| With the quickening pace of social life, the increasing degree of labor heavy work and changing in lifestyle and behaviors, secondary cervical spinal stenotic myelopathy in patients with increasing year by year, there tends to younger tendency. Multilevel cervical disc herniation, cervical ossification of posterior longitudinal ligament and ossification of ligamentum flavum are main reason causing cervical spinal stenotic myelopathy. Expansive open-door laminoplasty of cervical spine is one of the effective methods in the treatment of cervical spinal stenotic myelopathy. Expansive open-door laminoplasty of cervical spine can expand the spinal canal while preserving the posterior bony structures, maintaining the integrity of part of the spinal canal.However,we found fixing the lamina after the expansive open-door laminoplasty of cervical spine is difficult, prone to "re-closed" phenomenon, so that the decompression disappear, or even result in serious spinal cord injury, a calamity consequences. For this reason, many scholars try to reform the kind of surgery of the traditional expansive open-door laminoplasty of cervical spine. Some scholars fixed the open door side lamina through the wire or nylon cord fixing grafts between the open side of the lamina and facet joints, but still can not completely avoid lamina sinking, canal diameter narrowing and re-closing phenomenon. Some scholars use the titanium miniplate (with bone graft fusion) fixing the open door side of the lamina, titanium miniplate screwed in the lamina.On the one hand, if the screws of fixing graft loose or bone graft can not block fusion of ossification, bone graft into the spinal canal with spinal cord injury may happen; the other hand, because the human lamina of cervical vertebra is thin, the titanium miniplate with screws in the lamina, the fixing power is small, which is can not form firmly fixed. Moreover, twisting into lamina screws has the risk of spinal cord injury, time-consuming and technique demanding. Some scholars have used anchor method, which is simple,without increasing the operative time and blood loss, reducing stiff neck and pain after surgery,but as time increased after surgery, there is thread broken down in the lamina risk. In addition, such non-rigid fixation, if the shaft lamina can not be integrated junction, can not effectively prevent the shaft lamina sinking. Some scholars implanted the coralline hydroxyapatite or ceramic devices in the open side, although taking into account the open side of the spinal canal repair, which is difficult to obtain the stability immediately after surgery, having the possibility of "re-closed" phenomenon and spinal cord compression. In view of the above problems, we developed a neotype adjustable open-door laminoplasty miniplate, in order to safely, effectively and easily to carry out cervical laminoplasty. At the same time, through independent research and development the neotype adjustable open-door laminoplasty miniplate to make homemade, try a large-scale clinical application, effectively reducing the cost of treatment of patients, and create objective economic and social benefits.Part I Applied anatomy of cervical unilateral open-door laminoplasty with reconstruction Iamina(titanium miniplate) fixationObjective To provide parameters for the cervical unilateral open-door laminoplasty with reconstruction lamina (titanium miniplate) fixation by exploring anatomic features of C3-C7 vertebrae..Methods 50 sets of dry cervical vertebrae specimens were observed in the study.The width, height and thickness of lateral masses(LMW, LMH, LMT), the surface length from the external border of lateral masses to the plane of 5mm above the basilar part of spinal process(LSL), the height and thickness of the lateralis and median part of laminar(LH1, LH2, LT1,LT2), the height and width of the basilar part of spinal process(SPH1,SPW1) and the plane of 5mm above the basilar part of spinal process(SPH2,SPW2) were measured and analyzed.Results LMW was about C3(9.89±0.97)mm,C7(12.09±0.93)mm. LMH C4(11.44±2.09)mm,C7(13.56±2.17)mm, which was linear correlated, increased gradually. LMT C3(9.03±1.46)mm,C7(6.66±0.78)mm, which was decreased gradually. LSL C3(25.21±2.08)mm, C6(27.09±1.80)mm, C7 and C4 was similar.LHl C3(11.54±1.66)mm,C7(16.83±1.77)mm and LH2C3(10.91±1.58)mm,C7(14.86±1.48)mm, increased gradually. LT1 C5(4.44±0.81)mm,C7(5.28±0.76)mm and LT2 C4(3.00±0.86)mm,C7(4.92±0.96)mm. SPH1 C4(9.33±1.67)mm,C7(11.34±1.57)mm and SPH2 C4(7.10±1.76)mm, C7(9.82±1.46)mm, C3 and C5 was similar. SPW1 C5(8.59±1.81)mm,C7(11.13±1.76)mm and SPW2 C5(6.66±1.86)mm, C7(8.50±1.58)mm, which was the shortest in C5, the longest in C7.Conclusions Cervical unilateral open-door laminoplasty with reconstruction lamina(titanium miniplate) fixation is feasible anatomically.lt can enlarge cervical vertebral canal and reconstruct the stability of lamina.Part II The research of the neotype adjustable open-door laminoplasty miniplateObjective To design a neotype adjustable open-door laminoplasty miniplate, in order to achieve open side of the lamina firmly fixed, increasing stability and installation of fixed flexibility and preventing "re-closed" phenomenon effectively.Methods Based on anatomical measurements people C3-C7 morphological parameters of cervical bone samples were obtained, in summarizing the clinical experience and learn the advantages and disadvantages of similar foreign products, to determine the structure and specifications initially. According to structure chart and specifications,we make this mini-titanium plate samples, and instal in the cervical spine model, to verify its feasibility.Results The neotype adjustable open-door laminoplasty miniplate includes mainbord and sliding hook. The one end of mainbord fixed at cervical lateral mass and the other end fixed on the the basilar part of spinal process. The mainbord can bend shaping according to the need of operation.The sliding hooks embedded in the guide slots on the mainboard, so you can slide guide groove to adjust the width of the door side of the distraction flexibly according to the individual differences and the need of operation distraction width. When adjusted to the proper width, you can tighten the screws to fix sliding hook. by the friction between two rough surface, the pressure inside the card claw hold and tighten the pressure of screw.Conclusion The design of the neotype adjustable open-door laminoplasty miniplate is feasible anatomicly. Every part of the fixation device has different parameter ranges. It can be installed successfully to enlarge cervical vertebral canal and reconstruct the stability of lamina cervical vertebra by cervical posterior approach,which is strong,safe and convenient.PartⅢThree-dimensional biomechanical test of the neotype adjustable open-door laminoplasty miniplate fixationObjective To compare three-dimensional motional stability of different groups and to evaluate the method for that neotype adjustable open-door laminoplasty miniplate and screws were used to secure the posterior elements in the open position after expansive unilateral open-door laminoplasty and its immediate effects and initial stability of cervical vertebrae.Methods Experimental material from the accidental death of the adult male fresh cadaver cervical spine in 6 cases (C1-T1), as self-control experiment, through cervical posterior approach simulated cervical unilateral open-door laminoplasty, which is C3-C6 on the right to open the door and the left as the gate axis.The specimens were dividede into intact cervical specimens group, sutures group, suture anchor fixation group, neotype adjustable open-door laminoplasty miniplate group. The top of the embedded specimens were connected with three-dimensional spine loading disc drive and the base of the embedded specimens were fixed lower working platform in the testing machine.The range of motion of different groups was measured by a three dimensional spinal stability test in the MTS-858 material testing machine.Each group samples were flexion and extension, lateral bending and rotation around the direction of motion stability, implementing pure couple moment load, load of 0.5-2.0Nm, maintaining 30s as a cycle.Measured before exercise, every condition, the specimen is loaded to the maximum torque of 2.0Nm, and then uninstall, also repeated 3 times, loading/unloading cycle after the data collection form 3 times load /unload cycles to the cervical spine viscoelastic removal of the effects to a minimum, be more stable the results of cervical spine movement when the load to 2.0Nm time for 30 seconds, allowing cervical specimens creep movement kinematics in the three-dimensional biomechanical test after loading.Directly obtained by the computer coordinates for each marker movement, calculated for each specimen using EVaRT software segment angular displacement, the angular displacement of the vertebral body is derived by adding the cervical spine range of motion.The moment was applied with±2.0N.m loads in flexion/extension, left/right lateral bending, and left/right axial rotation on the three-dimension motion stability test. Multi-level motion was measured by using Motion Analysis Motion Capture System. The motion measure system included six infrared camera placed around cervical specimen and used specialized acceptable infrared, sphericity markers. Four markers were rigidly attached to each vertebral level(C3-C6) in noncolinear position and oriented to permit detection by infrared camera. Each marker motion coordinate was calculated by computer using EVaRT software and angular displacement parameters were calculated, including the range of motion(ROM),neutral zone(NZ),and elastic zone(EZ),in flexion and extension, right/left lateral bending, and left/right rotation.The results obtained are used SPSS 13.0 statistical package for statistical treatment, range of motion among the four groups was used to compare changes in single factor analysis of variance (one-way ANOVA).Analysis of variance used Welch method missing correction; further multi-LSD was used to compare method (Least-Significant Different), Heterogeneity of variance with Games-Howell method.Differences were considered significant at P<0.05.Results After expansive unilateral open-door laminoplasty, there was significant difference between sutures group and intact cervical specimens group/neotype adjustable open-door laminoplasty miniplate group in extension, left lateral bending and left axial rotation range of motion (p<0.05), with the neotype adjustable open-door laminoplasty miniplate group was no significant difference.There was significant difference between suture anchor fixation group and intact cervical specimens/neotype adjustable open-door laminoplasty miniplate group in left lateral bending and left axial rotation range of motion (p<0.05), with the sutures group was no significant difference.There was significant difference between neotype adjustable open-door laminoplasty miniplate group.and sutures group in flexion/extension, left lateral bending and left axial rotation range of motion (p <0.05), between neotype adjustable open-door laminoplasty miniplate group and suture anchor fixation group in left lateral bending and left axial rotation range of motion (p<0.05),with the intact cervical specimens group was no significant difference.Conclusion The biomechanical stability of expansive unilateral open-door laminoplasty with neotype adjustable open-door laminoplasty miniplate fixing the open door side lamina is good,which can reconstruct the stability of cervical vertebrae. |
PDF Full Text Request