Classification Of Calcaneal Fractures Based On Three Dimensional Finite Element And Mimics Techniques

Objective:The biomechanical effect of calcaneal fracture was analyzed by using3 D finite element and Mimics technology,combined with calcaneal sectional anatomy,and the mechanism of fracture was discussed to establish a new classification.Methods:1.CT thin-slice Imaging data of 77 patients with calcaneal fractures admitted to our hospital between June 2015 and June 2018 were collected to obtain the standard data of Dicom(Digital Imaging and Communications in Medicine).2.The 3D model of calcaneal bone was obtained by 3D reconstruction of the collected CT images using the software Materialise's interactive medical image control system.After heel bone joint surface is divided into four quadrants(left foot counterclockwise,right foot clockwise,a,d quadrant in the lateral,b and c quadrant in the inside),the incidence of fracture statistics each quadrant,fracture analysis of fracture location tendency,at the same time,determine the specific degree of each joint surface subsidence numerical,statistical methods count data on the frequency and frequency,said measurement data using mean ± standard deviation,according to multiple sets of measurement data using analysis of variance.3.Ansys three-dimensional finite element software was used to simulate the stress mode and analyze the stress changes in different positions of the posterior calcaneal joint surface,so as to establish a new classification of calcaneal fracture and guide clinical treatment.4.The shape and density of trabeculae of calcaneus were observed and the classification of calcaneal fracture was verified.Results:1.Quadrant incidence of fractures on the posterior articular surface(each articular surface fracture may involve one or several quadrants): 82 feet in total,30 feet in quadrant a,accounting for 36.6%;Quadrant b: 29 feet,accounting for 35.4%;C quadrant 43 feet,accounting for 52.4%;D quadrant71 feet,accounting for 86.6%.The fourth quadrant had the highest incidence of fractures,at 86.6 percent.2.Incidence of collapse quadrant of posterior calcaneus articular surface(each articular surface collapse may involve one or several quadrants,and in some cases,no collapse occurred or the degree was small): 63 feet in total,5 feet in quadrant a,accounting for 7.9%;5 feet in quadrant b,accounting for 7.9%;23 feet in quadrant c,accounting for 36.6%;Quadrant d is 54 feet,accounting for 85.7%.The fourth quadrant articular surface had the highest probability of collapse displacement(65.9%).The average collapse degree of quadrant a was 2.77±0.85 mm,the average collapse degree of quadrant b was 3.50±0.85 mm,the average collapse degree of quadrant c was 4.90±2.40 mm,and the average collapse degree of quadrant d was 5.78±2.29 mm.The degree of collapse in different quadrants was compared,and the comparison results showed statistically significant differences(F=4.327,p=0.007).Further pantwise comparison showed that the collapse degree of quadrant d was higher than that of quadrant a and quadrant b,and the difference was statistically significant(P<0.05).3.According to the three-dimensional finite element analysis,the stress of the calcaneus in the neutral position without load was concentrated in the c and d quadrants and the spacer protrusion of the joint surface below the back distance,while the stress in the joint surface below the back distance was concentrated in the c and d quadrants and the stress change value was greater than that in the a and b quadrants.4.The transect anatomy of the calcaneus revealed the trabecular shape:dense inwardly and posteriorly,sparse externally and anteriorly.The bone trabecular density was higher at the lower part of the anterolateral articular surface,at the spacer process and at the calcaneus nodule,and the bone cortex was thicker and decreasing forward.The density of the medial calcaneus trabecular was higher than the lateral,and the thickness of the medial cortex was thicker than the lateral,consistent with the statistical data and 3d finite element data,which could verify the classification of calcaneal fractures.Conclusion:1.Three-dimensional finite element analysis combined with Mimics technology can accurately analyze the stress distribution of calcaneus under different loads and the specific values of stress changes in each part.2.In this study,the results of finite three-dimensional analysis,statistical results of clinical data,and sectional anatomy results of solid calcaneal specimens were mutually verified and supplemented,and it could be concluded that there was a certain regularity and tendency in the occurrence of fractures and articular surface collapse of posterior calcaneal bone.Thus,the fractures of posterior calcaneal articular surface were initially divided into types ?,?,? and ?.Type ? was a single quadrant fracture,which was divided into four subtypes ?a,?b,?c and ?d according to the corresponding four quadrants.Type ? is a bi-quadrant fracture,which is divided into ?ab,?ac,?ad,?bc,?bd and ?cd subtypes.Type ? is a three-quadrant fracture,which is divided into ?abc,?abd,?acd and ?bcd subtypes.Type ? is a total articular fracture involving four quadrants.There are many types of fractures involving the c and d quadrants,and the degree of articular surface collapse is relatively serious.