The Biomechanical Study On The Stress Change And Clinical Research Of The Adjacent Superior Intervertebral Space After Double Segment Artificial Cervical Disc Replacement

Cervical disc between interbody from C₂ to T₁ play important roles in maintaining intervertebral space height, absorbing oscillation and distributing stress evenly, cervical stabilization and action. Cervical disc degenerative disease(CDDD) is very common in spinal disease, while, intervertebral disc degeneration is archae-basis of pathology of cervical disc degenerative disease. Therefore, study to the morphous, biomechanics and clinical of intervertebral disc is very important.The higher occurred place of CDDD is C_4/5,C_5/6 and C_6/7segment, can possess 80.7ï¼…of all patients. The incidence of C_5/6 disc hernia is very high and always compare with one or two adjacent discs hernia. The traditional anterior surgical managements to CDDD is disc decompression/excision and discectomy with interbody fusion. Discectomy possibly lead to segment instability, vertebral canal narrow and degeneration of facet joints. Cervical interbody fusion change the biomechanical environment and scarify motion and function of the segment fused, lead to the stress and range of motion(ROM) of the adjacent segment increase and accelerate to its degeneration. The more segments had been fused, the degenerate of adjacent segment were more significant, and the recurrence rate were higher. Based on the idea of cervical arthroplasty, artificial disc replacement of cervical spine(CADR) is developed quickly in the past few years. But whether CADR can fulfill the function of the disc, or decrease the side effect on adjacent segments? Especially in the treatment to the higher occurrence in clinical practice of C_4/5 and C_5/6 double segments CDDD, whether CADR can remain the normal biomecharlical performance of cervical spine, the effect of clinical therapeutic is excellent or poor? Unfortunately, all of those had few been reported in past years.In our study, first of all, measured the sagittal diameter of vertebral body and canal of cervical spine by X ray, SCT and flesh cadaver. Then, cyclo-shaped pressure sensor was used to measure the intervertebral space stress change during the biomechanical test, built the C_4/5 and C_5/6 double segments intervertebral disc complete, discectomy, CADR and fusion models, measured the change of the stress of intervertebral space between C_3/4 which applied with load of neutrality and pure moments of axial, flexion, extension, lateral bending. Finally, conclude the clinical effect on the adjacent superior intervertebral space of the different disc degenerative disease treatment. Furthermore the clinical cases of the artificial disc replacement and the intervertebral fusion were followed in different time. The clinical result of the different treatment were evaluated, and the relationship of the different treatment and the superior intervertebral space were also evaluated. To investigate the reasons of degeneration after discectomy and fusion in long-time follow up. To provide theories evidence of double segments CADR.Chapterâ… The measurement and its significance of inferior cervical spinal vertebral body and canalObjectives To apprehend the difference of sagittal diameter of vertebral body and canal of cervical spine between X ray, SCT and fresh cadaver practical measurement, and provide benefit to diagnosis of CDDD from anatomy and imageology.Methods The sagittal diameter of vertebral body and canal of 9 fresh cervical specimens from young adult cadavers(C₃～C₇) were measured by X ray, SCT and fresh cadaver practical measurement. One-Way ANOVA and Paired-Samples T Test were used to detect significant changes of the difference in dimensions in each disc. (α=0.05)Results 1. The measurement of X ray to the sagittal diameter of vertebral body is higher than SCT and practice method(P＜0.05). The data between SCT and practice measures have no significance changes(P＞0.05). 2. The canal of cervical spine and the rate of canal and body are lower then them, the difference is significant(P＜0.05), SCT and practice measures have no significance changes. 3. The rate of vertebmal canal and body, X ray method is lower than practical and SCT measures, there are no difference between practical and SCT(P＞0.05). 4. In C3 and C4 segments, the rate is similar (P＞0.05), and they are higher than C5, C6 and C7 segments(P＜0.05). In the inferior three segments, the difference has no significance (P＞0.05).Conclusions 1. SCT can measure the verteberal body and canal more really than computed X ray. 2. The rate of vertebral canal and body in SCT can be a excellent indicate in diagnosis of canal stenosis in cervical spine.Chapter H The biomechanical research of the stress of superior intervertebral space after C4/5 and C5/6 double segments CADRObjectives To observe the biomechanical effect and compare the stress changes of C_3/4 intervertebral space pre-and post C_4/5 and C_5/6 double segments discetomy, CADR and intervertebral fusion, provide a basis to the clinical application of the C_4/5 and C_5/6 double segments CADR.Methods Eleven healthy adult fresh-frozen multi segmental cervical spine segments(C₃ to T₁) were utilized in this investigation and biomechanically evaluated under the following C_4/5 and C_5/6 double segment disc intact spine, discectomy, the Bryan Disc prosthesis implantation, interbody fusion model. The testing was performed by using INSTRON computed mechanics test system. The load(25N～150N) of neutrality and pure moments(0.25Nm～1.5Nm)of axial, flexion, extension, and lateral bending were applied on each group. The stress changes of the superior(C_3/4) intervertebral space was tested by modified cyclo-shaped miniature transducer. The data was analyzed by SPSS for windows 13.0, the statistic significance was set atα=0.05.Results 1. Under axial, flexion, extension and lateral bending loading, the discectomy indicated a significant increase in the stress of the superior(C_3/4) intervertebral space compared to intact condition(P＜0.05). 2. The interbody fusion resulted in significant increase of the stress in the superior(C_3/4) intervertebral space compared to intact condition(P＜0.05). 3. The Bryan Disc prosthesis implantation indicate minor increase of the stress in the superior(C_3/4) intervertebral space over intact condition(P＞0.05). 4. There were significant difference between CADR and fusion groups in the stress of the superior(C_3/4) intervertebral space(P＜0.05). 5. There were significant difference between CADR and discectomy in the stress of the superior(C_3/4) intervertebral space(P＜0.05). 6. Interbody fusion group resulted in significant decrease of the stress in the superior(C_3/4) intervertebral space compared to discectomy(P＜0.05).Conclusions 1. Intervertebral fusion and discectomy of C_4/5 and C_5/6 double segments can increase the stress of superior(C_3/4) intervertebral space, maybe lead to or accelerate its degeneration. 2. To compare the effect on the adjacent superior intervertebral space among CADR and intact spine group, there was no difference between them, and lower than those in discectomy and fusion groups, so provide theory evidence to clinical apply C_4/5 and C_5/6 double segments CADR.Chapterâ…¢The clinical research of the effect of adjacent superior segment after C_4/5 and C_5/6 double segments CADRObjectives To investigate the clinical outcome of the patient who accepted the C4/5 and C5/6 double segments Bryan artificial disc replacement and cervical interbody fusion, and the effect to superior segment.Methods In Jan 1998 to Feb 2006, 35 patients with cervical C_4/5 and C_5/6 double segments disc degenerative disease were treated with two different operations. Five cases were treated with CADR, 30 cases underwent interbody fusion. With the phone call, letters and outpatient service. The score of JOA, the scale of Odom, the X-ray film pre-operation, 6, 12 months and 2-year, 5-year post-operation were collected. The clinical effect were evaluated through analysis the score of JOA and scale of Odom with the paired-sample T test. The intervertebral space height, the vertebral height and the range of flexion-extension of adjacent superior segment were measured directly on the lateral film at different period, and calculate the ratio R between the intervertebral space height and the vertebral height and the ratio of disc degeneration. The data was analyzed by SPSS for windows 13.0, Paired-samples T Test was used to detect the difference among the different groups, the statistic significance was set atα=0.05.Results 1. The JOA score and Odom scale increased significantly in both two operations(P＜0.05). In CADR and fusion groupâ… , pre-operation and 6 months, 12 months post operation, there were no significant difference(P＞0.05). In long-time follow up, fusion groupâ…¡, the therapy effect decreased significantly in 5 years when compared to 12 months and 2 years(P＜0.05). 2. Compared the range of flexion-extension in adjacent segment, there were no statistics means in fusion groupâ… and CADR in pre-operation and 6 months and 12 months post operation. It was increased in fusion groupâ…¡after operation 5 years when compared to 6 months, 12 months and 2 years(P＜0.05). 3. In the follow-up of the ratio of disc degeneration and R of vertebral body and space, there were no difference in CADR and fusion groupâ… pre-operation and post-operation 6 months, 12 months(P＞0.05). In the long-time follow-up groups, the ratio decreased in 5 years post-operation when compared to pre-opemtion, 12 months and 2 years after operation..Conclusions 1. This study has shown that the C_4/5 and C_5/6 double segments artificial disc replacement is a good choice to cervical disc degenerative disease, the morphous and function of the adjacent superior intervertebml space can be maintained in the near future, while the long time fellow-up should been carded up. 2. The interbody fusion was also an effective method to treat the cervical disc degenerative disease in near time, it can remain the height of intervertebral space and range of movement. However, in 5-years follow up, the ratio of disc degeneration of adjacent superior segment increase significantly.