| Objective: To investigate the pathogenesis of steroid-induced femoral head osteonecrosis,and to explore the intervention of L-dopa on non-traumatic osteonecrosis of femoral head.Methods:Thirty-six chinese albino rabbits weighed 2.5±0.6Kg were randomly divided into 3 groups.Group A was the group with Levodopa(L-dopa) intervention which contained 12 rabbits,the animals of this group were treated by injection of 10ug/Kg LPS via ear vein,3 consecutive MPS sodium succinate injections (20mg/Kg) via right buttock were then carried out 24h later with 24h interval.then oral intake of levodopa(L-dopa)( 0.4g/Kg/day) at the same day of the last injection of MPS sodium succinate was carried out.Group B was the model group with 12 rabbits ,the animals of this group were treated by the same method as to the rabbits in the group A Without pharmacological intervention.Group C was the control group contained 12 rabbits which were injected with Sodium Chloride in the same way as to the animals of the other two groups.During the experiment,every group rabbits were fed with standard fodder,all animals were injected with peniciliniun(800,000U/rabbit)twice a week for infection prophylaxis.Blood samples about 2ml were taken from every three group rabbits,ear veins 2weeks,6weeks and 8weeks .The blood samples were all centrigugated,and the serums above were collected carefully.ELISA Reagent was used for levels of BALP, PINP detection in the serum of every rabbit;Bilateral proximal femurs of every rabbit were performed bone mineral density (BMD)(including the femoral head) .Radiographic and MRI images of both hip joints were taken in 6 rabbits from every group 6weeks and 8weeks later respectively,then the rabbits were killed by aeroembolism.Both femoral head samples were taken out and immersed in 10% formalin,the samples were decalcified,embedded,sliced,for HE as well as apoptosis staining and observed microscopically to observe ultrastructure change of trabecular bone, bone marrow cells and fat cells. All data from experiment were dealed with SPSS18.0 statistical package .The data was presented as (?X±s) , The statistical analysis was carried out with completely randomized design variance method,and LSD pairwise comparison test was performed between groups to test significant difference. The dynamic changes of group A and group B in 2 weeks,6weeks and 8 weeks were analyzed in randomized block design variance to test different change.Results: The imaging examination among group A,group B and group C had no evident different change in 2 weeks later.After 6 weeks , the color of the femoral head surfaces in group B were white, dark and dull, the joint cartilage was rough but still complete, the X-ray of 15 hip joints of 8 rabbits in group B showed that the femoral head shapes were round,but there were uneven of bone mineral density(BMD), partial lower density areas of femoral head and bone trabecula were disorder and fuzzy . Color of the femoral head surfaces in group A were rosy ,the joint cartilage was smooth and complete, X-ray showed the shapes of femoral heads were round ,and the bone trabecula was unclear, the bone density in the femoral head increased slightly, no cystic change happening, and the joint space was normal.8 weeks later, the femoral heads in group B had different degree of deformation, and the cartilage surfaces lost smooth performance, part of cartilage surfaces collapsed with stripping notch, the hardness of bone specimens were down, and easily been cut,the X-ray showed that the femoral head shapes were not regular,round,and but bone mineral density in the femoral was uneven, somewhat slightly collapsing, the bone trabecula structure was disorder, cystic change in the femoral head. the density of proximal femur bone reduced and the joint space narrowed slightly. MRI examination revealed:the shapes of femoral heads were irregular,and articular surfaces were not plain.there were uneven low signals near adjacent joints above femoral heads, T1W1 showed small strip and low flake signal;T2W2 showed thin strip,sheet high signal or low signal ; GESTIR showed high signal of bone marrow edema in the femoral head and metaphysis.HE staining of the samples of group B showed the bone trabecula thinned and sparse with discontinuity of the integrity,Fat accumulated between the bone trabecula, the volume of fat cells increased, part of the them integrating. The normal bone cells decreased ,and more condensation nuclei could be seen, nuclear deviated in the side of the bone cells around the trabecula.The color of femoral heads in group A was dim slightly,and the articular surface was round without collapse.resistance was bigger compared with group B when the samples were cut.the X-ray showed that the femoral head shapes of both joints were normal, no collapse happened.the bone mineral density(BMD) increased, no cystic and sclerotic changes were found,the joints space were normal. MRI examination revealed:the shape of femoral heads were smooth,joint space was normal, there were signals near adjacent joints above femoral head, T1W1 showed small low flake signal;T2W2 showed sheet high signal or low signal , and there was no subchondral fracture occuring. HE staining of the samples of group A showed the bone trabecula was regular and coarse ,some connecting. There were lots of bone cells among trabecula, fat cells were normal,and the bone nuclei were big and clear, few empty lacuna could be seen. The normal bone cells decreased ,and more condensation nuclei could be seen,2weeks later after treatment ,the average level of PINP among group A,groupB and group C were not obvious.After 6 weeks ,the level of PINP in group A was (1.73±0.22μg/L),compared with group C(1.57±0.13μg/L), there was a significant difference(P<0.05),and it was statistically higher than group B(1.60±0.10μg/L), there was a significant difference(P<0.05).the PINP level of group B was higher than group C, there was no significant difference(P>0.05).8 weeks later, the level of PINP in group A was(2.08±0.31μg/L),compared with group C(1.61±0.28μg/L), there was a significant difference(P<0.05),and it was statistically higher than group B(1.67±0.28μg/L), there was a significant difference(P<0.05).the PINP level of group B was higher than group C, there was no significant difference(P>0.05), .the PINP level of group A in 6 weeks and 8weeks increased obviously comparing with that in 2 weeks, there was a significant difference(P<0.05).The average level of BALP among group A,groupB and group C were not obvious respectively 2 weeks later after treatment .After 6 weeks ,the level of BALP in group A was(1.49±0.09 U/L),compared with group C(1.13±0.10 U/L), there was a significant difference(P<0.05),and it was statistically higher than group B(1.21±0.08 U/L), there was a significant difference(P<0.05).the BALP level of group B was higher than group C, there was no significant difference(P>0.05).8 weeks later, the level of PINP in group A was(1.70±0.07 U/L),compared with group C(1.18±0.25 U/L), there was a significant difference(P<0.05),and it was statistically higher than group B(1.31±0.26 U/L), there was a significant difference(P<0.05).the BALP level of group B was higher than group C,but there was no significant difference(P>0.05), .the BALP level of group A in 6 weeks and 8weeks increased obviously comparing with that in 2 weeks, there was a significant difference(P<0.05).2 weeks after treatment ,the bone mineral density(BMD) among group A,group B and Group C had no evident difference.After 6 weeks, the bone mineral density(BMD) of group B(0.272±0.017 g/cm2) and group A(0.298±0.015 g/cm2)both decreased obviously,when compared with group C(0.328±0.016 g/cm2), there were significant difference(P<0.05).and the bone mineral density(BMD) of group B was lower than group A, there was a significant difference(P<0.05).After 8 weeks, the bone mineral density(BMD) of group A(0.312±0.014 g/cm2)increased,but it was still lower than group C, the bone mineral density(BMD) of group B ( 0.263±0.006 g/cm2 ) decreased progressivly,it was lower than group A and group C respectively , there were significant difference(P<0.05).Conclusions:1. Single low dose of LPS combined with 3 consecutive high dose use of glucocorticoid in short-term would induce osteonecrosis of femoral head successfully , the relation between glucocorticoid and femoral head necrosis is close.2. Duing the pathogenesis of femoral head necrosis caused by glucocorticoid, metabolism of bone tissue change significantly,and early levels detection of the bone turnover biochemical markers BALP and PINP in the body which reflect the activity of osteoblasts can incarnate the situation of bone formation and repairment indirectly.3. Bone mineral density(BMD) is an important indicator reflecting thickness of cortical bone, structure of trabecular bone and bone mass,non-invasive measurement of bone mineral density (BMD) can be performed easily which may be used to predict collapse of femoral head.4. L-dopa can intervent necrosis of femoral head effectively by stimulating proliferation of osteoblasts, increasing bone formation and accelerating bone repairment.It also can slow down the development of osteonecrosis, contributing to prevention of collapse of the femoral head. |
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