Investigation Of Biomechanics Behavior In Unstable Pertrochanteric Fracture Treated With Three Types Of Nails By 3D Finite Element Analysis

Intertrochanteric fracture of femur is a serious and common injury that would lead to permanent disability, pneumonia, pulmonary embolism, and even death. The ongoing debate on the surgical treatment of trochanteric hip fracture, particularly unstable fracture, has triggered continuous changes in the design of well-established implants and prompted the development of new ones. The goal of this paper is to use finite element simulation to compare the biomechanical behaviour of three implants most often used in the hospital in China: DHS,DCS and the standard Gamma-nail. The focus was on the displacement of the fracture focus and the stress distributions along the interface of the femur and the implant. Computed tomographic (CT) scan-based finite element (FE) modeling technique is a tool that can predict proximal femoral fracture load in vitro. CT scans of the left proximal femur of human were obtained, from which three-dimensional FE models with nonlinear mechanical properties were constructed. Maximum femoral head reaction force was applied as the FE-predicted fracture load.The effects of the different types of fracture were investigated. The results showed that, according to biomechanic principle in the treatment of peritrochanteric fracture, fracture treated with Gamma-nail is satisfactory. It is found that Gamma-nail could produce higher contact stress between the tip of the nail and the endosteum. Furthermore, this contact stress is reducedwhen the distal region of the nail is made more flexible either by incorporating longitudinal slots or by assuming the material of a lower modulus of elasticity. On the unstable conditions,the Gamma-nail is stiffer than the DHS and DCS .In the A2 fracture,the DHS can be regarded as realistic surgical model to treat the unstable intertrachanteric fracture of the femur,not the DCS.But in the A3 fracture,the DCS can be regarded as satisfiable surgical model to treat the intertrachanteric fracture of the femur,DHS is not suitable in this type frctures. The key to successful treatment is accurate implantation of the internal fixation device and appropriate perioperative managanent.