PSI - Issue 42

Guilherme Opinião et al. / Procedia Structural Integrity 42 (2022) 1266–1273 Guilherme Opinião / Structural Integrity Procedia 00 (2022) 000 – 000

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Figure 4(B) shows an example of the irregularities of the holes in one of the samples, as well as the layer effect of the FFF process, underlining that such aspects can affect the behavior and life performance of each screw. 5. Final Remarks Bioabsorbable interference screws are the most used implants for ACL fixation due to their mechanical resistance, biocompatibility, and ability to promote osteoconduction. In this work, 52 screw models were designed and evaluated through FEA. From this analysis, 4 screw models were selected and produced by FFF and then inserted in a foam plate, used to simulate the bone. Results confirm that screw geometry and its defining parameters have a significant influence on allowable torque, and this conclusion is in line with other research, such as the experiment by Costi et al. [10]. Even if insertion of tested screws was only possible at low tightening torques, by developing an interference screw with FFF, the mechanical resistance of the screw can be tailored to only sustain its integrity under service during a previously defined life, potentiating the bio-absorption of the material once is service is complete. Authors believe that FFF bioabsorbable interference screws might be a solution in order to promote early rehabilitation during ACL reconstruction. For this goal, future research should focus both on tightening and pull-out tests, and on a deeper design for AM study of the screws that aims at quantifying and minimizing FFF inherent defects. Acknowledgements This work was supported by FCT - Fundação para a Cíência e Tecnologia, through IDMEC, under LAETA, Project UIDB/50022/2020. Manuel Sardinha gratefully acknowledges FCT, for his PhD research grant reference 2021.04919.BD. MFV acknowledges FCT within the project PTDC/CTM-CTM/3354/2021. References [1] M. Marieswaran, I. Jain, B. Garg, V. Sharma, and D. Kalyanasundaram , “A Review on Biomechanics of Anterior Cruciate Ligament and Materials for Reconstruction,” 2018, doi: 10.1155/2018/4657824. [2] S. L- y Woo, J. Marcus Hollis, D. J. Adams, R. M. Lyon, and S. Takai, “Tensile properties of the human femur-anterior cruciate ligament- tibia complex The effects of specimen age and orientation*,” 1990. [3] G. A. Malanga, J. Giradi, and F. Nadler, “The Spontaneous Healing of a Torn Anterior Cruciate Ligament CASE REPORT 118,” 2001. [4] L. T. Buller, M. J. Best, M. G. Baraga, and L . D. Kaplan, “Trends in anterior cruciate ligament reconstruction in the United States,” Orthop J Sports Med , vol. 3, no. 1, pp. 1 – 8, Jan. 2015, doi: 10.1177/2325967114563664. [5] D. Stengel, D. Casper, K. Bauwens, A. Ekkernkamp, and M. Wich, “Bioresorbabl e pins and interference screws for fixation of hamstring tendon grafts in anterior cruciate ligament reconstruction surgery a randomized controlled trial,” American Journal of Sports Medicine , vol. 37, no. 9, pp. 1692 – 1698, 2009, doi: 10.1177/0363546509333008. [6] M. Kurosaka, S. Yoshiya, and J. T. Andrish, “A biomechanical comparison of different surgical techniques of graft fixation in anterior cruciate ligament reconstruction.” [7] A. R. Sadeghi-Avalshahr, M. Khorsand-Ghayeni, S. Nokhasteh, A. M. Molavi, and M. Sadeghi-Avalshahr, “Physical and mechanical characterization of PLLA interference screws produced by two stage injection molding method,” Prog Biomater , vol. 5, no. 3 – 4, pp. 183 – 191, Dec. 2016, doi: 10.1007/s40204-016-0056 4. [8] D. B. Purcell, J. R. Rudzki, and R. W. Wright, “Bioabsorbable interference screws in ACL reconstruction,” Oper Tech Sports Med , vol. 12, no. 3, pp. 180 – 187, 2004, doi: 10.1053/j.otsm.2004.07.014. [9] D. N. M Caborn, W. P. Urban, D. L. Johnson, J. Nyland, and D. Pienkowski, “Biomechanical Comparison Between BioScrew and Titanium Alloy Interference Screws for Bone-Patellar Tendon-Bone Graft Fixation in Anterior Cruciate Ligament Reconstruction,” 1997. [10] J. J. Costi, A. J. Kelly, F. Orth, T. C. Hearn, and D. K. Martin, “Comp arison of Torsional Strengths of Bioabsorbable Screws for Anterior Cruciate Ligament Reconstruction*,” 2001.