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Limited open reduction and internal fixation via an anterior-lateral approach for extra-articular distal-third diaphyseal fractures of the humerusBackground: Traditional open reduction and internal fixation(ORIF)of extra-articular distal humerus fractures has a risk of iatrogenic radial nerve injury due to the manipulation of nerve,extensive soft tissue stripping,and long incision scar.Minimally invasive plate osteosynthesis(MIPO)is not considered suitable for these fractures.Therefore,we designed a limited open reduction(LOR)technique via an anterior-lateral approach for distal-third diaphyseal fractures of the humerus and evaluated clinical and radiographic outcomes through this respective study.Methods: From April 2010 and June 2016,28 cases of extra-articular distal-third diaphyseal fractures were treated in our department with an anterior-lateral approach LOR procedure.Patient demographics,Disabilities of the Arm,Shoulder and Hand(DASH)Score,Mayo Elbow Performance(MEP)Score,elbow range of motion(ROM),scars and postoperative complications were recorded and analyzed regarding clinical results.Results: All fractures were united with a mean time of 3.5 months.One patient exhibited delayed union(3.6%),with a union time of 9 months.No nonunion,iatrogenic neuropraxia,or implant failure occurred.The mean DASH Score was 6.6,and all patients had excellent or good MEP Score values.The average scar length was 6.8 cm,and the shortest was 4.5 cm.There was no significant difference in clinical outcomes when two or three screws were used at the distal fragment.Conclusions: The LOR technique via an anterior-lateral approach for extra-articular distal-third diaphyseal fractures of the humerus results in predictable union,less iatrogenic radial nerve injury,less invasion and scaring,and excellent functional results..Part ? Mechanical Junction Fractures of Humeral Diaphyseal: Injury Mechanism Study with Finite Element AnalysisPurpose: We simulated the mechanical junction fractures of distal-third humeral diaphyseal with finite element analysis,discussed the injury mechanism.Methods: Eleven humerus CT data of healthy volunteer were collected.With the use of professional medical image processing software Amira,we managed the 2D image data for reconstruction and modification.The grid models were imported into the finite element analysis software marc/mentat,for the defining of material properties,set the material parameters.Eight force conditions were simulated the stress of humerus with two groups and each group having 4 kinds of force types,including axial force of 100 N,shear force of 100 N,torsion force 100 N and torsion force 200 N.With different parts of the force,direction,size,we simulated humerus indirect violence injury,and analyzed the reality injury mechanism.Results: Analysis of 88 kinds of equivalent von Mises stress results,we found that,in the B group,high stress conditions distributing variably.In the group A,all the high stress conditions distributed on the deformation zone of dital-third humerus.It's the same with our study.In order to express von Mises,we set the highest 10% regional to the mechanical junction,it was located in the range of 74%(SD + 2.33)to 83%(SD + 2.01)region of the whole length humerus,the highest point was average in the 79.8% of humerus length(SD + 2.56).Conclusions: The structure morphology is the basis of distal-third fracture of the humerus.The injury mechanism is condition when the distal end of the humerus is fixed,and the stress exerted on the proximal humerus,the mechanical junction appears relatively concentrating of force,resulting in fracture.The mechanical junction of distal-third humerus located approximately 74% to 83% of the whole length of the humerus region,the highest point average in the 79.8%.Part ? Mechanical Junction Fracture of humerus: Dynamic Finite Element Simulation and New Fracture Classification Purpose: Explicit finite element analysis was used to simulate the dynamic fracture process of the distal-third mechanical fracture of the humerus,and a new fracture classification system based on the force condition was obtained.Methods: We collected 1 CT data of a healthy volunteer.With the use of professional medical image processing software Amira,three-dimensional image was reconstructed.The grid model was imported in the finite element analysis software Ansys/LS-DYNA to define failure material properties,fracture criterion and set the relevant parameters.To simulate the real stress damage,we applied 6 kinds of load conditions,including model A: axial compression,model B: bending force and model C: torsion force.Model D,E,F had two force loads.We collected 205 cases of distal-third mechanical junction fractures of humerus,and saved the imaging data for comparing with the results of finite element analysis.Results: In the one load case,the fracture line followed the direction of force,showing three fracture morphology: group A: transverse fracture,group B: short oblique fracture and group C: spiral fracture.In the D,E,F groups,there were long oblique fracture or a wedge block fracture morphology.When three loads were added,there were comminuted fractures with a number of irregular fracture line.According to the results,we classified the fractures with the type I: transverse fracture,type ? short oblique fracture,type ? spiral fracture,type IV long oblique fracture,type ? spiral wedge fracture,type ? bending wedge fracture,type ? comminuted fracture.According to the clinical data of 205 cases,we got type I fracture in 30 cases,type II fractures in 24 cases,type III fractures in 27 cases,type IV fractures in 22 cases,type ? fractures in 57 cases,type ? fractures in 33 cases,12 cases of fracture of type ?,which contained all the type of fracture.Conclusions: With the explicit finite element analysis,we simulated the dynamic process of mechanical junction fractures of humerus and had the accurate and reliable results.A simple and effective new fracture classification was obtained with finite element analysis and clinical imaging,can be applied to the clinical treatment. |
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