Establishment and significance of a three-dimension finite element model of the whole cervical spine (C0-T1) in normal human / 中国组织工程研究

BACKGROUND: The spine structural unit of the cervical spine is a common site of degeneration and trauma. Establishing a good cervical spine model is of great practical significance for studying the biomechanical changes of cervical vertebrae under various conditions, preventing and treating cervical injuries, and improving the treatment methods of neck and effects. OBJECTIVE: To establish a three-dimension finite element model of the whole cervical spine (C0-T1) in normal human and provide a good experimental application basis for further biomechanical research. METHODS: A healthy adult volunteer was selected as the object for data collection. The original data obtained by 256-row CT thin layer scanning, which then has been extracted and edited by software to implement reverse reconstruction. The three-dimensional finite element model of whole cervical spine (C0-T1) was established by the numerical simulation. The range of motion at various directions and mechanical characteristics were verified. RESULTS AND CONCLUSION: The model had 208 631 nodes and 660 876 solid elements. The range of motion in all directions was good. In addition to the larger C0-C1mobility, all the rest of the segmental motions were consistent with previous literatures. The geometric and biomechanics characters of three-dimensional finite element model of the whole cervical spine (C0-T1) were highly similar to the intact one. The validation of the model was positive.

Lumbar intervertebral disc degeneration assessed by the nine-point system with X-ray / 中国组织工程研究

BACKGROUND: The X-ray 9-point grading system is established based on cervical disc degeneration and its suitability for evaluation of lumbar disc degeneration has not been validated. OBJECTIVE: To investigate the feasibility of the evaluation of lumbar intervertebral disc degeneration using the 9-point grading system with X-ray, and to explore its clinical application value. METHODS: The correlation between 9-point grading system and Pfirrmann system was statistically analyzed. Magnetic resonance imaging (MRI) and X-ray images of 172 cases with lumbar disc degeneration or simple lumbago, who were treated in the Shanghai Changzheng Hospital from June 2013 to June 2016, were retrospectively analyzed. The MRI scores of lumbar disc degeneration were evaluated according to Pfirrmann standard, and the X-ray scores were evaluated according to 9-point grading system. The two groups of scores were respectively analyzed by the correlation and regression tests via Spearman rank sum test with SPSS software. RESULTS AND CONCLUSION: (1) MRI scores (the independent variable X): 2 cases scored 1; 8 cases scored 2; 55 cases scored 3; 84 cases scored 4; 23 cases scored 5. X-ray scores (the dependent variable Y): 2 cases scored 0; 6 cases scored 1; 21 cases scored 2; 43 cases scored 3; 40 cases scored 4; 26 cases scored 5; 16 cases scored 6; 8 cases scored 7; 7 cases scored 8; 3 cases scored 9. (2) The Spearman correlation test showed that significant positive correlation was found between Pfirrmann system and 9-point grading system (P <0.01). Significance test of correlation coefficient proved that there was significant linear correlation between Pfirrmann system and 9-point grading system. Further regression analysis showed the linear regression between Pfirrmann system and 9-point grading system. (3) These findings suggested that Pfirrmann system and X-ray 9-point grading system had a good consistency in evaluating lumbar disc degeneration. As a scientific, fast and effective evaluation method, the X-ray 9-point grading system has a certain reference value in the diagnoses of lumbar degenerative diseases.

Short-term clinical results of interspinous dynamic fixation of Coflex for the prevention of adjacent segment degeneration after lumbar fusion / 中华外科杂志

<p><b>OBJECTIVE</b>To observe the short-term clinical results of the adjacent segment degeneration after the implantation of Coflex system at the interspinous space of adjacent segment to lumbar fusion.</p><p><b>METHODS</b>Fifty patients with grade III disc (Thompson MRI classification) of adjacent segment to lumbar fusion were included and divided alternately into two groups according to the order of hospitalization from January to November 2009. Coflex system was implanted at the interspinous space of adjacent segment to lumbar fusion in 25 patients as Coflex group, the other 25 patients did not have any surgical treatment were as control group. The followed up time was 2 years. Visual analogue scale (VAS) score of low back pain, changes of disc height and motion range of adjacent segment to lumbar fusion on X-ray imaging were evaluated by independent sample t-test or paired samples t-test.</p><p><b>RESULTS</b>There were 22 patients in Coflex group and 21 patients in control group were followed up 2 years post-operation. The difference of VAS score between two groups was no significance (P > 0.05). In Coflex group, the change of postoperative disc height was no significance (P > 0.05), but the motion range was significantly reduced to 47% of the preoperative value (t = 7.99, P < 0.05). In control group, the postoperative disc height decreased slightly, without significant difference to the preoperative value (P > 0.05). Between the two groups, no differences of the disc height and motion range were found before operation, but the differences of the disc height changes (t = 6.7, P < 0.05) and motion rang (t = -14.5, P < 0.05) were significant in 2 years post-operation. No complications such as Coflex system loosen, immigration and spinal process fracture were occurred.</p><p><b>CONCLUSIONS</b>Coflex system can obviously limit the motion range and maintain the disc space height of adjacent segment to lumbar fusion, and prevent its degeneration in some degree.</p>

Finite element analysis on intra-segmental fixation and inter-segmental fixation for lumbar spondylolysis / 医用生物力学

Objective To compare the stresses on the end plate of adjacent lumbar vertebrae between intra-segmental fixation and inter-segmental fixation in treating lumbar spondylolysis by three-dimensional finite element analysis. Method Based on the established finite element model of L4 lumbar spondylolysis, the lumbar internal fixation such as rods and trans-pedicle screws were reconstructed to make the finite element models of intra segmental and inter segmental internal fixation with the same constraint and loading conditions. The stresses on endplate of adjacent lumbar vertebrae of finite element models were measured under three mechanical conditions:spondylolysis, intra-segmental fixation and inter-segmental fixation. Results High stresses were observed under two kinds of internal fixation conditions compared with the spondylolysis condition at the lower endplate of L4 under axial loading(P<0.05). The stresses at the lower endplate of L4 under intra segmental fixation condition were similar as that of the spondylolysis condition under flexion, extension and lateral bending loading. With the same loading, higher stresses were observed under inter-segmental fixation condition compared with the spondylolysis condition, and so did the lower stresses at upper endplate of S1(P<0.05). The lower stresses at the upper endplate of S1 under intra-segmental fixation condition were observed compared with the other two conditions under rotating loading (P<0.05). Conclusions The intra segmental fixation can not only provide stability for lumbar spondylolysis under axial, flexion, extension, lateral bending,but also preserve the normal activity at adjacent disc levels, especially under rotating loading.

Biomechanics of lumbar spondylolysis: Finite element modeling and validation / 医用生物力学

Objective To construct three-dimensional finite element model of lumbar spondylolysis,then to verify its validity by comparison of biomechanics in vitro.Method According to the radiological data of a patient with lumbar spondylolysis,the bone and intervertebral disc of L4-S1 were reconstructed by Simpleware software.The lumbar attaching ligaments and articular capsule were added into simulating model by Ansys software.The three-dimensional finite element model of lumbar spondylolysis was finally simulated successfully,and validated by lumbar spondylolysis biomechanical experiment in vitro.Results The reconstruction of digital model contained the bones of lumbar spine which include vertebral cortical bone,cancellous bone,facet joint,pedicle,lamina,transverse process and spinous process,as well as the annulus fibrosus,nucleus pulposus,superior and inferior end-plates.Besides,anterior and posterior longitudinal ligaments,flavum ligament,supraspinal and interspinal ligaments and articular capsule of facet joint are also attached.The model consisted of 281,261 nodes and 661,150 elements.Imitation of spondylolysis is well done in this model.The validity of the model was verified by comparison of the results of biomechanics in vitro which involved in the trends under loading of stress/strain of L4 inferior facet process,L5 superior and inferior facet process,S1 superior facet process and the trends of stress/strain of lateral and medial L4 inferior facet process.Conclusions Three-dimensional model of lumbar spondylolysis is reconstructed using finite element analysis,and can be further used in the research in biomechanics of lumbar spondylolysis.

Biomechanics of lumbar spondylolysis: Finite element modeling and validation / 医用生物力学

Objective To construct three-dimensional finite element model of lumbar spondylolysis,then to verify its validity by comparison of biomechanics in vitro.Method According to the radiological data of a patient with lumbar spondylolysis,the bone and intervertebral disc of L4-S1 were reconstructed by Simpleware software.The lumbar attaching ligaments and articular capsule were added into simulating model by Ansys software.The three-dimensional finite element model of lumbar spondylolysis was finally simulated successfully,and validated by lumbar spondylolysis biomechanical experiment in vitro.Results The reconstruction of digital model contained the bones of lumbar spine which include vertebral cortical bone,cancellous bone,facet joint,pedicle,lamina,transverse process and spinous process,as well as the annulus fibrosus,nucleus pulposus,superior and inferior end-plates.Besides,anterior and posterior longitudinal ligaments,flavum ligament,supraspinal and interspinal ligaments and articular capsule of facet joint are also attached.The model consisted of 281,261 nodes and 661,150 elements.Imitation of spondylolysis is well done in this model.The validity of the model was verified by comparison of the results of biomechanics in vitro which involved in the trends under loading of stress/strain of L4 inferior facet process,L5 superior and inferior facet process,S1 superior facet process and the trends of stress/strain of lateral and medial L4 inferior facet process.Conclusions Three-dimensional model of lumbar spondylolysis is reconstructed using finite element analysis,and can be further used in the research in biomechanics of lumbar spondylolysis.

Biomechanics of lumbar spondylolysis : Finite element modeling and validation / 医用生物力学

Objectives To construct three-dimensional finite element model of lumbar spondylolysis, then to verify its validity by comparison of biomechanics in vitro. Methods According to the radiological data of a patient with lumbar spondylolysis, the bone and intervertebral disc of L4-S1 were reconstructed by Simpleware software. The lumbar attaching ligaments and articular capsule were added into simulating model by Ansys software. Finally, the three-dimensional finite element model of lumbar spondylolysis was simulated successfully, and validated by lumbar spondylolysis biomechanical experiment in vitro. Results The reconstruction of digital model is contained of the bones of lumbar spine which includes of vertebral cortical bone, cancellous bone, facet joint, pedicle, lamina, transverse process and spinous process,as well as annulus fibrosus, nucleus pulposus,superior and inferior end-plates. Besides, anterior and posterior longitudinal ligaments, flavum ligament, supraspinal and interspinal ligaments and articular capsule of facet joint are also attached. The model consisted of 281,261 nodes and 661,150 elements. Imitation of spondylolysis is well done in this model. The validity of the model is verify by comparison of the results of biomechanics in vitro which involved in the trends under loading of stress/strain of L4 inferior facet process, L5 superior and inferior facet process, S1 superior facet process and the trend of stress/strain of lateral and medial L4 inferior facet process. Conclusions Lumbar spondylolysis is reconstructed to three-dimensional model using finite element analysis, and can be further used in the research of biomechanics of lumbar spondylolysis.

Sagittal diameters measurements on MR of the cervical spinal cord in normal subjects / 中华外科杂志

<p><b>OBJECTIVE</b>To offer normal reference of diameter of the cervical spinal cord and available diameter of cervical spinal canal and to screen scientific radiographic criteria to define and quantify cervical spinal cord disease.</p><p><b>METHODS</b>The magnetic resonance images of 120 normal people had been measured. The data of diameters of cervical spinal cord, CSF, M, the ratio of diameters of cord and CSF, and the ratio of diameters of cord and M had been collected and statistical analysis was made. And the relationships between the data above and each of gender, the length of C-spine and age were evaluated. In addition, the ratio of diameters of cord and CSF, and the ratio of diameters of cord and M was evaluated.</p><p><b>RESULTS</b>The study showed that in healthy people, the diameters of cervical spinal cord, CSF and M was larger in the males than in the females, decreased with age, and increased with the length of C-spine but the diameter of CSF. And the ratio of diameters of cord and CSF increased with age and not affected by the length of C-spine. However, the ratio of diameters of cord and M was not affected by age and the length of C-spine.</p><p><b>CONCLUSION</b>The ratio of diameters of cord and M is not affected by individual variation and can be used to evaluate cervical spinal cord atrophy, compression and impaired in patients with cervical myelopathy and can be important information in looking for clinically critical points.</p>

Anterior radical decompression for severe ossification of the posterior longitudinal ligament in the cervical spine / 中华外科杂志

<p><b>OBJECTIVE</b>To report the outcome of anterior radical decompression for the treatment of severe ossification of the posterior longitudinal ligament (OPLL) with an average occupying ratio exceeding 50% in the cervical spine.</p><p><b>METHODS</b>From July 2002 to February 2006, 26 patients with cervical OPLL occupying ratio of the spinal cord exceeding 50% underwent anterior decompression and fusion. There were 18 males and 8 females. The average age was 59 years (ranged from 43 to 73 years) and the mean occupying ratio was (65 +/- 20)%; Before operation, the JOA score was 8.7 +/- 2.8, and the sagittal diameter of spinal cord was (25 +/- 7)%. The ossified ligament was classified into two groups, the base-open group and the base-closed group. The occupying ratio was measured on 3-D CT scans, and the sagittal diameter of the deformed spinal cord was measured at the narrowest level on sagittal T2-weighted MRI. All patients received anterior decompression with the ossified ligament removed completely. Among them, 10 cases underwent one level corpectomy combined with one level diskectomy, 3 cases underwent 2 level corpectomy, and the other 13 patients underwent one level corpectomy. The decompressed segments were reconstructed either with a iliac crest strut or a titanium cage, and an anterior locking plate was implanted to prevent graft extrusion in every patient. All patients were monitored with ECP during decompression.</p><p><b>RESULTS</b>The occupying ratio decreased to (10 +/- 5)%, the sagittal diameter of spinal cord increased to (75 +/- 15)%, and the average diameter of spinal cord at the narrowest site increased 3 times after operation. The JOA score was 14.2 +/- 2.5, with an average improvement ratio of (61 +/- 24)%. Three patients accompanied with diabetes presented with temporarily neurological deterioration. There were two cases complicated with cerebrospinal fluid leaks but cured within 2 weeks after surgery. One case accompanied with diabetes underwent a second emergency reexploration for hematoma in the spinal canal which caused a dyspnea.</p><p><b>CONCLUSIONS</b>Anterior radical decompression is an optimal method for the management of severe OPLL in the cervical spine. Higher rate of neuro-function recovery can be anticipated.</p>

Surgical strategy for severe cervical spine dislocations / 中华外科杂志

<p><b>OBJECTIVE</b>To evaluate the rate of open reduction and surgical strategy of severe cervical dislocation.</p><p><b>METHODS</b>From March 2001 to March 2006, the data of 92 cases of cervical dislocation over 1/2 were retrospectively studied. Garden Well traction with 1 - 3 kg weight were performed before operation. The patients were performed with diskectomy and reduction with anterior approach initially, for those that can not be reduced, corpectomy were performed and reduction procedures were repeated. The posterior reduction and fixation were followed when reduction can not be reached with anterior approach only. The succeed rate of reduction, rate of tracheotomy were recorded and fusion rate, Frankel score and visual analog scale (VAS) were evaluated.</p><p><b>RESULTS</b>Reduction succeed in 38 cases after diskectomy, 44 after corpectomy and 7 after combined anterior-posterior-anterior procedure. Three cases got incompleteness reduction. Tracheotomy was done in 29 cases. The Frankel score increased 0.5 degree and VAS was 2 averagely at the last follow-up.</p><p><b>CONCLUSIONS</b>The succeed rate of anterior open reduction was 89.2%, and only 10.8% patients needs an additional combined posterior and anterior approach. For patients with completed spinal cord injury with dislocation above C(4), or with dislocation below C(5) but the edema on MRI T2 image are above C(4) level need tracheotomy. The operation be done until respiratory function stable. For patients with completed spinal cord injury with dislocation below C(4) and uncompleted spinal cord injury with dislocation above C(4), the rate of tracheotomy is relatively lower and early operation is recommended.</p>

Diagnosis and treatment for the injury of cervical disc and longitudinal ligament / 中华外科杂志

<p><b>OBJECTIVES</b>To study the diagnosis and treatment for the injury of cervical disc and longitudinal ligament.</p><p><b>METHODS</b>From 2001 to 2005, the clinical data of sixty-three patients with cervical disc and longitudinal ligament injury were studied. Early treatment was done based on spinal cord injuries and spinal stabilities by X rays and MRI. Early operation was done in fifty-four cases and early non-operation in nine cases.</p><p><b>RESULTS</b>The follow-up time was six to forty-one months in all patients. The neurological recovery was found in two of eight complete SCI post-operation, thirty-one in thirty-nine incomplete SCI. Cervical collar or plaster orthotic were used in nine cases with four to six weeks. Evidence of instability was noted in four patients, who were operated with anterior decompression fusion. Neck chronic pain was found in two patients, anterior decompression and fusion was done in one with cervical spinal cord compression.</p><p><b>CONCLUSIONS</b>MRI examination is the most value measure for the diagnosis of cervical disc and longitudinal ligament injury. Early anterior decompression and fusion was an important approach for cervical disc and longitudinal ligament injury.</p>

Surgical treatment and its related factors of cervical spondylotic myelopathy / 中国医学科学院学报

<p><b>OBJECTIVE</b>To observe the results and its related factors of surgical treatment of cervical spondylotic myelopathy (CSM).</p><p><b>METHODS</b>Totally 365 CSM patients were reviewed. All patients were treated with anterior cervical decompression and fusion with autogenous iliac bone or titanium mesh cages with local bone graft. Anterior locking plates were used for fixation. Five patients received revision surgery 3 to 6 months after the initial operation.</p><p><b>RESULTS</b>Clinical function was excellent in 175 patients (47.94%), good in 129 patients (35.34%), fair in 44 patients (12.05%), and poor in 17 patients (4.66%).</p><p><b>CONCLUSION</b>Anterior cervical decompresion of CSM has good clinical efficacy. The timing of operation, disease severity, and surgical technique are the important factors affecting the outcome of treatment.</p>

Key points about atlanto-axial internal-fixation and fusion using Gallie's technique / 中华外科杂志

<p><b>OBJECTIVE</b>To study the clinical problems about posterior atlanto-axial internal-fixation and fusion for atlanto-axial instability or dislocation.</p><p><b>METHODS</b>Surgical treatments of 138 cases with atlanto-axial instability or dislocation were reviewed. There were 62 cases of odentoid malformation, 54 cases of odentoid fracture or rupture of transverse ligament, 22 cases of subluxation and rotation. All cases were treated using Gallie's technique. Six cases were also fixed with transarticular screws, and protected with Philadelphia collar. Other patients were fixed with plaster paris brackets. The followed-up period was 1 to 12 years with an average of 3 year and 5 months.</p><p><b>RESULTS</b>According to Sumi's criteria, excellent 70 cases (50.7%), good 40 cases (29.0%), fair 15 cases (10.9%), poor 13 cases (9.4%). 9 cases with bone graft postponed fusion were cured by enhance external-fixation. 2 cases with nonunion were treated with revision surgery. Complication of cord injury happened in 1 case.</p><p><b>CONCLUSION</b>Gallie's fusion technique is an effective method to manage the atlanto-axial instability or dislocation. Skull distraction before operation and reliable external-fixation post operative are important assistant measures. Key points for successful operation are careful wiring or cable traversing, decortication of posterior arc of C1, and maintaining the physiological height between C1 and C2 posterior arc. Indications and objectives should be conformed before revision surgery for failure cases.</p>

Diagnosis and surgical management of Hangman's fracture combined with intervertebral disc injury / 中华外科杂志

<p><b>OBJECTIVE</b>To study the pathology characteristics and management of Hangman's fracture combined with intervertebral disc injury.</p><p><b>METHODS</b>Twenty-one patients suffered from this special injury were converged in this study. All patients underwent anterior C(2 - 3) discectomy and fusion, 18 cases were fixed by anterior cervical plate. The type of fractures, radiology characteristics, and clinical outcomes were investigated.</p><p><b>RESULTS</b>No graft displacement or absorption, infection and neurologic deterioration occurred. All fresh dislocation of axis and C(2 - 3) angulation were corrected. Fusion of C(2 - 3) intervertebral space and pedicle fracture were acquired in all of the patients. After a mean follow-up of 31 months, ranging from 8 to 48 months, nearly all of the complains disappeared after operation.</p><p><b>CONCLUSIONS</b>Hangman's fracture is not restricted at pedicle of the axis. Fracture combined with intervertebral disc injury is a special type of Hangman's fracture. Anterior discectomy and fusion of C(2 - 3) intervertebral disc is an effective operation method in accord with the pathophysiology of this special injury.</p>

Evaluation of long-term outcome of surgical treatment for cervical spondylotic myelopathy / 第二军医大学学报

Objective: To investigate the long-term outcome of anterior decompression and bone graft fusion for cervical spondylotic myelopathy(CSM) and factors affecting the outcome. Methods: Two hundred and forty-five patients with CSM were treated with anterior cervical decompression and auto iliac bone graft fusion, of whom 31 had a second operation between 4 months and 2 years after operation. Follow-up studies were carried out within 5 to 15 years after operation, averaging 6.8 years. Results: Function evaluation: excellent in 118 cases (48.16%), good in 71 (28.98%), passable in 35 (14.29%) and poor in 21 (8.57%). According to the 40 points score method, there was an average of 8 point increase in all cases, of which 101 were between 36 to 40 points, 54 between 31 to 35 points. Conclusion: The long-term outcome of surgical treatment for CSM is definite. Significant factors affecting the outcome include timing of operation, degree of pathology and technique of surgery.

Evaluation of long-term outcome of surgical treatment for cervical spondylotic myelopathy / 第二军医大学学报

Objective: To investigate the long-term outcome of anterior decompression and bone graft fusion for cervical spondylotic myelopathy(CSM) and factors affecting the outcome. Methods: Two hundred and forty-five patients with CSM were treated with anterior cervical decompression and auto iliac bone graft fusion, of whom 31 had a second operation between 4 months and 2 years after operation. Follow-up studies were carried out within 5 to 15 years after operation, averaging 6.8 years. Results: Function evaluation: excellent in 118 cases (48.16%), good in 71 (28.98%), passable in 35 (14.29%) and poor in 21 (8.57%). According to the 40 points score method, there was an average of 8 point increase in all cases, of which 101 were between 36 to 40 points, 54 between 31 to 35 points. Conclusion: The long-term outcome of surgical treatment for CSM is definite. Significant factors affecting the outcome include timing of operation, degree of pathology and technique of surgery.

Preventionand management of complications in anterior cervical spine surgery / 中华骨科杂志

Objective To study the prevention and treatment of complications occurring in anterior cervical spinal surgery.Methods3163cases with cervical spondylotic meylopathy,spinal injury,spinal tu-mor and spinal tuberculosis treated by anterior cervical surgery,were included in this study.Trephination,corpectomy,disectomy and debridement were used for decompression,iliac bone autograft,BAK cage,cubic shaped cages and titanium mesh cages were used for bone grafting,while anterior cervical spine locking plates were performed in some of the cases.1848cases were followed-up from6months to8years with an aver-age of 2years and3months.646cases suffered from operative complications,372cases were immediate due to anterior cervical surgery,and the incidence of morbidity was11.76%.Results26cases of transient laryn-geal nerve or superior laryngeal nerve injury recovered in4to12weeks without special treatment.Most of 16cases with cervical hemotoma were caused by bleeding of smaller blood vessels and obstruction of drainage.13cases of spinal cord or nerve root irritation or injury were treated with medicine for dehydration,12of them had good result.11cases of CSF leakage were cured with cervical spinal immobilization and moderate local compression.8cases of local infection were cured with antibiotics or combined with debride-ment and suturing.2cases of esophagus perforation were repaired and healed.8cases of grafted bone dis-placement were re-operated on the day or second day of occurring.17cases of pseudoarthritis had revision surgery.6of 35cases of adjacent segments degeneration with new symptoms of spinal cord compression were treated with anterior cervical decompression again,and had good results.Most of 342cases of iliac donor side com plications were local pain or lateral femoral cutaneous nerve injury,infection occurred in some cases.Compli cations related to instruments included10cases of BAK subsidence,1case of plate breakage,1case of screws and plate back-out and7cases of titanium mesh cage subsidence.216cases of cervical axial pain were cured3to6months later with medicine.There was1case of sudden death in this group.Conclusion Many kinds of operative complications could occur in anterior cervical surgery.A standardized procedure in diagnosis and surgery methods are the key points to decrease and prevent operative related complications.