Biomechanical effects of cross-pin's diameter in reconstruction of anterior cruciate ligament - A specific case study via finite element analysis.

For anterior cruciate ligament reconstruction (ACL-R), one of the crucial aspects of treatment is the fixator selection that could provide initial graft fixation post-operatively. Literature on biomechanical stabilities of different sizes of fixators as femoral graft fixation is limited. Therefore, this study aims to analyse the influence of different diameters of cross-pins on the stability of graft fixations after ACL-R via finite element analysis (FEA). In the methodology, three-dimensional (3D) models of three different diameters of cross-pins were developed, of which anterior tibial loads (ATL) were applied onto the tibia. From the findings, the cross-pin with a smaller diameter (4 mm) provided optimum stability than larger diameter cross-pins, whereby it demonstrated acceptable stresses at the fixators (both cross-pin and interference screw) with a different percentage of 28%, while the stresses at the corresponding bones were favourable for osseointegration to occur. Besides, the strains of the knee joint with 4 mm diameter cross-pin were also superior in providing a good biomechanical environment for bone healing, while the recorded strain values at fixators were comparable with a larger diameter of cross-pins without being inferior in terms of deformation. To conclude, the cross-pin with 4 mm diameter depicted the best biomechanical aspects in graft fixation for ACL-R since it allows better assistance for the osseointegration process and can minimise the possibility of the breakage and migration of fixators. This study is not only useful for medical surgeons to justify their choices of pin diameter to treat patients, but also for researchers to conduct future studies.

Biomechanical analysis of three different types of fixators for anterior cruciate ligament reconstruction via finite element method: a patient-specific study.

Complication rates of anterior cruciate ligament reconstruction (ACL-R) were reported to be around 15% although it is a common arthroscopic procedure with good outcomes. Breakage and migration of fixators are still possible even months after surgery. A fixator with optimum stability can minimise those two complications. Factors that affect the stability of a fixator are its configuration, material, and design. Thus, this paper aims to analyse the biomechanical effects of different types of fixators (cross-pin, interference screw, and cortical button) towards the stability of the knee joint after ACL-R. In this study, finite element modelling and analyses of a knee joint attached with double semitendinosus graft and fixators were carried out. Mimics and 3-Matic softwares were used in the development of the knee joint models. Meanwhile, the graft and fixators were designed by using SolidWorks software. Once the meshes of all models were finished in 3-Matic, simulation of the configurations was done using MSC Marc Mentat software. A 100-N anterior tibial load was applied onto the tibia to simulate the anterior drawer test. Based on the findings, cross-pin was found to have optimum stability in terms of stress and strain at the femoral fixation site for better treatment of ACL-R.