Experimental evaluation of selected mechanical properties of anterior cruciate ligament and posterior cruciate ligament complex

Abstract

Purpose

Ligaments are fibrous connective tissues that transmit force from bone to bone. One of the most important ligaments in the human body is the knee-joint ligament, which is exposed to large and dynamic forces during daily activities. Owing to their frequent injuries, cruciate ligaments are among the most studied in the current literature. Thus far, research has focused mainly on the study of individual ligament structures and less frequently on analysing entire bone-ligament systems. Therefore, this study examines the mechanical properties of the entire cruciate ligament system.

Materials and methods

Tensile tests were conducted on 18 porcine forelimb knee joints. The joints were mounted on a holder, ensuring freedom of the ligament positioning during the examination. The test consisted of three stages: preconditioning (stage 1), relaxation (stage 2), and breaking (stage 3).

Results

In stage 1, the tissue showed a decrease in reaction force with subsequent conditioning cycles, with a slower decrease at lower tensile velocities. The dissipated energy and stiffness decreased with each cycle, but increased at higher tensile velocities. In stage 2, an increase in stiffness was observed with the elongation of the structure. In stage 3, injuries mainly occurred in the bone fragments and attachments rather than in the ligament structures.

Conclusions

The testing stage and tensile velocity influenced the mechanical response of the tissue. The obtained results are important for a better understanding of the mechanism of intra-articular periarticular injuries.