Finite Element Analysis Of Proximal Femoral Nail Ant-irotation Treated Intertrochanteric Fractures With Lateral Wall

Objective: Based on the normal CT data of the proximal femur in old people,using finite element analysis(FEA)to analyze the stress value of the implants at the proximal femur.the femoral intertrochanteric fractures involved the lateral wall and was treated by proximal femoral nailing(PFNA),to research the establishment of proximal femoral finite element model and the significance of lateral wall integrity to intertrochanteric fracture.Methods: Choose an old male,whose hip joint disease was excluded by imaging examination.After making sure standard normal proximal femoral in anatomy,Medical CT scan was performed and three-dimensional finite element model of proximal femur was established by the Mimics17.0.Then the Geomagic studio2012 software simulate AO-type 31-A1.2 intertrochanteric fractures and intertrochanteric fractures with coronal planes and lateral wall fractures displacement.The two models were both assembled with the PFNA into a three-dimensional finite element model.The mechanical loading and finite element analysis were completed by Abaqus software.Finite element analysis was performed at the femoral head,neck,fracture ends,lateral wall,and internal components of the model to observe the stress values under the same load,with different degrees of fracture reduction and with or without lateral wall.Clinical significance of the lateral wall was further analyzed after collecting and collating the data.Results: The stress distribution at the proximal femur was calculated by using the software.The stress values at femoral head,neck,main nail,internal components were 0.40 MPa,30.05 MPa,74.35 MPa and 121.68 MPa respectively when fracture ends were anatomically reduced and integrity of the lateral wall.Howener,the stress of each site above with lateral wall fracture Were: 0.82 MPa,47.32 MPa,151.92 MPa,266.88 MPa,an increase of about 100%.With every horizontal reduction loss increasing by 5% forward or backward,the stress exerting on the corresponding spots would see a 10% progressive growth.plus 20% lateral wall fracture and reduction loss,The stress of the main nail(468.43MPa)was three times that(121.68MPa)of the stress posing on the complete lateral wall while with the fracture end 100% reduced.Conclusion: The use of PFNA in the treatment of lateral femoral intertrochanteric fractures,stress of internal components would be doubled.with loss of coronal reduction,the main nail and screw blade bonding site,shared the most significant increase in stress.