Computational comparison of different plating strategies in medial open-wedge high tibial osteotomy with lateral hinge fractures

Chen et al. Journal of Orthopaedic Surgery and Research https://doi.org/10.1186/s13018-020-01922-0 (2020) 15:409 RESEARCH ARTICLE Open Access Computational comparison of different plating strategies in medial open-wedge high tibial osteotomy with lateral hinge fractures Yen-Nien Chen1*† , Chang-Han Chuang2†, Tai-Hua Yang3,4,5,6,7, Chih-Wei Chang4,7*, Chun-Ting Li8, Chia-Jung Chang3 and Chih-Han Chang3,6 Abstract Background: Lateral hinge fracture (LHF) is associated with nonunion and plate breakage in high tibial osteotomy (HTO). Mechanical studies investigating fixation strategies for LHFs to restore stability and avoid plate breakage are absent. This study used computer simulation to compare mechanical stabilities in HTO for different LHFs fixed with medial and bilateral locking plates. Methods: A finite element knee model was created with HTO and three types of LHF, namely T1, T2, and T3 fractures, based on the Takeuchi classification. Either medial plating or bilateral plating was used to fix the HTO with LHFs. Furthermore, the significance of the locking screw at the combi hole (D-hole) of the medial TomoFix plate was evaluated. Results: The osteotomy gap shortening distance increased from 0.53 to 0.76, 0.79, and 0.72 mm after T1, T2, and T3 LHFs, respectively, with medial plating only. Bilateral plating could efficiently restore stability and maintain the osteotomy gap. Furthermore, using the D-hole screw reduced the peak stress on the medial plate by 28.7% (from 495 to 353 MPa), 26.6% (from 470 to 345 MPa), and 32.6% (from 454 to 306 MPa) in T1, T2, and T3 LHFs, respectively. Conclusion: Bilateral plating is a recommended strategy to restore HTO stability in LHFs. Furthermore, using a Dhole locking screw is strongly recommended to reduce the stress on the medial plate for lowering plate breakage risk. Keywords: High tibial osteotomy, Lateral hinge fracture, Plating strategy, Finite element simulation * Correspondence: ; ; † Yen-Nien Chen and Chang-Han Chuang contributed equally to this work. 1 Department of Physical Therapy, Asia University, 500, Lioufeng Rd., Wufeng, Taichung 41354, Taiwan 4 Department of Orthopedics, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan Full list of author information is available at the end of the article © The Author(s). 2020 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. 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Journal of Orthopaedic Surgery and Research (2020) 15:409 Introduction High tibial osteotomy (HTO) with a locking plate is a well-established surgical approach to adjust the mechanical axis of the low extremity with medial compartmental knee osteoarthritis (KOA) and restore the joint space of the medial knee of the KOA [1–3]. In recent years, HTO has gained popularity because of its satisfactory clinical outcome, particularly in patients aged 40–60 years [4–6]. Furthermore, HTO slows down the KOA process, and approximately 90% of patients could resume their original work and sports within 1 year of HTO [7]. To ensure the bone healing of the medial open wedge after HTO, stable fixation is required, and recently, the locking plate has been shown to provide excellent stability for early rehabilitation exercise [8, 9]. Although HTO showed satisfactory clinical outcomes, complications such as the need for symptomatic hardware removal, deep wound infection, hardware failure with correction loss, nonunion, early conversion to arthroplasty, displaced (> 2 mm) and undisplaced (< 2 mm) lateral hinge fracture (LHF), delayed wound healing, and undisplaced lateral tibia plateau fracture are common [10]. Other studies have reported an LHF incidence of 19.8– 41.2% after HTO [7, 11–13]. Furthermore, LHF is highly related to nonunion and plate breakage [14]. Many studies have investigated LHF incidence after HTO and complications following LHFs. The biomechanical effect of the LHFs on the HTO with medial opening wedge and the bone plate was also revealed [15]. In the study, the stress of the medial plate was increased with the LHFs. However, no mechanical study has investigated the fixation strategies of HTO for LHFs to restore stability and avoid plate breakage. Bilateral plating was demonstrated to re-correct the loss and nonunion after HTO [16], whereas mechanical stability was not investigated. Furthermore, only one type of LHF was involved in the study [16]; the other types of LHFs were not investigated. The aim of this study was to compare the mechanical stability, including gap shortening at the osteotomy site, the displacement of the proximal tibial fragment, and the stress on the metallic bone plates, in HTO with various LHFs, and medial and bilateral plates by using the finite element (FE) method. The FE method is a numerical tool to obtain mechanical responses, including internal stress and deformation, of the whole model [17, 18]. Additionally, the FE method excludes the variation between the samples in the study. Methods A reliable FE HTO model, which was validated and used to compare HTO stability with various screw configurations in a previous study [19], was modified to conduct HTO with LHFs and following medial and bilateral plate fixation. Page 2 of 9 Solid model The HTO model, with medial TomoFix plate and without LHF, used in a previous study was modified according to various hinge fractures. The angle of the medial open wedge and the width of the lateral hinge were set to 12° and 10 mm, respectively. The width of the lateral hinge refers to the distance from the apex of the wedge to the lateral edge of the tibia. In this study, three types of LHF fractures, namely type 1 (T1), type 2 (T2), and type 3 (T3), were created according to the Takeuchi classification [20]. T1 fracture referred to a crack, parallel to the osteotomy line of the open wedge, in the open wedge extending to the proximal site of the tibiofibular joint. T2 fracture referred to a crack in the open wedge extendi (...truncated)