A comparison of stress, contact pressure, and contact area on menisci in re-injury mechanisms after reconstruction of the anterior cruciate ligament with autograft and synthetic graft: a finite element study.

PURPOSE

The anterior cruciate ligament (ACL) is crucial in maintaining knee stability. Some motion mechanisms, which are common in sports, cause excessive load to be passed on the ACL. In non-contact ACL injuries, the ACL cannot sustain the high stress and becomes injured or ruptures in the valgus-external rotation mechanism (VERM) and varus-internal rotation mechanism (VIRM). The mechanical strength of the grafts used to repair the torn ligament varies. The purpose of this study is to look at the alterations in the menisci after anterior cruciate ligament repair with autografts and synthetic grafts in cases of non-contact re-injury mechanisms.

METHODS

In the finite element analysis, VERM and VIRM motions of the injury were simulated with different ACL graft materials. During the simulations of these mechanism motions with polyethylene terephthalate (PET) and patellar tendon (PT), the contact pressures, contact areas, and von mises stress values created in the medial and lateral meniscus were compared.

RESULTS

The peak contact pressures on the menisci during the VERM are higher than the peak contact pressures during the VIRM, except for one variation. The peak contact pressure of the medial meniscus is almost the same for both graft materials and mechanisms. Furthermore, the peak contact pressures in the menisci are higher than in the VERM. For all injury mechanisms, the peak contact stresses on the lateral meniscus are higher than on the medial meniscus.

CONCLUSIONS

The findings suggest that VERM can induce further knee joint injury. It was found that the PET will lessen the pressure on the menisci even more. It is also advantageous since it does not damage the anterior extremities and transmits less pressure to the menisci. In conclusion, using a high-strength ACL is healthier for the menisci. Even though synthetic grafts are not clinically preferred, the study demonstrates that enhancing the material properties of synthetic grafts will increase the chance of their use in the future, based on the current results.