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: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 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.

OBJECTIVE: To explore the effectiveness of a new point contact pedicle navigation template (referred to as "new navigation template" for simplicity) in assisting screw implantation in scoliosis correction surgery. METHODS: Twenty-five patients with scoliosis, who met the selection criteria between February 2020 and February 2023, were selected as the trial group. During the scoliosis correction surgery, the three-dimensional printed new navigation template was used to assist in screw implantation. Fifty patients who had undergone screw implantation with traditional free-hand implantation technique between February 2019 and February 2023 were matched according to the inclusion and exclusion criteria as the control group. There was no significant difference between the two groups ( P>0.05) in terms of gender, age, disease duration, Cobb angle on the coronal plane of the main curve, Cobb angle at the Bending position of the main curve, the position of the apical vertebrae of the main curve, and the number of vertebrae with the pedicle diameter lower than 50%/75% of the national average, and the number of patients whose apical vertebrae rotation exceeded 40°. The number of fused vertebrae, the number of pedicle screws, the time of pedicle screw implantation, implant bleeding, fluoroscopy frequency, and manual diversion frequency were compared between the two groups. The occurrence of implant complications was observed. Based on the X-ray films at 2 weeks after operation, the pedicle screw grading was recorded, the accuracy of the implant and the main curvature correction rate were calculated. RESULTS: Both groups successfully completed the surgeries. Among them, the trial group implanted 267 screws and fused 177 vertebrae; the control group implanted 523 screws and fused 358 vertebrae. There was no significant difference between the two groups ( P>0.05) in terms of the number of fused vertebrae, the number of pedicle screws, the pedicle screw grading and accuracy, and the main curvature correction rate. However, the time of pedicle screw implantation, implant bleeding, fluoroscopy frequency, and manual diversion frequency were significantly lower in trial group than in control group ( P<0.05). There was no complications related to screws implantation during or after operation in the two groups. CONCLUSION The new navigation template is suitable for all kinds of deformed vertebral lamina and articular process, which not only improves the accuracy of screw implantation, but also reduces the difficulty of operation, shortens the operation time, and reduces intraoperative bleeding.
Humans ; Orthopedic Procedures ; Pedicle Screws ; Retrospective Studies ; Scoliosis/surgery* ; Spinal Fusion/methods* ; Spine ; Surgery, Computer-Assisted/methods*

Objective:To explore the effect of a new 5-point positioning point contact clamping fixation pedicle navigation template in treating cases of scoliosis and complex pedicle.Methods:From February 2019 to February 2023, 30 patients with scoliosis and complicated pedicle were admitted for orthopedic surgery. There were 11 males and 19 females, with an average age of 16.54±6.23 years (range 7 to 35 years). A total 60 cases treated before February 2019 were matched as a control group, including 23 males and 37 females, with an average age of 16.72±6.34 years (range 6 to 35 years). During the operation, the 5-point positioning point-contact clamping fixation pedicle navigation template was used to guide the screws. Screw placement time, screw placement bleeding volume, fluoroscopy frequency, manual redirection frequency, Rao pedicle screw placement classification and accuracy, screw placement complications, and main curve correction rate were recorded.Results:All the 30 cases from the study group successfully underwent the surgery with a total of 354 screws placed, while in the control group a total of 727 screws were placed in 60 cases. The surgery times and intraoperative bleeding volumes for the study group and the control group were 279.45±57.72 min vs. 292.54±58.87 min and 921.57±371.32 ml vs. 932.83±376.65 ml with significant differences ( t=-2.13, P=0.022; t=-1.87, P=0.024). The time for screw placement from the start of skin incision to the placement of the last screw and the bleeding volume during screw placement in the study group and the control group was 82.87±24.46 min vs. 97.53±25.56 min and 72.25±43.66 ml vs. 106.53±61.22 ml with significant differences ( t=-2.66, P=0.031; t=-2.32, P=0.027). The screw placement fluoroscopy frequencies and manual redirection frequencies in the study group and the control group were 4.21±1.11 times vs. 6.32±1.81 times and 0.47±0.64 times vs. 0.93±0.86 times with significant differences ( t=-4.66, P<0.001; t=-2.78, P=0.018). According to the Rao pedicle screw placement classification, the study group had 329 screws classified as level I, 19 screws as level II, and 6 screws as level III. In the control group, there were 669 screws classified as level I, 45 screws as level II, 12 screws as level III, and 1 screw as level IV with no significant difference (χ 2=4.26, P=0.547). The screw placement accuracy and the main curve correction rate in the study group and the study group was 98.31%±3.10% vs. 98.21%±4.92% and 57.85%±9.46% vs. 6.64%±9.22% with no significant differences ( t=0.88, P=0.384; t=0.42, P=0.663). No complications of nerve damage, major vascular injury, cerebrospinal fluid leakage, infection, or death happened during surgery or postoperatively. There were no complications of internal fixation displacement, loosening, or breakage. The outcomes of the patients were good with significantly improved appearance and trunk balance after surgery. Conclusion:The new navigation template provided an accurate and safe way of placing screws in treating various deformities of the lamina articular process without extensive and complete dissection of the posterior structure, leading to reduced fluoroscopy and operation time.

Objective:To investigate the safety and clinical efficacy of osteotomy after halo pelvic traction in severe scoliosis accompanied with split cord malformation.Methods:The clinical data of 14 patients with severe scoliosis accompanied with split cord malformation admitted to the Department of Spinal Surgery, Guizhou Orthopedic Hospital from August 2015 to August 2019 were retrospectively analyzed.There were 6 males and 8 females, aged (19.8±5.0) years (range:13 to 34 years). All patients received spinal orthopedic surgery after halo pelvic traction for 3 to 7 weeks.The data of traction time, height, Cobb angle in the main curved coronal plane and sagittal plane, lung function and nutritional status of the patient were collected before and after the treatment. Paired t test was used to compare the evaluation indexes. Results:The traction time of the 14 patients was (35.2±8.3)days (range:20 to 49 days), and the height of them increased from (156.7±7.6)cm (range:141 to 166 cm) before traction to (167.0±6.4)cm (range:154 to 177 cm) after traction（ t=-10.49， P<0.01）. The Cobb angle on the main curved coronal plane decreased from (117.4±17.2) ° (range: 91°to 176°) before traction to (56.4±8.1) ° (range:44°to 68°) after traction（ t=13.90， P<0.01）. The sagittal Cobb angle decreased from (92.5±11.6) ° (range:62°to 132°) before traction to (41.7±7.7) °(range:29°to 51°) after traction（ t=12.11， P<0.01）. No complications such as loosening of nailing and infection occurred during traction, and no decrease of nerve function occurred. Nine patients underwent single segment acromial transpedicle osteotomy and five underwent double segment adjacent asymmetric shortening osteotomy. None of the patients underwent longitudinal fracture resection. The lung function and nutritional status were improved after traction and surgery(all P<0.01). Postoperative follow-up was (22.5±9.1)months (range:12 to 36 months). At the last follow-up, the coronal Cobb angle was (56.3±7.1) °, and the sagittal Cobb angle was (37.7±6.5) °, showing no statistically significant difference from the angle after traction( t=0.16, P=0.88; t=2.28, P=0.32). There was no loss of orthopedic angle. None of the patients had internal fixation displacement, loosening or fracture. Conclusion:The treatment of severe scoliosis with accompanied with split cord malformation by halo pelvic traction is safe and effective, which is worthy of further confirmation by large sample study.

Objective:To investigate the safety and clinical efficacy of osteotomy after halo pelvic traction in severe scoliosis accompanied with split cord malformation.Methods:The clinical data of 14 patients with severe scoliosis accompanied with split cord malformation admitted to the Department of Spinal Surgery, Guizhou Orthopedic Hospital from August 2015 to August 2019 were retrospectively analyzed.There were 6 males and 8 females, aged (19.8±5.0) years (range:13 to 34 years). All patients received spinal orthopedic surgery after halo pelvic traction for 3 to 7 weeks.The data of traction time, height, Cobb angle in the main curved coronal plane and sagittal plane, lung function and nutritional status of the patient were collected before and after the treatment. Paired t test was used to compare the evaluation indexes. Results:The traction time of the 14 patients was (35.2±8.3)days (range:20 to 49 days), and the height of them increased from (156.7±7.6)cm (range:141 to 166 cm) before traction to (167.0±6.4)cm (range:154 to 177 cm) after traction（ t=-10.49， P<0.01）. The Cobb angle on the main curved coronal plane decreased from (117.4±17.2) ° (range: 91°to 176°) before traction to (56.4±8.1) ° (range:44°to 68°) after traction（ t=13.90， P<0.01）. The sagittal Cobb angle decreased from (92.5±11.6) ° (range:62°to 132°) before traction to (41.7±7.7) °(range:29°to 51°) after traction（ t=12.11， P<0.01）. No complications such as loosening of nailing and infection occurred during traction, and no decrease of nerve function occurred. Nine patients underwent single segment acromial transpedicle osteotomy and five underwent double segment adjacent asymmetric shortening osteotomy. None of the patients underwent longitudinal fracture resection. The lung function and nutritional status were improved after traction and surgery(all P<0.01). Postoperative follow-up was (22.5±9.1)months (range:12 to 36 months). At the last follow-up, the coronal Cobb angle was (56.3±7.1) °, and the sagittal Cobb angle was (37.7±6.5) °, showing no statistically significant difference from the angle after traction( t=0.16, P=0.88; t=2.28, P=0.32). There was no loss of orthopedic angle. None of the patients had internal fixation displacement, loosening or fracture. Conclusion:The treatment of severe scoliosis with accompanied with split cord malformation by halo pelvic traction is safe and effective, which is worthy of further confirmation by large sample study.

Objective To investigate the effects of xenogenic bone with chitosan/norvancomycin sustained-release biomaterials in treating infectious bone defects in rabbits.Methods Xenogenic bone with chitosan/norvancomycin sustained-release biomaterials was made by electrospinning technique.Rabbit infectious bone defect models were made by Methicillin-resistant Staphylococcus aureus.A successful model was evaluated with the standard of more than three points in Norden score assessment.All models were divided into two groups by random number table method,with eight models in each.The control group was treated with surgical debridement,and the experimental group was implanted with bone particles of xenogenic bone with chitosan/norvancomycin sustained-release system after debridement.Postoperatively,general conditions,X-ray,histological results of HE staining,and bacteriological examination results of the rabbits were observed.Results X-ray showed significant bone defects,sequestration,periosteal reaction,and soft tissue swelling after one month of modeling,with Norden score of (3.84 ± 0.52) points.The general conditions were good and the sinus tracts were healed in experimental group after two months of treatment.The control group demonstrated generally poor conditions with swollen sinus and purulent discharge.Two rabbits were died of sepsis.The pathological scores of tibial were (0.41 ± 0.08) points in experimental group,and (3.27 ± 0.26) points in control group by gross observation.The pathological score of experimental group was significantly lower than control group(P ＜ 0.05).The bone defects were basically repaired in experimental group.The longest diameter of bone defect in experimental group was (0.11 ± 0.02)cm,significantly smaller than (0.48 ± 0.06) cm in control group (P ＜ 0.05).There were no obvious signs of osteomyelitis and the bone defects were well repaired in experimental group.Periosteal reaction,soft tissue swelling,a substantial number of bone destruction,and sequestration were observed in control group.The Norden score was (1.32 ± 0.23) points in experimental group,lower than (5.21 ± 0.48) points in control group(P ＜ 0.05).HE staining showed a large amount of trabecular bone formation,bone cell formation,and fibrous hyperplasia in experimental group,with no obvious signs of infection.On the other hand,infiltration of inflammatory cells,necrotic tissue,and sequestration were observed in control group.The histological score was(0.61 ± 0.10) points in experimental group,lower than (4.21 ± 0.41) points in control group (P ＜0.05).The negative rate of bacterial culture in experimental group was 33％,lower than 100％ in control group (P ＜ 0.05).Conclusion Xenogenic bone with ehitosan/norvancomycin sustained-release biomaterials has excellent effect in infection clearance and bone defect reparation in treatment of infectious bone defects in rabbits.

Objective To investigate the clinical efficacy of asymmetric osteotomy via posterior adjacent vertebrae in the treatment of traumatic thoracolumbar kyphotic scoliotic deformity.Methods A retrospective case series study was conducted on the clinical data of 16 patients with traumatic thoracolumbar kyphotic scoliotic deformity admitted to our department from January 2012 to January 2017.There were 10 males and six females,aged (42.5 ±7.6) years (range,20-62 years).According to the location of injured vertebrae,there were two patients with T11,five with T12,six with L1,and three with L2,all of which had scoliosis deformity and obvious low back pain.All patients underwent asymmetric osteotomy via posterior adjacent vertebrae.The operation time and intraoperative bleeding were recorded.The imaging parameters such as kyphosis Cobb angle,scoliosis Cobb angle,distance between C7 plumbline and central sacral vertebral line (C7-CSVL),and distance between C7 plumbline and sagittal vertical axis (SVA) were measured before and after operation.At the same time,the visual analogue scale (VAS),Oswestry dysfunction index (ODI),and SRS-22 scale were used to evaluate the clinical efficacy.The AISA score was used to evaluate the neurological function recovery before and after operation.Results All patients were followed up for (26.3 ± 16.8) months (range,15-65 months).The operation time was (6.0 ± 1.4) hours (range,4.5-9.0 hours),and the intraoperative bleeding was (900.5 ± 360.8)ml (range,800-1600 ml).The kyphosis Cobb angle was improved from (70.3 ± 9.8) °before operation to (12.2 ± 2.9) ° after operation (P ＜ 0.01).The scoliosis Cobb angle was improved from (47.6 ± 11.6) ° before operation to (4.0 ± 0.9) ° after operation (P ＜ 0.01).The C7-CSVL decreased from preoperative (3.1 ±0.8)cm to postoperative (1.2 ±0.4)cm (P ＜0.01),and the SVA decreased from preoperative (5.0 ± 0.9) cm to postoperative (2.9 ± 0.5) cm (P ＜ 0.01).No severe complications such as spinal cord and nerve injury occurred.The VAS decreased from preoperative (6.8 ± 1.0) to (1.9 ± 0.9) points at the last follow up.The ODI decreased from (54.6 ± 4.2) ％ before operation to (8.1 ± 2.5) ％ at the last follow up.The SRS-22 score was increased from (64.6 ±7.5) points before operation to (87.4 ± 3.2) points at the last follow-up.In terms of the ASIA classification,two patients were improved from grade C to grade D after operation,and six patients were improved from grade D to grade E.Conclusion Asymmetric osteotomy via posterior adjacent vertebrae is safe and effective in the treatment of traumatic thoracolumbar scoliosis,with high correction rate of scoliosis and kyphosis at the same time.

Objective To explore the accuracy and clinical efficacy of advanced 3D printing navigation templates in assisting placement of atlantoaxial pedicle screw.Methods A retrospective analysis was carried out on 49 cases of patients with atlanto-axial vertebral fractures and dislocations between June 2013 and June 2016,and all of them were given posterior incision,reduction and internal fixation of atlantoaxial pedicle screw.The patients were divided into advanced 3D printing navigation template group (14 cases),early 3D printing navigation template group (16 cases),and routine pedicle screw placement group (19 cases).Atlantoaxial CT data of patients in advanced 3D printing navigation template group and early 3D printing navigation template group were input into Mimics 17.0,then advanced 3D printing navigation template group and early 3D printing navigation which were used in clinic surgery were designed and printed.The relationship between positions of pedicle screw with the pedicle and bone cortex in plain CT image was observed after operation.The quality of the screw position was assessed and the accuracy of three kinds of screwing methods was compared.The accuracy of the screwing angle was assessed by comparing with the differences between the preoperative designed channel inclination angle and postoperative actual screwing angle.Three groups were compared for differences between operation time,intraoperative blood loss,and scores of cervical nerve scale and visual analogue scale (VAS) of neck and shoulder pain by Japanese Orthopaedic Association (JOA).Results All 49 cases of patients successfully completed the surgery.Patients of the routine pedicle screw placement group,early 3D group and advanced 3D group correspond operation time for 141.2±20.7 min,112.5±12.1 min and 103.1±10.4 min,intraoperative blood loss for 314.0±81.4 ml,243.6±71.2 ml and 181.0+59.1 ml;total accuracy of screwing for 75.0％ (54/72),93.75 ％ (60/64) and 96.43 ％ (54/56).There were statistically significant differences among the routine group,3D group and advanced 3D group in the mentioned programs.There were no statistical differences between advanced 3D group and 3D group in the inclination angle and head tilt angle with the pre-designed values,while there was statistically significant difference between the routine group and the pre-designed value.The accuracy of the inclination angle and bead tilt angle screwing angle were obviously superior in the advanced 3D group and early 3D group to that of the routine group.There were statistically significant differences between preoperative with postoperative VAS scores and JOA scores in the same group,while there were no statistically significant differences among groups in JOA.But there was statistically significant difference between the routine group and the advanced 3D in VAS,and there was no statistically significant difference between the routine pedicle screw placement group and the early 3D in VAS.All three groups of patients had bony fusion of atlantoaxial vertebral body,without loosening,dislocation and fracture of the internal fixators.Conelusion Advanced 3D printing templates in assisting the surgical treatment for atlantoaxial fracture and dislocation can improve the accuracy of pedicle screwing and safety of the surgery,reduce the surgery risk,and obtain satisfied clinical curative effects.