Biomechanical Comparison Of Three Different Locking Plate Fixation Methods In Vancouver B1 Periprosthetic Femur Fractures

Objectives: Through the analysis of the biomechanics of the different internal fixator of the femur and femoral prosthesis fracture after femoral prosthesis replacement,we can analysis the imperfection of the current fixed mode,and explore how to improve the strength of the femoral prosthesis fracture of the old patients with osteoporosis,so that the patients can do activity as early as possible,restore their life state before fracture and reduce postoperative complications and mortality.Methods: Nine matched pairs of fresh-frozen,complete cadaver femurs were choosen(provided by anatomy teaching and research section of Hebei medical university)and all the selected specimens were divided into three groups(n=6).All the selected specimen were scanned by dual X-ray absorptionetry,eliminating osteolytic disease and fracture,such as rheumatism?tuberculosis?tumour.All the femoral samples were completed the femoral prosthesis replacement,and the prosthesis size of all the femurs kept same.All the femur specimens were made into Vancouver B1 proximal femoral prosthesis fracture model.All the cadavers were prepared for the cemented insertion of the femoral component of a total hip implant.The eight hole of locking plate was placed on the lateral femur and symmetrically placed on both sides of the fracture of all the femoral prosthesis fracture specimen model.Periprosthetic femoral fractures were created in the femurs and subsequently fixed with Construct A(wire-plate system),Construct B(screw-plate systems),Construct C(wire-screw-plate systems).Axial,torsional,four-point bending tests and the axial ballast single damage experiment were accomplish to obtain stiffness values.Results: This study was made up of nine fresh cadaver,including six male cadaver and three female cadaver.The average age was 70±5.Axial test: Structure A,the experiment result of wire-plate system's compression stiffness was 1796.8±90.6N/mm;Structure B,the experiment result of screw-plate system 's compression stiffness was 2239.1±213.0N/mm;Structure C,the experiment result of wire-screw-plate system's compression stiffness was 2926.2±56.6N/mm.Structure C,the wire-screw-plate system's compression stiffness was the highest of all the three fixation methods.Three kinds of compression stiffness between the fixed structure exists significant difference(P<0.01).Torsional test:Structure A,the experiment result of wire-plate system's torsional stiffness was 0.169±0.018 N·m/degree;Structure B,the experiment result of screw-plate system 's torsional stiffness was 0.353±0.038 N·m/degree;Structure C,the experiment result of wire-screw-plate system's stiffness was 0.544±0.045 N·m/degree.Structure C,the wire-screw-plate system's torsional stiffness was the highest of all the three fixation methods.Three kinds of relative stiffness between the fixed structure exists significant difference(P<0.01).Medial-lateral four-point bending test:Structure A,the experiment result of wire-plate system's bending stiffness was 437.4±3.3N/mm;Structure B,the experiment result of screw-plate system 's bending stiffness was 737.8±3.8N/mm;Structure C,the experiment result of wire-screw-plate system's bending stiffness was 916.1±8.4Nm/m.Structure C,the wire-screw-plate system's bending stiffness was the highest of all the three fixation methods.Three kinds of bending stiffness between the fixed structure exists significant difference(P<0.01).Front-back four-point bending test:Structure A,the experiment result of wire-plate system's bending stiffness was 416.5±8.9N/mm;Structure B,the experiment result of screw-plate system 's bending stiffness was 722.0±15.9N/mm;Structure C,the experiment result of wire-screw-plate system's bending stiffness was 908.4±6.7N/mm.Structure C,the wire-screw-plate system's bending stiffness was the highest of all the three fixation methods.Three kinds of relative stiffness between the fixed structure exists significant difference(P < 0.01).The axial ballast single damage experiment: Structure A,wire-plate system's axial ballast single damage experimental result was 1273.16±23.56N;Structure B,screw-plate system's axial ballast single damage experimental result was 1655.05±52.57N;Structure C,wire-screw-plate system's axial ballast single damage experimental result was 1968.70±40.69 N.Structure C,the wire-screw-plate system's axial ballast single damage experimental result was the highest of all the three fixation methods.Three kinds of the axial ballast single damage experiment result between the fixed structure exists significant difference(P<0.01).Conclusion: Periprosthetic femoral fractures were created in the femurs and subsequently fixed with wire-plate system,wire-screw-plate,screw-plate systems.Wire-screw-plate systems provide an improved rotational stability and holding force than wire-plate system and screw-plate systems for periprosthetic femur fracture near the tip of a total hip arthroplasty.