The femur injury criterion for anthropomorphic test devices (ATDs), used in car crash testing, is well established in crash biomechanics literature:​ however, the knee slider criterion and the tibial injury indices have less well-developed biomechanical bases. There is a need to investigate the biomechanical properties and behavior of the posterior cruciate ligament (PCL) and tibia during high energy impacts and verify these knee and tibia criteria. The Ohio State University Injury Biomechanics Research Laboratory has been conducting high energy tibia impacts on fresh post-mortem human subjects (PMHS). This research project uses PMHS and focuses on the displacement of the tibia in relation to the femur while the tibia is loaded from an anterior location as seen in frontal car crashes.

The objective of this research is to design and evaluate a measurement system used in high energy tibia impact testing on PMHS, allowing accurate measurement of PCL and tibia displacements as well as identifying the time of failure. From February 2005 through April 2006, seven PMHS (13 tibias) have been tested. A number of constraints have been placed on the test setup in order to reduce the number of test variables, allowing the tibia and PCL displacements to be examined in greater detail. These constraints include eliminating applied tibia load from previous research, testing a single femur angle and securing the foot to the test platform. The tibia displacement is currently measured using three tri-axial accelerometers, one attached to the femur and two attached to the tibia, one anteriorly and one medially. A positive comparison has been made between the relative tibia-to-femur displacements recorded from the accelerometers and the displacements recorded from high speed video. In all tests resulting in a tibia fracture the time of failure can be clearly identified;​ however, determining the time of failure in a test which results in a ligament injury has proven to be more difficult. A small Differential Variable Reluctance Transducer (DVRT) [displacement transducer]r is attached to the PCL to identify stretch and rupture. With the use of the accelerometers to determine tibia displacement and improvements in the method for attaching the DVRT to the PCL, determining the time of failure for both tibia fractures and PCL injuries has been achieved.

With time of injury for both tibia and PCL failures determined and the relative tibia-to-femur displacement accurately measured, the next step in this research is to start removing the constraints placed on the test setup. This will provide a more “real world” situation improving our understanding of the biomechanical properties of the knee in a frontal car crash. Finally, the test data can be used to improve the knee slider criterion and tibia displacement injury index.