| Part ?:The design of anatomical locking plate of posterior malleolus based on CT dataObjective:According to the data of CT images of adult normal ankle joints in China,the surface information database was constructed.The Mimics software was used to quickly segment the images of normal adult ankle joint CT three-dimensional reconstruction medical images,and the anatomical data of the posterior malleolus was measured.The anatomical locking plate of the posterior malleolus was designed and developed according to the anatomic shape of the posterior malleolus with angular stability.At the same time,monte carlo method was used to fit the relevant anatomical parameters of the anatomical locking plate of the posterior malleolus.Methods:The CT images of normal ankle joints of 300 adults(18-65 years old)in the Yangtze River Delta region of China were collected.Through the current internationally recognized Mimics software,a powerful medical image processing software,data analysis was carried out to develop an anatomical locking plate of posterior malleolus that conforms to the anatomy of the Chinese people.The angle a between the posterior condylar surface and the posterior condyle notch surface,the angle p between the posterior condyle and the posterior condylar tangential plane,and the angle y between the posterior condyle and the plane of fibula incisure of the tibia of the inferior tibiofibular joint.Draw the safety area of the posterior for screw placement,set the screw placement point and the direction of the nail in the safety area of the posterior malleolus,and measure the angle of the safe insertion of the screw placement.Various anatomical parameters required for posterior malleolus anatomical locking plate were designed by Monte Carlo method for large-data fitting of normal ankle CT images.Including the angle ? of the posterior condyle plane-the posterior condyle notch surface,the angle ? between the posterior condyle and the posterior condylar tangential plane,and the angle ? between the posterior condyle and the plane of fibula incisure of the tibia of the inferior tibiofibular joint.The position of the screw placement and the direction of the nail path were set in the safety area of the posterior malleolus,and the angle of the nail at the distal end of the plate was measured.Results:The angle between the plane of the posterior malleolus and the plane of the posterior malleolus notch,the angle between the plane of the posterior malleolus notch and the tangent plane of the dome of the posterior malleolus,and the angle between the plane of the posterior malleolus notch and the plane of the tibiofibular notch of the inferior tibiofibular joint showed no significant difference between men and women(P>0.05).Conclusions:The results showed that the Mimics software could be used to measure the anatomic data of the posterior malleolus after the design and development of the anatomical locking plate.The method is simple and easy to visualize.The anatomical characteristics and differences of the posterior malleolus can be described in detail according to the anatomical parameters of the posterior malleolus.At the same time,monte carlo method can be used to fit the related data of various anatomical parameters of the CT image data of the normal ankle joint,which fiurther verify the anatomical characteristics of the anatomic locking plate of the posterior malleolus.Part ?:Finite element analysis of posterior malleolar fractures treated with anatomical locking plateObjective:1.To analyze the biomechanical stability of anatomical locking plate for fixation of different types of posterior malleolus fractures by finite element method.2.Analyze and compare the biomechanical stability of ankle fracture after fixation with cannulated screw and 1/3 tubular plate.Methods:Taking the ankle joint of a normal adult male volunteer as the subject,the CT image data obtained by the right ankle joint of the normal adult male was taken by Siemens 64-row dual-source spiral CT.The finite element modeling technique was used to establish a three-dimensional finite element model of the ankle joint,and the validity of the model was verified.By segmenting and cutting the type of posterior malleolar fracture,the fracture displacement degree under normal stress,the degree of fracture displacement at different degrees of stress,the maximum stress,the maximum displacement and other related parameters were simulated under different posterior malleolar fracture conditions.The biomechanical stability and characteristics of different types of posterior malleolar fractures were analyzed by posterior malleolar anatomical locking plate.The finite element method was used to analyze the biomechanical stability of the posterior malleolar fractures with cannulated lag screw and 1/3 tubular plate fixation.The biomechanical characteristics and advantages of the posterior malleolar anatomical locking plate were evaluated.Results:The biomechanical stability of posterior malleolar anatomical locking plate fixation for different types of posterior malleolar fractures was significantly better than that of cannulated lag screw and 1/3 tubular plate fixation.The trend of the displacement cloud map corresponding to the three fixed methods such as cannulated screw?1/3 tubular plate and anatomical locking plate indicates that the displacement of the displacement is similar to the cloud image,and the comparability is high;the displacement value decreases in turn,and the fixation effect is Upgrade.The trend of stress cloud diagrams of three fixed modes shows that the results of stress changes are similar in cloud map distribution,and the comparability is high;the stress values decrease in turn,and the effect is obvious.The anatomical locking plate has a lower stress value than the cannulated screw and the 1/3 tubular plate.Conclusions:By constructing the finite element analysis of the posterior malleolar fracture model of the adult ankle,the designed posterior malleolar anatomical locking plate has more biomechanical angular stability compared with the cannulated screw and the 1/3 tubular plate.Part ?.Biomechanical study of posterior malleolus anatomical locking plateObjective:1.To analyze the biomechanical properties of the posterior malleolar fracture of the fixed cadaver with the anatomical locking plate and the 1/3 tubular plate.2 Through the universal biomechanical test system to test the mechanical strength of the designed anatomical locking plate,such as anti-axial compression and anti-torsion,calculate the ratio of mechanical strength to volume.Methods:The research project of this group cooperated with Changzhou Huasen Medical Instrument Co.Ltd.to develop and produce the posterior malleolar anatomical locking plate designed by the company.The titanium alloy material(Tc4),which was similar to the elastic modulus of the human bone,was used to design the anatomical locking plate and perform relevant factory inspection.At the same time,this experiment used 1/3 tubular plate produced by the same manufacturer as the experimental control plate.The biomechanical test used six adult calf specimens(the Department of Anatomy of Pudong Branch of Huashan Hospital affiliated to Fudan University and the Anatomy Laboratory of Yanbian University),including 4 males and 2 females,with an average age of 50 years(36-65 years old).Disengaged from the knee joint,retaining the calf and ankle joint.Specimens were randoruly divided into 2 groups,group A was the posterior malleolar anatomical locking plate group,and group B was the 1/3 tubular plate group.The internal fixation materials of Group A and Group B were tested by plates produced by the same manufacturer,Changzhou Huasen Medical Devices Co.Ltd.The posterior malleolar fractures of the cadaver specimens were fixed separately,and the mechanical test of the posterior malleolar anatomical locking plate of different lengths and the 1/3 tubular plate was designed by universal biomechanical test system,such as the mechanical test of anti-axial compression and torsion resistance.To evaluate the biomechanical properties and advantages of anatomical locking plate in the treatment of posterior malleolar fracture.Results:The results of this study showed that the posterior malleolar anatomical locking plate was fixed with different types of posterior malleolar fractures compared with 1/3 tubular plate.That achieved good results in anti-axial compression test and anti-torsion test.Both were significantly different,statistically(P<0.05).Conclusions:This study shows that the posterior malleolar anatomical locking plate fixes different types of posterior malleolar fractures compared with 1/3 tubular plate.It has good effects in anti-axial compression and anti-torsion.And it has biomechanical angular stability to prevent axial displacement of the posterior malleolar fracture.Therefore,the posterior malleolar anatomical locking plate has good biomechanical stability characteristics when the posterior malleolar fracture is fixed.Part ?.Clinical application of posterior malleolus anatomical locking plate in posterior Pilon fractureObjective:To compare the clinical effect of anatomical locking plate fixation,1/3 tubular plate and cannulated lag screw internal fixation for the treatment of posterior malleolar fracture.Methods:This study retrospectively analyzed the clinical data of 82 patients with ankle fractures involving the posterior malleolar fracture from January 2017 to August 2018,and the posterior malleolar joint surface was larger than 25%of the fracture ot the ankle joint.According to different fixation methods,it was divided into three groups,such as posterior malleolar anatomical locking plate fixation group(anatomical locking plate group,group A),1/3 tubular plate fixation group(tubular plate group,group B)and cannulated screw fixation group(cannulated screw group,Group C),using the posterior lateral approach.There were 24 patients in group A,15 males and 9 females,aged 20-65 years,mean(43.3±12.4)years old.According to the Denis-weber fracture classification,there were 10 cases of type B and 14 cases of type C.There were 28 patients in group B,18 males and 10 females,aged 21-62 years,mean(44.0±11.8)years old.According to the Denis-weber fracture classification,there were 16 cases of type B and 12 cases of type C.There were 30 patients in group C,18 males and 12 females;aged 20-65 years,mean(49.9±11.3)years old.According to Denis weber fracture classification,there were 14 cases of type B and 16 cases of type C.The study compared the duration of surgery,the number of intraoperative fluoroscopy,the amount of bleeding,and the X-ray findings at 1 month,3 months,6 months,and 12 months after surgery.The ankle joint function was assessed at the last follow-up of.The ankle function was assessed at the last follow-up of the patient,using the hindfoot scoring criteria of the American Orthopedic Foot and Ankle Society(AOFAS).Results:The results showed that the average operation time of the three groups were(0.88±0.14)h in group A,(1.23±0.12)h in group B,and(1.14±0.14)h in group C.The operation time of group A was shorter than that of group B and group C,and the difference was statistically significant(P<0.05).The mean bleeding volume of the three groups was(108.33±11.87)ml in the group A,(136.61±11.10)ml in the group B,and(117.67±9.46)ml in the group C.The intraoperative blood loss was smaller in the group A than in the group of C and B.There was no significant difference between the two groups(P>0.05).However,the group of anatomical locking plate had shorter operation time and less relative intraoperative bleeding.The number of fluoroscopy in the three groups during operation was(6.04±1.14)times in the group A,(7.75±1.45)times in the group B,and(9.3±1.72)times in the group C,respectively.The number of fluoroscopy in the group A was less than that in the group B and the group C,respectively.The difference was statistically significant(P<0.05).Postoperative X-ray findings,fracture healing time,postoperative function and complications were compared.The results showed that there were no wound infections in the three groups after operation,and no delayed incision and nonunion occurred,There were three patients in the group C who had a poor reduction of posterior malleolar fracture and a fracture displacement greater than 2 mm.In the group C,there were 2 patients with poor position of the cannilated screws,which were placed in the lower tibiofibular syndesmosis.One patient in the group A and three patients in the group B had mild flexion contracture of the toe.Two patients in the group A and 5 patients in the group B had discomfort during ankle joint activity.The symptoms disappeared after rehabilitation exercise.The ankle-hindfoot scores of AOFAS were compared between the three groups at 1 month,3 months,6 months,12 months after surgery,and the last follow-up.The comparison was not statistically significant(P>0.05).However,the scores of ankle-hindfoot in the three groups were better than those in the group B and group C,the difference was statistically significant(P<0.05).At the last follow-up,the AOFAS ankle-hindfoot scores of all patients were significantly different from the corresponding 3 months,6 months,and 12 months(P<0.05).Conclusions:Posterior Pilon fractures were fixed in three different ways through the posterolateral approach.The cannulated screws were relatively minimally invasive,but the quality of the reduction was uncertain.The number of intraoperative fluoroscopy was high,and the operation time was long.The tubular plate and the anatomical locking plate can be directly viewed for the anatomical reduction of fracture.The wound is relatively large,but it is easy to perform early functional exercise and weight-bearing walking after surgery.However,the intraoperative tubular plate needs to be shaped to increase the operation time,the screw direction is not easy to control,and it is easy to enter the joint,resulting in adverse complications. |
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