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Complication rates of anterior cruciate ligament reconstruction (ACL-R) were reported to be around 15%. Although it is a very common arthroscopic surgery with good outcomes, breakage and migration of fixators are still possible to occur due to stability issue. One of the factors that affects the mechanical stability of fixators is its length. Therefore, the aim of this paper is to analyze the biomechanical effects of different lengths of fixators (cross-pin technique) towards the stabilities of the knee joint after ACL-R. Finite element analyses of knee joint with DST grafts and fixators were carried out. Mimics and 3-Matic were used in the development of knee joint models, while the grafts and fixators were designed by using SolidWorks software. All models were remeshed in the 3-Matic and numerical analysis was performed via MSC.Marc Mentat software. A 100 N anterior tibial load was applied onto the tibia to simulate the anterior drawer test after the surgery and proximal femur was fixed at all degrees of freedom. Based on the findings, cross-pin with 40[Formula: see text]mm in length provided the most favorable option for better treatment of ACL-R, where it could promote osseointegration and preventing fracture.

An external fixator device is a medical implant used to keep fractured bones stabilized and in alignment. It consists of pins which are placed into the bone, extending outside the surface of the skin, and attached to a rigid external rod to keep it in place. The aim of this study is to investigate the most suitable material used for the external fixator. Firstly, the 3D model of two unilateral uniplanar external fixator with the properties of titanium and stainless steel were constructed at Solidworks software with all the other parameters set to constant. Meanwhile, CT images of the lower limb were used to reconstruct a 3D model of the femur fracture at Mimics Medical software. Positioning and meshing of both the external fixator and the femur done at 3-Matics Medical and export as Patran for simulation at Marc Mentat software. 375 N load was applied at the most proximal femur to simulate stance phase of a gait cycle. From the findings, external fixator by using stainless steel as material properties have lower maximum von Mises Stress (18.40 MPa) at the femur and (103.69 MPa) at the fixator compared to the titanium (32.38 MPa) at the femur and (182.93 MPa) at the fixator. The result shows a difference of 75% of maximum von Mises Stress at the femur and the external fixator. Configuration by using stainless steel displaced 1.15 mm at the femur and 1.01 mm at the fixator which almost double value of displacement for titanium material for both femur (2.35 mm) and external fixator (2.11 mm). In conclusion, stainless steel external fixators provide better stability when compared to titanium external fixators.

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