Objective:To analyze the risk factors for clinically relevant delayed gastric emptying (CR-DGE) following laparoscopic pancreaticoduodenectomy (LPD) and to develop a model to predict the postoperative CR-DGE after LPD using the machine-learning approach with multi-model comparison.Methods:Clinical data of 278 patients with tumors located in the pancreatic head and periampullary region undergoing LPD at People’s Hospital of Zhengzhou University from January 2019 to December 2023 were retrospectively analyzed, including 167 males and 111 females, aged 59 (53, 66) years. According to the occurrence of DGE, patients were divided into the CR-DGE group ( n=94) and the non-CR-DGE group ( n=184). Main clinical characteristics were compared between the groups, including pancreatic duct diameter, intraoperative blood loss and operative time. The perioperative indicators were selected using the least absolute shrinkage and selection operator (LASSO) algorithm. Following variable selection, 278 patients were allocated into a training set ( n=222) and a validation set ( n=56) in an 8∶2 ratio. Eight machine learning models were selected to model the training set: random forest, adaptive boosting, light gradient boosting, multilayer perceptron, support vector machine, K-nearest neighbor algorithm, decision tree and complementary set plain bayes. The area under the curve (AUC) of receiver operating characteristic curve of the validation set was utilized to identify the optimal model. The predictive performance of the optimal model was evaluated using calibration plots and decision curve analysis (DCA). The contribution of each feature to the prediction is assessed using Shapley additive explanation (SHAP). Results:Univariate analysis showed statistically significant differences between the CR-DGE and non-CR-DGE groups in terms of age [66(62, 69) years vs. 56(51, 60), years], diabetes [42.6%(40/94) vs. 11.4%(21/184)], level of fibrinogen [3.43(2.74, 4.18) g/L vs. 3.84(3.19, 4.68) g/L], pancreatic duct diameter [2.00(1.50, 2.70) mm vs. 3.40(1.60, 5.00) mm], intraoperative blood loss [300(200, 600) ml vs. 200(150, 300) ml], operative time [472(430, 502) min vs. 430(365, 475) min], clinically relevant postoperative pancreatic fistula [34.0%(32/94) vs. 3.8%(7/184)], abdominal fluid accumulation [46.8%(44/94) vs. 12.5%(23/184)], postoperative hemorrhage [20.2%(19/94) vs. 3.3%(6/184)], abdominal infection [28.7%(27/94) vs. 11.4% (21/184)] and duration of postoperative gastrointestinal decompression [4.00 (2.00, 6.00) d vs. 3.00 (2.00, 5.00) d] (all P<0.05). The eleven variables selected via LASSO were incorporated into each of the eight machine learning models. Results demonstrated that the random forest model achieved the highest performance in the validation set, with an AUC of 0.894 (95% CI: 0.800-0.985), accuracy of 0.820 and sensitivity of 0.606. Calibration plots and DCA confirmed the robustness of the random forest model. SHAP analysis indicated that age, pancreatic duct diameter and preoperative aspartate aminotransferase were important predictors in the random forest model. Conclusion:The random forest model developed in this study demonstrated a good predictive performance for CR-DGE after LPD and may assist in the early identification of high-risk patients in clinical practice.

Demyelination and remyelination play key roles in spinal cord injury (SCI), affecting the recovery of motor and sensory functions. Research in rodent models is extensive, but the study of these processes in non-human primates is limited. Therefore, our goal was to thoroughly study the histological features of demyelination and remyelination after contusion injury of the cervical spinal cord in Macaca fascicularis. In a previous study, we created an SCI model in M. fascicularis by controlling the contusion displacement. We used Eriochrome Cyanine staining, immunohistochemical analysis, and toluidine blue staining to evaluate demyelination and remyelination. The results showed demyelination ipsilateral to the injury epicenter both rostrally and caudally, the former mainly impacting sensory pathways, while the latter primarily affected motor pathways. Toluidine blue staining showed myelin loss and axonal distension at the injury site. Schwann cell-derived myelin sheaths were only found at the center, while thinner myelin sheaths from oligodendrocytes were seen at the center and surrounding areas. Our study showed that long-lasting demyelination occurs in the spinal cord of M. fascicularis after SCI, with oligodendrocytes and Schwann cells playing a significant role in myelin sheath formation at the injury site.
Animals ; Spinal Cord Injuries/physiopathology* ; Demyelinating Diseases/etiology* ; Remyelination/physiology* ; Macaca fascicularis ; Disease Models, Animal ; Myelin Sheath/pathology* ; Oligodendroglia/pathology* ; Schwann Cells/pathology* ; Female ; Spinal Cord/pathology* ; Axons/pathology*

Objective To investigate the effects of inclined axial compressive force and flexion moment on the anterior and posterior shear stiffness of the lumbosacral segment.Methods Six fresh-frozen human cadaveric L5-S1 segments were tested under intact and two progressively impaired structural conditions:intact,a 4-mm bilateral facet joint gap,and anterior discectomy with nucleus pulposus removal plus circumferential release of the inner annular fibers(disc injury).A 300 N axial compressive force was applied either vertically downward or with a 10° or 20° anterior inclination through the disc's shear center.Anterior(0 N to 250 N)and posterior(-50 N to 0 N)shear tests were conducted using a material testing machine.These tests were repeated under a 5 N-m flexion moment.The relative motion between L5 and Si was measured using a three-dimensional motion capture system.Results In the intact state,the inclination of the axial compressive force did not significantly alter anterior or posterior shear stiffness.However,the application of a flexion moment increased anterior shear stiffness by 49.3％.Progressive structural damage resulted in incremental increases in anteroposterior shear translation and corresponding reductions in stiffness.Notably,under combined loading with axial compression and flexion moment,anterior stiffness decreased from 939 N/mm(intact)to 224 N/mm(disc injury),while posterior stiffness decreased from 572 N/mm to 217 N/mm.Within the low-load range,no significant differences in shear stiffness were observed across any structural conditions,regardless of axial force inclination or combined with a flexion moment.Conclusions This study supports the clinical view that retro-inclination of the pelvis serves as a compensatory mechanism to enhance segmental shear stability.However,this compensatory capacity gradually diminishes and ultimately fails as spinal degeneration progresses.

Objective To investigate the effects of inclined axial compressive force and flexion moment on the anterior and posterior shear stiffness of the lumbosacral segment.Methods Six fresh-frozen human cadaveric L5-S1 segments were tested under intact and two progressively impaired structural conditions:intact,a 4-mm bilateral facet joint gap,and anterior discectomy with nucleus pulposus removal plus circumferential release of the inner annular fibers(disc injury).A 300 N axial compressive force was applied either vertically downward or with a 10° or 20° anterior inclination through the disc's shear center.Anterior(0 N to 250 N)and posterior(-50 N to 0 N)shear tests were conducted using a material testing machine.These tests were repeated under a 5 N-m flexion moment.The relative motion between L5 and Si was measured using a three-dimensional motion capture system.Results In the intact state,the inclination of the axial compressive force did not significantly alter anterior or posterior shear stiffness.However,the application of a flexion moment increased anterior shear stiffness by 49.3％.Progressive structural damage resulted in incremental increases in anteroposterior shear translation and corresponding reductions in stiffness.Notably,under combined loading with axial compression and flexion moment,anterior stiffness decreased from 939 N/mm(intact)to 224 N/mm(disc injury),while posterior stiffness decreased from 572 N/mm to 217 N/mm.Within the low-load range,no significant differences in shear stiffness were observed across any structural conditions,regardless of axial force inclination or combined with a flexion moment.Conclusions This study supports the clinical view that retro-inclination of the pelvis serves as a compensatory mechanism to enhance segmental shear stability.However,this compensatory capacity gradually diminishes and ultimately fails as spinal degeneration progresses.

Objective:To analyze the risk factors for clinically relevant delayed gastric emptying (CR-DGE) following laparoscopic pancreaticoduodenectomy (LPD) and to develop a model to predict the postoperative CR-DGE after LPD using the machine-learning approach with multi-model comparison.Methods:Clinical data of 278 patients with tumors located in the pancreatic head and periampullary region undergoing LPD at People’s Hospital of Zhengzhou University from January 2019 to December 2023 were retrospectively analyzed, including 167 males and 111 females, aged 59 (53, 66) years. According to the occurrence of DGE, patients were divided into the CR-DGE group ( n=94) and the non-CR-DGE group ( n=184). Main clinical characteristics were compared between the groups, including pancreatic duct diameter, intraoperative blood loss and operative time. The perioperative indicators were selected using the least absolute shrinkage and selection operator (LASSO) algorithm. Following variable selection, 278 patients were allocated into a training set ( n=222) and a validation set ( n=56) in an 8∶2 ratio. Eight machine learning models were selected to model the training set: random forest, adaptive boosting, light gradient boosting, multilayer perceptron, support vector machine, K-nearest neighbor algorithm, decision tree and complementary set plain bayes. The area under the curve (AUC) of receiver operating characteristic curve of the validation set was utilized to identify the optimal model. The predictive performance of the optimal model was evaluated using calibration plots and decision curve analysis (DCA). The contribution of each feature to the prediction is assessed using Shapley additive explanation (SHAP). Results:Univariate analysis showed statistically significant differences between the CR-DGE and non-CR-DGE groups in terms of age [66(62, 69) years vs. 56(51, 60), years], diabetes [42.6%(40/94) vs. 11.4%(21/184)], level of fibrinogen [3.43(2.74, 4.18) g/L vs. 3.84(3.19, 4.68) g/L], pancreatic duct diameter [2.00(1.50, 2.70) mm vs. 3.40(1.60, 5.00) mm], intraoperative blood loss [300(200, 600) ml vs. 200(150, 300) ml], operative time [472(430, 502) min vs. 430(365, 475) min], clinically relevant postoperative pancreatic fistula [34.0%(32/94) vs. 3.8%(7/184)], abdominal fluid accumulation [46.8%(44/94) vs. 12.5%(23/184)], postoperative hemorrhage [20.2%(19/94) vs. 3.3%(6/184)], abdominal infection [28.7%(27/94) vs. 11.4% (21/184)] and duration of postoperative gastrointestinal decompression [4.00 (2.00, 6.00) d vs. 3.00 (2.00, 5.00) d] (all P<0.05). The eleven variables selected via LASSO were incorporated into each of the eight machine learning models. Results demonstrated that the random forest model achieved the highest performance in the validation set, with an AUC of 0.894 (95% CI: 0.800-0.985), accuracy of 0.820 and sensitivity of 0.606. Calibration plots and DCA confirmed the robustness of the random forest model. SHAP analysis indicated that age, pancreatic duct diameter and preoperative aspartate aminotransferase were important predictors in the random forest model. Conclusion:The random forest model developed in this study demonstrated a good predictive performance for CR-DGE after LPD and may assist in the early identification of high-risk patients in clinical practice.

Objective:To evaluate the feasibility of the screw and plate for clival fixation using a transoral expanded approaches.Methods:The transoral expanded approaches were performed on craniocervical segment specimens obtained from 7 subjects, including transoral approach (TO), transoral with soft (TOP) or hard (TOHP) palate split, mandibulotomy (MO) and mandibuloglossotomy (MLO). The distribution and thickness of soft tissue, the configuration of the vertebral arteries, the distance between the midline and the vertebral arteries, the exposed area of the clivus and cervical spine, and the range of screw angle (the angle between the line from the lower incisor or the central base of the mandible to the exposed area of the clivus and the tangent line of the clivus) were evaluated.Results:The thickness of the soft tissue on the posterior pharyngeal wall above the clival pharyngeal nodules was 3.5±0.6 mm. That on the anterior C 1-C 5 vertebrae was 5.0±0.5 mm. The distances from the bilateral vertebral arteries to the midline was 19.5±1.2 mm at C 1, 2, 14.6±2.7 mm at C 2, 3, 14.0±2.7 mm at C 3, 4, and 13.9±2.7 mm at C 4, 5. For the TO approach, the longitudinal diameter of the exposed clivus was 8.3±3.0 mm. The distance from the lower incisor to the superior margin of the exposed clivus, the lower margin of the exposed clivus, the anterior arch of C 1, the vertebral body of C 2 and C 3 were 104.7±4.3 mm, 99.2±6.8 mm, 81.4±4.3 mm, 75.1±4.0 mm and 68.7±6.5 mm, respectively. Six specimens were exposed to the C 3, while one was exposed to the C 2. For the TOP approach, the longitudinal diameter of the exposed clivus was 18.5±4.8 mm. The distance from the lower incisor to the superior margin of the exposed clivus and the pharyngeal nodules were 107.9±6.7 mm and 104.8±6.7 mm, respectively. For the TOHP approach, the longitudinal diameter of the exposed clivus was 26.3±1.8 mm (the clival length) with distance from the lower incisor to the superior margin of the clivus 112.4±12.6 mm. For the MO/MLO approach, the entire clivus was exposed. The distance from the central base of the mandible to the superior and inferior margin of the exposed clivus and the pharyngeal nodules were 141.8±15.7 mm, 131.0±9.9 mm and 120.5±8.2 mm, respectively. The inferior margin of the exposed cervical vertebra was C 5, 6. The rate of the clival screw placement through anterior occipitocervical fixation using TO, TOP, TOHP, MO and MLO was 0%, 71% (5/7), 86% (6/7), and 100%, respectively. The screw angle was 99.0°±1.8°, 92.6°±7.7°, 92.6°±7.7°, 75.1°±7.7°, and 75.1°±7.7°, respectively. Conclusion:Occipitocervical fixation with clival screw and plate could be conducted in most cases via TOP and TOHP approaches. However, in some cases with small split-mouth or mouth opening limited, smaller clival screw angle caused by basilar impression or basilar invagination, requiring fixation and reconstruction of the lower cervical spine, and the MO/MLO approaches could be still required to achieve the fixation.

Extreme lateral interbody fusion (XLIF) can be used to treat various lumbar diseases, such as lumbar facet joints intervertebral disc herniation, spondylolisthesis, stenosis. Compared with other approaches, XLIF establishes the surgical channel behind the peritoneum through lateral abdomen, with the advantages of less blooding in the surgery, smaller invasion, lower complications rate and shorter rehabilitation period. Meanwhile，this technique can not only reduce the risk of vascular injury, but also avoid the damage of back structures，such as muscles and facet joints. Therefore, XLIF has been attracting more and more attention and application. However, there is no conclusive evidence to prove that XLIF is better than other surgical approaches in terms of clinical results and complications rates. This paper reviewed the effects of XLIF for reconstructing spinal stability, as well as its biomechanical properties compared with other classical surgeries.

Objective To compare biomechanical properties of cortical bone trajectory (CBT) screw and traditional trajectory screw for fixing upper-middle thoracic spine. Methods The tomography images were obtained by CT scanning of normal T7 and T8 segments, and the three-dimensional (3D) model of T7-8 was reconstructed by Mimics software. The finite element model of upper-middle thoracic spine was established by optimizing FreeForm model and pre-processing function of ANSYS software. On this basis, the CBT screw and pedicle screw fixation models after discectomy were established, and 5 N·m flexion, extension, lateral bending and rotation loads were applied to the two model groups, respectively. The displacement and peak stress of vertebrae and implants under different working conditions were compared and analyzed. Results Under different loading conditions, the maximum displacement of CBT screw group was lower than that of pedicle screw group, and the range of motion of CBT screw group was lower than that of pedicle screw group. The stress level of both models was close, and the stress of CBT screw group was slightly lower than that of pedicle screw group. Under the load of flexion, extension and rotation, the maximum vertebral stress of pedicle screw group decreased by 31%, 17% and 18% compared with that of CBT screw group, and under lateral bending load, the vertebral stress of CBT screw group was 20% lower than that of pedicle screw group. Under the load of flexion and rotation, the maximum stress of pedicle screw group decreased by 2% and 11%; however, the maximum stress of CBT screw group was 11% and 1% lower than that of pedicle screw group. Conclusions The stability of CBT screw was better than that of pedicle screw, and the overall stress distribution was similar to that of pedicle screw. However, the vertebral stress distribution of CBT group was slightly inferior. The research findings provide a theoretical basis for the clinical application of cortical screw fixation after the failure in pedicle screw fixation for the upper-middle thoracic vertebrae.

The stability of the occipitocervical region mainly depends on the integrity of the bony structure,surrounding ligaments and joint capsules.The instability of this region often leadsto the clinical symptoms of compression injury of nerve and vascular,which requires early surgical intervention to rebuild its stability.Posterior occipitocervical fixations are main surgical treatment for the occipitocervical diseases.However,the posterior fixations are not suitable for some patients with congenital or iatrogenic causes.Recently,the anterior occipitocervical fixation with the screws anchored at clivus or into the occipital condyles have been used for the following operations.1.Anterior bone graft fusion.One case which was performed by oral approach was reported well fusion,but the stability was poor and there was a possibility of displacement.2.Anterior shaped titanium cage and plate fixation.The literatures reported that this anterior operation was completed in 35 cases by oral,oral combined with mandibulotomy,and anterior retropharyngeal approaches.This fixation has a good biomechanical stability and is widely used in clinical applications,including occipitocervical tumors and deformities.And the complications including intraoperative vascular,spinal and dural injuries,postoperative drinking cough,non-fusion,deep infection,and death.3.Anterior occipital-atlantoaxial joint screw fixation.Seven cases were performed by anterior occipital-atlantoaxial joint screw fixation through anterior percutaneous approach.This fixation is less trauma,but required precise placement of screw and not conducive bone fusion,and it is suitable for traumatic instability of the upper cervical spine,atlantoaxial dislocation and basilar invagination.Each procedure of anterior occipitocervical fixation is not suitable for all patients,and it should be adopted according to the patient's condition,surgical hardware conditions and the surgeon's habits.

Objective To analyze the correlation of vertebral osteophyte and lumbar disc degeneration in the elderly people and explore the possible mechanism of osteophyte formation. Methods X-ray and MRI data of 120 elderly people with backache or leg pain were retrospectively analyzed. Osteophyte was classified into four grades by X-ray according to the method proposed by Nathan. Discs with osteophyte were defined as occurring when osteophyte of grade II or greater were present. Lumbar disc degeneration was classified into five grades by MRI according to the method proposed by Pfirrmann. The obtained parameters were statistically treated and analyzed. Results Osteophyte and age were positively correlated at every lumbar disc level (P < 0.05). The proportion of osteophyte in L3/4 (76.7%) and L4/5 (70.08%) were more severe than that in L1/2 (31.7%) and L2/3 (46.7%). Osteophyte and lumbar disc degeneration were positively correlated at every lumbar disc level (P < 0.01). Conclusion Osteophyte becomes more severe with the increasing of lumbar disc degeneration. The vertebral stress after lumbar disc degeneration may be the main cause of osteophyte.