Finite element analysis of the correlation between tilt angle of titanium cage and postoperative subsidence of titanium cage after anterior subtotal cervical corpectomy,decompression and fusion / 中国组织工程研究

BACKGROUND:Anterior subtotal corpectomy,decompression and fusion is a conventional method to treat cervical degenerative diseases.A titanium cage is an important implant to maintain the stability of the cervical spine after subtotal corpectomy.In recent years,many patients have complications such as titanium cage sinking,which are highly controversial. OBJECTIVE:To investigate the internal biomechanical relationship between the tilt angle of the titanium cage and postoperative titanium cage subsidence after anterior subtotal cervical corpectomy,decompression and fusion. METHODS:A three-dimensional finite element model of the C4-C6 segment was established by CT images of a normal human cervical spine,in which the anterior subtotal resection,decompression and fusion of the C5 vertebral body were simulated,and titanium cages with different tilt angles(-6° to-1° negative angle,that is,the front edge of titanium cage is shorter than the rear edge of titanium cage;1° to 6° positive angle,that is,the front edge of titanium cage is longer than the rear edge of titanium cage)were placed.After setting the boundary conditions,preloads of 50,100 and 150 N were applied respectively on the C4 vertebral body.The stress value of each contact point between the titanium cage and C4 lower-end plate and C6 lower-end plate(seven stress contact points on the contact surface of titanium mesh)was recorded and statistical analysis was conducted. RESULTS AND CONCLUSION:(1)The tilt angles of the titanium cage of the positive angle group and negative angle group under 50,100 and 150 N stress respectively were found by Mann Whitn test,with P<0.05,which was statistically significant.The dispersion coefficients of the positive angle group were smaller than those of the negative angle group under 50,100 and 150 N stress conditions.(2)Under 50,100 and 150 N stress conditions,the Wilcoxon sign rank test in the positive angle group of titanium cage tilt angle found that when the angle was set to 1° to 5°,the difference was not statistically significant(P>0.05).However,when the tilt angle of the titanium cage was set to 6°,the difference was statistically significant(P<0.05).(3)Under 50,100 and 150 N stress conditions,the Wilcoxon sign rank test in the negative angle group of titanium cage tilt angle found that when the tilt angle was set to-1° to-6°,the difference was not statistically significant(P>0.05).(4)It is concluded that in the sagittal position,the titanium cage with a positive tilt angle is more stable than with a negative tilt angle,which is more suitable for clinical use.The tilt angle of the titanium cage is relatively stable in the range of 1° to 5°.When the tilt angle is 6°,the stability starts to decline,which is easy to cause complications of titanium cage sinking after surgery.It is more suitable to select the titanium cage with a tilt angle of 1° to 5° according to the clinical situation during surgery to improve the efficacy.

Buckling of the Ligamentum Flavum as a Rare Complication of Anterior Cervical Corpectomy and Fusion: A Case Report

Introduction and Importance Neurological deterioration due to buckling of the ligamentum flavum (LF) is an uncommon complication after anterior cervical corpectomy or discectomy with fusion. Case Presentation In this report, we present the case of a 66-year-old male who underwent anterior cervical partial corpectomy of C5 and discectomy of prolapsed C5- C6 with fusion. Postsurgery, the patient displayed signs of neurological deterioration. Upon immediate cervical magnetic resonance imaging (MRI), posterior canal stenosis and severe compression with cord signal due to LF buckling were detected. A posterior laminectomy procedure and canal decompression at the C5-C6 level with bone fusion were performed. Clinical Discussion Patient presented with walking difficulty, then walking disability, followed by bilateral upper and lower limb paresthesia with burning sensation. Examination showed ⅘ muscle strength in both handgrips. Further investigation showed brisk deep tendon reflexes, positive Hoffman sign unilaterally, equivocal Babinski sign, and progressive quadriparesis. Magnetic resonance imaging showed mild and diffuse building of some cervical discs, with spinal cord progression. We performed an anterior cervical corpectomy and fusion (ACCF) and anterior cervical discectomy and fusion (ACDF); a titanium mesh with plates and screws was used for fusion, with removal of a calcified and herniated subligamentous disc. Postoperatively, upper and lower limb strength deteriorated; immediate cervical and thoracic MRI showed LF buckling, which caused canal stenosis and severe compression. Urgent posterior laminectomy and canal decompression with bone fusion was scheduled on the same day. The patient underwent physiotherapy and regained upper and lower limb strength and his ability to walk. Conclusion This indicates the possibility of neurological deterioration as a result of LF buckling, whichmay be a result of LF thickening accompanied by hyperextension in the cervical region. In this regard, immediate imaging following signs of neurological complications after anterior cervical corpectomy or discectomy warrants early detection, which results in a better prognosis.

Recent Advances of Biomechanical Studies on Cervical Spine Anatomy and Titanium Mesh Cage / 医用生物力学

Titanium mesh cage is one of the fusion devices used in anterior cervical corpectomy and fusion (ACCF). It can not only immediately rebuild the stability of cervical spine during the operation, maintain the height and physiological curvature of intervertebral vertebrae, but also avoid the complications of bone donor area caused by autologous bone extraction. Therefore, titanium mesh cage has become the most commonly used internal plant in ACCF. However, there exist many problems in traditional titanium cage, such as stress shielding and titanium cage sinking, which will affect the surgical effect to a certain extent, and even lead to serious postoperative complications requiring revision surgery. At present, a variety of new titanium cages have been invented, which can solve the problems caused by traditional titanium cage to a certain extent. Biomechanical evaluation and its testing methods are an indispensable process for judging whether a new type of spinal fusion cage can be used in clinical practice. This article reviews the biomechanical studies related to cervical spine anatomy, the biomechanical properties of traditional titanium cages and new titanium cages, so as to provide new ideas for the improvement of traditional titanium cages and the development of new titanium cages.

Evaluation of Results of Anterior Cervicothoracic Junction Decompression & Fusion (ACTJDF) of C7-T1-T2 Spinal Tuberculosis by Transmanubrial Transclavicular Approach.

Spinal tuberculosis is the most frequently encountered & destructive form of skeletal tuberculosis. We wanted to evaluate the advantages of transmanubrial transclavicular approach in the surgical management of the pathologies (mainly tuberculosis) at the cervicothoracic junction (C7,T1-2).METHODSFrom June 2013 to August 2019, thirty patients with tuberculosis of CTJ presented to SCBMC & H and were operated with transmanubrial transclavicular approach. Debridement with corpectomy of tuberculosis of C7-T1 and T1 vertebral bodies were followed by fusion of C6-T2 and C7-T2 vertebra respectively with the help of titanium mesh cage and anterior cervical plating. Advantages & limitations of this surgical approach were evaluated retrospectively. Visual analogue scoring & Frankel scoring were used for assessing postoperative clinical outcome.RESULTSAll 30 cases were of tuberculosis of CTJ involving either C7-T1 or T1-T2. They presented with a permutation combination of upper thoracic pain, paraparesis, and collapse of vertebra & cord compression. All patients were followed up for 12.37 ± 5.38 months on average (range 4 -24 m). The mean postoperative visual analogue scale score was 7.86 ± 1.02 (range 6-10) preoperatively, which improved to 3.27 ± 0.88 (range 0-5) postoperatively at final evaluation (p<0.005). There was also postoperative increase in Frankel score in seventeen cases (56%). Three patients developed temporary hoarseness postoperatively, two cases got infected (one superficial & one deep) & one patient died. There was no non-union or persistent pain at manubrium or clavicle end.CONCLUSIONSThe transmanubrial transclavicular approach for tuberculosis of CTJ lesions can achieve favourable clinical outcomes by providing wide exposure, direct decompression of lesions, fusions and less complications as compared to standard approaches.

Screw Migration into Colon after Anterior Cervical Plating - An Unusual Complication: A Case Report

@#Complications in the form of esophageal injury, tracheal injury, injury to carotids, implant failure, loosening of screws, etc do occur after anterior cervical surgeries. Although intra-operative esophageal injuries are as such rare, there have been few reports of delayed esophageal perforation as well after anterior cervical surgeries. We report a very rare case of migration of missing screw from anterior cervical plate after anterior cervical corpectomy and plating, which had ultimately migrated down to colon and had to be removed via colonoscopy. Along with removal of migrated screw from colon, revision of failed anterior cervical surgery was done wherein plate and screws were removed with mesh cage left in-situ as it was snug-fit while pharyngeophageal perforation was explored and was found to be spontaneously healing, with addition of posterior Bohlman’s interspinous wiring for added stability. Migration of screw from the anterior cervical plate into the colon although very rare, should be always kept in mind and its potentially serious complications. We also conclude that particular attention should be given to elderly people with poor bony quality who have high chances of implant failure, along with attention to proper cage size, screw position and proper locking of the screw to further lessen the chances of implant failure.

Comparison of clinical effects of two anterior cervical decompression with fusion on treating two segment cervical spondylotic myelopathy / 中国骨伤

OBJECTIVE@#To explore the clinical effects of anterior cervical discectomy with fusion (ACDF) and anterior cervical corpectomy with fusion (ACCF) in treating adjacent two-segment cervical spondylotic myelopathy (CSM).@*METHODS@#The clinical data of 37 patients with adjacent two segment CSM treated from January 2016 to December 2017 were retrospectively analyzed, including 15 males and 22 females, aged from 43 to 69 years old with an average of 54.6 years. The patients were divided into ACDF group (group A, =17) and ACCF group (group B, =20) according to the different surgery. The operation time and intraoperative blood loss were recorded;the Cobb angle and cervical curvature in the cervical fusion segments before surgery and 1, 12 months after surgery were observed;Japanese Orthopaedic Association (JOA) score was used to evaluate the surgical efficacy, and the postoperative complications were analyzed.@*RESULTS@#All patients were followed up for 12 to 24 months with an average of 18.5 months. Operation time and intraoperative blood loss in group A were (106.3±22.6) min, (52.2±26.4) ml, respectively, while were (115.6±16.8) min, ( 61.7±20.7) ml in group B. There was no statistically significant in operation time between two groups(>0.05);intraoperative blood loss in group B was larger than group A(0.05). At the final follow up, in group A, dysphagia occurred in 2 cases, cage displacement in 1 case, and no titanium plate screw loose was found;and in group B, dysphagia occurred in 4 cases, titanium mesh collapse in 2 cases, titanium plate screw loose in 1 case.@*CONCLUSION@#Two types of anterior cervical decompression and fusion for the treatment of two segment cervical spondylotic myelopathy can effectively decompress and improve the Cobb angle and cervical curvature of the affected vertebra. The ACDF surgical procedure can directly removethe compressive thing at intervertebral level, which will lead to little vertebral body damage and favorably recovered cervical curvature. The ACCF surgical procedure has a large operation space, which can easily remove the posterior vertebral osteophyte and the calcified posterior longitudinal ligament. Long-term follow-up shows that ACDF and ACCF have good surgical procedures, mature technology, and close efficacy.

Experience Of Anterior Debridement, Decompression, Bone Grafting, And Instrumentation For Lower Cervical Spine And Upper Dorsal Pott's Spine

BACKGROUND Spine tuberculosis is very common in the Indian people with high morbidity, although the Govt. of India has included treatment of the spine tuberculosis in pulmonary tuberculosis programme, the burden of the patients remained high. MATERIAL AND METHOD. Twenty patients with cervical and upper dorsal Pott’s spine were operated with anterior deidement, decompression, bone grafting, and instrumentation and were given ATT after wards and were followed for 6 months. OBSERVATION AND RESULTS. Seventeen ( 85.0%) of patients showed excellent–to–good results. The fusion rates for 1–level and 2–level anterior cervical corpectomy, and for anterior plate fixation were 100%. There were no postoperative deterioration neurologically and had minimum complication which resolved over weeks’ time. CONCLUSION. The improved fusion rate, low cost of the treatment with lower complication rates associated with anterior cervical plating may justify its use in the treatment of cervical and dorsal Pott’s associated myelopathies as the burden of tuberculosis in our country is large.

Palliative Posterior Instrumentation versus Corpectomy with Cage Reconstruction Treatment for Thoracolumbar Pathological Fracture

STUDY DESIGN: Single-center, retrospective cohort study. PURPOSE: We aimed to evaluate and compare the clinical outcomes in patients who underwent palliative posterior instrumentation (PPI) versus those who underwent corpectomy with cage reconstruction (CCR) for thoracolumbar pathological fracture. OVERVIEW OF LITERATURE: The requirement for anterior support after corpectomy has been emphasized in the treatment of pathological fractures of the vertebrae. However, for patients with a relatively short life expectancy, anterior reconstruction may not be required and posterior instrumentation alone may provide adequate stabilization. METHODS: A total of 43 patients with metastases of the thoracolumbar spine underwent surgery in the department of orthopaedic and traumatology of Istanbul University Faculty of Medicine from 2003 to 2016. Surgical outcomes were assessed on the basis of survival status, pre- and postoperative pain, complication rate, and operation time. RESULTS: PPI was performed for 22 patients and CCR was performed for 21 patients. In the PPI group, the follow-up period of the five surviving patients was 32 months. The remaining 17 patients died with a mean survival duration of 12.3 months postoperatively. In the CCR group, the five surviving patients were followed up for an average of 14.1 months. The remaining 16 patients died with a mean survival duration of 18.7 months postoperatively. No statistically significant difference (p=0.812) was noted in the survival duration. The Visual Analog Scale scores of the patients were significantly reduced after both procedures, with no significant difference noted on the basis of the type of surgical intervention (p>0.05). The complication rate in the CCR group (33.3%) was higher compared with that in the PPI group (22.7%); however, this difference was not noted to be statistically significant (p=0.379). The average operation time in the PPI group (149 minutes) was significantly shorter (p=0.04) than that in the CCR group (192 minutes). CONCLUSIONS: The PPI technique can decompress the tumor for functional improvement and can stabilize the spinal structure to provide pain relief.

Comparison of clinical effects between anterior cervical discectomy combined with corpectomy and cervical posterior single open-door laminoplasty in treating three-segment cervical spondylotic myelopathy / 中国骨伤

<p><b>OBJECTIVE</b>To compare the clinical effects between anterior cervical discectomy and fusion(ACDF) combined with anterior cervical corpectomy and fusion(ACCF) and cervical posterior single open-door laminoplasty with mini-titanium plate fixation in treating three-segment cervical spondylotic myelopathy.</p><p><b>METHODS</b>The clinical data of 63 patients (39 males and 24 females) with three-segment cervical spondylotic myelopathy underwent surgical treatment from March 2014 to March 2016 were retrospectively analyzed. Among them, 43 cases were treated by ACDF combined with ACCF(anterior group), and 20 cases were treated by cervical posterior single open-door laminoplasty with mini-titanium plate fixation(posterior group). Operative time, intraoperative blood loss, postoperative complications were compared between two groups. And according to JOA score to evaluate the clinical effect.</p><p><b>RESULTS</b>All the patients were follow-up from 16 to 40 months with an average of 25.8 months. Operative time of anterior group and posterior group were (123.70±6.21) min and(118.70±5.41) min, respectively, there was no significant difference between two groups(>0.05). Intraoperative blood loss of anterior group and posterior group were (85.23±7.51) ml and (107.18±9.41) ml, respectively, there was significant difference between two groups(<0.05). In anterior group, axial symptoms occurred in 6 cases, dysphagia in 1 case, and no C₅ nerve root palsy, hoarseness and choking cough were found, the incidence rate of complication was 16.3%(7/43); and in posterior group, axial symptoms occurred in 5 cases, C5 nerve root palsy in 1 case, and no dysphagia, hoarseness and choking cough were found, the incidence rate of complication was 30.0%(6/20); there was significant defference in incidence rate of complication between two group(<0.05). At 1 week after operation and final follow-up, the JOA scores of anterior group were obviously better than that of posterior group(<0.05).</p><p><b>CONCLUSIONS</b>Above-mintioned two surgical treatment for cervical spondylotic myelopathy can provide instantly stability, the method of ACDF combined with ACCF was obviously better that of the method of cervical posterior single open-door laminoplasty in intraoperative blood loss, the incidence rate of complications, clinical effect.Thus, for the treatment of three-segment cervical spondylotic myelopathy, the method of ACDF combined with ACCF would be firstly chosen.</p>

Change of 3D cervical range of motion after single-level anterior cervical corpectomy and fusion / 中国骨伤

<p><b>OBJECTIVE</b>To study the change trend of cervical range of motion(ROM) after single-level anterior cervical corpectomy and fusion(ACCF) in treating cervical spondylotic myelopathy.</p><p><b>METHODS</b>The clinical data of 23 patients with cervical spondylotic myelopathy was retrospectively analyzed from February 2015 to April 2016. There were 11 males and 12 females, with an average age of (54.6±13.3) years. All the patients were diagnosed as cervical spondylotic myelopathy by interrogation, physical examination and radiology, and were treated by ACCF. The Coda motion system was applied to assess the cervical range of motion pre-and post-operation. JOA and VAS scores were used to evaluate the clinical outcomes.</p><p><b>RESULTS</b>The mean follow-up time was (9.4±1.6) months. Cervical ROM in all directions at 3 months postoperatively were significantly lower except for the left rotation(<0.05). There was significant difference of cervical ROM in all directions between preoperative and 6 months postoperatively(>0.05). The right lateral bending and the left rotation at 9 months postoperatively increased significantly(<0.05). Postoperative extension at 6 months was significantly better than that of 3 months postoperatively(<0.05). The extension, left and right lateral bending and left rotation at 9 months postoperatively were significantly better than of 6 months postoperatively(<0.05). Postoperative JOA scores at each time points were significantly higher than that of preoperative(<0.05) and VAS scores at each time points were significantly lower than that of preoperative(<0.05).</p><p><b>CONCLUSIONS</b>The change trend of three-dimensional cervical ROM after single-level ACCF revealed that the ROM decreased in short term, and later increased and was better than the preoperative level. Meanwhile, the neurological function improved significantly. But the short-term and long-term change trend of ROM postoperatively and the change trend of ROM after multi-level ACCF need to be further studied.</p>

Preventing Construct Subsidence Following Cervical Corpectomy: The Bump-stop Technique

Cervical corpectomy is a viable technique for the treatment of multilevel cervical spine pathology. Despite multiple advances in both surgical technique and implant technology, the rate of construct subsidence can range from 6% for single-level procedures to 71% for multilevel procedures. In this technical note, we describe a novel technique, the bump-stop technique, for cervical corpectomy. The technique positions the superior and inferior screw holes such that the vertebral bodies bisect them. This allows for fixation in the dense cortical bone of the endplate while providing a buttress to corpectomy cage subsidence. We then discuss a retrospective case review of 24 consecutive patients, who were treated using this approach, demonstrating a lower than previously reported cage subsidence rate.

Clinical effects of ACCF and double-segment ACDF in treating continuous double-gap cervical spondylotic myelopathy / 西安交通大学学报(医学版)

Objective To compare the postoperative imaging anatomical parameters and the related perioperative parameters of continuous double-gap cervical spondylotic myelopathy patients who underwent anterior cervical disectomy and fusion (ACDF)or anterior cervical corpectomy and fusion (ACCF)and ACDF so as to learn about the clinical effects of the two methods.Methods We included 5 1 patients in ACDF group (male∶female ratio=32∶19;mean age 56.3±29.4 years),and 47 patients (male∶female ratio=35∶12;mean age 49.1±22.8 years)in ACCF group.We measured the sex ratio,mean age,average length of hospital stay,mean operative time, and average intraoperative blood loss in ACDF group and ACCF group.The patients were followed up at six months,1 year,and 2 years after operation.The JOA score and imaging parameters were recorded for statistical analysis by SPSS 19.0.Results Patients in ACDF group had shorter operative time,less operative bleeding and shorter hospitalization duration than those in ACCF group.There was no significant difference in postoperative JOA score between ACDF and ACCF group.Patients in ACDF group had better imaging indexes than those in ACCF group.Conclusion ACDF has better screening efficacy than ACCF in treatment of continuous double-gap cervical disc herniation of cervical spondylotic myelopathy.

Corporectomía por acceso único posterior con colocación de caja expandible y fijación transpedicular en fracturas toracolumbares / Posterior corpectomy, transpedicular fixation and expandable cage placement in thoracolumbar fractures

Resumen: Objetivo: Evaluar el resultado de la corporectomía por acceso único posterior con colocación de caja expandible y fijación transpedicular en pacientes con fracturas toracolumbares. Material y métodos: Estudio retrospectivo en el que se evaluaron ocho pacientes con fracturas por estallido entre Mayo de 2011 y Mayo de 2014, quienes fueron tratados de manera quirúrgica mediante corporectomía, colocación de caja expandible y fijación transpedicular con abordaje posterior. El estado neurológico fue valorado a través de la escala de ASIA prequirúrgico y postquirúrgico a un año de evolución y se midió la corrección angular de las deformidades. Resultados: El estudio comprendió cinco personas de sexo masculino y tres de sexo femenino, con un promedio de edad de 38 años (de 24 a 58 años). Todos los pacientes presentaron fracturas por estallido del cuerpo vertebral, uno de ellos con componente rotacional. A los ocho se les realizó solamente la corporectomía de un nivel vertebral. El tiempo quirúrgico promedio fue de 236 minutos (rango: 195-330 min). El sangrado quirúrgico en promedio fue de 1,731 ml. Conclusión/Discusión: Los pacientes que se sometieron a corporectomía por vía posterior mostraron resultados clínicos favorables, sin presentar lesiones neurológicas o lesiones asociadas al procedimiento, por lo que esta técnica puede ser una opción terapéutica al disminuir las complicaciones de una vía anterior o de un doble abordaje.

Abstract: Objective: The objective is to evaluate the outcome of vertebral corpectomy and placement of an expandable cage in patients with thoracolumbar fractures, using a posterior-only approach. Material and methods: A retrospective, case series study in the period from May 2011 to May 2014, in which eight patients with thoracolumbar burst fractures were treated surgically with corpectomy of fractured spinal body, placement of expandable box and fixation with transpedicular system, via posterior-only approach. Neurologic examination was done pre- and postoperatively with the ASIA score in a one year span. The angular deformity correction was also measured. Results: The mean age was 38 years (24 to 58 years); five male and three female patients. All the patients had burst fracture, one of them with aggregate rotational component. Only one vertebral level was worked with corpectomy in all patients. Mean surgical time was 236 minutes (195-330 min). Mean surgical bleeding was 1,731 ml. Conclusion/Discussion: Patients who underwent posterior approach corpectomy showed favorable clinical results. None presented neurological damage or surgical-related injury. This technique can be a useful option to avoid complications related to anterior vertebral approach or double approach.

Finite element analysis on lower cervical spine by anterior cervical corpectomy and fusion sugery / 医用生物力学

Objective To establish the three-dimensional finite element model of human lower cervical spine C3-7 motion segments after anterior cervical corpectomy and fusion (ACCF) surgery with titanium mesh and bone graft, and to analyze the stability of cervical spine and stress distribution of internal fixation devices after ACCF surgery. Methods The finite element model of cervical spine C3-7 segments after ACCF of C5 segment with titanium mesh, bone graft, plate and screw fixation was established，and C3-7 segment intact model of cervical vertebra was also constructed. The torque moment of 0.5, 1.0, 1.5, 2.0 N﹒m was applied to the ACCF surgery model. The ROM, maximum stress in facet joint and stress distributions on internal fixation devices under flexion, extension, lateral bending and torsion movement were analyzed. Results ROM of reconstructed C5 segment increased with the torque moment increasing after ACCF surgery. In the case of 1.0 N﹒m torque moment and 50 N preload, the ROM of reconstructed C5, C3-4, C6-7 and C3-7 segment was reduced by 81%, 62%, 58% and 80% compared with the intact model. The maximum stress in facet joint of reconstructed C5 segment reduced and the stress in adjacent segments significantly increased. The stress of titanium mesh was mainly distributed on the compression side of movement, and high stress was located in the roots of screws. Conclusions ACCF surgery can promote the stability of cervical spine, decrease the stress in facet joint of operation segment, and has better treatment effect on easing compression from spinal cord caused by cervical spondylotic myelopathy. The research results will provide some theoretical basis for clinical application of ACCF.

Finite element analysis on lower cervical spine by anterior cervical corpectomy and fusion sugery / 医用生物力学

Objective To establish the three-dimensional finite element model of human lower cervical spine C3-7 motion segments after anterior cervical corpectomy and fusion (ACCF) surgery with titanium mesh and bone graft,and to analyze the stability of cervical spine and stress distribution of internal fixation devices after ACCF surgery.Methods The finite element model of cervical spine C3-7 segments after ACCF of C5 segment with titanium mesh,bone graft,plate and screw fixation was established,and C3-7 segment intact model of cervical vertebra was also constructed.The torque moment of 0.5,1.0,1.5,2.0 N · m was applied to the ACCF surgery model.The ROM,maximum stress in facet joint and stress distributions on internal fixation devices under flexion,extension,lateral bending and axial rotation movement were analyzed.Results ROM of reconstructed C5 segment increased with the torque moment increasing after ACCF surgery.In the case of 1.0 N · m tomue moment and 50 N preload,the ROM of reconstructed C5,C3-4,C6-7 and C3-7 segment was reduced by 81％,62％,58％ and 80％ compared with the intact model.The maximum stress in facet joint of reconstructed C5 segment reduced and the stress in adjacent segments significantly increased.The stress of titanium mesh was mainly distributed on the compression side of movement,and high stress was located in the roots of screws.Conclusions ACCF surgery can promote the stability of cewical spine,decrease the stress in facet joint of operation segment,and has better treatment effect on easing compression from spinal cord caused by cervical spondylotic myelopathy.The research results will provide some theoretical basis for clinical application of ACCF surgery.

Finite element analysis on lower cervical spine by anterior cervical corpectomy and fusion sugery / 医用生物力学

Objective To establish the three-dimensional finite element model of human lower cervical spine C3-7 motion segments after anterior cervical corpectomy and fusion (ACCF) surgery with titanium mesh and bone graft,and to analyze the stability of cervical spine and stress distribution of internal fixation devices after ACCF surgery.Methods The finite element model of cervical spine C3-7 segments after ACCF of C5 segment with titanium mesh,bone graft,plate and screw fixation was established,and C3-7 segment intact model of cervical vertebra was also constructed.The torque moment of 0.5,1.0,1.5,2.0 N · m was applied to the ACCF surgery model.The ROM,maximum stress in facet joint and stress distributions on internal fixation devices under flexion,extension,lateral bending and axial rotation movement were analyzed.Results ROM of reconstructed C5 segment increased with the torque moment increasing after ACCF surgery.In the case of 1.0 N · m tomue moment and 50 N preload,the ROM of reconstructed C5,C3-4,C6-7 and C3-7 segment was reduced by 81％,62％,58％ and 80％ compared with the intact model.The maximum stress in facet joint of reconstructed C5 segment reduced and the stress in adjacent segments significantly increased.The stress of titanium mesh was mainly distributed on the compression side of movement,and high stress was located in the roots of screws.Conclusions ACCF surgery can promote the stability of cewical spine,decrease the stress in facet joint of operation segment,and has better treatment effect on easing compression from spinal cord caused by cervical spondylotic myelopathy.The research results will provide some theoretical basis for clinical application of ACCF surgery.

Finite element analysis on lower cervical spine by anterior cervical corpectomy and fusion sugery / 医用生物力学

Objective To establish the three-dimensional finite element model of human lower cervical spine C3-7 motion segments after anterior cervical corpectomy and fusion (ACCF) surgery with titanium mesh and bone graft,and to analyze the stability of cervical spine and stress distribution of internal fixation devices after ACCF surgery.Methods The finite element model of cervical spine C3-7 segments after ACCF of C5 segment with titanium mesh,bone graft,plate and screw fixation was established,and C3-7 segment intact model of cervical vertebra was also constructed.The torque moment of 0.5,1.0,1.5,2.0 N · m was applied to the ACCF surgery model.The ROM,maximum stress in facet joint and stress distributions on internal fixation devices under flexion,extension,lateral bending and axial rotation movement were analyzed.Results ROM of reconstructed C5 segment increased with the torque moment increasing after ACCF surgery.In the case of 1.0 N · m tomue moment and 50 N preload,the ROM of reconstructed C5,C3-4,C6-7 and C3-7 segment was reduced by 81％,62％,58％ and 80％ compared with the intact model.The maximum stress in facet joint of reconstructed C5 segment reduced and the stress in adjacent segments significantly increased.The stress of titanium mesh was mainly distributed on the compression side of movement,and high stress was located in the roots of screws.Conclusions ACCF surgery can promote the stability of cewical spine,decrease the stress in facet joint of operation segment,and has better treatment effect on easing compression from spinal cord caused by cervical spondylotic myelopathy.The research results will provide some theoretical basis for clinical application of ACCF surgery.

Single-Stage Posterior Subtotal Corpectomy and Circumferential Reconstruction for the Treatment of Unstable Thoracolumbar Burst Fractures

OBJECTIVE: To illustrate the technique of single-stage posterior subtotal corpectomy and circumferential reconstruction for the treatment of unstable thoracolumbar burst fractures and to evaluate the radiographical and clinical outcomes of patients treated using this technique. METHODS: 16 consecutive patients with unstable thoracolumbar burst fractures were treated with single-stage posterior subtotal corpectomy and circumferential reconstruction. The mean patient age was 54.8 years. The mean follower up period was 25 months. Five patients suffered from T12 fractures, 10 from L1, 1 from L2. The segmental kyphosis, neurologic status, visual analogue scale for back pain was evaluated before surgery and at follow up. RESULTS: The segmental kyphotic angle improved from 18.5 degrees before surgery to -9.2 degrees at the last follow up. The mean correction angle was 28.9 degrees. The mean surgical time was 255 minutes, and a mean intraoperative blood loss was 1073 mL. Intraoperative complications included two dural tears, and a superficial wound infection. There were no other severe complications. The mean visual analog scale of back pain decreased from a mean value of 6.6 to 2 at the last follow up. CONCLUSION: The single-stage posterior subtotal corpectomy and circumferential reconstruction achieved satisfactory kyphosis correction with direct visualization of the circumferentially decompressed spinal cord, as well as good fusion with less blood loss and complications. It is a safe and reliable surgical treatment option for unstable thoracolumbar burst fractures.

Artificial disc and vertebra system: a novel motion preservation device for cervical spinal disease after vertebral corpectomy

OBJECTIVE: To determine the range of motion and stability of the human cadaveric cervical spine after the implantation of a novel artificial disc and vertebra system by comparing an intact group and a fusion group. METHODS: Biomechanical tests were conducted on 18 human cadaveric cervical specimens. The range of motion and the stability index range of motion were measured to study the function and stability of the artificial disc and vertebra system of the intact group compared with the fusion group. RESULTS: In all cases, the artificial disc and vertebra system maintained intervertebral motion and reestablished vertebral height at the operative level. After its implantation, there was no significant difference in the range of motion (ROM) of C3-7 in all directions in the non-fusion group compared with the intact group (p>0.05), but significant differences were detected in flexion, extension and axial rotation compared with the fusion group (p<0.05). The ROM of adjacent segments (C3-4, C6-7) of the non-fusion group decreased significantly in some directions compared with the fusion group (p<0.05). Significant differences in the C4-6 ROM in some directions were detected between the non-fusion group and the intact group. In the fusion group, the C4-6 ROM in all directions decreased significantly compared with the intact and non-fusion groups (p<0.01). The stability index ROM (SI-ROM) of some directions was negative in the non-fusion group, and a significant difference in SI-ROM was only found in the C4-6 segment of the non-fusion group compared with the fusion group. CONCLUSION: An artificial disc and vertebra system could restore vertebral height and preserve the dynamic function of the surgical area and could theoretically reduce the risk of adjacent segment degeneration compared with the anterior fusion procedure. However, our results should be considered with caution because of the low power of the study. The use of a larger ...

Outcomes of Secondary Laminoplasty for Patients with Unsatisfactory Results after Anterior Multilevel Cervical Surgery

OBJECTIVE: To investigate the causes for failed anterior cervical surgery and the outcomes of secondary laminoplasty. METHODS: Seventeen patients failed anterior multilevel cervical surgery and the following conservative treatments between Feb 2003 and May 2011 underwent secondary laminoplasty. Outcomes were evaluated by the Japanese Orthopaedic Association (JOA) Scale and visual analogue scale (VAS) before the secondary surgery, at 1 week, 2 months, 6 months, and the final visit. Cervical alignment, causes for revision and complications were also assessed. RESULTS: With a mean follow-up of 29.7+/-12.1 months, JOA score, recovery rate and excellent to good rate improved significantly at 2 months (p0.05). Mean VAS score decreased postoperatively (p0.05). The causes for secondary surgery were inappropriate approach in 3 patients, insufficient decompression in 4 patients, adjacent degeneration in 2 patients, and disease progression in 8 patients. Complications included one case of C5 palsy, axial pain and cerebrospinal fluid leakage, respectively. CONCLUSION: Laminoplasty has satisfactory results in failed multilevel anterior surgery, with a low incidence of complications.