In vitro testing protocols for the cruciate ligaments and ligament reconstructions.

The techniques that have been used to characterize the biomechanical behavior of the knee, cruciate ligaments, and cruciate ligament replacements differ, making comparisons between studies difficult or, at times, impossible. Therefore, it is important to standardize the testing protocols and techniques that describe the biomechanical behavior of the knee and cruciate ligaments. This will allow investigators to express opinions with respect to the interpretation of data, rather than based on differences between testing techniques. Standardized techniques are proposed to locate the origins of the tibial and femoral coordinate systems, and thus, allow comparisons of knee kinematics (e.g., displacements and rotations) between investigations. Standard techniques that can be used to measure the load-displacement behavior of the knee are described, and important considerations that should be appreciated with respect to preparing and testing of the joint are summarized. It is important to evaluate the single cycle load-to-failure characteristics and the cyclic loading response of an anterior cruciate ligament graft, and techniques to evaluate cruciate ligament graft fixation are proposed. The strengths of different models to characterize the biomechanical behavior of the knee are reviewed.