Análisis numérico de la reconstrucción del ligamento cruzado anteriorInfluencia del diámetro del túnel tibial

Abstract

The number of variables that determines the success of an anterior cruciate ligament (ACL) reconstruction is so high that an in-depth analysis of the problem can only be carried out through numerical tools. Once the diameter of the substitute plasty and the interference screw has been chosen for a given patient, one of the main concerns of the surgeon is to find the most suitable diameter of the tibia tunnel for its fixation. In this work, a finite element model (FEA) was developed to simulate both the reconstruction and the subsequent rehabilitation process of the ACL at its tibia insertion. The process in which a 4 mm diameter tendon was intended to be fixed using a 7 mm diameter and 25 mm long screw using different diameters of the tibia tunnel (7, 8, 9 and 10 mm) was simulated. The parameters of the behaviour models of the different materials (screw, bone and tendon) were obtained through experimental tests. The results obtained show that, as the diameter of the tunnel decreases, the contact surface between the screw and the material that surrounds it (bone and tendon) increases, growing the compressive stress, the theoretical objective of fixation. However, so that compression damage to the trabecular bone does not occur, the maximum values of that pressure must be limited to those that are sufficient to ensure that the reconstruction is effective, that is, the tendon does not slip during the subsequent rehabilitation process. After this verification process consisting of pulling the tendon once fixed to the object of extraction, it is obtained that, regardless of the patient's age, the most suitable diameter is 8 mm, since it provides sufficient support with tension values and deformation that do not cause damage to the trabecular bone.