Combination Of CAD,FEM And 3DP For Clinical Cranioplasty And The Biomechanical Properties Of Triangular Parabolic Knob PEEK Nets With Hole Lock

For patients with brain injury(subdural hematoma,epidural hematoma,intracerebral with diffusing of hematoma and swelling of cells),malignant cerebral infarction,skull or intracranial tumor such as large area glioma,etc.in order to save lives or ensure good postoperative effect,reducing the mortality / disability rate,the bone flap is often removed during the operation.Decompressive craniectomy(DC)Is to remove the bone flap and / or cut the meninges to increase the potential space in the skull to accommodate swollen brain tissue so that to reduce intracranial hypertensionism and to prevent hernia of brain hernia.Besides DC can improve cerebral perfusion(CPP)? Cerebral blood volume((CBV)? cerebral blood flow(CBF)? cerebral oxygen metabolism(CMRO2)and oxygen extraction fraction(OEF),basing on the theory formula of(CBF=(MAP-ICP)/CVR=CPP/CVR).But after DC patients often with complication of skull defective syndrome,Therefor,Cranioplasty which had a long history is need,outside/inside temporal muscle are two typles of cranioplasty.materials concern about craniplasty including autogenous bone,allograft bone,bone cement,titanium alloy,polyetheretherketone(PEEK)and so on.Currently,The material for craniplasty widely used by neurosurgenons is three-dimensional titanium mesh,because of its excellence immune compatibility,easy to plasticity,no cells and genetic toxicity.But,after implantation,it always appear the risk of reeling,nail pulling,deformation,et.,and it may even cause the exposure of titanium mesh so intracranial infection is possibly.PEEK is a new polymer which non-thermoplastic-degradable.It is a linear polymer composed of aryl,ketone and ether bonds in the main chain of macromolecules.It has outstanding biomechanical propertiess such as radiation resistance,corrosion resistance,high temperature resistance and high pressure resistance.High biocompatibility and x-ray transmissibility.computer-aided design enable digitize the body structure,after 3D reconstruction and virtual reality technology processing,we can get visible and freely regulated virtual simulation human body named “visual 3D anatomical model”,themodel not only can accurately and intuitively show the anatomy of lesion and the periphery of lesions which is helpful for docters to underand the degree of lesions and anatomic more comprehensively but also it can simulate the operation before operation,so,reduing the rate of operation error and time of operation.improving the therapeutic effective.Finite Element Methods(FEM)is discretization continuum into series the limited size units to solve continuum? s mechanical problems.Tigh efficiency and easy operation is its characteristics.3D printing(3DP)also named“rapid prototyping technique” is based on digital models,and material power is utilized,by layer by layer to produce implants.The combination of CAD,FEM,and3 DP for craniplasty can not only improve the quality of operation but also imorove the prognosis.The design of triangular Parabolic knob Peek mesh with Hole Lock(TPHLPM)is based on Overlay three-dimensional titanium mesh(OTDTM)and wedge styple PEEK mesh(WPM),The aim is to improve the biomechanical properties of the implants and the long-term post implantation effect,to reduce the time of operation and the potential risk of surgery.TPHLPM has been granted a national patent for practical use(patent no.: 2l201621158289.9),and a "five-new" clinical transformati-on project for ShenKang specialist diseases(Chictr-inr-16009392).Objective:In this study,we use PEEK material,combining CAD,FEM and 3DP to make personalized customized implant-triangular parabolic mesh with hole locking button.At the same time,four kinds of implants are evaluated by finite element method.Method:Select a patient with left frontotemporal-parietal skull defect requiring craniplasty,using CAD software mimics17.0 and matic8.0 and FEM software ansys17.0 designed triangular parabolic PEEK mesh with hole locking button for the patient.DICOM data of CT imaging of a complete skull was need,repeated leading-in mimics17.0 and 3-matic8.0 software to establish three-dimensional skull model and doDC,40 skull defect models were obtained,divided into a.b.c.d groups,10 per group,designed of prosthesis of OTDTM,WPM,TPHLTM,TPHLPM onmatic8.0 and other software for a.b.c.d group,when Cranioplasty,The defect skull and the prosthesis of a.b.c.d group were imported into ansys-workbench17.0software in turn.Vertical loading of a 500 n static force over an area of 3.982 cm in the central area of the implants,Simulation of forces acting on four kinds of implants in life when heavy objects or motor vehicles impact on them,The stress distribution,maximum stress,maximum strain and maximum displacement of the four kinds of implants and the corresponding defect skull were compared.Result:Through stress-strain analysis,the maximum stress of 5 knobs(triangular parabolic knob mesh model?=5.7228e6;defective skull?=4.1904 e6)and maximum strain(triangular parabolic knob mesh model ?=9.053e-7;defective skull;?=1.9363e-7),corresponding cloud charts were obtained,the distribution of concentrated force is relatively uniform,5 lock button thickness 1mm,area 21.6mm,hole diameter 2mm.Under the load of 500 n,none of the four kinds of implants and defective skulls have burst or deformed.The stress is concentrated on the temporal,orbital,contact areas of implants and defective skull and forces point of the implants on OTDTM and TPHLTM.The WPM? s stress is concentrated on the foreheadparietal,the area of forces on the implant,the temporal part of the skull base and the titanium strips.The result of TPHLPM is near same to WPM except strips without concentarte force.The ?and?of implants of OTDTM?WPM?TPHLTM?TPHLPM are243.800mpa?21.002mpa?386.2001mpa?2.731 mpa and 0.1644mm?0.0825mm?0.2782mm?0.0828 mm respectively.Conclusion:Craniplasty with Triangular-parabolic knob Peek mesh not only ensures high biomechanical properties after implantation but also restores the original beauty of the patient.The morphological structure of the implants can be customized on Mimics and Matic software according to the patient's anatomic defect.