Objective: To compare the changes of scoliosis and kyphosis angles after Halo-pelvic traction with posterior spinal osteotomy versus simple posterior spinal osteotomy for severe rigid spinal deformity. Methods: A clinical data of 28 patients with severe rigid spinal deformity between January 2015 and November 2017 was retrospectively analyzed. Sixteen patients were treated by Halo-pelvic traction with posterior spinal osteotomy (group A) and 12 patients were treated with posterior spinal osteotomy only (group B). There was no significant difference between the two groups ( P>0.05) in gender, age, body mass index, and preoperative pulmonary function, coronal and sagittal Cobb angles, and flexibility. The operation time, intraoperative blood loss, and complications were recorded. The coronal and sagittal Cobb angles were measured on X-ray films before operation (before traction in group A), at 10 days after operation, at last follow-up in the two groups and after traction in group A. The improvement rate of deformity after traction in group A, the correction rate of deformity after operation, and the loss rate of correction at last follow-up were calculated. Results: All patients were followed up 24-30 months (mean, 26.5 months). The operation time and intraoperative blood loss were significantly less in group A than in group B ( t=7.629, P=0.000; t=8.773, P=0.000). In group A, 1 patient occurred transient numbness of both legs during continuous traction and 2 patients needed ventilator support for more than 12 hours. In group B, 7 patients needed ventilator support for more than 12 hours, including 1 patient with deep incision infection. The incidence of complications was 18.75% (3/16) in group A and 58.33% (7/12) in group B, and the difference between the two groups was significant ( χ2=4.680, P=0.031). The coronal and sagittal improvement rates of deformity after traction in group A were 40.47%±3.60% and 40.70%±4.20%, respectively. There was no significant difference between the two groups ( P>0.05) in the coronal and sagittal Cobb angles at 10 days after operation and at last follow-up, in the correction rate of deformity after operation, and in the loss rate of correction at last follow-up. Conclusion: For the severe rigid spinal deformity, Halo-pelvic traction with posterior spinal osteotomy and simple posterior spinal osteotomy can obtain the same orthopedic effect and postoperative deformity correction. However, the Halo-pelvic traction can shorten operation time, reduce blood loss and incidence of perioperative complications.

BACKGROUND:Posterior atlantoaxial pedicle screw rod internal fixation is the main method for treating atlantoaxial dislocation,and the horizontal crosslink plays an important role in the antirotation ability of the internal fixation system.The new horizontal screw-screw crosslink can effectively overcome the disadvantages of traditional horizontal crosslink,such as inconvenient installation,impact on bone grafting bed,and potential spinal cord injury.However,the biomechanical properties of the new horizontal screw-screw crosslink with different installation modes are still unclear. OBJECTIVE:To investigate the biomechanical characteristics of new different installation modes of horizontal screw-screw crosslink in the C1-C2 pedicle screw-rod fixation and to provide a theoretical basis for optimal installation mode. METHODS:Six fresh human occipitocervical specimens were divided into the intact state group(group A),and the atlantoaxial instability model of type Ⅱ odontoid fracture was established based on the intact state group as the instability group(group B).The C1-C2 pedicle screw-rod fixation was performed on each specimen based on the instability group(group C).In group C,different installation modes of horizontal screw-screw crosslink were successively installed in each specimen,including upper transverse connection(two atlas screw tails)as group D,lower transverse connection(two axis screw tails)as group E,diagonal transverse connection(upper left and lower right for group F,lower left and upper right for group G),and cross transverse connection as group H.The specimen models were tested in order of flexion,extension,lateral flexion and lateral rotation on a three-dimensional motion machine,and the atlantoaxial range of motion of each group of specimens was obtained.Repeated measure analysis of variance was used to evaluate the biomechanical properties of each group. RESULTS AND CONCLUSION:(1)Under six states,the range of motion of groups A,C,D,E,F,G and H was smaller than that of group B,and there were statistically significant differences(P＜0.05).(2)In the flexion and extension states,there was no significant difference among the five types of horizontal screw-screw crosslink groups(P＞0.05).(3)In the left and right rotation directions,there were significant differences in D and E groups compared with F,G and H groups(P＜0.05);there were no significant differences between D and E groups,and F and G groups(P＞0.05),and there were no significant differences in F and G groups compared with H group(P＞0.05).(4)In conclusion,under flexion-extension states,the biomechanical stability of five types of horizontal screw-screw crosslink groups was similar,but under the rotation state,the stability of diagonal horizontal screw-screw crosslink group and cross horizontal screw-screw crosslink group was obviously better than that of transverse horizontal screw-screw crosslink group;however,the stability of diagonal horizontal screw-screw crosslink group is similar to the cross horizontal screw-screw crosslink group,so the former is more worthy of clinical recommendation.

BACKGROUND:The addition of traditional rod-rod fixation for atlantoaxial joint disease to C1-C2 pedicle screw-rod fixation(C1-C2 PSR)can provide stronger anti-rotation stability for screw/rod fixation,but there is a risk of installation difficulties,impact on bone graft bed,and spinal cord injury.The new horizontal screw-screw crosslink(hS-S CL)designed by the authors can effectively overcome the above shortcomings,but its biomechanical properties are unclear. OBJECTIVE:To analyze biomechanical properties of new horizontal screw-screw crosslink in C1-C2 PSR by three-dimensional finite element analysis. METHODS:CT thin layer scanning data were collected from the occipital base to the axis(C0-2)of one adult healthy male volunteer.The atlantoaxial finite element models were established respectively:the normal group,the unstable group,the non-crosslink group(unstable+C1-C2 PSR),and the crosslink group(C1-C2 PSR+hS-S CL).Range of motion and Von Miss Stresses in flexion and extension,lateral flexion and rotation of the four groups were calculated by applying 1.5 Nm torque to each finite element model,and the stress cloud was extracted. RESULTS AND CONCLUSION:(1)Range of motion of the unstable group was increased by 43.8%-78.7%compared with the normal group,and the range of motion of the internal fixation groups was 90.2%-98.7%lower than that of the unstable group under six conditions.The range of motion of the crosslink group and the non-crosslink group was basically the same in flexion and extension states,but in lateral flexion and rotation states,the range of motion of the crosslink group decreased 34.3%-43.8%and 78.6%-79.1%,respectively,compared with the non-crosslink group,and range of motion decreased most obviously in rotation state.(2)The stress peak of the internal plant model:The maximum stress of the crosslink group was generally smaller than that of the non-crosslink group,and the stress peak value of all the internal fixation groups was the lowest when the extension was carried out.(3)The stress cloud of internal plants showed that there was no obvious stress concentration phenomenon in the internal fixation,and the main stress distribution areas were the screw root and bone joint,and the crosslink ends were the screw tail groove or the joint rod joint.(4)The new horizontal screw-screw crosslink can obviously improve the anti-rotation stability of internal fixation and it can share part of the pressure in the three-dimensional motion direction of the internal fixation system and reduce the maximum stress of the internal plants.However,the stress distribution is obvious at both ends of the crosslink,and this part may be prone to fracture of the crosslink.

BACKGROUND:The pedicle navigation template has many advantages,but there are still some problems.For example,poor soft tissue dissection leads to poor adhesion of the pedicle navigation template,resulting in screw path deviation;careful dissection of soft tissue to fit the pedicle navigation template leads to prolonged surgery time and increased bleeding;the design of the pedicle navigation template cannot predict the vertebral rotation and the impact of body position changes,resulting in the poor fitting. OBJECTIVE:To explore the utility of a new 5-point positioning point-contact pedicle navigation template in the case of scoliosis and complex pedicle. METHODS:A total of 20 patients with scoliosis and complicated pedicle admitted to the Department of Spinal Surgery,Guizhou Hospital,Beijing Jishuitan Hospital from February 2020 to February 2023 were selected for scoliosis orthopedics.During the operation,the 5-point positioning point-contact pedicle navigation template was used to guide the screws.According to the inclusion and exclusion criteria,34 cases were matched as the empirical nail placement group,and conventional barehanded nail placement was performed.The time of placement,the amount of bleeding,the number of fluoroscopies,the number of manual diversions,the level and accuracy of pedicle screws,the complications of placement,and the rate of correction of main curvature were compared between the two groups. RESULTS AND CONCLUSION:(1)There were no significant differences in sex,age,coronal Cobb's angle of the main curvature,bending Cobb's angle of the main curvature,pedicle variation,apex rotation,fusion segment,number of screws,level of screws,accuracy of screws,and rate of correction of main curvature between the navigation template group and the empirical nail placement group(P>0.05).(2)Compared with the empirical nail placement group,the navigation template group had more advantages in time of placement(P=0.034),amount of bleeding(P=0.036),number of fluoroscopies(P=0.000)and number of manual diversions(P=0.021).(3)There were 0 cases of screw-related complications in both groups.(4)In conclusion,the 5-point positioning point-contact 3D printing pedicle navigation template has a claw-like structure.It can firmly adapt to various deformities of the lamina articular process,avoid drift,and accurately place the screws.It has a point-like contact lamina structure to avoid extensive and complete dissection of the posterior structure,and reduce bleeding,operation time,and trauma.Pre-designed screw entry points and directions can reduce the number of fluoroscopy and operation time.Segmental design can avoid discomfort due to changes in anesthesia position.The operation is simple and the accuracy of screw placement is high.