Design And Clinical Application Study Of CUF In The Cervical Vertebra With Posterior Fixation

Recent ten years, with the study on spinal injury and development ofbiomechanics, the multiformity of pedicle reduction-fixation systems appear bothhere and abroad, such as Axis,improved Steffee,Cevifix syetem,Stavlock system,Vertex system and so on. In clinical practice different reduction-fixation systems makebetter result separately, but some exist insufficience. Through researching andanalyzing above-mentioned ones, combining the characteristic of three columnsdamage of cervical vertebra, we develop one kind inside-fixation system of CUF, thatis putted simply, fixed firmly, and has reset function.Part 1: Design characteristic of the CUFThe rod entering the U-shaped hole of pedicle screws and the pull-in screwbeing long ring-shaped are connected with the hole at the end of the rod by ring orIocknut. Furthermore by wrapping the rod, the inside fixation can pull off or compressthe centrum, maintain the height of the centrum and centrum space, keep thephysiological flexure degree of the centrum. The pedicle screws have U-shaped holeof long or short and the long kind have the result of rest orating the centrumspondylolisthesis. The U-shaped hole being on top of the screw is connected with therod conveniently in the process of operation. The screw thread showing Itself taperreduces stress concentration and prevent the screw rupture. The various kinds are inuse for the fixation of the pedicle screw or lateral mass.Part 2: Biomechanical Test of CUFSix fresh spinal specimens were prepared. After establishing the model of testand dividing them into four groups: NS,CUF,SP and AF, we tested some variance,such as the straining, displacement, strength, stiffness and so on. The resultshowed: firstly the strength of model fixed with the CUF instrument was near to the group of NS, there was no significant difference(p＞0.05) between axial compression,flexion,extention and latent bend, but batter than that of SP and AF. Secondlystiffness achieved the level of NS and there was no remarkable difference(p＞0.05)compared with SP, but more superior to AF(p＜0.05). Thirdly on torsional strength andstiffness of cervical spine CUF was batter than that of AF and SP. Fourthly thehigh-point carrying capacity of CUF approached the level of NS and preceded the AFand SP. Finally pull-out power of the U-shaped screw was batter than that of AF andSP.Part3: The preliminary clinical application of Cervical United FixationBy now, 25 cases treated with CUF are followed up from 2 month to 24months. Basing on the patients' symptom, physical symptom and analyzing the X-rayfilm and CT between before operation and after operation, we could draw a conclusionthat 18 patients operated with nerve-function injury had a better improvement thanever. Height of the centrum, height of the centrum space and reparablespondylolisthesis had no change. 20 cases reached bone-fusion, bone graft place of5 cases operated in short time became clouding. From operation to now there has nocomplication of screw breakage, loosening, pullout etCo Long-dated effect will dependon studying and follow-up further.