Experimental evaluation of 3-dimensional kinematic behavior of the cruciate ligaments.

PURPOSE The purpose of this study was to evaluate a low-cost and easily reproducible technique for biomechanical studies in cadavers. In this kind of study, the natural effect of loading of the joint and shear forces are not taken into account. The objective is to describe the plastic deformation of the ligaments into 3-dimensional space. METHOD For 18 intact human cadaver knees, the cruciate ligaments were divided into 3 fiber bundles, the tibial or femoral fixation points were marked, and 2 perpendicular different x-ray exposures were performed, thus obtaining radiographs of spatial projections of the bundle in 3 anatomic planes (frontal, sagittal, and transversal). From the measurements made on the x-ray films, we obtained the average distance between the 2 fixation points of the cruciate ligaments on the tibia and the femur at 4 different flexion angles. RESULTS The distance between the fixation points of the medial and lateral fiber bundles of the cruciate ligaments did not change significantly during movement. There were, however, significant variations (P < .05) in the distance between the fixation points of the posterior fiber bundles of the anterior cruciate ligament and the anterior fiber bundles of the posterior cruciate ligament. CONCLUSIONS This technique was efficient for demonstrating the plastic deformability of the cruciate ligaments. The results proceeding from this type of study can assist in the planning of physical rehabilitation programs.