The Finite Element Analysis To The Treatment Of Proximal Femoral Nail Antirotation And Media Sustainable Nail In Fixation Of The Femoral Intertrochanteric Fractures

Background and Object:Intertrochanteric fractures are mostly happened in the senior citizen. With the arrival of human aging society, life expectancy continues to improve, the incidence of intertrochanteric fractures raised from year to year. Conservative treatment for the intertrochanteric fractures always causes serious complications, so the surgery is becoming the popular way to the fractures. Among the surgery treatments, intramedullary fixations has been widely used in the treatment of the intertrochanteric fractures. However there are some adverse situations existing in some intertrochanteric fracture cases. Combining with the anatomical structure of proximal femur and biomechanical characteristics, we designed a new intramedullary nail name Medial Sustainable Nail (MSN). The mechanical structure of proximal femur can be reconstructed by the upper side of this nail which is characterized by the triangular stabilization. In this study, using the methods of finite element analysis, we tend to compare the biomechanical quality of Proximal Femoral Nail Antirotation (PFNA) and Medial Sustainable Nail (MSN), which could provide biomechanical evidence to the clinical treatment and postoperative rehabilitation.Methods:1. The three-dimensional model of Sawbones femur was reconstructed in MIMICS software. And then we established the fracture model of 31-A 1.1, A1.3, A2.1, A2.2, A2.3, A3.1, A3.2, A3.3 according to the OTA and AO classifications respectively using 3-MATIC software.2. The standard model of PFNA and MSN was designed in UG software.3. The pre-process of finite element analysis like model matching and meshing was performed.4. We then finished the procedure of assembly, interaction, the load and run the job.5. Finally, we read the results of finite element analysis and got the interpretation.Results:1. In 31-A1.1 fracture model, the maximum bear stress in PFNA is 2645MPa, while in MSN is 3046 MPa. The maximum distance of fracture displacement in PFNA is 3mm, and in MSN is 0.06mm.2. In 31-A1.3 fracture type, the maximum bear stress in PFNA is 2134MPa, while in MSN is 2353 MPa. The maximum distance of fracture displacement in PFNA is 2mm, and in MSN is 0.16mm.3. Slight coxa varus happened in the PFNA fixion model and there is nothing adversely happened in the MSN model in the fracture model of 31-A2.1.4. In the type of 31-A2.2 intertrochanteric fracture, we don’t see any significant differences in terms of changing the displacement of the fracture fragments in PFNA and MSN models. The maximum bear stress in PFNA is 1403MPa, while in MSN is 2478MPa.5. In the intertrochanteric fracture type 31-A2.3, coxa varus emerges in PFNA models, and the appearance of cut-off in PFNA nail is happened, in which the distance of the nail to back is about 9mm. MSN fixation model is more stable.6. In the 31-A3.1 fractures, the fracture model fixed by PFAN emerges the phenomenon of slightly coxa varus and the distance of lateral fracture gap is 6mm. The maximum bear stress in PFNA is 1573MPa, while in MSN is 2268MPa.7. In 31-A3.2 intertrochanteric fracture type, The maximum bear stress in PFNA is 927MPa, while in MSN is 2363MPa. The fracture gap in PFNA fixed model is 4mm, while there is no distance existing in the MSN model.8. The 31-A3.3 fracture model fixed by PFNA emerged serious coxa varus and the displacement of proximal fracture bone. The distance of cut-off happened in PFNA is 9mm. We don’t observe any bad appearance in the MSN model.Conclusion:1. The fixtion effect of PFNA and MSN is equally when fixed into the fracture model of 31-A1.1 and 31-A1.3.2. We get the better effect when PFNA is used in 31-A2.2 and 31-A3.2.3. When MSN is used in the 31-A2.1,31-A2.3,31-A3.1 and 31-A3.3, the results is better.