Observation On Various Parts Of Anatomic Microstructure Of Rabbit Proximal Femur And Dynamic Variations After Them Were Induced To Form ANFH

PART I OBSERVATION ON THE PARTITION AREA OF ANATOMIC MICROSTRUCTURE OF RABBIT PROXIMAL FEMURObjective:To analyze the characteristics of orientation,parameters in bones and bone histology of trabecular bone in rabbit proximal femur.To investigate the partition area between the compressive group and the tensile group of rabbit trabecula bone.Methods:10 New Zealand rabbits(male,twelve months) used as experimental animals in the study.To observe:(1)The conducting direction of gravity and the distribution of muscles of proximal femur in the back-extending position.(2)MSCT.(3) The bone histology,parameters in bones and distribution of trabecular bone and sclerotin in rabbit proximal femur were analyzed by Micro CT.Results:When rabbit hind limbs was in posterior extension, the angle between proximal femur and horizontal plane was 90°.The distribution of trabecular bone in rabbit proximal femur was as follows: The trabecular bone of rabbit greater trochanter of femur went from superomedial to inferolateral, trabecular bone between the inferolateral part of the greater trochanter of femur and the lateral moving of the upper part of collum femoris became fused. Trabecular bone at the top of collum femoris formed lateral moving structure. Trabecular bone of caput femoris went from superomedial to inferolateral, trabecular bone inside caput femoris connected middle and bottom, formed from superomedial to inferolateral moving structure. Trabecula bone of lesser trochanter of femur formed from superomedial to inferolateral moving structure, but only in the lesser trochanter of femur. Trabecula bone of the third trochanter of femur was formed nearly lateral moving structure.The BMD and BV/TV value of caput femoris、collum femoris and the lesser trochanter of femur were bigger than the greater trochanter of femur and the third trochanter of femur(P<0.001).The Tb.sp of caput femoris,collum femoris and the lesser trochanter of femur was lesser than the greater trochanter of femur and the third trochanter of femur(P<0.001). The Tb.Th of caput femoris and the lesser trochanter of femur was bigger than collum femoris,the greater trochanter of femur and the third trochanter of femur(P<0.001). The rate of empty lacunae of various parts of proximal femur was less than 20%.Conclusion:The trabecula bone of rabbit proximal femur would be divided into 4 groups: group 1(the principal compressive curve): trabecular bone went from superomedial to inferolateral of caput femoris and collum femoris; group 2(the principal tensile curve): trabecular bone went from extra-superior to intra-inferior of the greater trochanter of femur and the top of collum femoris;group 3(the secondary compressive curve): trabecular bone went from superomedial to inferolateral of the lesser trochanter of femur;group 4(the secondary tensile curve): Trabecular bone of the third trochanter of femur was formed lateral moving structure. Trabecular bone histomorphology shew differentiation between rabbit and human in group 2,group 3 and group 4.PART II DYNAMIC EVALUATION OF ANATOMIC MICROSTRUCTURE OF RABBIT PROXIMAL FEMUR IN AVASCULAR NECROSIS OF FEMORAL HEAD AT EARLY STAGEObjective:To establish the models of rabbits early osteonecrosis with glucocorticoid combined with lipopolysaccharide, and to explore the dynamic changes of the proximal femoral in bone microstructure and histopathology.Methods:25 adult New Zealand rabbits were used as experimental animals in the study. Animal model was established by using hormone combined with lipopolysaccharide method.Rabbits in model group were injected with the improvement modeling technology on osteonecrosis of the femoral head in rabbits.Model group animals were killed at 1,2,3,4weeks: model group was killed 5 rabbits.The data of control group came from normal rabbits in PART I. Both bilateral proximal femur was observed by Micro CT, anatomy and histological method. Statistical methods: The quantitative data were described by x s±,the comparison of indicators at the same position between left and right femurs at different time points used double-factor variance analysis,and neighboring comparative was used by SNK at different time points. An analysis of ROC curve analyzed the diagnostic values of indicators at different time points. The value was 0.05 as a standard test, there was a significant difference when P<0.05.Results:(1)Histopathology: In model group, specimens were observed that the colour of the top and the front and rear parts of caput femoris gradually became kermesinus, the range of the colour gradually became large, the top of caput femoris gradually became flat, but no sclerotin collapse was found. The rate of empty lacunae of every observational proximal femur region were >25% from the first weeks to the fourth weeks.(2)Micro CT(coronal section, three-dimensional reconstruction): In model group, light transmittance increased, cortex of bone became thinner, bone trabeculae became the rarefaction, trabecula changed to thinner in every observational proximal femur region, but the bone trabeculae in caput femoris became slightly thicker. The changes of thickness of caput femoris and the lesser trochanter of femur were not obvious,but bone trabecula of the rest parts were tapered.(3) Bony analysis: The BMD of every observational proximal femur region: model group were less than control group,and BMD decreased with the extending of time(P<0.05). BV/TV value: The difference of BV/TV at different weeks were statistically significant(Pthe greater trochanter of femur<0.001,Pcaput femoris =0.028,Pcollum femoris <0.001,P the third trochanter of femur<0.001,P the lesser trochanter of femur =0.001), and BV/TV decreased with the extending of time. The BV/TV from various parts in both model group and control group at 4th week were statistical difference(P<0.05). BV/TV value from various parts(4th week) were valuable in the diagnosis analyzed by ROC curve, the diagnostic value in model group was less than control group. The Tb.Sp of various parts at different weeks were statistically significant(Pthe greater trochanter of femur<0.001,Pcaput femoris =0.011,P the third trochanter of femur<0.001,Pthe lesser trochanter of femur <0.001) except collum femoris(Pcollum femoris=0.108), and Tb.Sp increased with the extending of time.The weeks which Tb.Sp of the greater trochanter of femur, caput femoris, the third trochanter of femur and the lesser trochanter of femur showed differences in both model group and control group started from 1st week. Tb.Sp value of the greater,the third and the lesser trochanter of femur were valuable in the diagnosis analyzed by ROC curve, Tb.Sp value in model group valuable in the diagnosis were larger than control group. The Tb.Th of the greater and the lesser trochanter of femur at different weeks had no statistically significant(Pthe greater trochanter of femur=0.058、Pthe lesser trochanter of femur=0.088), The Tb.Th of caput femoris, collum femoris and the third trochanter of femur in both model group and control group at 3nd week were statistical difference.After 3nd week, Tb.Th were valuable in the diagnosis analyzed, Tb.Th value of caput femoris in model group valuable in the diagnosis was larger than control group. The rest Tb.Th valuable in the diagnosis of model group were tapered than control group.Conclusion:Histopathology could reflect changes of bone cell in every proximal femur anatomic part,but it was difficult to evaluate the morphology of trabecular bone; MPR and three-dimensional reconstruction of Micro CT could show the changes of the morphology of trabecular bone; Bony analysis used by Micro CT, BMD could reflect changes of bone mass in different parts of proximal femur. To observe with relevant parameters of bony analysis at 4th week, morphological Changes of trabecular bone could be observed more fully and effectively. In the models of rabbits early osteonecrosis, Tb.Th of caput femoris would be thickening, the changes of Tb.Th from the lesser trochanter of femur were not obvious, the changes of Tb.Th from collum femoris were obvious at 3nd week, and Tb.Th of the rest parts became less. BMD and BV/TV almost got smaller,while Tb.Sp got larger,its trend of the change were as follows: the speed of change of the greater and the third trochanter of femur(the tensile curve) was faster than that of caput femoris, collum femoris and the lesser trochanter of femur(the compressive curve).