| Because of disease or trauma,some vertebrae with pathological changes such as tumor,tuberculosis,inflammation or fracture,will be excised partly or totally.And the vertebra replacement will be used in the operation for the spine stability.Nowadayes,the prosthestic vertebral body replacement,from Hamdi reported in 1969,is used more and more,because it can redeem the coloboma of the operated vertebrae and get them adequate height and stability. The materials be utilizated include mainly metal, inorganic stuff and biont composite.At recent years,with the histio-engineering going on, the exploratory and exploitation of the biont composite in the spine surgery is lasting well.The artificial vertebra by those materials not only can offer the spine instantly stability but also can get permanent fusion after the operation,so the main research current of the replacement come to it.The nano-hydroxyapatite/polyamide 66 composite (n-HA/PA66)contrived by Li Yubao, in bionics, is a new nanometer biont composite.Its texture is the crystal of nano-hydroxyapatite ( n-HA ) scattering uniformly in the polyamide 66(PA66).The n-HA has the resemblance to osteolith of human bone in structure,ingredient, and appearance.The PA66 has the micelle just like collogen,which profit to the vegetation of rhagiocrine cell.It has be demonstrated that the n-HA/PA66 is non-virulence and non-incentive,and has good histocompatibility and haemato-compatibility,and high ratio of fusion after operation,and its disposition of vitodynamics match well to natural bone.But there is a problem that we need to know whether the artificial vertebra by it,that we called n-HA/PA66 vertebra,is so satisfactory or not.We need to know if the n-HA/PA66 vertebra can get fusion with the vertebra bone on the interface,and that the application in clinic is safe or not. This research has been done on these grounds,and it include two part.Partâ… :Experimental study of the artificial vertebra by nano-hydroxyapatite/polyamide 66 composite on the cervical vertebra of goats.Partâ…¡:Trial clinical application of the artificial vertebra by nano-hydroxyapatite/polyamide 66 composite.OBJECTIVE:To explore theoretical evidence and authenticate the possibility for clinical application of the n-HA/PA66 vertebra. The artificial vertebra,with iliac bone being control,were implanted in the goats'cervical vertebra to check the interfacial fusion and osteogenesis.In the clinical experiment 12 cases were involved. The local response and the symptom were observed,and the spine stability,the interfacial fusion and the height of the vertebae were examined by X-ray film.Then,we can know the n-HA/PA66 vertebra application in clinic is safe or not.METHODS1.Experimental study of the artificial vertebra by nano-hydroxyapatite/polyamide 66 composite on the cervical vertebra of goats. There were 20 goats divided to 2 groups randomly. Group A is the experiment group including 10 goats which were implanted the n-HA/PA66 vertebra on the C3. B group ,the control, in which self iliac bone was implanted,included the other goats. X-ray film and CT were taked after the operation 4W,12W and 24W respectively to survey the position of the implant and to check the fusion. 5 goats would be executed in each group while 12W and 24W respectively after operation to get sample for macroscopic observation of the fusion and the repair of the vertebra defect,and to check how nice were the growth and concrescent of the limiting surface in histology by light microscope.Then we assembled the data and did statistics analysis by SAS11.0,the statistical software.2.Trial clinical application of the artifical vertebra by nano-hydroxyapatite/polyamide 66 composite. We have get 12 patients suffering from cervical spondylotic myelopathy or fracture of cervical vertebra by trauma,and treated them by deuto-total vertebrae resection to decompress by anterior approach,the n-HA/PA66 vertebra implanted and slim-loc system fixed.The follow-up lasted 3 month or more.Local soreness or effusion and the symptom would be observed,so we can do know the histocompatibility of the n-HA/PA66 vertebra and if foreign body reaction is there or not.And the spine stability,the interfacial fusion and the height of the verteba were examined by X-ray film.RESULTS1.Experimental study of the artifical vertebra bynano-hydroxyapatite/polyamide 66 composite on the cervical vertebra of goat.The goats in both group can keep normal activity after operation.There have no rejection or inflammation be found in the tresis vulnus region,and no paraplegina or decease happen.The wounds healed well.We can observe that osteotylus grow around the implant and conjugate the vertebra bone step by step on X-ray film of both group while 4W,12W afer operation.New bone in both group sample was seen by naked eye, which connected the implant to the vertebra bone while 12W. By histology,we found quite a few fibrous bone and new bone trabecula distributing around the implant,in which some osteoblast and inflammatory cell scattered,and cartilaginous tissue was ossifying. In group A,bit of absorption appeared on the material edge, and the cartilaginous tissue being clump. And a few osteoclast and implant bone resorption were seen in goup B,with the cartilaginous tissue scattering.When 24W lasted,the X and CT shew that osteotylus get more than 12W in group A as well as B,and the implant had bind to the bone,and get fused. Histology: bone trabecula have fused with the inplant, osteoblast and inflammatory cell still be there but less. Absorption of the material in group A get more,the osteoclast and implant bone resorption in group B didn't be found again. According to the data from the score of all film and histology picture,the statistics analysis showes that there has no difference between group A and B(P>0.05).2.Trial clinical application of the artifical vertebra by nano-hydroxyapatite/polyamide 66 composite.The preoperative symptoms of all case has get well without any serious complication,and no patient complain lasting soreness.No effusion or flare be found. No recurrence happened in the follow-up. The X-ray film shows that every patient has get solid fusion with good curvature and height,no loose or breakage of the screw or stick be found,and the stability is satisfactory.CONCLUSIONS1.Becouse of its good biocompatibility for its resemblance to human bone in constituent and formation,the n-HA/PA66 vertebra has good osteogenesis as well as iliac bone implant,and the new osteotylus can congeal it with the vertebra bone. It works by entochondrostosis. At the same time,its degradation just matching to its osteogenesis would appear in vivo.So,based on the prophase verification,we can draw a conclusion that the n-HA/PA66 vertebra could be applied to clinical trial safely.2.Becouse of its security and high rate of fusion and firm fixation,the convenience to observe the fusing after operation,and its good biocompatibility for its resemblance to human bone in constituent and formation,the n-HA/PA66 vertebra is a satisfactory substitute for bone transplantation. Furthermore,because of its extremity design,the sinking and collapse will be avoided. Therefore,its clinical application should be spread safely.
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