Different Remedial Measures For High Tibial Osteotomy Accompanied With Lateral Hinge Fracture: A Finite Element Analysis And Biomechanical Test

Part Ⅰ:Establishment and validation of finite element model for high tibial osteotomy accompanied with lateral hinge fractureObjective: Open wedge high tibial osteotomy is a well establishment procedure for treating medial compartment osteoarthritis of the knee.Lateral hinge fracture(LHF)is one of the most common complications of OWHTO,which could lead to the instability of the osteotomy site.While instability of the osteotomy site could result in loss of correction,nonunion of the osteotomy,implant failure,and recurrent varus deformity before osteotomy union.There are a limited number of finite element analyses(FEA)studies concerning LHF.The objective of this study aimed to establish a FEA model of LHF and verify its validity as the basis for subsequent analysis.Methods: CT data of healthy adult volunteers’ knee joint was acquired and imported into MIMICS 20.0 software in a DICOM format to establish a threedimensional model of knee joint,and then was materialized by Geomagic Studio12.0.The materialized model,orthopedic plate and screws were imported into Solid Works 2018,and the OWHTO model accompanied with LHF was established according to the standard OWHTO surgical techniques.A matching biomechanical test was performed,and the posterior height change of the osteotomy gap was measured.The validity of the model was verified by comparing the FEA results with biomechanical test results.Results: An OWHTO model with LHF was successfully established with a total of 277,839 elements and 481,744 nodes.The trend of posterior height changes of osteotomy gap was consistent with biomechanical test,and the validity of the model was verified.Conclusion:The FEA OWHTO model with LHF has a perfect structure and reliable results,which could be used for the subsequent analysis.Part Ⅱ: Finite element analysis of different remedy measures for lateral hinge fractureObjective: LHF is one of the common complications of OWHTO,which could decrease the stability of the structure.In this part,the FEA method was used to explore whether BSM,LPS,LPS+BSM,LP and LP+BSM could increase the stability of OWHTO accompanied with LHF.Methods: Five remedial models of BSM filled,LPS,LPS+BSM,LP and LP+BSM were established respectively on the basis of previously established LHF model,and the materials properties were assigned and meshed.The three levels axial compressive load of 800 N,1600N and 2500 N and 10 Nm internal and external rotational load were applied to the tibial plateau respectively.The vonMises stress of orthopedic plate,screws and cortical bone were calculated.The total deformation,axial compressive displacement of the proximal osteotomy segment and the height changes of the osteotomy gap were calculated under axial compressive load,while the torsional angle of the proximal osteotomy was calculated under torsional load.Results: Under axial compressive load,LHF could lead to the collapse of the proximal osteotomy segment and increasement of tibial slope.Peak von-Mises stress concentrated at the D hole of orthopedic plate and lateral hinge point of cortical bone,which could result in implant failure and cortical fracture at the hinge.When remedial measures were adapted,LPS+BSM could acquire the maximal axial stability and exhibit the maximal load sharing effect,followed by LP+BSM,LP,LPS and BSM,respectively.Under external rotational load,BSM,LPS,LPS+BSM,LP and LP+BSM can reduce the torsional angle of the proximal osteotomy segment by 0.00%,74.90%,87.06%,81.38% and 81.54%,respectively.BSM filled alone could not increase the rotational stability of the osteotomy site.Under internal rotational load,BSM,LPS,LPS+BSM,LP and LP+BSM could reduce the torsional angle of the proximal osteotomy segment by 18.14%,22.28%,27.54%,30.23% and 43.00%,respectively,without clinical significance however.Conclusion: Only BSM,LPS or LP had limited contribution to the stability restoration of the osteotomy site under axial compressive load.LPS and LP could significantly improve the anti-rotational stability of the structure,while only BSM had no contribution to the anti-rotational stability.The axial compressive and rotational stability of the structure can be improved simultaneously if BSM stabilized by LPS or LP.