Objective To observe the clinical effect of GSS pedicle screw system and interbody autogenous iliac bone graft fusion in the treatment of lumbar spondylolisthesis.Methods Twenty-one lumbar spondylolisthesis patients was treated by GSS pedicle screw system and interbody autogenous iliac bone graft fusion.Followed up and analyzed the clinical therapeutic efficacy,rate of detachment and reduction,interbody fusion and intervertebral height change.Results Postoperative rate of detachment and reduction had significant difference compared with preoperative [(6.41 ± 6.90)％ vs.(36.75 ± 7.11)％,(86.75 ± 24.40)％ vs.0](q =19.60,19.72,P＜ 0.01).Final follow-up rate of detachment and reduction had no significant difference compared with postoperative (q =0.70,0.96,P ＞ 0.05).Postoperative intervertebral height had significant difference compared with preoperative[L4-5:(7.6 ± 1.3) mm vs.(5.2 ± 0.8) mm; L5S1:(8.4 ± 2.2) mm vs.(6.5 ± 1.5) mm] (q =6.64,3.83,P ＜ 0.01).Final follow-up intervertebral height had no significant difference compared with postoperative (q =2.48,2.42,P ＞ 0.05).All patients were bony fusion,rate of fusion was 100.00％(21/21).In accordance with the Japan institute of orthopaedics (JOA) low back pain surgery standards,the scores of 6 months,1 year,2 years significant increased compared with preoperative [(20.50 ± 3.83),(23.58 ± 3.60),(24.91 ± 2.90) scores vs.(9.67 ± 4.45) scores] (F =71.92,q =13.28,17.06,18.69,P ＜ 0.01).No complication of internal fixation for fracture or looseness.Conclusions The clinical effect of GSS pedicle screw system and interbody autogenous iliac bone graft fusion in the treatment of lumbar spondylolisthesis is good.It has advantages of bone graft area and bone mass,rate of fusion.It is one of better methods in the treatment of lumbar spondylolisthesis.

ObjectiveTo investigate the changes of the opposite structures with the minimally invasive transforaminal lumbar interbody fusion and unilateral fixation.MethodsFrom January 2009 to January 2010,a total of 34 patients with low back pain underwent the minimally invasive transforaminal lumbar interbody fusion and unilateral internal fixation were retrospectively analyzed.Visual analogue scale (VAS) and Japanese Orthopaedic Association(JOA) low back pain scores were used to assess the outcome of the surgery.All patients were followed up for at least 6 months after surgery.The opposite structures of the segments with fusion and unilateral fixation were investigated with CT scans.CT imaging of the patients with opposite low back pain after surgery were analyzed for exploring possible causes of the pain.ResultsThere were significant differences between the pre- and post-operation in VAS and JOA scores(P＜0.01).Four patients met pain in the opposite lumbosacral area after surgery.The CT scans showed that the rebuilding of the lordosis and disc height of the opposite side were more difficult.Rotation could happen in the progress of surgery.For the 4 patients with opposite low back pain after surgery,the insufficiency of the rebuilding of lordosis and disc height of the opposite side,and the rotation between the vertebras were more obvious,and changes were observed in the opposite facet joint on the post-operational CT scan of one patient.Conclusion The minimally invasive transforaminal lumbar interbody fusion and unilateral fixation are effective for patients with low back pain.It's important to pay more attention to the rebuilding of the lordosis and disc height of the opposite side,and the rotation of the vertebras in the surgery.

Objective To study the effect of the expansive open-door laminoplasty on the three-dimensional motion and stiffness of the cervical spine. Methods 55 cases after open-door laminoplasty of cervical spine due to myelopathy were follow-up for an average of 35.9 months. Cervical axial symptoms, neural functionality (JOA scoring system) and pre- and post-surgery dynamic cervical spine lateral X-ray films were evaluated. The Three-dimensional Motion and Stiffness of the Cervical Spine of Human Body Measuring Equipment was used in 12 post-operative open door laminoplasty cases and 10 pre-operative cases to measure the active and passive range of motion(ROM), load-displacement relationship, stiffness of cervical spine and torque caused by the isometric contraction of the extensors and flexors of the cervical spine. Results The average rate of improvement was 66. 2%. The excellent and good rate was 78.2%. The number of cases with distinct or severe cervical axial symptoms increased after the surgery ( P ＜ 0. O1 ) . The patients who have severe axial symptoms tend to have less curved cervical spine (P ＜ 0. 01 ) . There was no significant statistic difference between the severity of post-surgery cervical axial symptoms and JOA improvement level (P ＞ 0. 05). The active and passive ROM of extension, rotation and lateral bending of cervical spine were decreased after the surgery ( P ＜ 0. 05), and the main affection was on the middle and lower part of the cervical spine. The load-displacement figure of cervical spine can fit into an exponential equation T= b0eb1θ. In each direction, the lateral bending had the strongest stiffness, then the extension and flexion. The stiffness of rotation was the weakest. The stiffness of cervical spine of the post-surgery group was stronger than that of the contrast group. Conclusion The open-door laminoplasty of cervical spine damages the static mechanic balance on the sagittal plane and decreases the ROM and the flexibility of cervical spine. The curvature of the cervical spine is related to the severity of the axial symptoms and seems not to be related to the JOA score improvement.

Objective To investigate the radiographic features and surgical approach of severe fixed cervical kyphosis.Methods Seventeen cases of severe fixed cervical kyphosis from January 2007 to January 2012 were studied retrospectively.There were 8 males and 9 females,with an average age of 49.7 years.The etiologies were 3 cases of infection,3 cases of degeneration,3 cases of neurofibromatosis,3 cases of prior laminectomy,2 cases of idiopathic,2 cases of trauma and 1 case of neuromuscular disease.The average length of kyphosis was 4.3 ± 1.2 segments.All patients complained of severe neck pain (visual analogue scale,VAS,7.6±1.5) or progressive cervical kyphosis.There were 4 cases with myelopathy,2 with radiculopathy,3 with difficulty of forward gaze and 1 with difficulty of swallowing.All patients were underwent dynamic flexion-extension radiographs and traction views.CT scans were carried out to identify the sites of fixed kyphosis.Continuous traction was performed after general anesthesia,and the surgical approach was decided according to spinal cord compression,length of kyphosis and the cause of fixed kyphosis.Surgical outcomes were assessed in terms of correction of Cobb angle and Odom criteria.Results All patients were followed-up for 2 to 5 years.According to the CT scans,the sites of fixed kyphosis were identified:anterior bony ankylosis in 7 cases,posterior in 6 cases and both anterior and posterior in 4 cases.The surgical approach were as following:anterior only in 4 cases,posterior only in 2 cases,anterior-posterior in 5 cases,posterior-anterior in 3 cases,anterior-posterior-anterior in 1 case and posterior-anterior-posterior in 2 cases.The Cobb angle was corrected from 49.3°± 14.6° preoperation to 2.1 °±6.8° at the latest follow-up,with an average correction of 47.2°.According to Odom criteria,there were 7 excellent outcome,8 good,2 fair and none poor outcome.Revision surgery was performed in 1 case due to proximal junctional kyphosis.At the latest follow-up,bony fusion was found in all patients.Conclusion CT scan is helpful in identifying the cause of fixed kyphosis.The surgical approach of fixed cervical kyphosis is decided by spinal cord compression,length of kyphosis and cause of fixed kyphosis.Anterior approach is suitable for anterior ankylosis,posterior approach for posterior ankylosis,combined approach for both anterior and posterior ankylosis.

[Objective] The efleet of sagittal orientations of articular facet on the contact force and contact regions of a lumbar spine segment was evaluated.[Methods] [Results]Three-dimensional geometrical and mechanical accurate finite element models of the lumbar L4、5 motion segment representing three sagittal-orientations articular facet were generated and invalidated by an effective CAD method.Contact force and contact regions of the articular facets of three finite element models were predicted under the pure shearing loads.[Result] Under anterior shear condition,the contact force on the facet decreased with the increase of sagittal 0rientation of articular facet.however.in posterior shear load,the contact force on the facet increased with the increase of sagittal orientation.Meanwhile,under both pure shear loading,the percentages of the sagittal and the transversal components are increased with the dectease of the sagittal angle.However,under the salne load condition,there are no difference between the contact regions of the three models with different facet joint angle.[Conclusion]The spatial orientation and geometric forms of the coronal facet articular surfaces are more effective in restricting motion in transversal and sagittal planes while assuming a minor role in resisting axial force or motion than sagittal facet articular surface.It Was presumed that anterior shear force play a more prominent contribution on the degeneration of the facet joint with coronal articular surface compared with posterior shear force.

Objective To research the connection between the sagittal orientation of facet joints and disc degeneration in lumbar spine and to investigate the contribution of which to development the degenerative spondylolisthesis. Methods A new effective CAD method was used to accurately establish 9 finite element models(FEM)which were assembled respectively with facet-joint angle 65?, 45?, 25?, with normal disc, light degenerative disc and severe degenerative disc. The biomechanical parameters of 9 finite element models were measured under axial compressive load within physiological range. Results Compared with FEMs with facet-joint angle 45? and 25?, anterior displacement of L4 vertebra in FEMs with facet-joint angle 65? was increased, where the maximum von Mises stresses on facet surface, isthmus and the contact force on facet surface in horizontal orientation were obviously increased. Meanwhile, FEMs with facet-joint angle 65? showed a decrease in end-plate bulge and an increase in stress of annular matrix. The stiffness in light degenerative disc FEMs was reduced and the von Mises stresses on facet surface and isthmus was slightly increased compared with the normal disc FEMs. Among all, the FEM with facet-joint angle 65? combined with light degenerative disc showed the poorest resisting anterior shear force. Conclusion Sagittal orientation of facet joints is not only the primary inducement of the degenerative spondylolisthesis but the secondary pathological change of remodeling of the facet-joints induced by the regional stress change. The inherent instability of lumbar motion segment of sagittal orientation of facet joints is influenced by the lumbar disc degeneration. The lumbar disc degeneration has no manifested contribution to the aggravation of the sagittal orientation of facet joints.

Objective To investigate the correlation between MR imaging and pathological features of nucleus pulposus degeneration in the lumbar disc, and to provide a reliable evidence to evaluate the nucleus pulposus degeneration by MR imaging relative signal intensity. Methods From January 2001 to December 2001, 91 patients who underwent operative treatment for lumbar disc diseases were recruited for the study, while 4 lumbar fracture patients with no previous low back pain and 2 fresh brain-injury cadavers were recruited for contrast study. Before operation, the relative signal intensity was measured in MRI T2WI images. All 117 specimens were dyed with HE and Alcian blue CEC. The water content was also detected. The correlation between MRI relative signal intensity and chondroitin sulfate index, water content was analyzed with SPSS 10.0 software, the correlation between chondroitin sulfate index and water content was analyzed as well. Results There was significant difference between the above mentioned two groups when MRI relative signal intensity, chondroitin sulfate index and water content was compared. Whereas there was no significant statistical difference when keratin sulfate index was compared between the two groups. MRI relative signal intensity positively correlated with water content and chondroitin sulfate index, and the chondroitin sulfate index positively correlated with water content. Conclusion The MRI relative signal intensity reflects not only the water content, but also the pathological characteristics of nucleus pulposus degeneration. The quantitative classification of relative signal intensity in MRI is a method to identify the grades of nucleus pulposus degeneration.

Objective To investigate the safe directions of screw trajectory in atlas via posterior arch and lateral mass and its clinical significance. Methods Lateral radiographs and CT axial scans of atlases were performed in 30 cases with normal morphology of atlases and axes. The minimal height of posterior arch, the maximum inclination of screw projection relative to sagittal plane, and the maximum medial angle of screw projection relative to axial plane were evaluated radiologically. According to the safe directions obtained radiologically 21 cases of atlantoaxial instability were treated with screw fixation atlas via posterior arch and lateral mass. During operation the influence of screws on surrounding structures was investigated and postoperative neural symptoms were documented also. Preoperative and postoperative radiographs and CT scans of 13 patients were available and some related parameters were measured to evaluate the safety of the screw placements. Results 1) The maximum angle of screw projection to sagittal plane is about 10? cephalad to 6? caudal, with the tendency of increasing maximum angle as the minimal height of posterior arch increases. 2) When the entry point on the posterior arch was switched laterally, the medial angle of screw projection should be adjusted from 0? to 30?, correspondingly. 3) The actual directions of screw trajectory might differ from preoperative ones, but all were in the estimation range. 4) All screws were placed successfully, and the postoperative radiographs and CT scans shows no neural or vascular complications relative to atlantal screws placed in traditional way. Conclusion There is a safe range to insert atlas screw via posterior arch and lateral mass both in sagittal and axial plane.

Objective To demonstrate the histopathological changes of sequestration-type herniated disc, and investigate the related factors of its absorption. Methods 39 tissue samples were surgically removed from 37 patients with sequestration-type lumbar disc herniation. All the tissues were performed with HE stain and immunohistochemical study. In HE stain, the origin of tissue was identified; in immunohistochemical study, anti-CD34 antibody was used for detecting the vascular endothelial cells, and anti-CD68 for macrophages. The sequestration-type lumbar disc was divided into 3 groups according to the content of nucleus pulposus: nucleus pulposus group, nucleus pulposus contained group and non-nucleus pulposus group. The correlation between the extent of angiogenesis and macrophage infiltration and the factor of age, disease duration, origin of sequestrated tissue and imaging features was studied. Results 62% (24/39) of the sequestrated tissues were mainly originated from nucleus pulposus. Granulation tissue with many macrophages around new blood vessels was found in 92%(36/39) of the sequestrated tissues. There was a significant difference of the extent of angiogenesis and macrophage infiltration among these 3 groups in terms of the content of nucleus pulposus group(F=5.663, P=0.008; F=3.604, P=0.038). There was no significant correlation between the extent of angiogenesis and macrophage infiltration and age or disease duration, whereas, a positive significant correlation was found for the size of sequestrated tissue (r=0.342, P=0.033; r=0.440, P=0.005). Furthermore, the extent of angiogenesis and macrophage infiltration was significant when the relative signal intensity of sequestrated tissue on MRI was in 0.30-0.72. Conclusion The origin of sequestration-type herniated disc is mainly from nucleus pulposus, and most of the sequestration tissue can be absorbed in different extent. The extent of spontaneous absorption was mainly depended on the origin of the sequestration tissue, but not the age or disease duration. Predominant absorption is found in bigger size of the sequestration tissue and their relative signal intensity on MRI being 0.30-0.72.