| Osteonecrosis of the femoral head is a common orthopedic disease with multiple pathogenic factors,complicated pathological process and unclear mechanism.It is often divided into non-invasive necrosis and traumatic necrosis of the femoral head.Among them,because of the extensive use of hormones,steroid necrosis of the femoral head accounts for the majority of non-traumatic necrosis of the femoral head.Due to the lack of effective drug treatment,patients with advanced necrosis of the femoral head often need surgical treatment.Patients not only face many problems such as high cost of treatment and unsatisfactory long-term treatment effect,but also are not accepted by many patients in limiting weight-bearing and multiple joint replacement.Therefore,the early diagnosis and treatment for osteonecrosis of the femoral head is very important.MRI is the gold standard for the early diagnosis of osteonecrosis of the femoral head because of its high accuracy,sensitivity and specificity.Clinical studies have shown that articular cartilage has changed significantly after osteonecrosis of the femoral head before imaging detection.Therefore,we take this as a starting point to explore the role and possible mechanism of cartilage in the necrosis of the femoral head.The thesis is divided into three parts:Part ? The changes of cartilage in steroid induced osteonecrosis of femoral headObjective:To investigate the changes of cartilage under the hormone loading of the model of steroid induced osteonecrosis of the femoral head and the mechanism of its action.Methods:20 SD male rats were divided into control group and model group.The model of osteonecrosis of the femoral head in rats was established by classical modeling method.After 4 weeks of modeling,the animals were killed to obtain the femoral head and blood samples.The pathological sections and staining,micro CT and other tests were carried out to evaluate the osteonecrosis of the femoral head.The blood samples were biochemical analysis of the supernatant.Results:1.Histopathology results:there were a lot of empty cartilage lacunae,cell degeneration,apoptosis of marrow cells and irregular arrangement of growth plates in the cartilage area of femoral head.Osteoclastic activity,ROS level and apoptosis were significantly increased around empty lacuna.2.Micro-CT showed that the cystic change of the femoral head on the coronal plane was obvious in the model group,and the ratio of bone surface area to bone volume(BS/BV)was significantly higher than that in the normal group.3.The results of serum biochemical test showed that there was no significant difference between the model group and the normal group,and the NTX index in the model group was significantly higher than that in the normal group(P<0.01).4.Special staining and immunohistochemistry:there was an increase of type III collagen fiber in the model group.Caspase-3 detection showed that the apoptosis and necrosis of the model cells were significantly higher than the other two groups(P<0.01),while Bcl-2 was significantly reduced.Conclusion:there are a large number of empty cartilage lacunae in the cartilage area of the femoral head,irregular arrangement of the growth plate area,interruption and bone bridge formation,and the osteoclastic activity,ROS level and Caspase-3expression are increased in the osteonecrosis model rats.Part ? Mechanisms involved in hormone regulation on chondrocyte proliferation and differentiationObjective:To observe the effect of hormone loading on the proliferation and activity of chondrocytes.Methods:chondrocytes were extracted from primary culture,and CCK-8 method was used to observe the effect of hormone on their proliferation,and PI/honey staining was used to detect their apoptosis.RT-PCR was used to detect the expression of chondrogenic genes.Finally,the changes of LC3,Caspase-3,ROS and MAPKs pathway in cartilage differentiation were detected.Result:1.Using 10-4,10-5,10-6,10-7M dexamethasone(DEX)to simulate the hormone loading conditions,it was found that there was no significant difference in cell value-added activities among the groups at 24 hours.After 28 hours of culture,only10-4M DEX group was significantly lower than control(P<0.05).After 72 hours of culture,the proliferation of chondrocytes in 10-5M DEX group was significantly lower than that in control group(P<0.05)2.DEX significantly reduced the expression of col 2 in chondrocytes(P<0.01),but significantly influenced the expression of aggrecan and Sox9.3.DEX can induce excessive ROS in cells(P<0.01).With the increase of DEX concentration,autophagy and apoptosis indexes such as caspase-3 and LC-3increased.It is suggested that DEX can induce autophagy of chondrocytes,and with the increase of autophagy,it will further lead to apoptosis of chondrocytes.Conclusion:1.DEX inhibited the proliferation of chondrocytes,DEX inhibited the differentiation of chondrocytes,and its cartilage representative genes col2,aggrecan and Sox9 were significantly reduced compared with the control group(P<0.01).2.DEX induced the increase of ROS in chondrocytes,and then activated the activation of MAPK and NF-?B.Part ? Clinical follow-up study of necrosis of femoral headObjective:in order to further observe the role of cartilage changes in osteonecrosis of the femoral head,we retrospectively analyzed the changes of cartilage in patients with traumatic osteonecrosis of the femoral head,and statistically analyzed the related risk factors of osteonecrosis of the femoral head.Methods:A total of 250 cases of femoral neck fracture treated at three hospitals in Xuzhou(Xuzhou Municipal Hospital Affiliated of Xuzhou Medical University,The Affiliated Hospital of Xuzhou Medical University,Xuzhou Central Hospital)from January 2002 to January 2016 were studied.The patients were followed up for 1?15years,and the clinical data on femoral head necrosis after the femoral neck operation were analysed retrospectively.Statistical analysis of the risk factors of osteonecrosis of the femoral head,and the imaging analysis of osteonecrosis of the femoral head,to evaluate the cartilage changes.Result:1.The average follow-up time was 7.5 years.Among 250 patients,none of them had nonunion,40(16.0%)had necrosis of the femoral head,the average time of which was 3.8 years.2.In the necrotic side of femur,there are different degrees of pathological changes in cartilage,mainly including collapse and destruction of cartilage area,morphological changes of cartilage area and changes of T2 map value,in which the T2 map value of Arco III and IV phase cartilage is significantly higher.3.Single factor analysis showed that the fracture type,reduction quality,internal fixation,BMI,ASAS classification were the factors that affected the occurrence of femoral head fracture4.The significant indexes in single factor analysis were all included in the multi-factor logistic regression.The results showed that the removal of internal fixation,fracture type(displacement),reduction quality(dissatisfaction),BMI(?25)and ASAS grade(?+?)were all independent risk factors(P<0.05).Conclusion:1.Many risk factors participate in the occurrence of osteonecrosis of the femoral head after the treatment of adult femoral neck fracture with hollow compression screw.In the treatment,targeted measures should be taken to reduce the occurrence of osteonecrosis of the femoral head.2.In the osteonecrosis of the femoral head,there are different degrees of pathological changes in cartilage,mainly including collapse and destruction of cartilage area,morphological changes of cartilage area and changes of T2 map value,in which the T2 map value of Arco III and IV phase cartilage is significantly higher. |
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