Three-dimensional Finite Element Analysis On Fixation Of The Unstable Intertrochanteric Fractures Of Femur With DHS,DCS And Gamma Nail

Objectives: The ongoing debate, surrounding the surgical treatment of trochanteric hip fractures, particularly unstable fractures, has led to continuous changes in the design of well-established implants and to the development of new ones. The goal of this paper was to use a finite element simulation to compare the bioniechanical behaviour of three implants most often used at the hospital of China: DHS. DCS and Gamma-nail. Materials & Methods: CT scans of the left proximal femur of human were obtained and three-dimensional FE models employing nonlinear mechanical properties were generated from each CT scan.Then the FE-predicted fractures (31-A2, A3; AO classfication) which fixed with DHS, DCS and Gamma-nail were developed. The load was the maximum femoral head reaction force.The effects of the different types of fracture ( 31-A2, A3; AO classfication) were investigated. The main focus was on the displacements of the fracture and the stress distributions along the femur and the implant.ResultS: (1)31-A2 type: the maximum von Mises stress of the lag screw of the DCS exceed 518Mpa, which may leads to fatigue failure ; DHS and Gamma-nail have sliding-compressing function, not the DCS . Under the loading , the fracturesseparate from each other*, ?31-A3 type: the stress can not be efficiently transmitted and there are many immoderate stress-concentrating points when the fracture fixed with DHSo ?when fixed with Gamma-nail, the Von mise stress of the bone is the smallest, but it could produce higher contact stress between the tip of the nail and the endosteumo ?Gamma is stronger than DHS, DHS is stronger than DCS° Conclusions: ? For treatment of unstable trochanteric fractures, the Gamma-nail is stiffer than the DHS and DCS and it suits all the frcturesa ?In the A2 fracture,when the medial cortex is not seriously comminution , the DHS can be regarded as satisfactory surgical model to treat the unstable intertrachantenc fractures,if the medial comminution is serious with big bone defect, Gamma-nail is more suitableo DCS is not suitable in this type frctures.(3)m the A3 fracture, when the medial cortex is not seriously comminution , the DCS can be regarded as satisfactory surgical model to treat the intertrachantenc fractures of the femur, if the medial comminution is serious with big bone defect, Gamma-nail is more suitable 0 DHS is not suitable in this type frctures,, The key to successful treatment are accurate implantation of the internal fixation device and appropriate perioperative managanent.