| Objective: China-Japan Friendship Hospital Classification for osteonecrosis of the femoral head(CJFH type)is based on three column structure of femoral head for Li Zi Rong,to select CT or MRI scan coronal median level classification,divided into M,C,L three type,L type divided L1,L2 and L3 three type.This study is based on L type of femoral head necrosis in CJFH type,using computational biomechanics research methods with tantalum rod implantation as an example.To establish three-dimensional finite element model of the hip joint simulation of normal,necrotic and L type necrotic area of the tantalum rod implantation,carrying out finite element analysis and comparison.Revealing the risk of avascular necrosis of the femoral head collapse of anterolateral column of CJFH L type,and discussing the importance of the integrity of the anterolateral column for hip preserving efficacy,to provide biomechanical evidence for the treatment of various types of CJFH.To analyze the effect of multiple factors on the prognosis of femoral head necrosis by retrospective study of the clinical data of the treatment of osteonecrosis of the femoral head with tantalum rod implantation,and moving forward analyze clinical effect.Comparing the experimental study with clinical study,it provides an effective basis for the treatment of femoral head necrosis CJFH classification.Methods:Experimental study: A normal adult male volunteer with health femoral head was selected,hose CT image was acquired;three adult male with type of L1,L2 and L3 ONFH were selected,whose MRI images was acquired respectively.3D solid model was established separately based on these images data by Mimics 15.0 、 Geomagic Studio 13 、 Geomagic Design X 、Solidworks2014 、 Hypermesh 、 Abaqus6.14 software.A three-dimensional finite element model of tantalum rod implantation of femoral head necrosis is established on the basis of frontal model,and carrying out finite element analysis.To observe the stress distribution and the maximum Mises stress value of cortical shell of normal femoral head,femoral head necrosis and tantalum rod implantation of femoral head necrosis,three comparing and statisticsing analysis.Clinical study: The study retrospect cases from January 1,2008 to December 31,2010 for the treatment of femoral head necrosis in the hip joint center of the First Affiliated Hospital of Guangzhou University of Traditional Chinese Medicine,and collect end point or deleted time,operating age,sex,inducement,sick location,CJFH type,ARCO stage,Harris score before and after operation and the collapse degree of postoperative X-ray,recording the corresponding data in the Excel file,following up from the beginning for tantalum rod implantation on the same day,observed the stoping for cases C collapse(collapse> 4mm)and occuring of deleted time.The data for statistical analysis,were compared with the preoperative Harris score using t test,the survival rate of the femoral head were analyzed using Kaplan-Meier test,the model were compared with log-rank test,resulting in the failure of tantalum rod many related outcomes of variables by COX regression analysis.Results:Experimental study: The maximum Mises of weight-bearing area of cortical bone shell was increased which L type of femoral head necrosis compare with the normal femoral head increased,L1 increased 21.76%,L2 increased 31.02%,L3 increased 42.79%;The maximum Mises of weightbearing area of cortical bone shell was decreased which tantalum rod implantation of afteroperation compare with preoperative,L1 decreased 13.38%,L2 decreased 8.81%,L3 decreased 11.45%.When the femoral head necrosis,bone necrosis due to the bearing capacity decreased,leading to femoral head bone shell stress concentration,so the maximum necrotic stress is increased than the maximum normal stress.The higher the degree of classification,the greater the stress concentration of the cortical bone shell;the tantalum rod after the implantation bear the weight of a part of the stress,the lower the degree of classification,the more obvious the correction.Clinical study:1.Result of class C collapse as the end point eventsThe collapse of the C level(collapse > 4mm)as the end of the event,the first 3 years,the survival rate of the femoral head is acceptable,in which the highest survival rate of first years,after the survival rate decreased year by year.The median survival time was 44.00 months,within the range of 95% confidence interval,it was found that only about 50% of the patients had C collapse.COX regression analysis showed that the variable of CJFH type P < 0.01,the difference was statistically significant,while other variables P > 0.05,the difference was not statistically significant,that CJFH type was affected the survival rate of the femoral head were significantly related factors.CJFH classification of the corresponding risk Exp(B)> 1,CJFH type is a risk factor associated with efficacy,the higher the degree of classification,the shorter the survival time.For the log-rank test results show the variable P < 0.01 to CJFH type,four group survival time distribution comparison were statistically significant difference.L3 type was the lowest survival rate for hip preserving,and C type was the highest survival rate,so the survival rate is decreased that C type > L1 type > L2 type > L3 type.2.Results of the Harris scoresThe hip function was evaluated by Harris score,and the Harris score of all the patients with postoperative follow-up was compared with that before operation,P < 0.01,statistically significant difference.Within 48 months after operation,the Harris score significantly improved,especially in the 24 months after the operation,the quality of life has been improved significantly and that tantalum rod implantation afteroperation can better improve the hip joint function in 4 years,and the after hip joint function becomes worse trend potential after 4year.Conclousion:1.Tantalum rod implantation corrected the necrosis of the femoral head bone shell stress,and had certain effect in the middle and long term for clinical practice.It is proved that the tantalum rod can be used to prevent collapse and to support the biomechanical effect of subchondral bone to a certain extent.2.The integrity of the lateral column of the necrotic femoral head affects the efficacy of hip preserving.The more preservation of the lateral column,the better of hip preserving.The higher the degree of CJFH classification,the higher the risk of collapse,and the worse the effect of hip preserving. |
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