[Feasibility of a novel type of complex anterior cervical fixation by using Mimics software].

OBJECTIVE: To investigate the feasibility of mimics software in analyzing a new type of complex anterior cervical fixation -- anterior transpedicular screw fixation+zero notch internal fixation. METHODS: From January 2021 to September 2022, 50 normal pedestrians who underwent cervical spine CT scanning were selected for C1-C7 segment scanning, including 27 males and 23 females, aged from 25 to 65 years old with an average of (46.0 ± 9.0) years old. The dicom format is exported and engraved into the CD, and use the mimics software to perform 3D reconstruction of each segment. A simulated screw is placed on the image according to the critical value of zero notch screw (head and tail angle 44°, internal angle 29°). The position of zero notch screw in each segment is observed to determine the feasibility of anterior transpedicular screw fixation plus zero notch internal fixation. RESULTS: For the upper zero notch screws the three-dimensional images of the cervical spine across all 50 subjects within the C3-C7 segments demonstrated safe position, with no instances of intersection with ATPS. For the lower zero notch screw, in C3-C4 and C4-C5, 4 out of 50 subjects are in the safe position in the three-dimensional images of cervical vertebrae, and 46 cases could achieve secure screw placement when the maximum caudal angle is(32.3±1.9) ° and (36.1±2.2) °, respectively. In C5-C6 and C6-C7 segments, no lower zero notch screws intersected with ATPS, and all screws are in safe positions. CONCLUSION: Lower cervical anterior pedicle screw fixation plus zero notch internal fixation can achieve successful nail placement through the selected entry point and position.

Measurement of anatomical parameters of anterior transpedicular root screw intervertebral fusion system of cervical spine.

OBJECTIVE: This study aims to investigate the feasibility of the anterior transpedicular root screw (ATPRS) intervertebral fusion system for the cervical spine and provide a basis for the design of the ATPRS intervertebral fusion system. METHODS: A total of 60 healthy adult cervical spine CT images examined from our hospital were selected, including 30 males and 30 females, with an average age of 39.6 ± 4.8 years. The image data was imported into Mimics 21.0 software in DICOM format for 3D model reconstruction. Simulated screw insertion was performed on both sides of the midline of the intervertebral space. The entry point (P1) was determined when the upper and lower screw paths did not overlap. When the screw was tangent to the medial edge of the Luschka joint, the insertion point was determined as the entry point (P2). Measurements were taken and recorded for the following parameters: distance from the screw entry point to the midline of the intervertebral space (DPM), the simulated screw length, inclination angle, cranial/caudal tilted angle, the anterior-posterior (AP) and mediolateral (ML) diameters of the cervical intervertebral space, the heights of the anterior, middle, and posterior edges of the cervical intervertebral space, and the curvature diameter of the lower end plate of the cervical vertebral body. Statistical analysis was performed on the measurement results. RESULTS: The screw entry area (P1P2) showed an increasing trend from C3-C7 in both male (2.92-6.08 mm) and female (2.32-5.12 mm) groups. There were statistical differences between men and women at the same level (P < 0.05). The average screw length of men and women was greater than 20 mm, and the upper and lower screw lengths showed an increasing trend from C3 to C7. In the area where screws could be inserted, the range of screw inclination was as follows: male group upper screw (47.73-66.76°), lower screw (48.05-65.35°); female group upper screw (49.15-65.66°) and lower screw (49.42-63.29°); The range of cranial/caudal tilted angle of the screw was as follows: male group upper screw (32.06-39.56°), lower screw (29.12-36.95°); female group upper screw (30.97-38.92°) and lower screw (27.29-37.20°). The anterior-posterior diameter and mediolateral diameter of the cervical intervertebral space showed an increasing trend from C3 to C7 in both male and female groups. The middle height (MH) of the cervical intervertebral space was greater than the anterior edge height (AH) and posterior edge height (PD), with statistical differences (P < 0.05). CONCLUSIONS: Through the study of CT images of the cervical spine, it was determined that the ATPRS intervertebral fusion system has a feasible area for screw insertion in the cervical intervertebral space.

[Establishment of finite element model of anterior cervical transpedicular system for reconstruction of cervical stability after subtotal resection of two segments of lower cervical spine].

OBJECTIVE: To establish the fixation model of anterior cervical transpedicular system (ACTPS) after subtotal resection of two segments of lower cervical spine(C3-C7) in order to provide a finite element modeling method for anterior cervical reconstruction. METHODS: The CT data of the cervical segment (C1-T1) of a 30-year-old adult healthy male volunteer was collected. Used Mimics 10.0, Rapidform XOR3, HyperMesh 10.0, CATIA5V19 and ANSYS 14.0 to establish the three-dimensional nonlinear complete model of lower cervical spine(C3-C7) as the intact group. The number of units and nodes of the complete model were recorded. After the effectiveness of the complete model was verified, the C5 and C6 vertebral subtotal resection was performed, and the ACTPS model was established as the ACTPS group. The axial force of 75 N and moment couple of 1N·m was loaded on the upper surface of C3 in intact group and ACTPS group, the range of motion(ROM)and stress distribution in states of flexion extension, lateral flexion, rotation was compared between two groups. RESULTS: There were 85 832 elements and 23 612 nodes in the complete model of lower cervical spine(C3-C7) which was established in this experiment. The stress distribution of ACTPS internal fixation model was relatively uniform. Comparing with the intact group, the overall range of motion in ACTPS group was decreased in flexion extension, lateral flexion and rotation directions, and the corresponding compensation of adjacent C3,4 segment was increased slightly. CONCLUSION: The stress distribution of ACTPS fixation system is uniform, there is no stress concentration area at the joint of screw and titanium plate, and the fracture risk of internal fixation is low. It is suitable for stability reconstruction after anterior decompression of two or more cervical segments.

[Comparative study between 3D guide plate assisted and free-hand insertion of anterior cervical transpedicular screw].

OBJECTIVE: To compare accuracy of anterior cervical pedicle screws between assist of rapid prototyping 3D guide plate and free-hand insertion, and evaluate the safety of two methods. METHODS: Eight adult cervical cadaver specimens after formaldehyde immersion, including 4 males and 4 females, aged 32 to 65(40.3±5.6) years old. After X-ray examination to exclude bone damage and deformity, 4 of them (3D guide plate group) randomly selected were for CT scan to obtain DICOM format data, and the data was imported into Mimics software for model, designed the ideal entry point and nail path for anterior cervicaltranspedicular screw (ATPS). After obtaining the personalized guide plate of the nail channel, it was exported as STL data, and the individual guide plate was printed by rapid prototyping and 3D printing technology. In turn, with the assistance of 3D guide plates, one-to-one personalized ATPS screws were placed on the four lower cervical cadaver specimens. Another 4 (free-hand group) lower cervical cadaver specimens were implanted with ATPS screws using free-hand technique. All specimens were performed CT thin-layer scanning and three-dimensional reconstruction after operation. The Tomasino method was used to evaluate the safety of the screws on the CT cross-sectional and sagittal images, to determine whether there was a cortical puncture of the lower and inner edges of the pedicle. According to the CT rating results, gradeⅠandⅡwere safe, and grade Ⅲ- Ⅴ were dangerous.And the accuracy of screws was recorded and analyzed between two groups. RESULTS: Two screws were inserted in each segment from C3 to C7 in 8 adult cadavers. A total of 80 screws were inserted, 40 in the 3D guide plate group, and 40 in the free-hand group. The Tomasino screw rating method was used to evaluate the safety of screw, 21 screws were gradeⅠ, 14 screws were gradeⅡ, 3 screws were grade Ⅲ, 1 screw was grade Ⅳ, 2 screws were grade Ⅴ in 3D guide plate group, while 14 screws were gradeⅠ, 8 screws were gradeⅡ, 8 screws were grade Ⅲ, 6 screws were grade Ⅳ, 2 screws were grade Ⅴ in free-hand group. The safety rate of 3D guide plate group was 87.5%, and 55.0% of the free hand group (χ2=8.7, P=0.003). CONCLUSION: The 3D printing rapid prototyping guide plate assisted insertion of the anterior cervical pedicle screw can significantly improve the accuracy and safety, and provide a theoretical basis for further clinical application.

[Effect of posterior osteotomy on the sagittal parameters of the spinopelvis in patients with lumbar degenerative kyphosis].

OBJECTIVE: To investigate the influence of posterior osteotomy on spinopelvic parameters in lumbar degenerative kyphosis (LDK) patients. METHODS: The clinical data of 21 patients with lumbar degenerative kyphosis who underwent osteotomy from January 2012 to December 2015 were retrospectively analyzed. There were 5 males and 16 females, aged from 55 to 76 years with an average of (66.24±5.13) years. All patients had taken preoperative and postoperative full length spinal X-ray, analyzing the spinopelvic parameters as thoracic kyphosis (TK), lumbar lordosis (LL), sagittal vertical axis (SVA), pelvic incidence (PI), pelvic tilt (PT) and sacral slope (SS). RESULTS: All operations were successful, the average operative time was 190 min (160 to 220 min) and intraoperative blood loss was 1 000 ml (800 to 1900 ml). Parameters of the patients between preoperative and period 1-year follow-up were as follows : preoperative TK increased from (31.67±21.13) ° to (34.67±11.60) °, LL corrected from (4.76±3.17) ° to (37.41±6.28) °, PT reduced from (33.94±5.01) ° to (20.12±5.36) °, and SS improved from (18.47±2.60) ° to (31.71±4.30) °, SVA restored from (13.24±3.60) cm to (2.82±1.33) cm. There were significant differences of spinopelvic parameters between preoperation and postoperation (P<0.05). CONCLUSION: Posterior osteotomy can effectively reconstruct the sagittal balance of spinopelvis in patients with lumbar degenerative kyphosis. The recovery of lumbar lordosis and sacral slope is closely related to the reconstruction of sagittal balance.

[Efficacy of bilateral sagittal cross percutaneous kyphoplasty for preventing recurrent fracture of the cemented vertebrae].

OBJECTIVE: To explore the efficacy of bilateral sagittal cross percutaneous kyphoplasty(PKP) for preventing recurrent fracture of the cemented vertebrae. METHODS: From January 2017 to June 2017, 85 patients with single-segment osteoporotic vertebral compression fractures(OVCFs) were treated by bilateral sagittal cross PKP(cross group). There were 35 males and 50 females with an average age of (70.1±8.3) years old in cross group. Another 85 patients with single-segment OVCFs were treated by traditional PKP (traditional group). There were 37 males and 48 females with an average age of (73.3±9.5) years old in traditional group. The cement distribution condition, recurrent fracture of the cemented vertebrae, the anterior vertebral body height and sagittal Cobb angle, visual analogue scale(VAS) were observed in two groups. RESULTS: All patients underwent operation successfully. The follow-up time were (11.8±4.5) months in cross group and (12.1±3.7) months in traditional group. In cross group, all patients' bone cement touched the upper and lower endplates of the vertebral body while 67 cases (78.8%) in traditional group did with significant difference between two groups (P<0.05). No patient in cross group suffered recurrent fracture of the cemented vertebrae while 10 cases (11.8%) in traditional group did with significant difference between two groups(P<0.05). The anterior vertebral body height, sagittal Cobb angle and VAS in both groups were obvious improved at 2 days after operation (P<0.05) and there were no significant difference between two groups at 2 days after operation and the final follow-up(P>0.05). CONCLUSIONS: Bilateral sagittal cross PKP was a simple, safe and effective technique which can make bone cement distribute in the fractured vertebral body and contact the upper and lower endplates of the vertebral body, thus preventing the recurrent fracture of the cemented vertebrae.

Sting is a critical regulator of spinal cord injury by regulating microglial inflammation via interacting with TBK1 in mice.

Spinal cord injury (SCI) is a devastating neurological condition that results in progressive tissue loss, secondary to vascular dysfunction and inflammation. Lack of effective pharmacotherapies for SCI is mainly attributable to an incomplete understanding of its pathogenesis. Stimulator of interferon gene (Sting), also known as Transmembrane protein 173 (TMEM173), activates the type I interferon-regulated innate immune response, playing crucial role in modulating inflammation. However, the mechanism underlying Sting activation in SCI is still unclear. Here, we reported that Sting functioned as a positive regulator of SCI. Sting expression was increased in the injured spinal cord samples of SCI mice, along with significantly up-regulated levels of pro-inflammatory cytokines including tumor necrosis factor α (TNF-α), interleukin (IL)-1ß and IL-6. Suppressing Sting expression in lipopolysaccharide-incubated mouse microglia markedly reduced the activation of nuclear factor-κB (NF-κB) and mitogen activated protein kinases (MAPKs) signaling pathways, as illustrated by the decreased phosphorylation of IKKß, IκBα, NF-κB/p65, p38, ERK1/2 and JNK. Furthermore, LPS-stimulated release of pro-inflammatory cytokines in microglial cells was also reversed by Sting knockdown. In contrast, LPS-induced inflammation was further accelerated in microglial cells with Sting over-expression through potentiating NF-κB and MAPKs signaling. Mechanistically, Sting directly interacted with the TANK-binding kinase 1 (TBK1), thus promoting its phosphorylation and the activation of down-streaming NF-κB and MAPKs signaling pathways. Notably, the effects of Sting on SCI progression were verified in mice. Consistently, Sting knockout alleviated inflammatory response and facilitated recovery after SPI in mice through blocking TBK1 activation and subsequent NF-κB and MAPKs phosphorylation. In summary, our findings may provide a novel strategy for prevention and treatment of SCI by targeting Sting.

[Digital modeling and analysis of the applicability of backward rotation method in lumbar kyphoplasty with unilateral puncture].

OBJECTIVE: The 3D model of lumbar spine was established by using Mimics software. To observe the applicability and needling parameters of lumbar vertebral kyphoplasty with unilateral puncture by backward rotation method using simulated puncture. METHODS: Twenty-four patients (12 males and 12 females) with osteoporotic thoracic fracture in the first time and no signs of lumbar misalignment and bone destruction were scanned by spiral CT on the lumbar spine. The original DICOM file was modeled in 3D with Mimics software, and the vertebral bodies were separated. After being imported into 3-matic software, the posterior wall of the vertebral body was restrained for standardized measurement. A sketch perpendicular to the mid-section of the pedicle and the posterior wall of the vertebral body was drawn. The simulated puncture was performed on the sketch. The angle and distance parameters of the range of motion of the puncture needle were recorded, and the puncture needle was recorded at the top. The crossing points of the anterior, middle and posterior zones of the tangential line of the vertebral body were located at the high extraversion angle, and the results were compared and analyzed. RESULTS: All the data in the left and right sides had no significantly differences(P>0.05). Data of different segments in different gender were significantly differences(P<0.05). The maximal extraversion angle in lumbar spine increased gradually from (33.41±1.31) degree to (56.53±4.71) degree in males, as same as in females from(28.58±2.55) to (53.86±2.68) degree. There was no crossing point in area A, 3.3% of males and 26.67% of females in area B, rest in area C. The distribution areas on gender showed statistically significance (P<0.05). CONCLUSIONS: Backward rotation method can theoretically meet the requirements of puncture point for vertebral compression fracture, especially for males and lower lumbar spine. The determination of the maximum inclination angle is of guiding significance to the backward rotation method.

[Progress on clinical application of anterior cervical pedicle screw fixation for instable cervical spine disease].

Instability of the cervical spine disease requires surgery to restore stability. In the past, surgical methods were divided into two kinds of anterior and posterior. But each has its own disadvantages:anterior vertebral screw has a higher failure rate, sometimes need a second operation; and posterior pedicle screw, lateral mass screw and facet joint screw may make greater trauma, lead to longer hospitalization. For general instable cervical spine disease, according to the location of the disease, only with the anterior or posterior approach can achieve a stable effect. However, it often fails to achieve the desired stability with only anterior or posterior approach for the three column injury of single segment, the disease need for multi-segment corpectomy and discectomy. Meanwhile, combined with the anterior and posterior have more obvious disadvantages:such as prolonged operation time, greater surgical injury, increased risk of infection and so on.In recent years, anterior transpedicular screw (ATPS) as a new technique was used for cervical spine fixation. Its laboratory and clinical studies have been conducted about biomechanical properties, morphological feasibility, pull-out strength, radiological features and new technology for inserting screws. Because of its strong stability, perfect mechanical properties and the satisfactory results of patients, which has been recognized by many scholars. Although this technique has been used in clinical practice, Its long-term clinical effect needs to be further clarified. Even so, the innovative proposal will provide a new thread for the majority of doctors and colleagues in treating unstable cervical disease.

[French door segmented laminectomy decompression for severe cervical ossification of posterior longitudinal ligament complicated with spinal cord injury].

OBJECTIVE: To evaluate the clinical effects of French door segmented laminectomy decompression for severe cervical OPLL complicated with spinal cord injury. METHODS: The clinical data of 38 patients with serious cervical OPLL complicated with spinal cord injury were retrospectively analyzed and these patients were treated with French door segmented laminectomy decompression and internal fixation from June 2012 to June 2014. There were 25 males and 13 females, aged from 42 to 78 years with an average of 58.2 years. Of them, 35 cases suffered from aggravating neurological symptoms with a definite precipitating factor. Spinal cord injury was related to minor injury of the neck, such as hyperextension of the neck in 3 cases. Preoperative Japanese Orthopaedic Score (JOA) was 8.1±1.7 and Neck Disability Index (NDI) was 19.8±4.4. Preoperative CT scans showed the range of OPLL was more than three segments. The spinal canal was occupied 50% to 85% with an average of 70.7%. RESULTS: All the patients were followed up for 10 to 24 months with an average of 15.6 months. The operative time was 90 to 150 min with an average of 120 min and blood loss was 300 to 800 ml with an average of (480±80) ml. At final follow-up, NDI and JOA were 7.5±2.5 and 13.5±2.0, respectively, and they were obviously improved compared with preoperation. Preoperative cervical Cobb angle was (8.10±2.70)° and at final follow-up was (15.60±1.80)°, and there was significant difference between preoperative and postoperative (P<0.05). Deep infection occurred in 1 case, epidural hematoma in 1 case, C5 nerve root palsy in 3 cases, and axial symptom in 8 cases after operation. No serious complications, such as vertebral artery injury, cerebrospinal fluid leakage, deterioration of neurological dysfunction, or internal fixation failure was found. CONCLUSIONS: French door segmented laminectomy decompression is safe and feasible for severe cervical OPLL complicated with spinal cord injury, and it is worth to be popularized in future.

[Research progress on reatment of unstable atlas fracture with single-segment fixation by transoral approach].

As a common type of fracture in cervical, atlas fracture is frequently unstable due to its special anatomical structure. In a previous treatment, external fixation was likely to bring low bony union rate and long-term neck pain, while occipito-cervical fusion and atlantoaxial fusion sacrifice range of motion in cervical spine. Reduction and single section fixation of atlas by anterior lateral mass screws through the transoral approach were reported by some scholars, and the retrospective study demonstrated the high healing rate, reservation of cervical ROM and less bleeding. But it also has high risks of cervical spinal cord and vertebral artery damage, as well as the post-operation infection. Moreover, the indication and fixation strength require further evidences. As a result, this surgical option provides a new way for spinal surgeons to deal with unstable atlas fractures.

[Asymmetrical osteotomy for elderly degenerative lumbar kyphoscoliosis].

OBJECTIVE: To investigate the safety and efficacy of asymmetrical osteotomy in treating elderly degenerative lumbar kyphoscoliosis. METHODS: From January 2010 to June 2012,17 elder patients with degenerative lumbar kyphoscoliosis were treated with asymmetrical osteotomy,their data were retrospectively analyzed. There were 6 males and 11 females with an average age of 61 years old (57 to 72). Total length spinal X-ray was performed for all patients before operation,and sagittal and coronal balance were analyzed. The follow-up time was 1 year at least. VAS score, thoracolumbar Cobb angle and pelvic parameters were analyzed. RESULTS: All patients were operated successfully. The average operation time was 210 min (180 to 260) and intraoperative blood loss was 1,100 ml (750 to 2 200). At 1 year after operation, VAS score decreased from preoperative 7.0 +/- 1.5 to 1.1 +/- 0.6; lumbar lordosis (LL) corrected from (1.9 +/- 9.6) degrees to (35.2 +/- 6.7) degrees; thoracic kyphosis (TK) increased from (26.3 +/- 9.7) degrees to (32.5 +/- 11.2) degrees; lumbar scoliosis decreased from (25.1 +/- 11.0) degrees to (7.9 +/- 3.6) degrees; pelvic tilt (PT) restored from (33.0 +/- 10.1) degrees to (25.3 +/- 8.9) degrees; sacral slope (SS) increased from (13.9 +/- 9.7) degrees to (27.2 +/- 11.0) degrees; sagittal balance improved from (10.3 +/- 8.1) cm to (3.1 +/- 4.2) cm,and coronal balance improved from (3.5 +/- 2.1) cm to (1.3 +/- 1.1) cm. There was statistically significant difference above data between preoperation and postoperation. CONCLUSION: Asymmetrical osteotomy can not only correct scoliosis deformity, but also restore lumbar lordosis, and may safely and effectively solve the problem of elderly degenerative lumbar kyphoscoliosis.

[The design and application of anterior cervical pedicle screw-plate system in lower cervical spine].

OBJECTIVE: To explore the applied feasibility of the anterior cervical pedicle screw-plate system in lower cervical spine,in order to provide basic data for clinical application. METHODS: Total thirty-two units (functional spinal unit, FSU) were got randomly from 16 cervical speciments, 8 units in each group of C3,4, C4,5, C5,6 and C6,7. The anterior cervical pedicle screw-plate system was implanted to reconstruct the stability of FSU after discectomy and bone graft. The adaptability was measured between the screw-plate system and vertebral body. X-ray and CT were used to evaluate the accuracy of anterior cervical pedicle screws. The subject will be dissected to identify the situation of involvement if screw perforating the pedicle. RESULTS: Sixty-four anterior pedicle screws were inserted smoothly in the 32 units. The screw and the plate were harmonious locked in the system. The position and length of all screws were satisfactory through X-ray views. However,6 screws perforated the transpedicular (degree 1) according to CT axial views,2 internally cortex and 4 laterally cortex. None perforation was degree 2 or more. None cervical sac compression and nerve root injury was observed in two internal perforation cadavers. One vertebral vein involvement was found in the four lateral perforation screws. The vertebral artery was not pinched though one screw near to the artery. CONCLUSION: The anterior cervical pedicle screw-plate system is adapted to reconstruct in lower cervical spine and it deserved to be used for clinical application.

[Clinical application of anterior transpediclar screw reconstruction in treating lower cervical spine fracture and dislocation].

OBJECTIVE: To investigate the clinical effects of anterior transpediclar screw (ATPS) fixation in treating lower cervical spine fracture and dislocation. METHODS: From January 2009 to December 2011, 18 patients with lower cervical spine fracture and dislocation were treated with ATPS technique, including 12 males and 6 females, aged from 17 to 47 years old with an average of 38.2 years. Severity score of lower cervical spine injuries (SLIC) ranged from 6 to 9 points with an average of 7.5 points. According to ASIA grade of spinal cord injury, 2 cases were classified in grade A, 8 cases in grade B, 6 cases in grade C and 2 cases in grade D. X-ray and CT scan were done after surgery in order to evaluate the safety of ATPS and observe the stability and fusion of injured segment. Spinal cord function was evaluated according to ASIA grade at 3 months after operation and last follow-up. RESULTS: All patients were followed up for 6 to 15 months with an average of 9.5 months. Three months after operation, in aspect of spinal cord function, 8 cases improved 1 grade, 2 cases improved 2 grades; and at final follow-up, 7 cases improved 1 grade, 4 cases improved 2 grades. All patients obtained bony fusion 6 to 8 months after operation with an average of 6.5 months. After operation, 1 case had transient hoarseness and recovered 2 months later;2 cases felt swallowing discomfort, but the symptoms disappeared after about 3 weeks by inhalation. No internal fixation breakage and loosening as well as nerve, blood vessel and esophageal injuries were found. CONCLUSION: As for three columns injury caused by lower cervical spine fracture and dislocation, treatment with anterior transpediclar screw reconstruction can achieve the effect of decompression thoroughly and restore the cervical spine height and physiological curvature. Moreover, this kind of treatment has good stability and can create the favorable conditions for the recovery of spinal cord function.

[Comparison of statics characteristics between anterior transpedicular screws system and vertebral body screws system in lower cervical spine].

OBJECTIVE: To compare statics characteristics between anterior transpedicular screws (ATPS) system and vertebral body screws (VBS) system in lower cervical spine. METHODS: Sixteen fresh cervical specimens were collected and dissected into 32 different units (functional spinal unit, FSU), 8 units in C3,4, C4,5, C5,6 and C6,7 each. The subjects were randomly divided into group A and B. The anterior transpedicular screw-plate system and anterior vertebral body screw-plate system were implanted separately in group A and B. Then, the maximum axial pull out strength was tested and compared between two fixation system. RESULTS: Maximum pull out strength was (604.68 +/- 48.76) N in group A and (488.24 +/- 32.42) N in group B, and there was significant difference between two groups (t = 2.147, P < 0.05). There was no statistically significant difference in all FSU between anterior transpedicular screws system and vertebral body screws system (F(A) = 2.27, F(B) = 2.05, P > 0.05). CONCLUSION: The pull out strength of anterior transpedicular screws system is better than vertebral body screws system, and the anterior transpedicular screws has the biomechanical feasibility in clinic.

[Treatment of flexion-distraction thoracolumbar fractures by postural reduction with instrumental reduction].

OBJECTIVE: To study the curative effect of postural reduction with instrumental reduction in treatment of flexion-distraction thoracolumbar fractures. METHODS: A retrospective study was performed on 43 patients with single thoracolumbar flexion-distraction fractures admitted from August 2009 to August 2011, included 28 males and 15 females with an average age of 44 years old (34 to 56 years old). All patients were treated with postural reduction with instrumental reduction. The kyphosis (Cobb angle) recovery of injured vertebral height and complication were analyzed. The visual analogue scale(VAS) and com-plications were followed up and recorded. RESULTS: There was no difference in recovery of injured vertebral posterior height among preoperative, 1 week and 1 year after operation (P > 0.05). There were significantly difference in kyphosis (Cobb angle) and recovery of injured vertebral anterior height between preoperative and postoperative at 1 week (P < 0.05). There was no difference in kyphosis (Cobb angle) and recovery of injured vertebral anterior height between 1 week and 1 year after operation (P > 0.05). VAS significantly improved from preoperative (7.2 +/- 1.2) to (0.8 +/- 0.7) at 1 year after operation (t = 18.47, P < 0.001). CONCLUSION: Postural reduction with instrumental reduction is effective for thoracolumbar flexion-distraction fractures and it is beneficial to the recovery of vertebral height and saggital alignment.

[Effect of reduction on spino-pelvic parameters in treating high-grade lumbar spondylolisthesis].

OBJECTIVE: To explore the effect of reduction on spino-pelvic balance in treating high-grade lumbar spondylolisthesis. METHODS: From Augest 2008 to Augest 2011, the data of 16 patients with high-grade lumbar spodylolisthesis (Meyerding grade III or more than grade III) underwent reduction treatment through posterior approach were retrospectively analyzed. There were 9 males and 7 females, aged from 24 to 65 years old with an average of 44 years. Preoperative, postoperative at 2 weeks and final follow-up, spino-pelvic parameters of all patients were measured and compared by total legth lateral X-rays, and spino-pelvic parameters included sacral slope (SS), pelvic tilt (PT), pelvic incidence (PI), lumbar lordosis (LL) and sagittal vertical axis (SVA); the informations of intervertebral bone fusion was observed by CT and postoperative complications were recorded; clinical effects were assessed according to clinical Oswestry score (CODI). RESULTS: All patients were followed up from 12 to 24 months with an average of 18 months. Four cases reduced anatomically, 8 cases reduced to grade I .4 cases reduced to grade II. There was statistically significant differences in sacral slope (SS), pelvic tilt (PT), lumbar lordosis angle (LL) and sagittal vertical axis (SVA) between before operation and two weeks after operation (P < 0.05), while pelvic incidence (PI) no statistically significant differences was found between before operation and two weeks after operation (P > 0.05). There was no statistically significant differences in SS, PT, LL, SVA, PI between two weeks after operation and final follow-up (P > 0.05). CODI had decreased from preoperative 36.6 ± 4.2 to 14.7 ± 4.0 at final follow-up (P < 0.05). One year after operation, all patients obtained bone fusion and can find the union of bone trabeculae by three-dimensional reconstruction CT. Three cases occurred transient nerve root pain, and recovered after medicinal treatment. No infection and internal fixation loosening and breakage were found. CONCLUSION: Surgical reduction for high-grade lumbar spondylolisthesis can improve spino-pelvic balance and acquire satisfactory outcomes.

[Analysis of epidural hematoma formative reason and its preventive measure after anterior cervical operation].

OBJECTIVE: To explore the risk factors,preventive measure of epidural hematoma after anterior cervical operation. METHODS: From June 2005 and December 2012, 1,452 patients underwent anterior cervical operation in our hospital. Epidural hematoma occurred in 5 cases after operation and the incidence rate was 0.34%. There were 4 males and 1 female with an average age of 46.4 years (ranged, 33 to 55); 3 cases with cervical myelopathy, 1 case with cervical myelopathy and C5 vertebral angeioma, 1 case with ossification of cervical posterior longitudinal ligament. The occurred time,main clinical situation,duration of symptoms,operative management of epidural hematoma were analyzed. RESULTS: Five patients with epidural hematoma occurred within 24 h; the average interval between onset of symptoms and surgery was 4 h (ranged, 2 to 7). Operative treatment was accomplished in 5 cases by exploration and hematoma evacuation. There was significant improvement in all patients after reoperation. Epidural hematoma occurred again in one patient at 5 h after hematoma evacuation, and reoperation were performed to treat it. All patients were followed up from 6 to18 months with an average of 13.8 months. No recurrence was found. CONCLUSION: Intensive care in 24 h postoperatively is important because of epidural hematoma often occurs in this period,especialy in the period of 6-8 h postoperativey. Clinical findings and MRI can early diagnose epidural hematoma and help treatment. Once it is identified and surgical evacuation would be performed on time.