Pedicle screw fixation for traumatic fractures of the thoracic and lumbar spine.

BACKGROUND: Spine fractures are common. The treatment of traumatic fractures of the thoracic and lumbar spine remains controversial but surgery involving pedicle screw fixation has become a popular option. OBJECTIVES: To assess the effects (benefits and harms) of pedicle screw fixation for traumatic fractures of the thoracic and lumbar spine. SEARCH METHODS: We searched the Cochrane Bone, Joint and Muscle Trauma Group Specialised Register (March 2011), the Cochrane Central Register of Controlled Trials (CENTRAL; The Cochrane Library, 2011 Issue 1), MEDLINE (1948 to March 2011), EMBASE (1980 to 2011 Week 11), the Chinese Biomedical Database (CBM Database) (1978 to March 2011), the WHO International Clinical Trials Registry Platform (March 2011), reference lists of articles and conference proceedings. SELECTION CRITERIA: Randomised controlled trials (RCTs) and quasi-randomised controlled trials comparing pedicle screw fixation and other methods of surgical treatment, or different methods of pedicle screw fixation, for treating traumatic fractures of the thoracic and lumbar spine. DATA COLLECTION AND ANALYSIS: Three review authors independently performed study selection, risk of bias assessment and data extraction. Limited meta-analysis was performed. MAIN RESULTS: Pedicle screw fixation versus other methods of surgery that do not involve pedicle screw fixation was not looked at in any of the identified trials. Studies that were identified investigated different methods of pedicle fixation.Five randomised and three quasi-randomised controlled trials were included. All were at high or unclear risk of various biases, including selection, performance and detection bias. A total of 448 patients with thoracic and lumbar spine fractures were included in the review. Participants were restricted to individuals without neurological impairment in five trials. The mean ages of study populations of the eight trials ranged from 33 to 41 years, and participants had generally experienced traumatic injury. Mean follow-up for trial participants in the eight trials ranged from 28 to 72 months.Five comparisons were tested.Two trials compared short-segment instrumentation versus long-segment instrumentation. These studies found no significant differences between the two groups in self-reported function and quality of life at final follow-up. Aside from one participant, who sustained partial neurological deterioration that was resolved by further surgery (group not known), no neurological deterioration was noted in these trials.One trial comparing short-segment instrumentation with transpedicular bone grafting versus short-segment fixation alone found no significant difference between the two groups related to patient-perceived function and pain at final follow-up. All participants had normal findings on neurological examination at final follow-up.Two trials compared posterior instrumentation with fracture level screw incorporation ('including' group) versus posterior instrumentation alone ('bridging' group). Investigators reported no differences between the two groups in patient-reported function, quality of life, or pain at final follow-up. One trial confirmed that all participants had normal findings on neurological examination at final follow-up.One trial comparing monosegmental pedicle screw instrumentation versus short-segment pedicle instrumentation found no significant differences between the two groups in Oswestry Disability Index results or in pain scores at final follow-up. No neurological deterioration was reported.Three trials compared posterior instrumentation with fusion versus posterior instrumentation without fusion. Researchers found no differences between the two groups in function and quality of life or pain. No participants showed a decline in neurological status in any of the three trials, and no significant difference was reported between groups in the numbers whose status had improved at final follow-up. Two trials stated that patients in the fusion group frequently had donor site pain. Other reported complications included deep vein thrombosis and superficial infection. AUTHORS' CONCLUSIONS: This review included only eight small trials and five different comparisons of methods of pedicle fixation in various participants while looking at a variety of outcomes at different time points. Overall, evidence is insufficient to inform the selection of different methods of pedicle screw fixation or the combined use of fusion. However, in the absence of robust evidence to support fusion, it is important to factor the risk of long-term donor site pain related to bone harvesting into the decision of whether to use this intervention. Further research involving high-quality randomised trials is needed.

[Preliminary study of influence of bone tissue from osteonecrosis of femoral head on the proliferation and differentiation of canine bone marrow mesenchymal stem cells].

OBJECTIVE: To examine the effects of bone tissue from osteonecrosis of femoral head on the proliferation and differentiation of canine bone marrow mesenchymal stem cells in vitro culture. METHODS: A canine model of femoral head osteonecrosis was induced by liquid nitrogen freezing. BMSC were isolated from dog ilium bone marrow by a combination of gradient centrifugation and adherent wall culture. Different bone tissues and BMSC were cultivated indirectly in vitro by co-cultured in Transwell plate. According to the culture media, 3 groups were established: blank group (10%FBS/DMEM), control group (10%FBS/DMEM+ bone tissue from natural femoral head) and experimental group (10%FBS/DMEM+ bone tissue from osteonecrosis of femoral head). Cell proliferation was measured by methyl-thiazol tetrazolium (MTT) method. Cell differentiation was examined by alkaline phosphatase (ALP) staining and its concentration examined. Alizarin red staining method was used to study the calcification effects and Oil red O staining method was used to detect if there was fat emergence. RESULTS: As compared with the blank group, the proliferation in the control and experiment groups were significantly promoted after culturing for Days 1, 3 and 5 (P < 0.05). The proliferation of the experiment group was higher than the control group at Day 5 and 7 day (P < 0.05). After a 7-day co-culturing, ALP staining was positive in the control and experiment groups. At Day 7 and 9, the ALP activity in culture fluid was in this order: control group > experiment group > blank group (P < 0.05). Alizarin red staining show control group had the most calcium nodules (12.17 ± 2.48, P < 0.05) and the number of calcium nodules in the experiment group was more than the blank group (P < 0.05). Oil red O staining show there was no fat emergence after 21 days in every group. CONCLUSION: Both natural and osteonecrotic bone tissue of femoral head could promoted the proliferation of canine BMSC and induces them osteogenic differentiation but not lipo differentiation, bone tissue from osteonecrosis of the femoral head had more competence in promoting proliferation but less capability in inducing osteogenic differentiation than natural bone tissue of the femoral head.

[Unilateral versus bilateral pedicle fixation at the level of fracture in the treatment of thoracolumbar fractures with mild to moderate instability].

OBJECTIVE: To evaluate the efficacies of unilateral versus bilateral pedicle screw fixation through the pedicle of fractured vertebra plus short-segment pedicle instrumentation (SSPI) in the treatment of thoracolumbar fractures. METHODS: Between June 2008 and September 2010, a total of 46 patients with fractures of thoracolumbar junction, whose scores of load sharing classification (LSC) ranging from 5 to 7, underwent the combined treatment of SSPI and fracture level pedicle screw at our department. They were divided into 2 groups. Group I included 25 patients undergoing SSPI plus unilateral pedicle screw fixation through the pedicle of fractured vertebra (5 screws) while Group II included 21 patients had SSPI plus bilateral pedicle screw fixation through the pedicle of fractured vertebra (6 screws). The data of anterior body height compression (AVHC), sagittal Cobb's angle, internal fixation failure, restoration of nervous function, visual analogue score (VAS) and Oswestry disability index (ODI) were analyzed. RESULTS: The groups were similar with regards to age, gender, LSC, AVHC and sagittal Cobb's angle preoperatively. Blood loss volume and operative duration were less in the Group I (109.2 ± 30.68 vs 110.0 ± 32.06 min, t = -0.086, P > 0.05 and 376.0 ± 303.1 vs 409.5 ± 361.1 ml, t = -0.342, P > 0.05). They were followed up for a minimum period of 12 months. In follow-up period was 17.48 ± 4.14 months in Group I versus 18.33 ± 4.31 months in Group II (t = -0.683, P > 0.05). All patients with initial partial neurologic deficits improved at the final follow-up. Radiographic parameters and clinical outcomes were similar in both groups. CONCLUSIONS: Pedicle screw fixation through the pedicle of fractured vertebra plus SSPI is an excellent surgical therapeutic choice for patients with a LSC range of 5-7 thoraclumbar fractures. The efficacies of unilateral and bilateral pedicle screw fixation at fracture level are the same.

[Experimental study of repairing femoral bone defects with nHA/RHLC/PLA scaffold composite with endothelial cells and osteoblasts in canines].

OBJECTIVE: To explore whether a tissue-engineered construct composed of autogenous endothelial cells, osteoblasts and a new bioresorbable nano-hydroxyapatite/recombinant human-like collagen/polylactic acid (nHA/RHLC/PLA) would enhance bone regeneration and repair femoral head defects in canine models. METHODS: The bone marrow stem cells (BMSCs) were isolated from bone marrow of canine ilium and cultured in Dulbecco's modified eagle medium:nutrient mixture F-12 culture media for 1 week and the second-generation BMSCs were further induced by osteogenic medium (1×10(-8) mol/L dexamethasone, 10 mmol/L B-sodium glycerophosphate and 50 µg/ml vitamin C) and by endothelial cell grow medium (vascular endothelial growth factor and basic fibroblast growth factor) for 14 days in vitro. Thus BMSCs were induced into ECs and OBs. After the second passage, cells were digested and collected.And cell density was adjusted to 1.0×10(6)/ml.The cells and nHA/RHLC/PLA scaffold were co-cultured for 2-4 hours then nHA/RHLC/PLA scaffold composites prepared. Cavity defects of 8 mm in diameter and 10 mm in height were made in femoral heads.The nHA/RHLC/PLA scaffold composited with ECs and osteoblasts (OBs) (group A) and composited with OBs (group B) were inserted into different defects while cell-free nHA/RHLC/PLA scaffold served as controls (group C). New bone formation and defect repair were evaluated at 3 and 6 months by radiographic examination, histology and bone histomorphometry. RESULTS: New bone formation was evident as early as 3 months in groups A, B and C.At 6 months, abundant bone tissue within defects was observed in group A. The control animals with cell-free scaffold showed less bone formation at both timepoints.The scaffold of nHA/RHLC/PLA was degraded and absorbed gradually with the formation of new bone tissues.Histology and bone histomorphometry further revealed significantly increased trabecular bones in group A compared with groups B and C at 6 months postimplantation (P < 0.01). CONCLUSION: More abundant new bone tissue may be found in the bone defect areas implanted with osteoblast-endotheliocyte composite than osteoblasts composite and scaffold materials only.ECs and osteoblasts derived from BMSC are ideal seed cells for repairing femoral head defects.

[Efficacy analysis of intermediate screws technique plus injectable calcium sulfate for thoracolumbar fracture in postmenopausal patients].

OBJECTIVE: To explore the clinical efficacies of intermediate screws plus injectable calcium sulfate MIIGX3 for thoracolumbar fracture in postmenopausal patients. METHODS: A total of 21 postmenopausal patients with vertebral compression fractures reconstructed with posterior internal fixation of intermediate screws technique and anterior vertebral augmentation of MIIGX3 technique in three dimension were retrospectively analyzed. The changes of fracture vertebral height and Cobb's angle were compared.Visual analogue scale (VAS) was performed to evaluate their symptoms. All patients were followed up. RESULTS: Intermediate screws surgical technique plus MIIGX3 was successfully performed. The average injection dose was 4.6 ml.Leakage occurred intraoperatively in two cases. The average follow-up period was 15 (6-36) months. The VAS system demonstrated that pain decreased significantly (preoperative:7.8, postoperative:2.2). The height and Cobb's angle of fractured vertebra improved greatly. The preoperative values were 45.0 ± 6.4% and 19.4 ± 4.5° and postoperative ones 15.4 ± 3.9% and 8.64 ± 3.18° respectively. There was no occurrence of severe complications related with treatment.Except for 2 patients with a loss of 15% of vertebral height, the average heights of fractured vertebra in other 19 patients recovered to 85% of normal ones. CONCLUSION: Thoracolumbar fracture in postmenopausal patients may be managed satisfactorily by intermediate screws and injectable calcium sulfate technique.Such a technique is both safe and effective. And its stable and durable reduction offers significant improvement.

The origins and dynamic changes of C3- and S100A10-positive reactive astrocytes after spinal cord injury.

Accaumulating studies focus on the effects of C3-positive A1-like phenotypes and S100A10-positive A2-like phenotypes of reactive astrocytes on spinal cord injury (SCI), however the origins and dynamic changes of C3- and S100A10-positive reactive astrocytes after SCI remain poorly understood. Through transgenic mice and lineage tracing, we aimed to determine the origins of C3- and S100A10-positive reactive astrocytes. Meanwhile, the distribution and dynamic changes in C3- and S100A10-positive reactive astrocytes were also detected in juvenile and adult SCI mice models and cultured astrocytes. Combing with bulk RNA sequencing (RNA-seq), single-cell RNA sequencing (scRNA-seq) and bioinformatic analysis, we further explored the dynamic transcripts changes of C3- and S100A10-positive reactive astrocytes after SCI. We confirmed that resident astrocytes produced both C3- and S100A10-positive reactive astrocytes, whereas ependymal cells regenerated only S100A10-positive reactive astrocytes in lesion area. Importantly, C3-positive reactive astrocytes were predominantly activated in adult SCI mice, while S100A10-positive reactive astrocytes were hyperactivated in juvenile mice. Furthermore, we observed that C3- and S100A10-positive reactive astrocytes had a dynamic transformation process at different time in vitro and vivo, and a majority of intermediate states of C3- and S100A10-positive reactive astrocytes were found during transformation. RNA-seq and scRNA-seq results further confirmed that the transcripts of C3-positive reactive astrocytes and their lipid toxicity were gradually increased with time and age. In contrast, S100A10-positive reactive astrocytes transcripts increased at early time and then gradually decreased after SCI. Our results provide insight into the origins and dynamic changes of C3- and S100A10-positive reactive astrocytes after SCI, which would be valuable resources to further target C3- and S100A10-positive reactive astrocytes after SCI.

Biomechanical response of lumbar intervertebral disc in daily sitting postures: a poroelastic finite element analysis.

This study aims to establish and validate a poroelastic L4-L5 finite element model to evaluate the effect of different sitting postures and their durations on the mechanical responses of the disc. During the sustained loading conditions, the height loss, fluid loss and von-Mises stress gradually increased, but the intradiscal pressure decreased. The varying rates of aforementioned parameters were more significant at the initial loading stage and less so at the end. The predicted values in the flexed sitting posture were significantly greater than other postures. The extended sitting posture caused an obvious von-Mises stress concentration in the posterior region of the inter-lamellar matrix. From the biomechanical perspective, prolonged sitting may pose a high risk of lumbar disc degeneration, and therefore adjusting the posture properly in the early stage of sitting time may be useful to mitigate that. Additionally, upright sitting is a safer posture, while flexed sitting posture is more harmful.

Dynamic changes in mechanical properties of the adult rat spinal cord after injury.

Spinal cord injury (SCI), a debilitating medical condition that can cause irreversible loss of neurons and permanent paralysis, currently has no cure. However, regenerative medicine may offer a promising treatment. Given that numerous regenerative strategies aim to deliver cells and materials in the form of tissue-engineered therapies, understanding and characterising the mechanical properties of the spinal cord tissue is very important. In this study, we have systematically characterised the spatiotemporal changes in elastic stiffness (elastic modulus, Pa) and viscosity (drop in peak force, %) of injured rat thoracic spinal cord tissues at distinct time points after crush injury using the indentation technique. Our results demonstrate that in comparison with uninjured spinal cord tissue, the injured tissues exhibited lower stiffness (median 3281 Pa versus 9632 Pa; P < 0.001) but demonstrated elevated viscosity (median 80% versus 57%; P < 0.001) at 3 days postinjury. Between 4 and 6 weeks after SCI, the overall viscoelastic properties of injured tissues returned to baseline values. At 12 weeks after SCI, in comparison with uninjured tissue, the injured spinal cord tissues displayed a significant increase in both elasticity (median 13698 Pa versus 9920 Pa; P < 0.001) and viscosity (median 64% versus 58%; P < 0.001). This work constitutes the first quantitative mapping of spatiotemporal changes in spinal cord tissue elasticity and viscosity in injured rats, providing a mechanical basis of the tissue for future studies on the development of biomaterials for SCI repair. STATEMENT OF SIGNIFICANCE: Spinal cord injury (SCI) is a devastating disease often leading to permanent paralysis. While enormous progress in understanding the molecular pathomechanisms of SCI has been made, the mechanical properties of injured spinal cord tissue have received considerably less attention. This study provides systematic characterization of the biomechanical evolution of rat spinal cord tissue after SCI using a microindentation test method. We find spinal cord tissue behaves significantly softer but more viscous immediately postinjury. As time passes, the lesion site gradually returns to baseline values and then displays pronounced increased viscoelastic properties. As host tissue mechanical properties are a crucial consideration for any biomaterial implanted into central nervous system, our results may have important implications for further studies of SCI repair.

T cell receptor ß repertoires in patients with COVID-19 reveal disease severity signatures.

Background: The immune responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are crucial in maintaining a delicate balance between protective effects and harmful pathological reactions that drive the progression of coronavirus disease 2019 (COVID-19). T cells play a significant role in adaptive antiviral immune responses, making it valuable to investigate the heterogeneity and diversity of SARS-CoV-2-specific T cell responses in COVID-19 patients with varying disease severity. Methods: In this study, we employed high-throughput T cell receptor (TCR) ß repertoire sequencing to analyze TCR profiles in the peripheral blood of 192 patients with COVID-19, including those with moderate, severe, or critical symptoms, and compared them with 81 healthy controls. We specifically focused on SARS-CoV-2-associated TCR clonotypes. Results: We observed a decrease in the diversity of TCR clonotypes in COVID-19 patients compared to healthy controls. However, the overall abundance of dominant clones increased with disease severity. Additionally, we identified significant differences in the genomic rearrangement of variable (V), joining (J), and VJ pairings between the patient groups. Furthermore, the SARS-CoV-2-associated TCRs we identified enabled accurate differentiation between COVID-19 patients and healthy controls (AUC > 0.98) and distinguished those with moderate symptoms from those with more severe forms of the disease (AUC > 0.8). These findings suggest that TCR repertoires can serve as informative biomarkers for monitoring COVID-19 progression. Conclusions: Our study provides valuable insights into TCR repertoire signatures that can be utilized to assess host immunity to COVID-19. These findings have important implications for the use of TCR ß repertoires in monitoring disease development and indicating disease severity.

[Unilateral pedicle screw fixation through the pedicle of fractured vertebra in combination with the short segment of pedicle screw in the treatment of thoracolumbar fracture of mild to moderate instability].

OBJECTIVE: To evaluate the efficacy of unilateral pedicle screw fixation through the pedicle of fractured vertebra in combination with the short segment of pedicle screw in the treatment of thoracolumbar fracture of mild to moderate instability. METHODS: Twenty-six patients with single segment thoracolumbar fracture received unilateral pedicle screw fixation through the pedicle of fractured vertebra in combination with the short segment of pedicle screw from January 2008 to December 2009. There were 16 patients were male and 10 were female with an average age of 47.3 years (range from 39 to 60 years). Fracture severity score was constructed by using the load-sharing classification (4 points for 2 cases, 5 points for 14 cases, 6 points for 10 cases). By Frankel assessment system, 2 cases were in grade C, 3 in grade D, 21 in grade E. The assessment included anterior vertebral body height, the sagittal Cobb angle, the restoration of nervous function, visual analogue score (VAS) and Oswestry disability index (ODI). RESULTS: The follow-up after the surgery was 13 - 26 months, with an average of 18.6 months. There were no fixation failure, defined as implant failure or ≥ 10° correction loss. The neurological status of 4 patients, who had an associated neurologic deficit preoperatively, was completely recovered. The Frankel grade of another case was re-rated D from the original C. The mean anterior vertebral body height increased from 57.0% ± 6.3% before the surgery to 93.1% ± 1.7% at the last follow-up(F = 455.276, P < 0.05). The sagittal Cobb angle decreased from 15.6° ± 4.7° before the surgery to 2.6° ± 5.2° at the last follow-up (F = 34.623, P < 0.05). VAS and ODI were 1.0 ± 0.7 and 17.0 ± 5.9 at the last follow-up. CONCLUSION: Unilateral pedicle screw fixation through the pedicle of fractured vertebra combined with the short segment of pedicle screw is effective for thoracolumbar fracture with mild to moderate instability.

Effect of Velocity and Contact Stress Area on the Dynamic Behavior of the Spinal Cord Under Different Testing Conditions.

Knowledge of the dynamic behavior of the spinal cord under different testing conditions is critical for our understanding of biomechanical mechanisms of spinal cord injury. Although velocity and contact stress area are known to affect external mechanical stress or energy upon sudden traumatic injury, quantitative investigation of the two clinically relevant biomechanical variables is limited. Here, freshly excised rat spinal-cord-pia-arachnoid constructs were tested through indentation using indenters of different sizes (radii: 0.25, 0.50, and 1.00 mm) at various loading rates ranging from 0.04 to 0.20 mm/s. This analysis found that the ex vivo specimen displayed significant nonlinear viscoelasticity at <10% of specimen thickness depth magnitudes. At higher velocity and larger contact stress area, the cord withstood a higher peak load and exhibited more sensitive mechanical relaxation responses (i.e., increasing amplitude and speed of the drop in peak load). Additionally, the cord became stiffer (i.e., increasing elastic modulus) and softer (i.e., decreasing elastic modulus) at a higher velocity and larger contact stress area, respectively. These findings will improve our understanding of the real-time complex biomechanics involved in traumatic spinal cord injury.

Effects of cortical intermittent theta burst stimulation combined with precise root stimulation on motor function after spinal cord injury: a case series study.

Activation and reconstruction of the spinal cord circuitry is important for improving motor function following spinal cord injury. We conducted a case series study to investigate motor function improvement in 14 patients with chronic spinal cord injury treated with 4 weeks of unilateral (right only) cortical intermittent theta burst stimulation combined with bilateral magnetic stimulation of L3-L4 nerve roots, five times a week. Bilateral resting motor evoked potential amplitude was increased, central motor conduction time on the side receiving cortical stimulation was significantly decreased, and lower extremity motor score, Berg balance score, spinal cord independence measure-III score, and 10 m-walking speed were all increased after treatment. Right resting motor evoked potential amplitude was positively correlated with lower extremity motor score after 4 weeks of treatment. These findings suggest that cortical intermittent theta burst stimulation combined with precise root stimulation can improve nerve conduction of the corticospinal tract and lower limb motor function recovery in patients with chronic spinal cord injury.

Effect of degenerative factors on cervical spinal cord during flexion and extension: a dynamic finite element analysis.

Spinal cord injury (SCI) is a global problem that brings a heavy burden to both patients and society. Recent investigations indicated degenerative disease is taking an increasing part in SCI with the growth of the aging population. However, little insight has been gained about the effect of cervical degenerative disease on the spinal cord during dynamic activities. In this work, a dynamic fluid-structure interaction model was developed and validated to investigate the effect of anterior and posterior encroachment caused by degenerative disease on the spinal cord during normal extension and flexion. Maximum von-Mises stress and maximum principal strain were observed at the end of extension and flexion. The abnormal stress distribution caused by degenerative factors was concentrated in the descending tracts of the spinal cord. Our finding indicates that the excessive motion of the cervical spine could potentially exacerbate spinal cord injury and enlarge injury areas. Stress and strain remained low compared to extension during moderate flexion. This suggests that patients with cervical degenerative disease should avoid frequent or excessive flexion and extension which could result in motor function impairment, whereas moderate flexion is safe. Besides, encroachment caused by degenerative factors that are not significant in static imaging could also cause cord compression during normal activities.

Comparison between closed suction drainage and nondrainage in total knee arthroplasty: a meta-analysis.

From individual randomized studies, it is not clear whether a closed suction drainage should be used after total knee arthroplasty. Our meta-analysis compares the clinical outcomes of closed suction drainage with nondrainage after total knee arthroplasty in randomized controlled trials reported between January 1966 and May 2010. Fifteen eligible trials involving 1361 knee incisions (686 knees with closed suction drainage and 675 knees without drainage) satisfied the inclusion criteria for our meta-analysis. The result of the meta-analysis indicates that closed suction drainage reduces the incidence of soft tissue ecchymosis and requirement for dressing reinforcement, but increases the rate of homologous blood transfusion. No significant difference between drainage and nondrainage was observed in the incidence of infection, deep venous thrombosis, or postoperative range of motion.

[Digital simulation of unipedicular thoracolumbar vertebroplasty puncture].

OBJECTIVE: To measure such operative parameters of unipedicular kyphoplasty as optimal entry point, angle and depth so as to provide rationales for its clinical management and formulate a standardized protocol for unipedicular vertebroplasty. METHODS: Ten dry thoracolumbar specimens were prepared for measurement. The entry and target points were defined according to the Roy-Camille method. A 3mm Kirschner wire was used to puncture and view in the anteroposterior and lateral aspects of radiography until a satisfying position. The outside oblique and upward oblique angles were measured on the radiographic pictures. After extraction, the depth of Kirschner wire was measured. The positions of entry point were changed and the largest upward oblique angle and largest declination angle measured on the radiographic pictures. RESULTS: For safe puncturing, as the outside oblique and upward oblique angles enlarged from T(11) to L(3), the length enlarged from T(11) to T(12) and L(1) to L(3). The accepted error was that the largest upward oblique angle and largest declination angle enlarged from T(11) to L(3). The alteration range for outside oblique angle was extremely narrow. CONCLUSION: The experimental results provide the guiding data for the operative management of unipedicular thoracolumbar vertebroplasty. If the pedicle is too small or the angle too narrow, the operative sophistication of vertebroplasty will be highly demanding.

[Building an effective nonlinear three-dimensional finite-element model of human thoracolumbar spine].

OBJECTIVE: To build an effective nonlinear three-dimensional finite-element (FE) model of T(11)-L(3) segments for a further biomechanical study of thoracolumbar spine. METHODS: The CT (computed tomography) scan images of healthy adult T(11)-L(3) segments were imported into software Simpleware 2.0 to generate a triangular mesh model. Using software Geomagic 8 for model repair and optimization, a solid model was generated into the finite element software Abaqus 6.9. The reasonable element C3D8 was selected for bone structures. Created between bony endplates, the intervertebral disc was subdivided into nucleus pulposus and annulus fibrosus (44% nucleus, 56% annulus). The nucleus was filled with 5 layers of 8-node solid elements and annulus reinforced by 8 crisscross collagenous fiber layers. The nucleus and annulus were meshed by C3D8RH while the collagen fibers meshed by two node-truss elements. The anterior (ALL) and posterior (PLL) longitudinal ligaments, flavum (FL), supraspinous (SSL), interspinous (ISL) and intertransverse (ITL) ligaments were modeled with S4R shell elements while capsular ligament (CL) was modeled with 3-node shell element. All surrounding ligaments were represented by envelope of 1 mm uniform thickness. The discs and bone structures were modeled with hyper-elastic and elasto-plastic material laws respectively while the ligaments governed by visco-elastic material law. The nonlinear three-dimensional finite-element model of T(11)-L(3) segments was generated and its efficacy verified through validating the geometric similarity and disc load-displacement and stress distribution under the impact of violence. Using ABAQUS/ EXPLICIT 6.9 the explicit dynamic finite element solver, the impact test was simulated in vitro. RESULTS: In this study, a 3-dimensional, nonlinear FE model including 5 vertebrae, 4 intervertebral discs and 7 ligaments consisted of 78 887 elements and 71 939 nodes. The model had good geometric similarity under the same conditions. The results of FEM intervertebral disc load-displacement curve were similar to those of in vitro test. The stress distribution results of vertebral cortical bone, posterior complex and cancellous bone were similar to those of other static experiments in a dynamic impact test under the observation of stress cloud. CONCLUSION: With the advantages of high geometric and mechanical similarity and complete thoracolumbar, hexahedral meshes, nonlinear finite element model may facilitate the impact loading test for a further dynamic analysis of injury mechanism for thoracolumbar burst fracture.

[Cartilage changes of femoral head osteonecrosis in stage II and III as detected by dGEMRIC].

OBJECTIVE: To detect the cartilage changes of hip joint with osteonecrosis of femoral head (ONFH) in stages II and III and provide evidence for understanding cartilage changes of femoral head of osteonecrosis before collapse. METHODS: The cartilage changes of ONFH were determined by delayed gadolinium enhanced magnetic resonance imaging of cartilage (dGEMRIC). According to ARCO classification of ONFH, the samples were divided into three groups: Group A, 11 hips, stageII; Group B, 13 hips, stage III; Group C, 10 hips, normal. All participates underwent the tests by dGEMRIC. And the data of T1Gd were collected and analyzed. RESULTS: The values of T1Gd were 420 ± 60 (Group A), 361 ± 54(Group B) and 538 ± 26 (Group C) respectively. There was a significant difference among three groups. The values of T1Gd in the ONFH patients were lower than their healthy counterparts. The values of TIGd of Group B was 14% lower than those of Group A. And the difference was significant statistically. CONCLUSION: Cartilage of the femoral head undergoes abnormal metabolic changes before collapse. There is a loss of GAG in the cartilage and it aggravates with the worsening of ONFH.

The Up-regulation of TNF-α Maintains Trigeminal Neuralgia by Modulating MAPKs Phosphorylation and BKCa Channels in Trigeminal Nucleus Caudalis.

Trigeminal neuralgia (TN) is a severe chronic neuropathic pain. Despite numerous available medical interventions, the therapeutic effects are not ideal. To control the pain attacks, the need for more contemporary drugs continues to be a real challenge. Our previous study reported that Ca2+-activated K+ channels (BK Ca ) channels modulated by mitogen-activated protein kinases (MAPKs) in the trigeminal ganglia (TG) neurons play crucial roles in regulating TN, and some research studies demonstrated that inflammatory cytokine tumor necrosis factor alpha (TNF-α) could promote neuropathic pain. Meanwhile, the trigeminal nucleus caudalis (TNC), the first central site of the trigeminal nociceptive pathway, is responsible for processing sensory and pain signals from the peripheral orofacial area. Thus, this study is aimed to further investigate whether TNF-α and MAPKs phosphorylation in the TNC could mediate the pathogenesis of TN by modulating BK Ca channels. The results showed that TNF-α of the TNC region is upregulated significantly in the chronic constriction injury of infraorbital nerve (ION-CCI) rats model, which displayed persistent facial mechanical allodynia. The normal rats with target injection of exogenous TNF-α to the fourth brain ventricle behaved just like the ION-CCI model rats, the orofacial mechanical pain threshold decreased clearly. Meanwhile, the exogenous TNF-α increased the action potential frequency and reduced the BK Ca currents of TNC neurons significantly, which could be reversed by U0126 and SB203580, the inhibitors of MAPK. In addition, U0126, SB203580, and another MAPK inhibitor SP600125 could relieve the facial mechanical allodynia by being injected into the fourth brain ventricle of ION-CCI model rats, respectively. Taken together, our work suggests that the upregulation of TNF-α in the TNC region would cause the increase of MAPKs phosphorylation and then the negative regulation of BK Ca channels, resulting in the TN.

Fixation of distal radius fracture with volar locking palmar plates while preserving pronator quadratus through the minimally invasive approach.

BACKGROUND: The volar locking plate technique with an L-shaped incision of the PQ muscle through the classic volar Henry approach is a popular method for treating distal radius fractures. Recently we revised and improved this traditional technique by performing mini-invasive surgery. OBJECTIVE: The purpose of this study was to evaluate the clinical effects after fixation of distal radius fracture with volar locking palmar plates while preserving the pronator quadratus through minimally invasive approach. METHODS: From May 2014 to March 2017, 58 patients (38 males and 21 females) with an age range of 22-72 years (mean age 44.6 years) and with distal radius fractures underwent open reduction and internal fixation with volar locking palmar plates. The patients were classified as 23A-2 through 23C-2 according to the Orthopedic Trauma Association fracture classification system. All surgeries were completed by one trained team. The group that received volar locking palmar plates of distal radius performed with the traditional method through Henry approach involved 33 patients (21 males and 12 females) and the group that received PQ through minimally invasive approach group involved 25 patients (16 males and 9 females). We compared the two groups for wrist pain, forearm range of motion, grip strength, preoperative complications and wrist functional recovery score. RESULTS: The minimum follow-up for the whole cohort was one year. The differences between the two groups were significant in terms of wrist pain, forearm range of motion, grip strength and wrist function at 1, 2, 6 weeks postoperatively, but insignificant at 3 and 12 months postoperatively. In the minimally invasive group a case of limited extension of the forefinger 3 months postoperatively was found. No significant differences were found for preoperative complications and radiographs postoperatively. CONCLUSION: Fixation with volar locking palmar plates through minimally invasive approach is a satisfactory and optional method in the treatment of distal radius fractures. This technique yields better early wrist function, shortens rehabilitation time and gets high psychological satisfaction.

Effects of a contusion load on spinal cord with different curvatures.

The cervical spine injury is a complicated procedure in the combination of different injury loads and postures. The aim of this study is to investigate the injury mechanism considering different types of cervical curvatures subjected to contusion loads. A finite element model of a cervical spinal cord was constructed. Gray matter, white matter and pia matter were modeled and hyperelastic material properties were assigned. Convergence analysis and validation analysis were carried out. The model was simulated in 3 different spinal curvatures and loaded by 2 directions with 4 compression degrees. The maximum von Mises stress in the whole model was concentrated in the pia matter in all loading cases. When investigating spinal cord injury, the pia matter must be considered. For all three curvatures, the stress in the gray matter and white matter was higher in front-to-back loading condition than that in back-to-front loading condition. The front-to-back impact may cause a larger damage. A back-to-front load damaged the structure around the central canal and a front-to-back contusion load damaged the anterior horn of the spinal cord at most time. From the view of the maximum stress, the lordotic curvature did not show significant buffering effect. However, the pathological curvature had large areas affected and the lordotic curvature showed some benefits to some degree from the view of stress distribution.