The Effects Of Peripheral Nerve Injuries On Epiphyseal Plate Development

Objective: The function of the vertebrate skeleton determins the skeletal shape and size ,but they develop with growth pattern which is enchondral bone formation.The epiphyseal plate between osteoepiphysis and metaphysis of the long bone unceasingly proliferates and thickens,the interstitial substance calcifies,and the cartilage cell generates apoptosis,finally newly formed bone deposites,which forms longitudinal growth of the diaphysis.The physiological activity and biological behaviour of the epiphyseal plate is complicated,which is affected by many factors.Recently although numerous scholars gain some achievement in the direct epiphyseal plate injury and microelement deficiency which affect the epiphyseal plate development, the research that the peripheral nerve injury influences the epiphyseal plate development is seldom.This research intends to establish the animal model of the sciatic nerve and femoral nerve injuries,and observe the developmental capacity of the epiphyseal plate through the methods of physical examination,imageology and microscope,in order to discuss the function and mechanism of peripheral nerve injuries on epiphyseal plate development,thus provide the theoretical basis for the more reasonable and effective clinic treatment to the peripheral nerve injury of the young children and teenager.Methods: Select 40 healthy rabbits aged 6~8 weeks,body weight 1.0~1.4kg,male or female,and introduce homobody reference method.Cut the sciatic nerve and femoral nerve of the left leg about 1 cm as the experimental group and the right leg isn't cut as the comparison group.After being anesthetized by intramuscular injection of ketamine (20mg/kg),apply a declined cut about 2.5cm long under the left-side fundament,expose and identify the sciatic nerve,and cut its distal segment about 1cm at the inferior margin of the piriform muscle about 0.5cm.The same method is to apply a cut about 2.0cm long under the left-side inguinal groove,expose and identify the femoral nerve which locates the femoral artery laterally,and cut its distal segment about 1cm at the inferior margin of the crural ligament about 0.5cm.They are bred under identical conditions and ten rabbits of each group are put to death 2 weeks,4 weeks,8 weeks and 12 weeks respectively after the operation to observe. Before being executing,imageology examination are carried out to measure and contrast the tibial angle and the tibial posterior slope angle,then obtain the whole tibia and measure its length by sliding caliper and contrast. The samples of the proximal tibia including the articular surface,the osteoepiphsis,the epiphyseal plate and the metaphysis is taken to conduct the light microscope observation,in order to observe the generation of the epiphyseal plate cells, then a statistics analysis is carried out on each group of data.Results:1 Imageology Examination:Measure the tibial angle and the tibial posterior slope angle on the anteroposterior and lateral radiograph respectively. The result of the experiment shows there is a substantial difference(P<0.01) between the experimental group and the control group in every stage,the tibial angle and the tibial posterior slope angle of the experimental group are distinctively lower than those of the control group. The tibial angle of the experimental group and the control group is 74.24±0.38°and 85.73±0.55°after 12 weeks respectively,while the tibial posterior slope angle is 6.95±0.41°and 15.67±0.39°respectively. The result illustrates that the peripheral nerve injuries influence the epiphyseal plate normal development and lead to the skeleton development malformation.2 Measurement of Tibia's Length: Measure the length of the tibia by sliding caliper and the result of the experiment shows there is a substantial difference(P<0.01) between the experimental group and the control group in every stage. The tibial's length of the experimental group is distinctively shorter than that of the control group.The tibial's length of the experimental group and the control group is 107.38±1.46mm and 110.62±1.82mm after 12 weeks respectively. The result illustrates that the peripheral nerve injuries influence the growth velocity of the epiphyseal plate and delay the skeleton development.3 Histological Examination of the Epiphyseal Plate: The light mirror observation shows the generation and differentiation of the cartilage cells in the control group is obvious and the cellular structure and layer is distinct.The germinal zone's cells of the epiphyseal plate are small and intensive.The cells of the proliferative zone are larger than those of the germinal zone and they are not only flat but also irregular.The cells heap up as the railings shape along the long bone axis,while the vesicular cells of the hypertrophic zone form columnar arrangement.The generation and differentiation of the cartilage cells in the experimental group isn't obvious and the cellular structure and layer isn't distinct. The proliferative and hypertrophic zone shrinks relatively,while the germinal zone enlarges relatively.Conclusion:The results of this experiment illustrate:the peripheral nerve is closely related to the epiphyseal plate development.The peripheral nerve injuries delay the speed of the epiphyseal plate development and cause the limb short, small and bent.For the peripheral nerve injury of the young children and teenager,it is very important to heal it and make the limbs recover innervation as soon as possible and minimize the effects of the peripheral nerve injuries on the epiphyseal plate development.