pivot shift phenomenon from multiple points of view allows for efficient side-by-side comparison of tibiofemoral motion tracking across conditions, which is not possible in the in vivo / in vitro settings. This, in turn, could lead to a better understanding of the kinematics in play during the pivot shift phenomenon.