| Part 1 Study on the imaging characteristics after articular surface collapse in patients with osteonecrosis of the femoral headBackground In previous studies about the imaging characteristics after femoral head collapse in patients with osteonecrosis of the femoral head(ONFH)are mainly about staging,predicting collapse and evaluating curative effect,but most of those studies put the starting point before collapse.The regular of changes in the femoral head after article collapse is not clear,and the relation between the degree of collapse and other factors like position and scope of the necrotic area,subluxation of the hip,is not been expounded.In addition,most previous studies think about a single factor but not all factors witch possibly related to collapse.Objective To preliminarily discussed the distribution characteristics of different stages of necrosis of femoral head,the extent,of necrosis,the location of necrosis and the subluxation of the hip in different degree of collapse from the imaging point of view.Methods The imaging data of patients with ONFH screened by inclusion and exclusion criteria in Linyi people's Hospital from March 2006 to December 2016 were retrospectively analyzed.Calculate the constituent ratio of classification of hip subluxation(with or without),ARC0 stage(stage ? or ?),collapse degree(<2mm,2-4mm or>4mm)and necrotic area(<15%,15%-30% or >30%),JIC type(A,B,C1 or C2)and type of China-Japan Friendship Hospital(CJFH)(M,C,L1,L2,or L3).The distribution of hip joint with or without subluxation,ARC0 staging,necrosis area,JIC type,type of CJFH in different degree of collapse were analyzed.Gender,age,the necrotic area,JIC type and CJFH type as independent variables,degree of collapse as the dependent variable were brought into the multinomial Logistic regression analysis.Then gender,age,the degree of collapse,the necrotic area,JIC type and CJFH type as independent variables,hip subluxation or not as dependent variables were brought into two Logistic regression analysis,to explore the factors related to the degree of collapse of femoral head,hip subluxation occursResults A total of 500 patients were included.Among them,there were 419 male and 81 female,and the ratio of male and female was 83.8% and 16.2% respectively.The age were from 17 to 83 years old,with average 50.59±13.11 years old.There were 166 cases with hip subluxation,accounting for 33.2%,334 cases without hip subluxation,accounting for 66.8%.There were 214 patients in ARCO stage?,accounting for 42.8% and 286 patients in stage ?,accounting for 57.2%.There were 113 cases with femoral head collapse<2mm,accounting for 22.6%;73 cases with femoral head collapse between 2-4mm,accounting for 14.6% and 314 cases with femoral head collapse >4mm,accounting for 62.8%.The necrotic area was less than 15% in 0 cases,32 cases with necrotic area between 15% to 30%,accounting for 6.4%;468 cases with necrotic area >30%,accounting for 93.6%.1 cases was JIC type Apatients,accounting for 0.2%;1 cases was type B patients,accounting for 0.2%;58 cases weretype C1 patients,accounting for 11.6%;440 cases were type C2 patients,accounting for 88%.0 cases was CJFH type M patients;4 cases were type C patients,accounting for 0.8%;11 cases were type L1 patients,accounting for 2.2%;19 cases were type L2 patients,accounting for 3.8%;466 cases were type L3 patients,accounting for 93.2%.When the degree of collapse wastaken into dependent variable,Logistic regression analysis showed that there was a significant difference between ARCO stge,JIC type and the degree of collapse(all P <0.05),and the odds ratios were 0.069 and 0.47,respectively,compared with collapse less than 2mm and collapse between 2-4mm.There was a significant difference between collapse less than 2mm and collapse more than 4mm.There was a significant difference between age,ARCO stage,JIC type and the degree of collapse(all P<0.01),and the odds ratios were 1.078,0.002 and 0.136,respectively.When hip subluxation or not was regarded as the dependent variable,Logistic regression analysis showed that gender,ARCO stage were independent risk factors(all P < 0.01),and the odds ratios were 0.279,30.887 respectively.Conclusion For patients with femoral head collapse,the risk of hip subluxation in women is lower than that of men.The increase of the degree of involvement of the load area of the femoral head may be accompanied by the increase of the age and the degree of collapse.ARCO staging as a comprehensive reflection of the condition of femoral head necrosis can reflect the severity of collapse to some extent,and predict the risk of hip subluxation.Part 2 Analysis of the survival rate in patients with non-traumatic osteonecrosis of the femoral head after femoral head collapseBackground Related epidemiological studies have shown that most of the osteonecrosis of the femoral head(ONFH)coursed by traumatic reasons.According to the principle of staging treatment,once the femoral head collapses,the value of conservative treatment is lost.But there are some patients who Imaging examination shows that the femoral head has collapsed,but pain is mild and joint function is good.This status can meet the needs of daily life and work through conservative treatment.We can call these patients “survival with collapse” patients.Previous studies on hip preserving treatment tended to focus on conservative treatment before collapse,or using hip preserving surgery at the early stage of collapse,but lack of conservative treatment in the late stage of collapse.The clinical group of patients “survival with collapse” was been ignored.Objective To explore the risk factors that can easily lead to the failure of “survival with collapse”,and to provide the basis and suggestions for the formulation of the treatment strategy of “survival with collapse”.Methods Survival analysis was made in patients “survival with collapse” screened by inclusion and exclusion criteria in the femoral head specialist,Linyi people's Hospital from January 1,2016 to December 31,2017,as well as Kaplan-Meier survival curve.Age,gender,body mass index(BMI),multi factor analysis of single/bilateral,degree of collapse,the lateral pill preserved or not,subluxation of the hip or not were analyzed by univariate and multivariable analysis.The risk factors lead to failing of “survival with collapse” would be found.Results A total of 69 patients were included,of which 55 were male,14 women.Ages from 17 years old to 73 years old,with an average of 42.7±10.68 years old.According to the etiology,19 cases were steroid induce,26 cases were alcoholic induce,5 cases were hormone combined with alcohol and 19 cases were idiopathic.At the time of study,29 hips(42.03%)were receivedhip arthroplasty(THA)and Harris hip score(HHS)was 48~62(58.3±11.63)before operation.In all patients,the HHS was 75~100(83.9±13.09)at the starting point and 48~95(73.5±14.81)at the end point.Statistical results of each variable: BMI 17.5~30.9,average of 24.6.BMI ?24 in 38 cases,BMI >24 in 31 cases.There were 39 cases of unilateral onset,30 cases with bilateral onset.Collapse degree: ?2mm in 47 hips,>2mm in 22 hips.The necrotic area ?30% in 7 hips,>30% in 62 hips.Lateral pill preserving: 39 hips were preserved and 30 hips were not preserved.Subluxation: subluxation of 17 hips,no subluxation of 52 hips.The survival rate of the collapse of the femoral head: the total survival time was 6.3 months to 144 months,and the median survival time was 66 months.During the follow-up period,3 people lost their visits and no deaths were found.The survival rate of femoral head in 2,4,6 and 8 years after collapse was 81.9%,62.2%,42.6% and 31.1% respectively.Multivariate analysis: Cox regression analysis showed that the incidence of bilateral onset,lateral column without retention,hip subluxation were the independent risk factors for the failure of “survival with collapse”(all P <0.05),the risk ratio was 1.913,1.559 and 1.347 respectively;but there was no significant correlation between age,gender,BMI,necrotic area,the degree of collapse and the “survival with collapse”(all P>0.05).Conclusion Bilateral onset,lateral pill without retention,hip subluxation may shorten the time of “survival with collapse”,and easily lead to failure of “survival with collapse”.Patients with risk factors above should be cautious when they choose to “survival with collapse”.Part 3 Mechanical analysis of osteonecrosis of the femoral head after articular surface collapse: a three-dimensional finite element studyBackground With the precision and individualization of the treatment of osteonecrosis of the femoral head(ONFH),“survival with collapse” will become a part of the standardized treatment of ONFH.The key to “survival with collapse” is the selection of cases,and the mechanical stability is the most important reference for selecting cases.Therefore,how to better “identify and treat” and choose the good mechanical stability of cases,to a large extent,determines the success or failure of “survival with collapse”.Finite element analysis(FEA)of previous research in the collapse of osteonecrosis of the femoral head are used to predict the collapse and necrosis of the femoral head model using normal contour reconstruction,but lack of related reports in reconstruction and mechanical analysis of collapse of the femoral head.In addition,the change law of internal mechanical environment after collapse is not clear.Objective To analyze and comparethe maximum stress and deformation of necrosis area of the femoral head among various case,investigate changes of internal mechanical environment of the femoral head after collapse and find the risk factors which may lead to mechanical structure failure of the femoral head,finally provide the basis for the development of therapeutic strategies for “survival with collapse”.Methods Use Mimics,Geomagicstudio,Solid Works and ANSYS to build models in different degree of collapse by CT data in patients with ONFH.The degree of collapse were 1mm,2mm and 3mm.These models were used to simulate the China-Japan Friendship Hospital(CJFH)type L1,L2 and L3,and build the corresponding subluxation model.Von Mises stress,deformation and stress distribution of the proximal femur and necrosis portion in each models under 9 working conditions including slow walking,normal walking,fast working,up stairs,down stairs,standing up,sitting down,standing on 2-1-2 legs and knee band were analyzed and compared.Results A total of 16 models were built,among which there were 8 initial models,3 models with 1mm collapse(L1,L2,L3),3models with 3mm collapse(L1,L2,L3)and 2 models with 5mm collapse(L2,L3).There were 8 subluxation models,including 3 models with 1mm collapse(L1,L2,L3),3models with 3mm collapse(L1,L2,L3)and 2 models with 5mm collapse(L2,L3).Initial model:(1)under different working conditions,the stress ofcortical bone of proximal femur in the initial models was significantly higher than that in cancellous bone and necrotic bone;the stress in cortical bone mainly concentrated between the medial inferior of the femoral head andseptum bronchiale.The stress in the necrotic region is mainly concentrated in the lateral basal part and near the normal cancellous bone.Under the loading force,the maximum value ofmaximum stress values of the necrotic area in 1mm,3mm,5mm collapse modelsappeared when the condition was down stairs(2.1308MPa),down stairs(3.6347MPa)and up stairs(2.309MPa)respectively.The maximum value ofmaximum deformation appeared when the situation was up stairs(0.5539mm),up stairs(0.6769mm)and standing on 2-1-2 legs(0.2149mm).(3)In the models with 1mm collapse,the maximum stress of L2 type necrosis under different working conditions were lower than that of L1 and L3 type necrosis.(4)The maximum deformation of necrotic area of type L2 necrosis in models with 1mm and 5mmcollapsewere less than that of L1 and L3 type necrosis.Subluxation model:(1)under different working conditions,the stress of proximal femoral cortical bone in subluxation model was significantly higher than that in cancellous bone and necrotic bone.The stress in cortical bone mainly concentrated between the medial inferior of the femoral head and septum bronchiale.The stress in the necrotic region was mainly concentrated in the place where the acetabulum was in contact.In the loading force,the maximum value ofmaximum stress values of the necrotic area in 1mm,3mm,5mm collapse modelsappeared when the condition was up stairs(3.8764MPa),up stairs(8.0303MPa)and fast walking(3.5231MPa).The maximum value ofmaximum deformation appeared when the situation was up stairs(1.8496mm),up stairs(4.2065mm)and normal walking(0.6420mm).(3)In the models with 1mm collapse,the maximum stress of L2 type necrosis under different working conditions were lower than that of L1 and L3 type necrosis.(4)The maximum deformation of necrotic area of type L2 necrosis in models with 1mm and 5mmcollapsewere less than that of L1 and L3 type necrosis. Comparison of initial models and modelswith subluxation: in 9 different conditions,the maximum stress of necrosis area in all models with subluxation were higher than that of the initial models,the difference of the model with 5mm collapse,L3 type necrosis was most obvious.The maximum stress of the necrotic area in slow walking,normal walking,fast working,up stairs,down stairs,standing up,sitting down,standing on 2-1-2 legs and knee band were increased by 116.12%,116.50%,165.48%,78.31%,291.07%,30.95%,130.70%,226.56%,230.94%compared to the initial model.In 9 different conditions,the maximum deformation of the necrotic area in all models with subluxation were higher than initial models.The difference of the model with 5mm collapse,L3 type necrosis was most obvious.The maximum deformation of the necrotic area in slow walking,normal walking,fast working,up stairs,down stairs,standing up,sitting down,standing on 2-1-2 legs and knee band were increased by 185.69%,166.49%,186.03%,173%,130.39%,148.81%,139.65%,190.16%,233.92%.Conclusion After the collapse of the femoral head,the necrotic area can still maintain relative mechanical stability in most cases,but the possibility of fatigue fracture in the necrotic area can not be ruled out.Hip subluxation can cause serious damage to the normal structure of mechanical stability of femoral head,selecting patients with hip subluxationas the “survival with collapse” patients need to be careful.Up and down stairs weretwo of the leading causes to increase the stress of the necrotic area in patient with ONFH.Going up or down stairs is not suggest for “survival with collapse” patients;when the shape of the femoral head is roughly complete,the medial pill may to some extent disperse stress of necrotic area and coordinate to maintain the mechanical stability. |
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