Risk factors for delayed colorectal postpolypectomy bleeding: a meta-analysis.

BACKGROUND: To systematically analyze risk factors for delayed postpolypectomy bleeding (DPPB) in colorectum. METHODS: We searched seven large databases from inception to July 2022 to identify studies that investigated risk factors for DPPB. The effect sizes were expressed by relative risk (RR) and 95% confidence interval (95% CI). The heterogeneity was analyzed by calculating I2 values and performing sensitivity analyses. RESULTS: A total of 15 articles involving 24,074 subjects were included in the study. The incidence of DPPB was found to be 0.02% (95% CI, 0.01-0.03), with an I2 value of 98%. Our analysis revealed that male sex (RR = 1.64), history of hypertension (RR = 1.54), anticoagulation (RR = 4.04), polyp size (RR = 1.19), polyp size ≥ 10 mm (RR = 2.43), polyp size > 10 mm (RR = 3.83), polyps located in the right semicolon (RR = 2.48) and endoscopic mucosal resection (RR = 2.99) were risk factors for DPPB. CONCLUSIONS: Male sex, hypertension, anticoagulation, polyp size, polyp size ≥ 10 mm, polyps located in the right semicolon, and endoscopic mucosal resection were the risk factors for DPPB. Based on our findings, we recommend that endoscopists should fully consider and implement effective intervention measures to minimize the risk of DPPB.

Machinability and Surface Properties of Cryogenic Poly(methyl methacrylate) Machined via Single-Point Diamond Turning.

Poly(methyl methacrylate) (PMMA), with a glass transition temperature (Tg) over 100 °C, shows good mechanical and optical properties and has broad applications after being machined with single-point diamond turning (SPDT) at room temperature. Because of the high Tg, current efforts mostly focus on optimizing machining parameters to improve workpiece precision without considering the modification of material properties. Cryogenic cooling has been proven to be an effective method in assisting ultra-precision machining for certain types of metals, alloys, and polymers, but has never been used for PMMA before. In this work, cryogenic cooling was attempted during the SPDT of PMMA workpieces to improve surface quality. The machinability and surface properties of cryogenically cooled PMMA were investigated based on the mechanical properties at corresponding temperatures. Nanoindentation tests show that, when temperature is changed from 25 °C to 0 °C, the hardness and Young's modulus are increased by 37% and 22%, respectively. At these two temperature points, optimal parameters including spindle speed, feed rate and cut depth were obtained using Taguchi methods to obtain workpieces with high surface quality. The surface quality was evaluated based on the total height of the profile (Pt) and the arithmetic mean deviation (Ra). The measurement results show that the values of Pt and Ra of the workpiece machined at 0 °C are 124 nm and 6 nm, respectively, while the corresponding values of that machined at 25 °C are 291 nm and 11 nm. The test data show that cryogenic machining is useful for improving the form accuracy and reducing the surface roughness of PMMA. Moreover, the relationship between temperature, material properties and machinability weas established with dynamic mechanical analysis (DMA) data and a theoretical model. This can explain the origin of the better surface quality of the cryogenic material. The basis of this is that temperature affects the viscoelasticity of the polymer and the corresponding mechanical properties due to relaxation. Then, the material property changes will affect surface profile formation during machining. The experimental results and theoretical analysis show that cryogenically cooled PMMA has good machinability and improved surface quality when using SPDT compared to that at ambient temperature.

Characteristics of cervical intervertebral disc signal intensity: an analysis of T2-weighted magnetic resonance imaging in 5843 asymptomatic Chinese subjects.

PURPOSE: The study aimed to observe cervical intervertebral discs (IVDs) in asymptomatic subjects and to explore the factors associated with cervical intervertebral disc degeneration (IVDD). METHODS: Cervical spine MRI of 5843 subjects was retrospectively analyzed. On the sagittal T2-weighted MR images, the mean signal intensities of the nucleus pulposus were obtained. Standard signal intensity (SSI) of intervertebral discs was defined as the ratio of mean disc signal intensity to mean CSF signal intensity. RESULTS: In subjects under 70 years old, the SSI of IVD was lowest at the C5/6 level. In those over 70, the SSI of IVD was similar among the disc levels from C2/3 to C7/T1. The disc SSI decreased significantly with age in both genders. In subjects under 70 years old, the SSI of the discs at each level was higher in females than in males. In those over 70 years old, no difference was found in disc SSI between two genders at most disc levels. Logistic regression analysis showed that kyphotic and straight cervical spine, obesity and older age were associated with higher risk of having lower disc SSI. CONCLUSION: To our knowledge, this is the largest cross-sectional study using MRI-based quantitative assessment to characterize cervical IVDD in asymptomatic subjects. Cervical IVDD was shown to progress with age and significantly correlated with gender, BMI and cervical alignment. Early intervention of related factors may help delay cervical IVDD and prevent future neck and shoulder pain.

Predictive Classification System for Low Back Pain Based on Unsupervised Clustering.

STUDY DESIGN: Retrospective study. OBJECTIVE: Lumbar magnetic resonance imaging (MRI) findings are believed to be associated with low back pain (LBP). This study sought to develop a new predictive classification system for low back pain. METHOD: Normal subjects with repeated lumbar MRI scans were retrospectively enrolled. A new classification system, based on the radiological features on MRI, was developed using an unsupervised clustering method. RESULTS: One hundred and fifty-nine subjects were included. Three distinguishable clusters were identified with unsupervised clustering that were significantly correlated with LBP (P = .017). The incidence of LBP was highest in cluster 3 (57.14%), nearly twice the incidence in cluster 1 (30.11%). There were obvious differences in the sagittal parameters among the 3 clusters. Cluster 3 had the smallest intervertebral height. Based on follow-up findings, 27% of subjects changed clusters. More subjects changed from cluster 1 to clusters 2 or 3 (14.5%) than changed from cluster 2 or cluster 3 to cluster 1 (5%). Participation in sport was more frequent in subjects who changed from cluster 3 to cluster 1. CONCLUSION: Using an unsupervised clustering method, we developed a new classification system comprising 3 clusters, which were significantly correlated with LBP. The prediction of LBP is independent of age and better than that based on individual sagittal parameters derived from MRI. A change in cluster during follow-up may partially predict lumbar degeneration. This study provides a new system for the prediction of LBP that should be useful for its diagnosis and treatment.

In vitro and in vivo effects of hyperglycemia and diabetes mellitus on nucleus pulposus cell senescence.

Diabetes mellitus contributes to intervertebral disc degeneration. Nucleus pulposus cell senescence plays an important role in intervertebral disc degeneration. However, the effects of hyperglycemia on human nucleus pulposus cells and the underlying process remains poorly understood. In the current study, we evaluated the effects of high glucose levels on human nucleus pulposus cell senescence in vitro and the effects of hyperglycemia on rat nucleus pulposus aging in vivo. Human nucleus pulposus cells were cultured in high-glucose medium (200 mM glucose) for 48 h. Senescence-associated ß-galactosidase staining, western blot analysis, and enzyme-linked immunosorbent assays were performed to evaluate human nucleus pulposus cell senescence. Flow cytometry and enzyme-linked immunosorbent assays were used to evaluate reactive oxygen species and advanced glycation end-product levels. Transcriptome sequencing followed by bioinformatics analysis was used to understand the abnormal biological processes of nucleus pulposus cells cultured in high-glucose medium. Diabetes mellitus rat models were established and histopathological and immunohistochemical analysis was conducted to examine nucleus pulposus tissue senescence in vivo. Exposure to a high glucose concentration promoted human nucleus pulposus cell senescence and increased the senescence-related secretion phenotype in human nucleus pulposus cells in vitro and in rat nucleus pulposus tissue in vivo. Bioinformatics analysis showed that hub genes were involved in nucleus pulposus cell cycle activities and cell senescence. The results suggest that appropriate blood glucose control may be key to preventing intervertebral disc degeneration in diabetic patients.

Impact of meteorological factors on hospital admissions for spinal diseases in Shanghai during 2015-2019.

PURPOSE: To assess the correlation between meteorological factors and spinal disease admissions. METHODS: Data was obtained from the electronic medical records of a tertiary general hospital. Meteorological data was collected from China Meteorological Science Data Sharing Service. Distributed lag nonlinear models were used to evaluate the impact of meteorological variables on weekly spinal disease admissions. RESULTS: A total of 2739 spinal cases were documented. Compared with estimates at the 50th, the cumulative relative risk (RR) for extremely high temperatures at the 97.5th over lag week 18 to lag week 20 increased by 75.7%. When the weekly maximum temperature reached 38°C during lag week 20, the maximum RR was 1.96 (95% CI:1.095-3.506). Moreover, the effects of extremely high temperatures on spinal disease admissions were more obvious in females and the age group ≥65 years old compared with males and the age group<65 years old. CONCLUSIONS: Extremely high temperatures were significantly associated with higher risks of spinal disease admissions.

A finite element analysis on comparing the stability of different posterior fixation methods for thoracic total en bloc spondylectomy.

OBJECTIVE: To compare the spinal stability with different fixation methods after thoracic TES using finite element analysis METHODS: The spinal finite element model was established from a healthy volunteer, and the validity was verified. The models of T8 thoracic total en bloc spondylectomy (TES) with and without artificial vertebral body were established combination with different fixation methods: the first was long segment fixation with fixed segments T5-7, T9-11; the second was short segment fixation with fixed segments T6-7, T9-10; the third was modified short segment with a pair of vertebral body screws on T7 and T9 added on the basis of short segment fixation. The motions of each model in standing state were simulated in software. The range of motion (ROM) and internal fixation stress changes were analyzed. RESULTS: When anterior support was effective, the three fixation methods could effectively maintain the stability of the spine. However, when anterior support failed, the ROM of the long segment fixation group and the short segment fixation group in the flexion-extension directions was significantly higher than that of when the anterior support existed, while the modified short segment fixation group had no significant changes. Meanwhile, the stress of internal fixation in the long segment fixation group and the short segment fixation group were greatly increased. However, there were no significant changes in modified short segment fixation group. CONCLUSION: After TES, the presence of the thoracic cage gives partial anterior stabilization. When the anterior support failed, the modified short segment fixation method can provide better stability.

Cage migration after unilateral instrumented transforaminal lumbar interbody fusion and associated risk factors: a modified measurement method.

OBJECTIVE: In this retrospective study, a modified measurement method was used to analyze cage migration during follow-up after unilateral instrumented transforaminal lumbar interbody fusion (TLIF) and identify associated factors. METHODS: We retrospectively evaluated 75 patients who had been treated with unilateral instrumented TLIF. Cage migration was quantitatively defined as anterior-posterior or lateral displacement of the cage. RESULTS: Five patients had significant cage migration (6.7%), but none developed severe neural symptoms during follow-up or underwent reoperation. The cages tended to migrate posteriorly or toward the side of surgery. The initial cage position and patient age were strongly associated with migration. Migration was less frequent when the cages were initially placed closer to the side of surgery. Patients of advanced age were more likely to develop anterior-posterior migration than were young patients. CONCLUSION: Cage migration is related to the initial position of the cage. Particular attention is required when performing unilateral instrumented TLIF in patients of advanced age because they are most likely to develop cage migration. Quantification of cage migration is an effective method of exploring the associated factors.

MiR-92b-3p promotes neurite growth and functional recovery via the PTEN/AKT pathway in acute spinal cord injury.

Emerging evidence indicates that microRNAs play an important role in neural remodeling, including neurite growth, after acute spinal cord injury (ASCI). This study aims to identify the mechanism by which miR-92b-3p regulates neurite growth in vivo and in vitro. Adult Sprague-Dawley rats were selected to establish the ASCI model, and the expressions of miR-92b-3p and phosphate and tensin homolog deleted on chromosome ten (PTEN) were quantified at different time points. The interaction between miR-92b-3p and PTEN was further detected in the PC12 cell line and dual-luciferase reporter assay. Neurite growth proteins (GAP43 and NF-200) were assessed by western blotting after miR-92b-3p mimics treatment. The PTEN/AKT pathway-related proteins and their roles in miR-92b-3p regulation were also identified using western blotting and immunofluorescence in vitro through LY294002, an AKT inhibitor. The effect of miR-92b-3p was further determined in vivo according to the Basso-Beattie-Bresnahan (BBB) Scale and GAP43 and NF-200 expressions. miR-92b-3p was downregulated after ASCI, while PTEN showed a simultaneous opposing trend. Overexpression of miR-92b-3p downregulated PTEN expression and promoted phosphorylation of AKT, as well as the expression of GAP43 and NF-200 in PC12 cells. Furthermore, the dual-luciferase reporter assay revealed that miR-92b-3p exerted its effect by targeting PTEN's 3'-untranslated regions and that this effect could be counteracted by AKT phosphorylation blocker LY294002 through western blotting and immunofluorescence. Moreover, miR-92b-3p could also improve the BBB scale as well as GAP43 and NF-200 expression levels in vivo. Collectively, these results indicate that miR-92b-3p promotes neurite growth and functional recovery through the PTEN/AKT pathway in ASCI.

Translaminar facet joint screw insertion with a rapid prototyping guide template: a cadaver study.

It is technically demanding and requires rich experience to insert the translaminar facet screw(TFS) via the paramedian mini-incision approach. It seems that it is easy to place the TFS using computer-assisted design and rapid prototyping(RP) techniques. However, the accuracy and safety of these techniques is still unknown. The aim of this study is to assess the accuracy and safety of translaminar facet screw placement in multilevel unilateral transforaminal lumbar interbody fusion using a rapid prototyping drill guide template system. A patient-matched rapid prototyping translaminar facet screw guide was examined in fourteen cadaveric lumbar spine specimens. A three-dimensional (3D) preoperative screw trajectory was constructed using spinal computed tomography scans, from which individualized guides were developed for the placement of translaminar facet screws. Following bone tunnel establishment, the 3D positioning of the entry point and trajectory of the screws was compared to the preoperative plan as found in the Mimics software.Among 60 trajectories eligible for assessment, no cases of clinically significant laminar perforation were found. The mean deviation between the planned and the actual starting points on spinous process was 1.22 mm. The mean tail and submergence angle deviation was found to be 0.68°and 1.46°, respectively. Among all the deviations, none were found to have any statistical significance. These results indicate that translaminar facet screw placement using the guide system is both accurate and safe.

Reduction of HIP2 expression causes motor function impairment and increased vulnerability to dopaminergic degeneration in Parkinson's disease models.

Huntingtin interaction protein 2 (HIP2) is an E2 ubiquitin-conjugating enzyme associated with neurodegenerative diseases, and HIP2 mRNA has been implicated as a potential blood biomarker for Parkinson's disease (PD). However, it is unclear whether the alteration of HIP2 expression may contribute to the development of PD, and whether the change of HIP2 in blood could reflect its expression in the brain or motor functions in PD patients. In this study, we established a mouse line with HIP2 haploinsufficiency. The reduction of the HIP2 expression led to spontaneous motor function impairment and dopaminergic neuronal loss. Furthermore, HIP2 haploinsufficiency increased the susceptibility of mice to 6-hydroxydopamine (6-OHDA) and caused severe loss of dopaminergic neurons. Interestingly, in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model for PD, we observed concurrent, highly correlated decrease of HIP2 expression in the brain and in the blood. Using blood samples from more than 300 patients, we validated the decreased HIP2 mRNA in PD patients, including de novo patients. Finally, in a 1-year, 20-patient study, we observed reversed blood HIP2 mRNA levels accompanying improved motor and overall daily functions in 75% of the PD patients with instructed Tai Chi training. Therefore, our in vivo studies have indicated HIP2 insufficiency as a contributing factor for PD, and functionally validated blood HIP2 as a useful and reversible biomarker for PD.

Pedicle Screw with Cement Augmentation in Unilateral Transforaminal Lumbar Interbody Fusion: A 2-Year Follow-Up Study.

OBJECTIVE: To evaluate safety and efficacy of pedicle screw with polymethyl methacrylate (PMMA) augmentation in unilateral transforaminal lumbar interbody fusion (uTLIF) in osteoporotic patients. METHODS: We randomly divided 50 osteoporotic patients with degenerative lumbar diseases diagnosed between February 2014 and November 2015 into 2 groups. One group underwent standard uTLIF, and the other group underwent uTLIF with PMMA augmentation. All patients were scheduled to attend a series of regular follow-up evaluations. Oswestry Disability Index, Japanese Orthopaedic Association score, visual analog scale score, lumbar lordotic angle, segmental lordotic angle, and disc space height (DSH) at each follow-up were collected and analyzed. RESULTS: The 2-year follow-up was completed by 24 patients in the uTLIF group and 23 patients in the PMMA group. Oswestry Disability Index, Japanese Orthopaedic Association score, and visual analog scale score showed significant improvements after surgery in both groups, with no significant difference between groups. DSH in the uTLIF group was 8.7 ± 2.3 mm and in the PMMA group was 10.7 ± 1.6 mm. Fusion rate in the uTLIF group was 19/24 and in the PMMA group was 21/23. DSH and fusion rate in the PMMA group were higher than those in the uTLIF group. No severe complications were observed after PMMA injection. CONCLUSIONS: Pedicle screw with PMMA augmentation can increase fixation stability and reduce DSH loss in uTLIF. Moreover, PMMA in the vertebral body did not impede the interbody fusion ability in uTLIF.

Neuroserpin restores autophagy and promotes functional recovery after acute spinal cord injury in rats.

This study is to reveal the characteristics of autophagy and the effect of neuroserpin (NSP) treatment on autophagy during the process of functional recovery following spinal cord injury (SCI). After the clip compress rat model of SCI had been made, autophagy­associated proteins, including LC3­II, beclin­1 and p62, were evaluated at 2, 4, 24, 72 h, and 168 h in the experimental group, and the sham group as control. Transmission electron microscopy (TEM) was further used for autophagy detection at 4 and 72 h. All the male rats were randomly divided into three groups: Sham, vehicle and NSP group. NSP or an equal volume of saline vehicle was administered via intrathecal injection immediately after SCI. Each group was further divided into subgroups for the following experiments: i)Western blot (LC3­II and p62); ii) Immunofluorescent double staining (LC3/MAP­2/DAPI); iii) Nissl staining and Basso Beattie Bresnahan (BBB score) for NSP neuroprotection evaluation. Our results revealed both LC3­II and p62 expression trended upward at 24, 72 and 168 h after SCI. The LC3­II peaked at 72 h, while p62 peaked at 24 h. Beclin­1 dropped significantly at 72 and 168 h. TEM results showed that autophagosomes largely accumulated at 72 h after SCI when compared with the sham group. Western blot analysis showed that LC3­II and p62 were markedly decreased with NSP treatment at 72 h after injury compared with that of the vehicle­group. Immunofluorescent double labeling indicated that accumulation of autophagosomes was reduced in the NSP group. Further, post­SCI treatment with NSP improved the BBB scale and increased the number of anterior horn motor neurons. Together, this study demonstrates that autophagic flux is impaired, meanwhile NSP restores autophagic flux and promotes functional recovery after SCI in rats.

Biomechanical evaluation of different surgical procedures in single-level transforaminal lumbar interbody fusion in vitro.

BACKGROUNDS: A variety of improved surgical methods were adopted in the transforaminal lumbar interbody fusion. A mechanical stability provides an ideal environment for the formation of a fusion mass and is the basis of their good outcomes. The object of this study is to evaluate the initial similarities and differences of four commonly-used posterior surgical procedures biomechanically. METHODS: Biomechanical testing was performed at L3-4 motion segment in 6 fresh-frozen human cadaveric lumbar spines (L2-L5), including the following sequentially tested configurations: 1) intact motion segment; 2) bilateral pedicle screw fixation; 3) unilateral pedicle screw fixation; 4) unilateral pedicle screw plus contralateral translaminar facet joint screw fixation according to the Magerl technique; and 5) bilateral pedicle screw fixation with bilateral facetectomies. The range of motion, neutral zone and stiffness of each method and intact segment were collected and compared. FINDINGS: All of four methods reduce the range of motion significantly in flexion and extension and lateral bending but not in axial torsion compared with the native segment. There is no significant difference among four procedures about the range of motion in all loading modes. All of methods increase the stiffness of segmental motion compared with intact segment in all loading modes, but only bilateral pedicle screw fixation showed significant increases in stiffness in flexion and extension(p=0.02) and lateral bending(p=0.023). The stiffness offered by instrumented constructs in different methods showed no significant difference in all loading modes. INTERPRETATION: The stiffness offered by four different posterior fixations in single segmental transforaminal lumbar interbody fusion is not significantly different.

Unilateral Versus Bilateral Pedicle Screw Fixation in Transforaminal Lumbar Interbody Fusion: A Monocentric Study of 215 Patients With a Minimum of 4-Year Follow-up.

STUDY DESIGN: A retrospective clinical study. OBJECTIVE: This study sought to retrospectively compare the mid-term to long-term outcomes between unilateral pedicle screw (UPS) and bilateral pedicle screw (BPS) augmented transforaminal lumbar interbody fusion (TLIF) in lumbar degenerative diseases. SUMMARY OF BACKGROUND DATA: Recently, UPS fixation has been applied in TLIF, for its satisfactory clinical outcome, less implants and less invasiveness. However, only short-term outcome has been reported, the mid-term to long-term outcome has not been well characterized. MATERIALS AND METHODS: From June 2007 to February 2011, 215 of 348 consecutive patients suffering from lumbar degenerative diseases were operated in our hospital and accomplished a minimum of 4-year follow-up. These patients were divided into 2 groups according to the operative techniques: UPS group (n=109), and bilateral pedicle screw group (n=106). Operative time, blood loss, length of hospital stay, hospital bill, fusion status, and complications were recorded and analyzed statistically. Visual analog scale, Oswestry disability index, and Japanese Orthopaedic Association scores were used to assess the preoperative and postoperative pain and functional outcome. RESULTS: The mean follow-up duration was 52.2 months. A significant decrease occurred in operative time, blood loss, and hospital bill in unilateral group, compared with bilateral group (P<0.05). The average postoperative visual analog scale, Oswestry disability index, and Japanese Orthopaedic Association scores improved significantly in each group than the preoperative counterparts (P<0.05); however, there were no significant difference between groups at any follow-up time point (P>0.05). No statistically difference was detected regarding fusion rate and complication rate between the 2 groups (P>0.05), except the cage migration rate (P<0.05). CONCLUSIONS: UPS fixation could achieve satisfactory clinical outcome similar to bilateral fixation in TLIF at a mid-term to long-term follow-up. To avoid cage migration, bullet-shaped cages should not be used in the unilateral group.

Miniopen Transforaminal Lumbar Interbody Fusion with Unilateral Fixation: A Comparison between Ipsilateral and Contralateral Reherniation.

The aim of this study was to evaluate the risk factors between ipsilateral and contralateral reherniation and to compare the effectiveness of miniopen transforaminal lumbar interbody fusion (TLIF) with unilateral fixation for each group. From November 2007 to December 2014, clinical and radiographic data of each group (ipsilateral or contralateral reherniation) were collected and compared. Functional assessment (Visual Analog Scale (VAS) score and Japanese Orthopaedic Association (JOA)) and radiographic evaluation (fusion status, disc height, lumbar lordosis (LL), and functional spine unit (FSU) angle) were applied to compare surgical effect for each group preoperatively and at final followup. MacNab questionnaire was applied to further evaluate the satisfactory rate after the discectomy and fusion. No difference except pain-free interval was found between ipsilateral and contralateral groups. There was a significant difference in operative time between two groups. No differences were found in clinical and radiographic data for assessment of surgical effect between two groups. The satisfactory rate was decreasing in both groups with time passing after discectomy. Difference in pain-free interval may be a distinction for ipsilateral and contralateral reherniation. Miniopen TLIF with unilateral pedicle screw fixation can be a recommendable way for single level reherniation regardless of ipsilateral or contralateral reherniation.

Etiology for Degenerative Disc Disease.

Degenerative disc disease is a multifaceted progressive irreversible condition and an inevitable part of aging, which has been found to be a contributing factor for low back pain and might cause radiculopathy, myelopathy, spinal stenosis, degenerative spondylolisthesis, and herniations. Its etiology is complex and multifactorial. Although genetics influence more dominant, the occupational and mechanical influences still persist as a major risk factor. This review emphasizes up-to-date knowledge regarding etiology of disc degeneration with special consideration on occupational, lifestyle factors, and genetic polymorphisms.