The Biomechanical And Clinical Study Of The Mophometric Change Of Inferior Interforamina After Two-level Cervical Artificial Disc Replacement

Anterior cervical decompression and fusion is an effective therapeutic method for cervical degenerative diseases,trauma,and tumor. It's a problem that the increase of movement because of the redistribution of stress after fusion leads to the development of adjacent cervical segments degeneration.Artificial cervical disc replacement(ACDR)is a new technique to replace the affected disc and exercise its function,with reservation of the movement of corresponding segment,and decrease adjacent degeneration.The intervertebral foramen dimension possesses decisive significance for the diagnosis of cervical intervertebral foramen stenosis and cervicalspondylotic radiculopathy.The study on the morphometric change of cervical intervertebral foramen has important significance because it is closely related to biomechanical characters and is one of the important indexes for evaluation of clinical efficiency.Recently,it's proved that the clinic application of ACDR can resume the function of cervical intervertebral disc.However there is still few cases of two-level ACDR,there is no report whether the artificial disc have any side effect on the replacement and adjacent disc or intervertebral foramen,especially the inferior one.The study is to perform from the following three aspects:(1)To provide data for experiment and clinic study through the observation, measurement and comparison of the cervical intervertebral foramen of cadaver and its' X ray.(2)To explore the morphometric change of the same level(C_5/6)and inferior(C_6/7)intervertebral foramen under different status and loading among groups of C_4/5C_5/6ACDR,normal disc, discectomy,anterior fusion.(3)To observe the clinic efficiency of two-level ACDR and two-level anterior fusion,And to compare the morphometric change of the same level(C_5/6)and inferior(C_6/7) intervertebral foramen after C_4/5C_5/6ACDR and anterior fusion at the same level. Chapter One:The Comparison of Anatomic and X-ray Measurement of the Low Cervical Intervertebral ForamenObjective To investigate the more availability method to measure the inferior cervical foramen for providing data of anatomy and imageology for the research of the biomechanical effect on the inferior cervical foramen and the observation of clinical cervical diseases.Method To observe the height,width of C₃～C₇ cervical intervertebral foramina from 15 antiseptic adult cervical specimens and their X-ray which a scale was put at the level of cervical intervertebral foramina when examined.All the data are analyzed with SPSS11.5(α=0.05).There is statistical significance when P is smaller than 0.05.Result The average height and width of the low intervertebral foramen were 8.02mm±0.85 and 5.65mm±0.61.The intervertebral foramen average height and width from X-ray divided by scale were 7.69mm±0.85 and 5.22mm±0.59.There is statistical significance in the Paired-Sample T test of the average width and average height of intervertebral foramen between anatomy and imageology(P＜0.05).The measurement numerical value of cadaver is smaller than that of X ray and bigger than that of estimation from X-ray divided by scale.The error for height and width is different among the different measurement.Conclusion The intervertebral foramen width and height become gradually large from side of head to caudal.The measurement numerical value of cadaver is smaller than that of X ray and bigger than that of estimative value.Chapter Two:The Biomechanical Research of the Morphometric Change of Cervical Intervertebral Foramen of C4/5,C5/6 After Two-level Artificial Disc ReplacementObjective To explore the effect of the five different motion condition under the different loading on the biomechanics of the morphometric change of cervical intervertebral foramen of C4/5,C5/6 with cervical intervertebral disc integrity,two-level ACDR,two-level discetomy,two-level intervertebral fusion in order to provide theoretical basis for clinic.Method 11 fresh cervical spinal specimens(C1～T1)obtained from young adult cadavers during the biomechanical measurement, Specimens are divided into integrity group,discectomy group,artificial disc replacement group and intervertebral fusion group of C_4/5,C_5/6.The C_4/5,C_5/6intervertebral foraminal dimension including height and width and the range of variety(ROV)among the four groups before and after loading are measured with migration sensor in each group during different movement and loading.All the data are analyzed with SPSS11.5. There is statistical significance when P is smaller than 0.05.Result The cervical intervertebral foramina height,width change of C_5/6foramen pre- and post C_4/5,C_5/6discetomy,ACDR,and the intervertebral fusion in all the five different test condition and different loading are as followed:there is no difference between the integrity group and ACDR group in all the five different test condition(P＞0.05).There is significant difference between integrity and discectomy group,ACDR and discectomy group(P＜0.05).The change of C_6/7foramen are as followed:(1)there is no difference between the ACDR and integrity group, ACDR and discectomy group in all the five different test condition(P＞0.05).There is significant difference between ACDR and intervertebral fusion group(P＜0.05).(2)There is significant difference between integrity and fusion group,discectomy and fusion group(P＜0.05).(3)the ROV of inferior intervetebral foramen height and width in fusion group is bigger than in other groups(P＜0.01)and in artificial disc replacement group is similar to that in the integrity group.The C_6/7intervetebral foramen height and width of the integrity group,the discectomy,ACDR and intervertebral fusion group increased significantly during flexion and contralateral bending(P＜0.01)while decreased significantly during axial, extension and ipslateral bending(P＜0.01).Conclusion 1,The biomechanic change of cervical intervertebral foramina of the inferior ACDR segment in two-level ACDR is similar to that of integrity group indicates there is no side effect between ACD in two-level ACDR;2,The biomechanic change of the adjacent inferior cervical intervertebral foramina in two-level ACDR is similar to that of integrity group;3,Dimension of adjacent inferior cervical intervetebral foramen in fusion group variated greatly and this is probably one of the causes which can lead to cervical degeneration or accelerated degeneration.4,The results initial prove that ACDR accords with the cervical normal desire of vitodynamics and provide theoretical basis for clinical two-level ACDR.Chapter Three:The Clinical Research of the Morphometric Change of the Intervertebral Foramen in C5/6,C6/7 After Two-level Artificial Disce Replacement and intervertebral fusionObjective To observe the clinical results of the patients who accepted the two-level Brayn artificial disc replacement and two-level cervical interbody fusion and analysis the effect on the C5/6,C6/7 cervical intervertebral foramen.Method 35 cases of C_4/5,C_5/6prolapse of intervertebral disc who accepted the two-level artificial disc replacement and the two-level intervertebral fusion are followed from 1998 to 2006.35 cases are divided into three groups according to the way of operation and time as followed:the group of artificial disc replacement,the first group of intervertebral fusion and the second group of intervertebral fusion,the score of JOA,the rank of Odom,the X-ray film of pre-operation and 6, 12,24 months,5 years post-operation are collected.The clinical effect are evaluated through analyzing the score of JOA and the rank of Odom with the paired-sample T test and chi-square test.The height and width of intervertebral foramen are measured directly on the film in oblique position at different period,and calculate the ratio between the height, width of foramen and the vertebral height.All the data are analyzed with SPSS11.5.Result(1)There are significant difference between pre-operation and different period post- operation(P＜0.01).The score of JOA and the rank of Odom increased significantly in different period post- operation in the three group.There are not difference in 6,12 months postoperation in score of JOA and rank of Odom between the group of artificial disc replacement and the first group of intervertebral fusion(P＞0.05).There are not difference in 12 months post- operation in score of JOA and rank of Odom between the group one and two of intervertebral fusion(P＞0.05).The score of JOA and rank of Odom decreased in 5 years post- operation and there are difference between 5 years and 12,24 months post- operation(P＜0.01)in group two of intervertebral fusion.(2)There are not difference of the ratio between the height,width of foramen and the vertebral height between pre-operation and different period post- operation(P＞0.05)in the group of artificial disc replacement and the group one.There are not difference of the ratio between the height,width of foramen and the vertebral height. between pre-operation and 12,24 months post- operation(P＞0.05)in the group two.There are difference of the ratio between the height, width of foramen and the vertebral height,between 5 years and 12,24 months post- operation(P＜0.01)in group two.Conclusion 1.The recent curative effect is comparatively good in the two-level cervical artificial disc replacement and anterior two-level intervertebral fusion,and there is no obvious influence on intervertebral foramen.2.Adjacent inferior intervertebral foramen becomes smaller in middle-long period in anterior intervertebral fusion,and it may be one of causes of cervicalspondylotic radiculopathy.3.The middle-long curative effect in two-level CADR need advanced observation.