Residual Compression Research Articles

The effect of short Kevlar fibers interfacial toughening on impact properties of carbon fiber/aluminum honeycomb sandwich panels

Due to the susceptibility of carbon fiber/aluminum honeycomb sandwich structures to interface damage under impact loading, their overall mechanical performance can be compromised, potentially leading to structural failure. This poses a severe risk to the safety of such structures in engineering applications. This study initially conducted low-velocity impact tests and post-impact compression tests on carbon fiber/aluminum honeycomb sandwich panels with both untoughened and short Kevlar fibers toughened interfaces, using four different impact energy levels (10 J, 20 J, 30 J, and 50 J). The experimental results indicated that the toughening with short Kevlar fibers significantly enhanced the impact resistance and residual compression performance of the sandwich panels. Subsequently, the impact test on the toughened specimen was simulated numerically and the experimental results were in good agreement with the numerical simulations. Finally, based on the numerical model, the study explored the influence of varying face sheet parameters on the impact resistance of short Kevlar fibers toughened carbon fiber/aluminum honeycomb sandwich panels. Layup quantity and layup angle have significant influence on the impact resistance of sandwich panels. With the increase of layup quantity, the impact resistance improves. In several layup angles, [0/45/90/-45/0/45] layering method shows the best impact resistance.

Impact response and compression-after-impact properties of foam-core sandwich composites incorporating scrap tyre rubber particles

Integrating scrap rubber particles as fillers into polymer matrix composites offers a cost effective and environmentally sustainable pathway to manage tyre waste through the creation of value-added products. This research explores the low-velocity impact (LVI) response and compression after impact (CAI) properties of rubberised foam-core glass fibre-reinforced epoxy (GFRE) sandwich composites. Syntactic foam cores integrated with rubber particles were manufactured using vacuum-assisted resin transfer moulding (VARTM). The compression properties of rubberised foam core, vital for resisting impact damage during LVI, were examined. Results show more than 40% reduction in compression strength and modulus of the syntactic foam upon the inclusion of 33 wt.% rubber particles. The LVI response and residual compression properties of rubberised foam-core composites were also evaluated. Rubberised foam cores caused a marginal reduction in the peak impact force and led to approximately 60% reduction in the delamination area. The pre-impact compression strength was unaffected by rubber particles within the core as the GFRE face sheets carried most of the compression load. Post-impact compression strength was slightly higher in rubberised foam-core composites due to reduced delamination. Digital Image Correlation (DIC) analysis tracking of the strain evolution during CAI experiments revealed the stress-raising effect of the impact damaged region. This study showcases sustainable scrap tyre management through the inclusion of rubber particles into foam-core composites without substantially reducing in-plane compression properties before or after low-velocity impact.

Factors that influence the results of indirect decompression employing oblique lumbar interbody fusion.

Indirect decompression is one of the potential benefits of anterior reconstruction in patients with spinal stenosis. On the other hand, the reported rate of revision surgery after indirect decompression highlights the necessity of working out prediction models for the radiographic results of indirect decompression with assessing their clinical relevance. To assess factors that influence radiographic and clinical results of the indirect decompression in patients with stenosis of the lumbar spine. This study is a single-center cross-sectional evaluation of 80 consecutive patients (17 males and 63 females) with lumbar spinal stenosis combined with the instability of the lumbar spinal segment. Patients underwent single level or bisegmental spinal instrumentation employing oblique lumbar interbody fusion (OLIF) with percutaneous pedicle screw fixation. Radiographic results of the indirect decompression were assessed using computerized tomography, while MacNab scale was used to assess clinical results. After indirect decompression employing anterior reconstruction using OLIF, the statistically significant increase in the disc space height, vertebral canal square, right and left lateral canal depth were detected (Р < 0.0001). The median (M) relative vertebral canal square increase came to М = 24.5% with 25%-75% quartile border (16.3%; 33.3%) if indirect decompression was achieved by restoration of the segment height. In patients with the reduction of the upper vertebrae slip, the median of the relative increase in vertebral canal square accounted for 49.5% with 25%-75% quartile border (2.35; 99.75). Six out of 80 patients (7.5%) presented with unsatisfactory results because of residual nerve root compression. The critical values for lateral recess depth and vertebral canal square that were associated with indirect decompression failure were 3 mm and 80 mm2 respectively. Indirect decompression employing anterior reconstruction is achieved by the increase in disc height along the posterior boarder and reduction of the slipped vertebrae in patients with degenerative spondylolisthesis. Vertebral canal square below 80 mm2 and lateral recess depth less than 3 mm are associated with indirect decompression failures that require direct microsurgical decompression.

Revision Chiari surgery in adults: surgical evaluation algorithm and outcomes in a continuity-of-care practice.

Patients with a prior surgical history for Chiari malformation (CM) as a child or an adult who presents with a recurrence or persistence of symptoms pose a challenging clinical scenario. The authors analyzed preoperative presentations, surgical histories, and outcomes of adult CM revision cases to create an algorithm for the assessment of revision surgery in adult CM patients and contrast this with the care of pediatric CM patients within the context of an integrated continuity-of-care CM practice seeing pediatric and adult patients. The authors retrospectively reviewed the records of patients with CM0, -1, and -1.5 who were 21 years of age or older, had a prior history of CM surgery as either children or adults, and underwent revision surgery as adults at the authors' institution from December 2009 to February 2020. The cohort was divided into three groups depending on the type of revision surgery performed: posterior fossa decompression with or without duraplasty (PFD/D group), occipitocervical fusion without ventral decompression (OCF group), and ventral decompression in the form of endoscopic endonasal odontoidectomy (VD group). A total of 50 adult revision cases were divided into 30 PFD/D cases, 13 OCF cases, and 7 VD cases. Forty cases had previously undergone one CM surgery, and 10 had undergone two. Preoperatively, the PFD/D group had significantly fewer cases of diagnosed craniocervical instability (CCI), Ehlers-Danlos syndrome, and dysautonomia than the OCF and VD groups. A retroflexed odontoid was significantly more common in the VD group than in the PFD/D and OCF groups. Postoperatively, rates of improvement were 60.0% with PFD/D, 84.6% with OCF, and 85.7% with VD, but differences in these rates were not statistically significant. In this challenging group of CM patients, possible etiologies warranting additional surgery included residual dorsal compression, persistent syrinx, CCI, and ventral brainstem compression from a significant retroflexed odontoid. Outcomes after revision were often favorable, but careful evaluation, patient selection, and communication with patients are needed in deciding to reoperate. The suggested algorithm can aid decision-making.

Experimental Analysis of the Low-Velocity Impact and CAI Properties of 3D Four-Directional Braided Composites after Hygrothermal Aging.

Three-dimensional braided composites (3D-BCs) have better specific strength and stiffness than two-dimensional planar composites (2D-PCs), so they are widely used in modern industrial fields. In this paper, two kinds of 3D four-directional braided composites (3D4d-BCs) with different braided angles (15°, denoted as H15, and 30°, denoted as H30) were subjected to hydrothermal aging treatments, low-velocity impact (LVI) tests, and compression after impact (CAI) tests under different conditions. This study systematically studied the hygroscopic behavior and the effect of hygrothermal aging on the mechanical properties of 3D4d-BC. The results show that higher temperatures and smaller weaving angles can significantly improve the moisture absorption equilibrium content. When the moisture absorption content is balanced, the energy absorption effect of 3D4d-BC is better, but the integrity and residual compression rate will be reduced. Due to the intervention of oxygen molecules, the interface properties between the matrix and the composite material will be reduced, so the compressive strength will be further reduced. In the LVI test, the peak impact load of H15 is low. In CAI tests, the failure of H15 mainly occurs on the side, and the failure form is buckling failure. The main failure direction of H30 is 45° shear failure.

Learned Video Compression with Adaptive Temporal Prior and Decoded Motion-aided Quality Enhancement

Learned video compression has drawn great attention and shown promising compression performance recently. In this article, we focus on the two components in the learned video compression framework, the conditional entropy model and quality enhancement module, to improve compression performance. Specifically, we propose an adaptive spatial-temporal entropy model for image, motion, and residual compression, which introduces a temporal prior to reduce temporal redundancy of latents and an additional modulated mask to evaluate the similarity and perform refinement. In addition, a quality enhancement module is proposed for predicted frame and reconstructed frame to improve frame quality and reduce the bitrate cost of residual coding. The module reuses decoded optical flow as a motion prior and utilizes deformable convolution to mine high-quality information from the reference frame in a bit-free manner. The two proposed coding tools are integrated into a pixel-domain residual coding–based compression framework to evaluate their effectiveness. Experimental results demonstrate that our framework achieves competitive compression performance in the low-delay scenario compared with recent learning-based methods and traditional H.265/HEVC in terms of Peak Signal-to-Noise Ratio (PSNR) and Multi-Scale Structural Similarity Index (MS-SSIM). The code is available at OpenLVC.

High Efficiency Deep-learning Based Video Compression

Although deep learning technique has achieved significant improvement on image compression, but its advantages are not fully explored in video compression, which leads to the performance of deep-learning-based video compression (DLVC) is obviously inferior to that of hybrid video coding framework. In this article, we proposed a novel network to improve the performance of DLVC from its most important modules, including Motion Process (MP), Residual Compression (RC), and Frame Reconstruction (FR). In MP, we design a split second-order attention and multi-scale feature extraction module to fully remove the warping artifacts from multi-scale feature space and pixel space, which can help reduce the distortion in the following process. In RC, we propose a channel selection mechanism to gradually drop redundant information while preserving informative channels for a better rate-distortion performance. Finally, in FR, we introduce a residual multi-scale recurrent network to improve the quality of the current reconstructed frame by progressively exploiting temporal context information between it and its several previous reconstructed frames. Extensive experiments are conducted on the three widely used video compression datasets (HEVC, UVG, and MCL-JVC), and the performance demonstrates the superiority of our proposed approach over the state-of-the-art methods.

Research on size effects in the low‐velocity impact (LVI) and compression after impact (CAI) characteristics of composite laminates

AbstractThe load‐bearing capacity and failure characteristics of composite structures are closely related to their dimensions. In this study, low‐velocity impact, ultrasonic non‐destructive testing, and compression after impact tests were conducted on composite laminates of varying widths to investigate the influence of size effects. Distinct impact response profiles and compression failure modes were characterized. The results indicate that under impact loading, the delamination threshold load (6700 N ~ 7200 N) and the knee‐point energy (40 J) are not affected by width. However, variations in width lead to differences in indentation depth, impact duration, peak load, delamination characteristics, and energy absorption. Furthermore, increasing impact energy further magnifies these differences. Under compression loading, wider laminates exhibit lower residual strength, with the influence of impact energy on residual strength decreasing as width increases. Importantly, the observed compression failure deformation mode transitions from localized buckling to widespread sub‐layer delamination‐induced compression failure. This suggests that changes in width alter the governing mechanical mechanisms of CAI failure. Consequently, the use of a single‐size laminate to represent both LVI and CAI processes is not recommended. Based on experimental results, the reliability of the equivalent damage method in predicting the residual compression strength of laminates of different widths was confirmed, providing valuable insights for practical engineering applications.Highlights Assess the variations in the low‐velocity impact process of laminates with different widths. Evaluate the delamination damage of laminates after impacts by ultrasonic C‐scan techniques. Investigate the effect of variation in widths on the compression behavior of laminates after impact. Validate the feasibility of equivalent damage modeling for calculating residual strength.

Large eddy simulations of sheet-to-cloud cavitation transitions with special emphasis on the simultaneous existence of the re-entrant jet and shock waves

Sheet-to-cloud cavitation transitions are very complex owing to the simultaneous appearance of the re-entrant jet and shock waves. The objective of this paper is to investigate the physics of compressible cavitating flows with emphasis on the simultaneous existence of the re-entrant jet and shock waves. A compressible cavitating solver, which considers the compressibility effects of both the liquid and the vapour, was used to account for the different shedding characteristics induced by the re-entrant jet mechanism (RJM), the shock wave mechanism (SWM), and both the re-entrant jet and the shock waves (RJM-SMW). The solver used Large Eddy Simulations (LES) and the Schnerr-Sauer cavitation model. The numerical results are first compared with available experimental data [1] which showed satisfactory agreement for various aspects of the flow, including the pressure distribution, cavity shapes, condensation front speed, and shedding frequency. The results first show three different cavity shedding processes induced by the re-entrant jet and the shock waves. Frequency analyses show that the shock waves produce a wider frequency distribution which indicates that shock waves induce more shedding than the re-entrant jet. The quasi-periodic characteristics of the transitions between the various cavity shedding characteristics are mainly induced by the variations of the pressure, residual cavity volume and medium compressibility. Further analyses show that the different pressure, residual cavity volume and medium compressibility amplitudes determine the cavity shedding characteristics in the subsequent shedding cycle. When the conditions favour both the re-entrant jets and the shock wave effects, both the re-entrant jet and the shock waves impact the cavity shedding.

Exploring the flowability, physical, and mechanical properties of eco-friendly colored cement mortars with metakaolin under sulfuric (H2SO4) and nitric acid (HNO3) attacks

This article aims to investigate the flowability, physical, mechanical, and durability properties of metakaolin (MK)-added colored cement mortars exposed to the effects of H2SO4 sulfuric acid (SA) and HNO3 nitric acid (NA). MK was used in 20 % replacement with cement, and yellow (YP) and red pigments (RP) were added to the mixtures at 1 % and 3 % of the cement by weight. According to the results, although MK reduced the workability and, therefore, the flow diameter (FD) of mortars, thanks to the void-filling feature of MK, filling the voids in the microstructure caused the samples' apparent porosity (AP) and relative dynamic modulus of elasticity (RDME) to decrease. Additionally, MK significantly improved the residual compressive (RCS) and residual flexural strengths (RFS) of the samples thanks to the calcium-silicate-hydrate (C–S–H) bonds it formed in the interior structure, owing to its high pozzolanic efficiency. Moreover, this improvement of MK is more remarkable in samples that remain subject to SA and NA attacks for more time.Furthermore, while YP reduces the workability of mortars and, therefore, the FD value due to its needle-tipped grain structure, RP increases the FD value of the mortars with its spherical grain structure. However, YP and RP contributed to reducing the AP of the samples and increasing RCS and RFS capacities at a meager rate by showing a micro-filling effect. In addition, there were significant increases in the total color changes (ΔE) of YP and RP-added colored mortar samples, especially after longer SA and NA attacks.

Deep Lossy Plus Residual Coding for Lossless and Near-Lossless Image Compression.

Lossless and near-lossless image compression is of paramount importance to professional users in many technical fields, such as medicine, remote sensing, precision engineering and scientific research. But despite rapidly growing research interests in learning-based image compression, no published method offers both lossless and near-lossless modes. In this paper, we propose a unified and powerful deep lossy plus residual (DLPR) coding framework for both lossless and near-lossless image compression. In the lossless mode, the DLPR coding system first performs lossy compression and then lossless coding of residuals. We solve the joint lossy and residual compression problem in the approach of VAEs, and add autoregressive context modeling of the residuals to enhance lossless compression performance. In the near-lossless mode, we quantize the original residuals to satisfy a given ℓ∞ error bound, and propose a scalable near-lossless compression scheme that works for variable ℓ∞ bounds instead of training multiple networks. To expedite the DLPR coding, we increase the degree of algorithm parallelization by a novel design of coding context, and accelerate the entropy coding with adaptive residual interval. Experimental results demonstrate that the DLPR coding system achieves both the state-of-the-art lossless and near-lossless image compression performance with competitive coding speed.

Experimental Investigation on Partial Replacement of Cement by Granite Powder on Mortar

This paper intends to investigate the possibility of producing low costs enhanced mortar by Granite powder. By taking the enormous amount of cement, it affects the environment badly and demand for cement was increasing day by day. So, by partially replacing Granite powder with cement in construction field. It can fulfill the objectives of catering to the needs of the construction sector while simultaneously promoting an eco-friendly and pristine atmosphere. Partial replacement of cement by using granite powder in mortar gives sufficient strength. The conventional mortar mix consists of cement, fine aggregate, and water. In this experimental study granite powder was used with different percentage, such as 20% 25%, 30% 35%. The mixture was prepared and mortar cubes were made and allowed for curing. It is concluded that, he immersion of cement mortar in magnesium sulphate is better when compared to sodium sulphate and the sulphate attack is lesser in magnesium sulphate. The residual compression strength for the cement mortar in the proportion of granite content 30% is higher.

Residual behavior of UHPC-filled Q690 high-strength steel tubular members after axial impact

Structures may suffer from accidental impact loads during the service life. While most impacts will not destroy structures completely, quantifying their residual behavior after impact is crucial for evaluating the damage and then providing recommendations for repair or removal. This may greatly reduce the time and economic losses caused by impacts. Hence, this study experimentally and numerically investigated the residual behavior of UHPC-filled high-strength steel tube (UHPC-FHST) members subjected to axial impact. Parameters including impact energy, steel ratio, specimen length, and steel grade (Q690 and Q355) were carefully considered. After tests, different failure modes and axial load-displacement curves were obtained. The residual ratio (β), a ratio of the bearing capacity of a damaged specimen to that of a specimen without impact, was employed to assess the damage level of UHPC-FHST members after axial impact. Tests showed that UHPC-FHST members have excellent axial impact resistance, high residual strength, and high residual ratio, especially under low-energy impact conditions. β decreases rapidly and linearly with increasing nominal strain and then stabilizes after a certain value. A finite element (FE) model was thereafter established and benchmarked by the available test results, where two analysis steps were established to continuously simulate the impact and residual compression processes. The FE results demonstrated a great agreement with the tests, which could provide a reference for further investigations in related studies.

Axial compression behavior of square steel tubes after artificial high-temperature cooling

This study focused on the impact of fires on steel-framed buildings and particularly emphasized the residual axial compression capacity of square steel tubes after fire suppression. To simulate fire conditions and observe the failure modes, high-temperature cooling experiments were conducted, residual axial compression capacity, and strain responses of the square steel tubes. The results demonstrated that the temperature and cooling methods significantly affected the residual strength. Below 700 °C, the residual axial compression capacity of the specimens cooled by water gradually decreased with the increasing temperatures, with a slight recovery at 900 °C. Conversely, as the temperature increased, the residual axial compression capacities of the specimens cooled with foam decreased. A simplified formula for calculating the residual axial compressive capacity of Q235 square steel tubes was proposed, and a finite-element model was established. This study utilizes simulation and parameter analysis to offer a framework for assessing the remaining axial compression capacity of Q235 square steel tubes after fire, providing valuable insights for their utilization in structural engineering and fire safety. This study aims to contribute to the reduction of economic losses and resource wastage caused by fires.

Enhanced freeze-thaw resilience of cement mortars through Nano-SiO2 and single/hybrid basalt fiber incorporation: Assessing workability, strength, durability

This study investigated how freeze-thaw cycles (FTC) impact concrete durability and structural integrity, exploring novel approaches like integrating nanomaterials and fibers into concrete compositions. After subjecting the materials to FTC, the study evaluated mortars enriched with nano-SiO2 (NS) and micro- and macro-basalt (BA) fibers. NS was incorporated by substituting 1 % and 2 % of the cement content. Meanwhile, 24 mm in length macro-BA fibers were added individually or in hybrid compositions with 6 mm micro-BA fibers at 0.5 % and 1 % volumetric ratios. The results revealed significant improvements in both the strength and durability of mortar specimens post-FTC, attributed to the enhancing properties of NS. Its capacity to fill voids and substantial pozzolanic activity notably improved the material's performance. However, adding BA fibers adversely affected mortar workability, causing a decrease in flow diameters (FD) as the fiber ratio increased.Nevertheless, BA fibers effectively maintained specimen integrity post-FTC despite leading to decreased residual compressive (RCS) and flexural strengths (RFS). This reduction was linked to the robust bonding between BA fibers and the matrix, impeding crack propagation post-FTC. Interestingly, combining BA fibers in hybrid configurations improved workability and significantly enhanced residual strength characteristics, surpassing singular applications. For instance, after 180 FTC, the K0 control specimen exhibited a 34.17 % and 34.56 % reduction in RCS and RFS, respectively. In contrast, the K10 specimen with 2 % NS and a hybrid combination of BA fibers at a volumetric ratio of 1 % displayed notably lower reduction rates of 23.69 % and 16.99 %, respectively.

Couple effects of multi-impact damage and CAI capability on NCF composites

Abstract In this study, the mechanical properties of non-crimp fabric (NCF) composite laminates under low-velocity impact and compression after impact (CAI) tests were studied by Scanning electron microscopy (SEM) and Digital image correlation (DIC) techniques. The impact response under different impact times, impact angles, and impact distance is studied. Similarly, in CAI test, DIC technique is used to reveal the whole process of NCF composite compression failure, and SEM is used to reveal the microscopic failure form. The experimental results show that the impact damage process of NCF composites has strong directivity. The concrete manifestation is that the internal failure will extend along the paving direction at the failure layer. The peak load generated under 20 J impact energy is about 1/2 of that under 40 J impact energy. The impact distance is one of the important factors affecting the coupling effect of multiple impacts, and the impact angle has little effect on the internal damage extension. The proportion of internal damage area also supports the relevant view, that is, the average difference in the proportion of internal damage area under different impact distance is about 5%, while the average difference in the proportion of internal damage area under different impact angles is about 3%. During the compression process, the main failure mode is shear failure and the failure mode is brittle fracture. The oblique fracture occurs only when the oblique is 45° and the impact distance is large (50 mm). The impact angle has little effect on the residual compression performance of NCF.

Short-term oxidation and residual compression properties of needle-punched carbon/carbon composites

Needle-punched carbon/carbon (NP C/C) composite is widely used in rocket-engine nozzles and re-entry vehicles. Recyclable technology expedited the research on repeated oxidation and residual mechaincal properties of thermal-protection materials. In this study, the critical longitudinal compression strengths before and after oxidation are derived based on the Timoshenko beam theory. Three repetitions of short-term oxidation cycles and compression experiments are investigated. The average oxidation rate of this composite was 5∼6% in 10 min and kept linear increase. In-plane and out-of-plane compressive strengths of NP C/C composite diminish quasi-linearly due to oxidation at 1000°C, with their moduli decreasing in a periodically slow-sharp pattern. After three oxidation cycles, the levels of residual in-plane modulus and strength were 55.20% and 56.89%, respectively, while the resudual out-of-plane modulus and strength were 44.65% and 47.23%, respectively. The results showed that the material exhibited the pesudo-plastical behaviour after oxidation, cracks grew along the punched conical structures formed by the punching technology. In-plane and out-of-plane modulus were more sensitive than their strengths after first oxidation cycle.

Role of intravascular ultrasound for the technical assessment of endovascular reconstruction of the aortic bifurcation

ObjectiveThe aim of this study was to evaluate the role of intravascular ultrasound (IVUS) for the technical assessment of kissing stents (KSs) and covered endovascular reconstruction of the aortic bifurcation (CERAB) in the treatment of aortoiliac obstructive disease involving the aortic bifurcation. MethodsWe conducted a single-center retrospective review of patients undergoing endovascular treatment of severe aorto-iliac obstructive disease (2019-2023). IVUS was performed in patients treated by KSs or CERAB according to preoperative indications, in cases of moderate/severe calcifications, mural thrombus, total occlusions, and lesion extension towards the proximity of renal or hypogastric arteries. Indications for IVUS-guided intraoperative revisions were residual stenosis or compression >30%, incomplete stent-to-wall apposition, or flow-limiting dissection at the landing site. Follow-up assessment was performed at 6 and 12 months, and then yearly. Thirty-day outcomes and 2-year patency rates were evaluated. Logistic regression was used to identify factors associated with significant technical defects detected by IVUS needing intraoperative revision. ResultsIVUS was used for the technical assessment of 102 patients treated by KSs (n = 57; 56%) or CERAB (n = 45; 44%) presenting with severe intermittent claudication (39%), rest pain (39%), or ischemic tissue loss (25%). Twenty-nine significant technical defects were identified by IVUS in 25 patients (25%) who then had successful intraoperative correction by additional ballooning (n = 23; 80%) or stenting (n = 6; 20%). Patients with a severely calcified chronic total occlusion (odds ratio, 1.85; 95% confidence interval, 1.01-5.27; P = .044) or severely calcified narrow aortic bifurcation with <12 mm diameter (odds ratio, 2.34; 95% confidence interval, 1.10-8.64; P = .032) were at increased risk for IVUS-guided intraoperative revision. There were no postoperative deaths and no major adverse events. Two-year primary patency was 100%. ConclusionsIVUS was used for the technical assessment of KSs/CERAB in a selected cohort of patients with severe aorto-iliac obstructive disease. This allowed the identification and intraoperative correction of a significant technical defect not detected by completion angiogram in one-quarter of patients, achieving optimal 2-year results. IVUS assessment of KSs/CERAB may be considered especially in patients with a calcified total occlusion or narrow aortic bifurcation.

Surgical intervention combined with weight-bearing walking training promotes recovery in patients with chronic spinal cord injury: a randomized controlled study.

JOURNAL/nrgr/04.03/01300535-202412000-00032/figure1/v/2024-04-08T165401Z/r/image-tiff For patients with chronic spinal cord injury, the conventional treatment is rehabilitation and treatment of spinal cord injury complications such as urinary tract infection, pressure sores, osteoporosis, and deep vein thrombosis. Surgery is rarely performed on spinal cord injury in the chronic phase, and few treatments have been proven effective in chronic spinal cord injury patients. Development of effective therapies for chronic spinal cord injury patients is needed. We conducted a randomized controlled clinical trial in patients with chronic complete thoracic spinal cord injury to compare intensive rehabilitation (weight-bearing walking training) alone with surgical intervention plus intensive rehabilitation. This clinical trial was registered at ClinicalTrials.gov (NCT02663310). The goal of surgical intervention was spinal cord detethering, restoration of cerebrospinal fluid flow, and elimination of residual spinal cord compression. We found that surgical intervention plus weight-bearing walking training was associated with a higher incidence of American Spinal Injury Association Impairment Scale improvement, reduced spasticity, and more rapid bowel and bladder functional recovery than weight-bearing walking training alone. Overall, the surgical procedures and intensive rehabilitation were safe. American Spinal Injury Association Impairment Scale improvement was more common in T7-T11 injuries than in T2-T6 injuries. Surgery combined with rehabilitation appears to have a role in treatment of chronic spinal cord injury patients.

Residual volume of extruded disc material and residual spinal cord compression measured on postoperative MRI do not predict neurological outcomes in dogs following decompressive surgery for thoracolumbar intervertebral disc extrusion.

Published studies on the validity of using quantitative MRI measures of pre- and postoperative spinal cord (SC) compression as prognostic indicators for dogs undergoing surgery for intervertebral disc extrusion (IVDE) are currently limited. The aim of this retrospective analytical study was to describe the volume of postoperative residual extradural material (VREM) and the ratio of the cross-sectional area (CSA) of maximum SC compression to the CSA of SC in a compression-free intervertebral space as MRI measures of preoperative and postoperative compression (residual spinal cord compression, RSCC), and to compare these measures between the neurological outcome in a group of dogs. Inclusion criteria were dogs that underwent surgery for thoracolumbar IVDE, were imaged pre- and immediately postoperatively by MRI, and had a neurological follow-up examination 2 to 5 weeks postoperatively. Two blinded observers independently performed measurements in pre- and postoperative MRI studies. Dogs were classified into positive outcome (PO) and negative outcome (NO) groups based on follow-up neurologic examination scores. Seventeen dogs were included (12 PO, 5 NO). Interobserver agreement for MRI measurements was good to excellent (ICCs: 0.76-0.97). The prevalence of residual extradural material in postoperative MRI studies was 100%. No significant differences in mean preoperative SC compression, mean RSCC, mean SC decompression, or VREM were found between outcome groups (P=.25; P=.28; P=.91, P=.98). In conclusion, neither postoperative VREM nor RSCC could predict successful neurological outcomes.