Finite Element Analysis Of Femoral Head Necrosis

BackgroundFemoral head necrosis is due to internal disruption or injury of the femoral head,causing bone cell grade bone marrow component death,and then lead to structural changes in the femoral head,and even lead to femoral head collapse,causing hip pain,dysfunction of a group of diseases.Recently,the research about osteonecrosis of femur head including traditional mechanics and three-dimensional finite element analysis.Finite element analysis is a technique that widely used in bio-mechanics,which can simulate the position and the size of femoral head.Finite element model can predict the collapse of femoral head and direct the surgical treatment of osteonecrosis of femur head.Scientists have made Substantive progress in osteonecrosis of femur head using three-dimensional finite element analysis and proved the availability and scientific about this technology.For early femoral head necrosis,preservation of the hip surgery can effectively limit the development of femoral head necrosis.Femoral head necrosis commonly used to save hip surgery,including pure core decompression,core decompression combined with artificial bone implantation and core decompression combined with tantalum rod implantation,and for the collapse of the femoral head Necrosis of the hip surgery is limited,usually using artificial hip arthroplasty.Objective Three cases of femoral head necrosis were established by three-dimensional finite element analysis.The postoperative finite element model was established,including normal femoral head model,simple necrotic femoral head model,four simple core decompression models and core decompression Combined with artificial bone implantation and core decompression combined with tantalum rod implantation model.To explore the stress changes of different core decompression in the treatment of early femoral head necrosis and the unique advantages of tantalum metal rod implantation in the treatment of avascular necrosis of the femoral head.Methods The right femur of healthy adults were choosen as the research object,and CT scanning was conducted to get the images of cross sections.The images were then inputted into computer to get contour of femur and rebuild 3D model.Distal end of femur was completely fixed,and 570 N pressure on the femoral head was applied according to the three-dimensional space distribution of femur force under physiological state.Three-dimensional finite element models were founded with the necrotic range of 15% and 30%,then the stress distributions of cancellous bone and cortical bone of femoral head were obtained through the models.Three-dimensional finite element model were calculated to got the collapse values in different necrotic areas of the femoral head.The stress value of the decompression portal area was significantly increased in the femoral head outside the femoral head area,the femoral neck area and the femoral neck under the greater trochanter.In order to further observe the stress distribution of the femoral head after different core decompression,the cross section of the three-dimensional finite element model The mean stress values of the cortical bone and the cancellous bone in the femoral head subcutaneous region,the femoral neck area and the femoral head bearing area were calculated and statistically analyzed.To evaluate the efficacy of three methods for the treatment of early avascular necrosis of the femoral head,the effects of core decompression on the mechanical support of the femoral head and the unique treatment of tibial block implantation and artificial bone implantation in the treatment of avascular necrosis of the femoral head Advantage.The collapse values of the femoral head and the necrotic area were calculated at 15% and 30%,respectively.The femoral head model was used to calculate the average collapse value of the femoral head,and the femoral head model was calculated in different necrosis range,different treatment methods The collapse of the surface of the femoral head before and after the collapse of the surface,compared with a simple core decompression and decompression combined with tantalum rod implantation of two surgical methods of femoral head load-bearing area of the surface subsidence changes,tantalum rod implantation treatment of femoral head necrosis Unique advantages.Results The results were compared with those of the femoral head model,and the results were compared with those of the preoperative femoral head model:Different methods of decompression and different numbers of channel cores would lead to a different stress value: stress concentration would appear on femoral head after core decompression.Multiple drilling technique would get a more stress concentration comparing to traditional single large channel core decompression,the stress value was summit of cortical bone and cancellous bone would both less than their yield strength and tensile strength of femoral hard.And then calculate the top of each model outside the bones and calculate the average collapse of the value,the comparison found: The core of the femoral head after decompression pulp collapse increased in value,loading the area most obviously(P>0.05),and with the increase of the femoral head necrosis areas value increased with the collapse.Conclusions According to the number of drilling holes,the stress distribution of the cancellous bone and the cortical bone in the femoral head and femoral neck at the entrance of the decompression hole was significantly higher than that of the untreated femoral head model.All the cancellous bone And cortical bone stress values were lower than the femoral head tensile strength,indicating that modified core decompression in the early necrosis of the femoral head to give effective intervention,and relative to the traditional large diameter core decompression has a smaller surgery After the risk.Simple core decompression and core decompression combined with tantalum rod implantation can be effective in the treatment of early necrosis of the femoral head,compared with the traditional large diameter single-channel decompression,modified porous core decompression treatment of early and mid-term Femoral head necrosis can reduce the stress concentration in the femoral head,the biomechanical advantage is more obvious.While the pure core decompression can clear the sequestrum,improve blood supply,but the decompression itself to further reduce the mechanical properties of the femoral head,changed the original structural support of the femoral head,core decompression based on the auxiliary tantalum rod Can provide safe and effective mechanical support for the femoral head and subchondral bone plate,which can effectively prevent the collapse and provide the conditions for the repair of bone tissue,has the unique advantage.Early diagnosis,effective prediction and prevention of collapse is to retain the patient’s own femoral head of the premise and foundation,treatment of early femoral head necrosis must emphasize its biomechanical factors,so that the mechanical structure to be restored.The collapse of the femoral head necrosis lesion has a direct relationship with the biomechanical factors.The main reason is that the stress level in the necrotic area is decreased and the stress concentration around the bone is concentrated.The pathologic basis is the micro-fracture of the trabecular bone,and its essence is a biomechanical Stable,we will call this phenomenon "head instability." Implanted tantalum metal rods can reduce the adverse stress in the femoral head,stabilize the internal structure of the femoral head,as much as possible to reduce the occurrence of femoral head collapse.