| The cervical vertebra of human are something like physical entity. So them have their own physical character about themselves. The viscoelasticity is one of their important characters. The sensibility about creep and stress relaxation of viscoelasticity are both indications that, somethings to reflect the flextion, the extend and the absorption characters about cervical vertebra. The degradation of them will reflect the stability change, under the effection of stress. So them will increase the compentation of IVD(intervertebral discs) and articular process. Them also make the hyperosteogeny, osteophyma and other complications which to result in serious palsy. Because the reasons discussed above, we consider that the study about viscoelasticity is very important. It is a very valuable work in order to prevent and cure about cervical vertebra injury. There are a lot of studies about viscoelasticity before, but almost concern about the vertebral plate and IVD. There are few study about articular process of cervical vertebra so far. But the articular process is important part for the stabilization. Because first, either articular process interlocking or decompress of nerve root, the doctors always need exairesis some or entire articular process. Secondly, there are more and more people prefer microsurgery. So we must to say that the significance of articular process viscoelasticity is more and more important .We get 6 normal adult male cadavers of goat, 3~4years old. We dissect them in 1 hour after them dead. Then we get 6 cervical vertebra of C2-T1, and check out them with X ray to make sure there are no pathematoloy change. We clear the skin and muscle, then put them in the plastic bag. We make them air tight , put into the refriger and keep them in -30℃. Before the experiment, we defrost the cervical vertebre of goats in common temperature, and handle them to entire cervical vertebra without skin and muscle. We measure 6 sample for stress relaxation and creep tests. After that, we bite left articular process 50% part of C4-C5 with gouge forceps like operation and measure for stress relaxation and creep tests too. ( The samples is putted into the refriger immediately after experiment. All the experiment finish in 48 hours. Each text of sample is finish in 6 hours after defrostion. ) Compare the viscoelasticity of the cervical vetebra between the normal group and control group( operation group ) in the stress relaxation and creep texts. We study for the effect of articular process operation to the viscoelasticity of the cervical vetebra. We get the data and curve of the stress relaxation and creep tests. We regression analysis and calculate the data about the normal group and contrel group for function and curve. We discuss about the effect of articular process operation to the viscoelasticity of the cervical vetebra, and discuss and analyses the result in clinic.The result of experiment show that the stress relaxation of normal group is 0.157 MPa in 3600s. The stress relaxation of contrel group is 0.1605 MPa in 3600s. The creep texting of normal group is 2.923834 in 3600s. The creep texting of contrel group is 2.76, the results about stress relaxation and creep texting both have no significant difference, P>0.05.The result of experiment show that the stress relaxation curve is logarithmic variation, in the same time the creep texting curve is exponential variation. The data of stress relaxation and creep texting are both have no significant difference. So we can obtain from the result that removing left articular process 50% part of C4-C5 with gouge forceps like operation, is not change the viscoelasticity of the cervical vetebra.The vitodynamics in modern times said that, the bone of human have their own special physical characteristic, because their complex reconstituent and struction. The bone have excellent characteristic of anti-drawn and anti-compress, and also have excellent hardness in the same time.The bone have their own time-dependent viscoelasticity. Concerning about construction of the bone, we can say that it has the perfect combination in macroscopy organisation and microscopy organisation, even in submicropic organisation. The bone have the hardest intension, the lest and the lightest stuff. So the construction of the bone make themselves to adapt both the physiology and mechanics. For example, there is hollowness of the bone, and the osintegumentale are all outside when the sponginess stuff are inside. The haversian canal of bone can prevent the surface crack introversion deeper. So we must say that we study the mechanical property of the bone must consider its characteristic all the time, because the bone is a biomaterial and a living connective tissue.In the entire living time of human, the bone perfect itself endlessly. It reconstitute new bone tissue, absorp the old bone tissue. It has this characteristic which the other architectonic stuff never have. But the characteristic make some diseases happen properly. The bone system is a feedback control system. In the normal time, the bone is under the optimization effect of stress and in balance situation. It mean that the formation rate is as same as the destroy rate of bone at the same time. When the stress or straining is change and not adapt the perfect rang either, the bone formation have the advantage than the destroy. So the hyperosteogeny happens in order to increase the area for endure,induce the range of stress and straining to the perfect. If the situation is contrary, the atrophy of bone happens in order to increase the stress and straining to the perfect. There are a lot of complication are ralative with this change, such as the hperostegeny or the cataplasia of close bone. The articuli intervertebrales are very important in the mechanotransduction of stress. Some experiments show that, the IVD take the 36% stress under the compressive stress when the articuli intervertebrales take 64% stress at the same time. So the study about the mechanics characteristic of articuli intervertebrales is very important obviously. The viscoelasticity is one parameter what can reflect the strain rate of bone under the stress, is one significance index of vitodynamics. The associated experiments about viscoelasticisity has been did always concerning on the operation such as only mono-open-door, ambi-open-door and the resection of IVD. Because there are few simple resections of articular process in the domestic. But the experments about viscoelasticisity which associate too many influential factors and too complex, can not explain the relationship between the viscoelasticisity of articular process and the viscoelasticisity of entire cervical vetebra. There are few significance for direction the microsurgen.We resection the left articular process 50% part of C4-C5 with gouge forceps like operation, and do not destroy the vertebra plates and ligaments. Because some experiments show that the soft tissue are take much effect on the viscoelastisicity. The result of our experiment is obvious. The viscoelastisicity are no significiant different between the normal group and the contrel group. That indicate the removing left articular process 50% part of C4-C5 with gouge forceps like operation is take little effect on the viscoelastisicity of cervical vetebra without destroy the soft tissue. It will not increase the compensation of IVD or articular process, because it take little effect on the the flextion, the extend and the absorption characters. In the practic clinic work, the objective of spinal operationa is reestablishment anatomy, relief compression and establishment stabile mechanics construction. So it is very important to recover and keep the spinal viscoelastisicity. The significance of our experiment for clinic is indication that, we do not need too many confluence and fixing the cervical vertebra in the operations if not serious injuries. Because those will induce the economic burden for patients, and induce the frequency of complication after operation. That is very good both for patients and doctors. |
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