| Objectives:Periprosthetic femoral fractures(PFF)have become the second largest complication after total hip arthroplasty(THA),second only to hip prosthesis loose.The treatment of periprosthetic fractures is quite difficult because of complications,inability to partially load,inability to in-situ bone graft,or severe osteoporosis.With the advent of an aging population,how to improve the postoperative quality of life and survival of elderly patients with periarticular fractures has become a great challenge for our orthopaedic surgeons.Therefore,how to improve the fixation strength of periprosthetic fractures in elderly patients with osteoporosis and avoid re-fractures,as soon as possible to lower the ground activity,to restore their pre-fracture life status,is an issue we should urgently solve.For the Vancouver C periprosthetic fracture that occurs far from the tip of the prosthesis,when the distal fixation of the femur is used,how much separation between the tip of the prosthesis and the proximal end of the plate can maximize the possibility of avoiding the occurrence of secondary fracture of the femur? In order to explore the effect of the distance between the distal locking plate of the femur and the distance between the prosthesis tip and the postoperative femoral stability,three models of different types of plate fixation Vancouver C fractures were designed in this study.Guide the clinical treatment of Vancouver C femoral prosthetic fractures around the choice of plate length,reduce the incidence of postoperative re-fracture and improve the quality of life of patients.Methods: Twelve female cadaver femoral specimens were selected and all femoral specimens used for the study were subjected to QCT scans(femoral condyle and femoral shaft scans).The scan results were analyzed to exclude statistical differences.The femurs with similar scan results and similar femoral specimen sizes were divided into 3 groups(4 in each group).)All femoral femoral specimens were assembled cement type femoral prosthesis with the same model and specifications,and then grouped with 9-hole(238mm),7-hole(198mm),and 5-hole(158mm)distal femur locking plates according to the group.All the femur experimental models were tested on the medial-lateral four-point bending stiffness test,and the front-back four-point bending stiffness test,the axial ballast stiffness test experiment,and the torsional stiffness test experiment on the biomechanics experiment machine.Results: The median anteroposterior four-point bending stiffness of the 238 mm femoral distal locking plate was 1120.950 N/mm(22.93 N/mm),and the median internal and external four-point bending stiffness was 1271.0 N/mm(25.27 N/mm).The median ballast stiffness was 1851.65 N/mm(19.78 N/mm)and the torsional stiffness median was 7.7541 N·m/degree(0.11 N·m/degree).The stiffness values of the second group with 198 mm distal femoral locking plates were 926.675 N/mm(10.68 N/mm),1073.6 N/mm(179.21 N/mm),1573.25 N/mm(23.38 N/mm)and 6.9989 N·m/degree(0.14 N·m/degree)respectively.The stiffness values measured in the third group of 158 mm femoral distal locking plates were 344.075 N/mm(29.49 N/mm),416.7 N/mm(20.16 N/mm),1032.45 N/mm(30.88 N/mm)and 6.2551 N·m/degree(0.26 N·m/degree)respectively.The non-destructive stiffness measured in each test decreased with the length of the steel plate.Conclusion: This study was a biomechanical test of the different stiffness caused by variations in the prosthesis tip and plate gap size trends for Vancouver C femoral component periprosthetic fracture.The experimental results showed that the overall structure increased with the length of the distal locking plate of the femur,and the stiffness increased.It was possible to obtain greater structural stability,thus ensuring bone fracture healing as soon as possible.These results could help surgeons reduce postoperative complications and position the plate to prevent fixation from failing resulting in fractures. |
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