Contents lists available at ScienceDirect Clinical Biomechanics journal homepage: www.elsevier.com/locate/clinbiomech Optimal configuration of a dual locking plate for femoral allograft or recycled autograft bone fixation: A finite element and biomechanical analysis Taweechok Wisanuyotin ⁎ , Winai Sirichativapee, Permsak Paholpak, Weerachai Kosuwon, Yuichi Kasai Department of Orthopaedics, Faculty of Medicine, Khon Kaen University, 40002, Thailand ARTICLE INFO Keywords: Finite element analysis Femur Allograft Recycled bone autograft Dual locking plating Biomechanical analysis ABSTRACT Background: Allografts and recycled bone autograft are commonly used for biological reconstruction. The dual locking plates fixation method has been advocated for increasing allograft stability and preventing fixation failure; however, the biomechanical properties of the various configurations of dual locking plates have not been extensively studied. Methods: In a finite element (FE) analysis, we developed 6 patterns of different dual locking plate configurations for fixation of the mid shaft of the femur. The maximum strains were recorded for each of the 6 models then axial, bending and torsion stiffness were calculated. The FE analysis was validated the results with mechanical testing (axial compression, bending, and torsional stiffness) on a cadaveric femur. Findings: The highest axial compression (715.41 N/mm) and lateral bending (2981.24 N/mm) was found in Model 4 (with two 10-hole locking plates placed at the medial and lateral side), while the highest torsional stiffness (193.59 N·mm /mm) was found in Model 3 (with 8- and 10-hole locking plates placed at the posterior and lateral side). Excellent agreement was found between the finite element analysis and biomechanical testing (r 2 = 0.98). Interpretation: The dual locking plate configuration with medial and lateral, 10-hole locking plates provided the most rigid and strongest fixation of the femur; both in terms of axial compression and lateral bending stiffness. 1. Introduction Biological reconstruction is one of the choices for management of large bone defects after bone tumor resection. Allografts and recycled bone autografts are commonly used for biological reconstruction. Since both types of bone graft are nonviable bone, the time to union takes longer than usual and there are numerous reports of complications in- cluding fracture and non-union (Aponte-Tinao et al., 2012; Igarashi et al., 2014; Sorger et al., 2001; Tsuchiya et al., 2005). The femur is the most common site for biological reconstruction (Bus et al., 2017; Sorger et al., 2001). The choices for fixation of the femur are intramedullary nailing, or locking plate and screws. Intramedullary nailing provides excellent resistance to bending but provides less stability against rota- tion (Meyer et al., 2000). Plates and screws are better than in- tramedullary nailing for rigid fixation and absolute stability, which are needed for allograft fixation (Aponte-Tinao et al., 2012; Aponte-Tinao et al., 2014); while locking plates have an advantage over standard compression plates in terms of superior stability, improved union rates, and less need for further surgeries (Strauss et al., 2008). Several authors suggest using dual locking plates for fixation to increase allograft sta- bility and to prevent failure of fixation (Buecker et al., 2006; El Beaino et al., 2019; Gupta et al., 2017). However, the biomechanical properties of the various configurations of dual locking plates have not been ex- tensively studied. The objective of the current study was thus to test the biomecha- nical properties of various configurations of dual locking plates for fixation between the allograft or recycled bone autograft and the host bone at the mid shaft of the femur. 2. Methods The study was reviewed and approved by the Khon Kaen University Ethics Committee in Human Research (HE611524). FE analysis was performed first followed by biomechanical testing. https://doi.org/10.1016/j.clinbiomech.2020.105156 Received 9 March 2020; Accepted 19 August 2020 ⁎ Corresponding author. E-mail address: tawwis@kku.ac.th (T. Wisanuyotin). Clinical Biomechanics 80 (2020) 105156 0268-0033/ © 2020 Elsevier Ltd. All rights reserved. T