Finite Element Analysis And Clinical Research By Implanting Tantalum Rod Into Femoral Head Necrosis To Prevent Collapse In Early Stage

Objective To construct a three dimensional finite element model of osteonecrosis of the femoral head based on CT images,Entity model of the simulation with the tantalum rod assembly.Necrosis of the femoral head was studied by finite element analysis of biomechanics change,analysis of tantalum rod support of femoral head necrosis.objective explore the recent clinical curative effect of Tantalum in treating the early avascular necrosis.Methods Research consists of two parts:(1)Select volunteers with the left side of the femoral head necrosis as the research object,by 0.4 mm thick layer of spiral CT scanning draw the cross section images,input recognition and extraction of femur contour parallel and 3 d reconstruction by computer,and assembly tantalum rod with entity model,according to the physiological state of 3 d spatial distribution of the shares proposed load,with femoral head joint force of 1258 n,abductor muscles strength 813 n,the vastus lateralis muscle force of 1370N were applied according to the 3D space distribution of femur force under physiological state.calculate the femoral head with finite element model,and the implantation of tantalum rod after necrosis of the femoral head in the stress nephogram of stress mode,area of maximum stress distribution of elastic micro,as well as the stress of the tantalum rod.(2)retrospective analysis in January 2008 to November 2008 in our hospital accept tantalum rod placement and follow-up treatment data whole early avascular necrosis of the patients 25 cases(39 hips),male 9 patients(11 hips),female 16 patients(28 hips);Average age of 37(18-74)years.Alcoholic 4 patients(6 hips),hormone sex 6 patients(8 hips),traumatic in 2 cases(2 hips),idiopathic(13 cases(23 hips),Steinberg preoperative stage:Ⅰ period and hip,Ⅱ period and hip,Ⅲ period and hip.Curative effect analysis including preoperative and postoperative Harris score,radiographic and hip replacement for follow-up to accept the end of the femoral head survival rate.Results A realistic appearance and calculation accuracy three-dimensional finite element model of osteonecrosis of the femoral head was established.After equipping tantalum rod,femoral head stress level has increased,tantalum rod local and lower regional stress block does not appear.Tantalum rod stress points on tantalum rod head,the maximum stress value of 61.95 MPa.patients were followed up 6-47 months,the average follow-up period was 37.4 months,a total of 12 hip imaging appear progress,including tantalum great exit 1 hip,hip hemiarthroplasty collapse 3,avascular necrosis of the area increased and hip,hip line 6 total hip replacement,including imaging progress of hip 5 to 41.7%(5/12),no imaging progress 1 hip 3.7%(1/27).All hip Kaplan-Meier survival curves show tantalum stick into 6 months after survival was 97.4%,1 year survival rate was 94.7%,and 2-year survival was 88.6%,3 years of survival rate was 72.5%.Age,basic diseases and prognosis is not relevant.Conclusion Through the finite element analysis,tantalum rod implantation after necrosis of the femoral head,femoral head stress level are increased obviously,implantation of tantalum rod partial stress shelter does not appear,so as to prevent the collapse of femoral head necrosis effectively.tantalum rod treatment early avascular necrosis of the recent symptoms,and curative effect and the avascular necrosis of the area and there is a positive view into the great tantalum correlation,he can effectively relieve femoral head replacement time.