Rate Of Consolidation Research Articles

[Translated article] Retrospective survival analysis of the use of uncemented modular tapered stems for revision in periprosthetic Vancouver B-type fractures. Is instability a threat to survival

Introduction and objectives: Periprosthetic hip fractures show increasing incidence and complexity, representing a challenge for the surgeon. We aimed to evaluate the survival of uncemented modular tapered stems in the treatment of periprosthetic Vancouver B2 and B3 type fractures and review the main complications and factors associated with decreased survival.Materials and methods: We performed a retrospective study of patients submitted to revision arthroplasty for treatment of periprosthetic femoral stem Vancouver B2 and B3 type fractures with an uncemented modular fluted tapered stem (MRP-Titan). Demographic and radiographic parameters were analyzed. The survival rate (free of reoperation) was calculated at 2- and 5-years using the Kaplan–Meier survivorship analysis.Results: Thirty-nine patients were included with a mean age of 73.5 years and a mean follow-up of 5 years. Arthroplasty survivorship at 2 years was 73.7% and at 5 years was 67.5% (mean 8.4 years; range 6.7–10.2). Survivorship was inferior in the patients with episodes of instability (mean 2.5 years; range 0–5.42) (p < 0.001). At least one episode of instability occurred in 26.3% of patients and 60% of these patients had a femoral head size 32 mm or lower. At least one episode of instability occurred in 71.4% of patients with a greater trochanter fracture (p = 0.008). The consolidation rate was 90.6% and the mortality rate was 23.7%. In the group of patients that died, 55.6% were submitted to at least one revision surgery (p = 0.044).Conclusion: Survivorship of an uncemented modular stem (MRP-Titan) in revision for PHF is significantly reduced by episodes of instability.

Analytical Solutions for Composite Foundations Reinforced by Partially Penetrated Stone Columns and Vertical Drains

ABSTRACTWhen stone columns or vertical drains are applied to improve soils, it is common to face situations where the soft soil layer is too thick to be penetrated completely. Although consolidation theories for soils with partially penetrated vertical drains or stone columns are comprehensive, consolidation theories for impenetrable composite foundations containing both two types of drainage bodies have been few reported in the existing literature. Equations governing the consolidation of the reinforced zone and unreinforced zone are established, respectively. Analytical solutions for consolidation of such composite foundations are obtained under permeable top with impermeable bottom (PTIB) and permeable top with permeable bottom (PTPB), respectively. The correctness of proposed solutions is verified by comparing them with existing solutions and finite element analyses. Then, extensive calculations are performed to analyze the consolidation behaviors at different penetration rates, including the total average consolidation degree defined by strain or stress and the distribution of the average excess pore water pressure (EPWP) along the depth. The results show that the total average consolidation rate increases as the penetration rate increases; for some composite foundations with a low penetration rate, the consolidation of the unreinforced zone cannot be ignored. Finally, according to the geological parameters provided by an actual project, the obtained solution is used to calculate the settlement, and the results obtained by the proposed solution are in reasonable agreement with the measured data.

Analytical Solutions for Consolidation of Soft Ground With Impervious Columns Considering Non‐Darcian Flow

ABSTRACTCohesive material columns have been extensively used in foundation improvement projects to enhance the bearing capacity of composite foundations and mitigate post‐construction settlement. However, the low permeability of cohesive material columns restricts the dissipation of pore water primarily through the top surface of the foundation, potentially resulting in longer drainage paths compared to foundations treated with granular material columns or vertical drains. Moreover, the impact of non‐Darcian flow within soils on consolidation behavior becomes increasingly pronounced as the drainage path increases. Consequently, a novel analytical model for the consolidation of impervious column‐assisted foundations is established, which can incorporate the seepage model accounting for the initial hydraulic gradient. The accuracy and reasonableness of the obtained solution are then validated by conducting a comparative analysis with existing models and through a detailed case study. Furthermore, a parametric analysis is conducted to delve into the influence of several crucial factors on the consolidation performance. The findings demonstrate that non‐Darcian flow has a greater influence on composite foundations compared to natural foundations. Additionally, the threshold value of the well‐diameter ratio decreases with the increase in the initial hydraulic gradient. Finally, the final seepage front remains at a shallower position when the column–soil modulus ratio becomes larger, and the influence of non‐Darcian flow on the consolidation rate becomes more pronounced.

Analytical solution for radial consolidation of combined electroosmosis-vacuum-surcharge preloading considering free strain and cyclic loading

In this study, electro-osmotic consolidation considering smear effect and free strain under cyclic loading was investigated. The analytical solution of radial consolidation of electroosmosis-vacuum-surcharge combined preloading is derived by using the Bessel function and eigenfunction methods. Subsequently, the effectiveness of the proposed method is validated through comparison with existing numerical solutions. Based on the derived solutions, the influence of the smear effect, applied voltage, vacuum pressure, and cyclic loading on soil consolidation characteristics was analyzed. The results showed that the smearing effect slows the rate of consolidation, but the final average consolidation and negative excess pore water pressure are enhanced. Compared with only cyclic loading, the combined effect of electroosmosis, vacuum, and surcharge preloading enables the soil to achieve higher strength and consolidation. When the effect of electroosmosis alone on reinforcing low-permeability soils is not significant, the combination of electroosmosis with vacuum preloading helps enhance the soil reinforcement effect.

Composite Sand–Clay Infrastructural Soil Fills: Characteristic Consolidation and Hydraulic Properties

In the design construction of infrastructural projects comprised of geotechnical applications, including composite soil fill layers, compacted sand-clay soil fills are widely preferred as barrier layers, particularly in solid waste landfills, to minimize leakage, to prevent leachate from entering into groundwater. When bentonite clay with high water absorption capacity and low hydraulic conductivity is mixed with sand possessing relatively enhanced frictional properties, greater shear strength capacity, an effective fill material exhibiting low sensitivity to frost, and low volume change in case of wetting, drying can be obtained. On the other hand, when montmorillonite clay is loaded, due to highly critical volumetric contraction or dilation characteristics (high compressibility nature of clay), the soil fill composed of sand-clay will significantly consolidate. This situation may cause differential settlement problems of infrastructural fills employed in geotechnical applications. In this regard, the load conditions (mechanical effects) and the environmental conditions (physicochemical effects) in the field control compressibility characteristics and consolidation properties of sand-bentonite clay mixtures. This will ultimately impact the desired stability conditions of sand-clay soil layers built for constructed infrastructural fill, resulting in a deviation from anticipated performance conditions. To this end, in this study, the specimens of sand-bentonite clay mixtures prepared with different contents of sand-bentonite clay were subjected to one-dimensional consolidation tests to investigate the effect of bentonite content used in the mixture on consolidation behavior, hydraulic properties, and effect of sand amount on rate of consolidation and on resulting compressive strength behavior.

One-bone forearm for the treatment of supination contractures secondary to neonatal brachial plexus injury.

The one-bone forearm procedure has been considered as a potential treatment for severe forearm deformities. However, its primary limitation lies in the elevated risks of nonunion and infection. In order to enhance union rates, a technical modification was introduced, aiming not only to establish end-to-end radio-ulnar fixation but also to incorporate an additional overlay and fixation between the proximal and distal radius osteotomy stumps. This technique, initially applied in a heterogeneous patient population including individuals with neurological, tumoral, and congenital conditions, yielded promising results, achieving a consolidation rate of 100% and enabling supination corrections of up to 120°. In this study, we present a retrospective cohort of 28 patients, with an average age of 9 years, all afflicted by forearm supination contracture exceeding 90° secondary to neonatal brachial plexus injury. These patients underwent treatment with the modified technique. The mean correction achieved in forearm rotation was 116°, and the average follow-up period extended to 43 months. Remarkably, all patients exhibited bone union within an average period of 6.6 weeks, without any complications. Our findings underscore the efficacy of this modified technique, which enables substantial rotational corrections, boasts a high union rate, and maintains a low incidence of complications. This approach is particularly valuable for young patients suffering from neonatal brachial plexus injury with severe fixed supination deformities. IV.

Radiologic evaluation of the healing of the greater tubercle after humeral hemiarthroplasty with Aequalis-fracture-implants for proximal humeral fracture: a retrospective cohort study in 45 shoulders

IntroductionDevelopment and use of specific anatomic prosthesis for shoulder’s fracture aimed to reach the best rate of consolidation of the greater tubercle, which means a cuff restitution to improve functional results. The lack of bone healing of the tubercles suggested the use of a fenestrated humeral implant with interposition of a bone graft in the metaphyseal part of the prosthesis. This characteristic of specific implant, have few reports in the literature, leading us to the current retrospective study aiming: 1) to evaluate the healing rate of the greater tubercle after implantation of fracture dedicated anatomic implant, which includes a fenestration in the prosthetic metaphysis for the addition of a cortico cancellous graft, 2) to asses on patients with proximal humerus fractures, the bone healing of the greater tubercle close to the intraprosthetic bone graft. HypothesisThe specific “implant-fracture” can achieve a high rate of bone healing of the humeral greater tubercle Patients and methodsBetween January 2001 and December 2020, fifty-one patients were operated on by implantation of fracture dedicated implant for proximal humerus fracture. Six were excluded (2 operated for revision, 2 operated after 3 weeks, 1 died, 1 without follow-up). In total 45 patients were included in radiological analysis, clinical analysis had been performed on 23/45 patients at the longest follow up, the other 22/45 were only analyzed on radiographies. Mean-aged 66 years (range, 47 years -88 years), 25/45 (56%) of women, with 3-4-parts fractures according to Neer’s classification. The techniques of tubercle fixation were isolated cerclages of combined horizontal cerclages and vertical sutures. Position and healing of the greater tubercle was controlled through antero-posterior and lateral X-Rays views at the longest follow-up (mean 50 months, range 3 to 193 months). Peroperative techniques of fixation, clinical and functional outcomes were noted and correlated to the radiologic position of the greater tubercle and the graft evolution. Factors associated with healing and anatomic position had been investigated. ResultsThe rate of greater tubercle healing was 32/45 (73%). Factors significantly associated with greater tuberosity consolidation were higher age (p = 0.04) and the addition of a vertical osteosuture to the horizontal suture of the greater tubercle (p = 0.01). The rate of anatomic position of the greater tubercle was 15/45 (33%) of cases. When the fixation of the tuberosity was made with vertical suture, good position of the tuberosity was observed in 68% (17/24) at the longest follow-up. DiscussionOur results were in accordance with the literature, but the current study underlined there were two types of factors influencing tubercle healing in the literature: the technique of fixation of the tubercle and the patient’s age. Level of evidencelevel IV cohort study without control group.

Clavicle Shaft Non-Unions-Do We Even Need Bone Grafts?

Background: The surgical treatment of bony non-unions is traditionally performed with additional bone grafts when atrophic and/or stronger implants when hypertrophic. In the case of the clavicle shaft, however, in our experience, a more controversial method where no additional bone graft is needed leads to equally good consolidation rates, independent of the non-union morphology. This method requires the meticulous anatomical reconstruction of the initial fracture and fixation according to the AO principle of relative stability. Methods: A retrospective review following the STROBE guidelines was performed on a consecutive cohort of all patients who received surgical treatment of a midshaft clavicle non-union at the Medical Center of the University of Freiburg between January 2003 and December 2023. Patients were identified using a retrospective systematical query in the Hospital Information System (HIS) using the International Statistical Classification of Diseases and Related Health Problems Version 10 (ICD-10) codes of the German Diagnosis Related Groups (G-DRG). Two groups were formed to compare the consolidation rates of patients who received additional bone grafting from the iliac crest with those of patients who did not. A 3.5 mm reconstruction LCP plate was used in all patients. Consolidation rates were evaluated using follow-up radiographs and outcomes after material removal with a mean follow-up of 31.5 ± 44.3 months (range 0-196). Results: Final data included 50 patients, predominantly male (29:21); age: 46.0 ± 13.0 years, BMI 26.1 ± 3.7. Autologous bone grafts from the iliac crest were used in 38.0% (n = 19), while no bone addition was used in 62.0% (n = 30). Six patients were lost to follow-up. Radiological consolidation was documented after a mean of 15.1 ± 8.0 months for the remaining 44 patients. Consolidation rates were 94.4% (n = 17) in patients for whom additional bone grafting was used and 96.2% (n = 25) in patients for whom no graft was used. There was no relevant difference in the percentage of atrophic or hypertrophic non-unions between both groups (p = 0.2425). Differences between groups in the rate of consolidation were not significant (p = 0.7890). The complication rate was low, with 4.5% (n = 2). Conclusions: Independent of the non-union morphology, non-unions of the clavicle midshaft can be treated successfully with 3.5 mm locking reconstruction plates without the use of additional bone grafting in most cases.

One‐dimensional consolidation analysis of layered soil with exponential flow under continuous drainage boundary

AbstractTo comprehensively consider the influence of boundary conditions, non‐Darcy flow, load forms, and soil stratification on soil consolidation, a one‐dimensional soil consolidation equation is established. By subdividing the soil layer and employing time discretization, the nonlinear consolidation equation is linearized, resulting in an analytical solution for layered soil foundation at any given time. Subsequently, an iterative approach for time solution is employed to obtain a semi‐analytical solution. The correctness of the solution is verified by comparison with solutions based on Darcy's flow and the semi‐analytical method under traditional drainage boundary conditions. Subsequently, the influence of interface parameters, loading conditions, flow index, and other factors on consolidation characteristics is analyzed. The results indicate that higher interface parameter values for continuous drainage boundaries correspond to faster average consolidation rates for stratified soil foundations, while these parameters have little effect on the time required for complete consolidation of the soil layers. Improved boundary drainage performance amplifies the influence of exponential flow on pore water pressure and average consolidation degree. Conversely, poor boundary drainage performance diminishes the impact of exponential flow on soil consolidation, rendering it negligible. Moreover, faster loading rates accentuate the influence of the flow index on the average consolidation degree defined by pore pressure.

Bone consolidation under septic condition and hardware retention: about 69 patients

IntroductionManagement of infection on internal fixation hardware is particularly complex.The main aim of the present study was to assess bone consolidation rates under septic conditions in patients treated for bone and joint infection (BJI) with hardware retention. Secondary objectives were to determine a time limit beyond which it is unreasonable to retain hardware, and to assess risk factors for non-consolidation and functional results. The study hypothesis was that bone consolidation is possible under septic conditions without hardware exchange. Material and methodA single-center retrospective observational study was conducted on 69 patients for the period January 1, 2009 to December 31, 2019. We included all patients aged over 15 years with infection after internal fixation or fusion whose files had been discussed in the multidisciplinary team meeting during the study period. Bone healing was screened for on X-ray or CT. Study data comprised type of fracture, smoking status, time to treatment for open fracture, initial surgery time, type of hardware, interval between fixation and revision, and type of irrigation. Functional results were assessed at follow-up: walking, pain, return to work and SF12 and QuickDASH scores. ResultsThe bone healing rate was 73.5% (50/68 patients) at a mean 24 weeks (range, 6–68 weeks).Time to revision did not significantly impact consolidation: 60% for 2 weeks (6/10 cases), 80% for 2−10 weeks (35/40 cases), and 64% for >10 weeks (9/14 cases) (p = 0.28). Smoking, longer initial surgery time and Gustilo type IIIb or IIIc were significant risks factors for non-consolidation. DiscussionBone consolidation under septic conditions with hardware retention adhering to an established medical and surgical protocol was reliable and straightforward, without extra morbidity. These findings are encouraging, and in line with the literature. We were unable to determine a time limit beyond which hardware prevented healing. Level of evidenceIV; descriptive epidemiological study.

Selective consolidation of learning and memory via recall-gated plasticity.

In a variety of species and behavioral contexts, learning and memory formation recruits two neural systems, with initial plasticity in one system being consolidated into the other over time. Moreover, consolidation is known to be selective; that is, some experiences are more likely to be consolidated into long-term memory than others. Here, we propose and analyze a model that captures common computational principles underlying such phenomena. The key component of this model is a mechanism by which a long-term learning and memory system prioritizes the storage of synaptic changes that are consistent with prior updates to the short-term system. This mechanism, which we refer to as recall-gated consolidation, has the effect of shielding long-term memory from spurious synaptic changes, enabling it to focus on reliable signals in the environment. We describe neural circuit implementations of this model for different types of learning problems, including supervised learning, reinforcement learning, and autoassociative memory storage. These implementations involve synaptic plasticity rules modulated by factors such as prediction accuracy, decision confidence, or familiarity. We then develop an analytical theory of the learning and memory performance of the model, in comparison to alternatives relying only on synapse-local consolidation mechanisms. We find that recall-gated consolidation provides significant advantages, substantially amplifying the signal-to-noise ratio with which memories can be stored in noisy environments. We show that recall-gated consolidation gives rise to a number of phenomena that are present in behavioral learning paradigms, including spaced learning effects, task-dependent rates of consolidation, and differing neural representations in short- and long-term pathways.

Total Hip Replacement and Femoral Nail Lengthening for Hip Dysplasia and Limb Length Discrepancy: A Literature Review.

Developmental dysplasia of the hip (DDH) is a serious condition resulting in inadequate acetabular development, distorted bone configuration, and substantially alteredhip biomechanics. An extensive leg length discrepancy (LLD) is commonly encountered in such cases, making a total hip arthroplasty (THA) procedure extremely challenging. Although good results in terms of patients' satisfaction, implant survival rates and overall improved quality of life have been reported, complication rates are considerably higher than primary THA procedures performed for idiopathic osteoarthritis. Reconstructing a dysplastic hip arthrosis and equalizing a preexisting LLD is a technically demanding procedure that is associated with significant bone and soft tissue complications. Intramedullary lengthening through motorized nails has become increasingly popular to address difficult cases with extensive LLD following THA in recent years. However, limited data on femoral lengthening procedures implemented following THA are available considering complications, radiological results, and patient-reported outcomes following staged THA and subsequent femoral lengthening using a femoral magnetically-driven intramedullary lengthening nail. We performed a literature review of the past 10 years in PubMed using the terms neglected hip dislocation, DDH, THA, and intramedullary lengthening nail as keywords. A total amount of eight cases addressing LLD through a telescoping intramedullary nail following THA in DDH have been reported in recent literature. All eight patients underwent primary THA for DDH followed by the implantation of the intramedullary lengthening nail. The mean THA was lengthened by 28.9 mm (from 13.0 to 45.0). The mean time for nail implantation after THA was 11.1 months (from 3.5 to 21). The mean time for lengthening per day through the nail was 0.94 mm (from 0.65 to 1.0) from 26 days to 70 days, and the mean lengthening through the nail was 37.6 mm (from 24.0 to 70.0). Good union and consolidation rates were reported by the authors, while there were no complications. The intramedullary distraction osteogenesis method with a telescopic rod can be an effective method to manage leg length discrepancies while avoiding soft tissue complications in challenging cases of DDH.

Evaluation of Aydın Koçarlı Plain Land Consolidation Project in Terms of Some Engineering Services

This study, which presents a general evaluation of the land consolidation project carried out in 14 settlements in the Koçarlı district of Aydın province, the 'Aydın Koçarlı Plain 1st Part Land Consolidation Project', completed by the Aydın Provincial Directorate of Agriculture in 2016, was examined. For this purpose, the consolidation rate, parcel reduction index, deduction rate, and changes in parcel size and parcel number values of the consolidation project carried out in Orhaniye, Madrandere, Çakırbeyli, Boydere, Cincin, Çakmar, Halilbeyli, Koçarlı, Büyükdere, Şahinciler, Sobuca, Dedeköy, Tekeli, and Güdüşlü neighborhoods were investigated. In the project area, the average deduction rate was 7%, the consolidation rate was 31%, and the parcel reduction index was 1.46. As an overall evaluation of agricultural enterprises, the average parcel size increased from 1.76 ha to 2.57 ha, while the number of parcels decreased from 0.93 to 0.64. Land consolidation projects have a high potential to increase agricultural productivity and promote sustainable farming practices. Therefore, the results obtained from the study can contribute to the planning and implementation of similar projects.

Percutaneous distal bicortical proximal phalanx osteotomy for second toe deformities – A two-year prospective cohort study

PurposeThe main purpose of our study was to evaluate satisfaction, recurrence, bone union and other complications after a minimum of two years follow-up in patients who had percutaneous claw and hammer (CHT) second toe correction utilizing a novel distal and bicortical proximal phalanx osteotomy (DBPPO). MethodsA minimum two-year follow-up prospective cohort study was conducted on consecutive patients with symptomatic CHT deformities of the second toe corrected with percutaneous surgery. Primary outcomes included satisfaction, recurrence, bony union, and other complication rates specific to the second toe deformity correction. Secondary outcomes included Metatarsophalangeal-Interphalangeal AOFAS scale and Visual Analogue Scale (VAS). ResultsBetween January and October 2020, 34 patients (43 feet) were clinically and radiologically evaluated pre and postoperatively at a mean of 26.6 months. Thirty-eight feet (88.4 %) were satisfied or very satisfied with their second toe deformity correction and 41 feet (95.3 %) would undergo surgery on this toe again. No deformity recurrence requiring revision was found. There were two complications (4.7 %): one toe (2.3 %) with persistent numbness and one (2.3 %) had a simple infection that resolved with oral antibiotics. All 43 s toe osteotomies demonstrated bony consolidation. Stiffness was reported in nine second toes (20.9 %), seven of them (77.8 %) having a rigid pre-operative deformity. Secondary outcomes demonstrated significant improvement in the mean ( ± standard deviation) AOFAS score which increased from 47.5 ± 17.9 preoperatively to 95.7 ± 7.7 postoperatively (p < .001). Mean VAS significantly improved from 4.9 ± 2.5 preoperatively to 0.3 ± 1.3 postoperatively (p < .001). ConclusionPercutaneous treatment of claw and hammer second toe deformities utilizing a DBPPO resulted in high levels of satisfaction with bony consolidation, no recurrence and low complication rates at two years follow-up.Level of evidence: Level II – Prospective cohort study

Experimental and numerical modeling on vacuum consolidation behavior of staged-filled soil slurry with prefabricated horizontal drain and flocculant

The vacuum-assisted prefabricated horizontal drain offers a promising method for strengthening soil slurry, allowing simultaneous filling and vacuum-dewatering via staged construction. However, there is limited research on the unique characteristics of staged filling. This study aims to investigate the vacuum consolidation process of staged-filled soil slurry through laboratory model tests and numerical simulations, also assessing the impact of anionic polyacrylamide. Comparative analyses are conducted between vacuum consolidation with and without anionic polyacrylamide, as well as self-weight consolidation without anionic polyacrylamide. Results reveal contour lines of excess pore pressure, water content, and soil strength forming an ellipse around the prefabricated horizontal drain board. During the consolidation process, a higher degree of consolidation, lower water content, and higher soil strength were observed closer to the prefabricated horizontal drain board. After treatment, the uppermost filling layer exhibits an average water content that was approximately 40% higher than the lower filling layer, and its average strength was about 60% lower. This discrepancy is primarily due to the absence of sealing on the top surface and the relatively short vacuum consolidation time caused by staged filling. The introduction of anionic polyacrylamide-induced flocculation significantly improves the initial consolidation rate but minimally affects the dewatering capacity of vacuum preloading. Using flocculant can enhance both the staged filling rate and soil strength (by 1–2 times). Additionally, employing a staggered arrangement between different prefabricated horizontal drain layers is advisable to prevent top-down penetration in areas with low soil strength.

Study of design parameters for staged-filled slurry treated by prefabricated horizontal drains under vacuum preloading

The method of using Prefabricated Horizontal Drains (PHDs) placed in layers under vacuum preloading can significantly speed up consolidation of staged-filled soil slurry. The PHDs can settle with the soil slurry and maintain their shape/pattern and dewatering capacity largely in comparison with Prefabricated Vertical Drains (PVDs). This study presents a field trial focused on treating dredged sediments using PHDs under vacuum preloading for land reclamation purposes. The staged filling involved in the field trial is analyzed using a finite strain consolidation model based on the piecewise-linear finite-difference method. Then, the effects of horizontal and vertical spacings of PHDs on settlement and vacuum consolidation rate are evaluated, considering various combinations of variables for staged-filled soil. It is found that for soils with low compressibility, the consolidation rate is primarily affected by the vertical spacing of PHD layers. For soils with higher compressibility, the consolidation rate is more significantly affected by the horizontal spacing of PHDs, and the final settlement after vacuum preloading is mainly influenced by the vertical spacing of PHD layers. This study provides practical recommendations for cost-effective design of horizontal and vertical spacings of PHDs in efficiently treating soil slurry with different compressibility and initial conditions.

Are omicron infections more frequently associated with bacterial co-infections?

Clinical observations suggest that Omicron infections may present with different radiographic findings and be more frequently associated with bacterial co-infections, but there is a paucity of published data. This study aimed to compare the clinical and radiographic findings of patients hospitalized with Omicron versus alpha-delta infections. Between January 1, 2021 and June 30, 2021 (alpha and delta period) and between January 1, 2022 and July 31, 2022 (Omicron period), respectively 149 and 163 COVID-19 PCR-positive patients who were followed up in the COVID-19 ward and intensive care unit of a tertiary care center were included in the study. Clinical (presence of fever and purulent sputum), laboratory and radiologic findings of the two groups were compared. Sputum culture results and antibiotic use were also evaluated. In the alpha/delta group, ground glass opacities were seen in 75.2% (112) of the patients, consolidation in 2.7% (4), and both findings together in 6.0% (9). In the Omicron group, ground glass was seen in 40.5% (66), consolidation in 5.5% (9), and both ground glass and consolidation together in 8.7% (13) (p< 0.001). Procalcitonin levels were 0.25 µg/L or higher in 29.6% and 43.9% of the patients in the alpha/delta and Omicron groups, respectively. Mean PCT values were 0.36 µg/L and 1.93 µg/L, respectively (p> 0.05). CRP levels were similar in both groups. Mean LDH level in the Omicron group was 278 U/L and was significantly lower than the alpha/delta group (381 U/L) (p< 0.001). The proportion of patients requiring intensive care during hospitalization was higher in the alpha/delta group (36.2% vs 26.4%) (p= 0.06). Lower LDH levels, less need for intensive care and less frequent development of ARDS indicate that Omicron causes milder disease, while a higher rate of consolidation and higher procalcitonin levels suggest a higher frequency of bacterial co-infections.

Improvements in Pediatric Bone Loss Reconstruction With the Induced Membrane Technique.

The induced membrane technique is now widely used for pediatric diaphyseal bone loss due to various etiologies. Although consolidation rates remain satisfactory, complications, and healing delays may occur requiring additional procedures. We studied a series of induced membrane bone reconstructions in which the second stage included an embedded endomembranous non vascularized fibular shaft, in addition to iliac bone grafts. The purpose of this study was to analyze the results in terms of bone consolidation and complications. This is a retrospective comparative and multicentric study of 32 children with large bone loss treated with the induced membrane reconstruction technique. Patients were divided into 2 groups according to the graft used during the second stage. The first group (G1) of 16 patients had a nonvascularized fibula embedded inside the membrane in addition with the corticocancellous grafts from the iliac crest. The second group (G2) of 16 patients underwent reconstruction using the original technique, with iliac crest graft only. The 2 groups were similar in terms of etiologies of bone loss and follow-up (mean: 44mo for G1 and 49mo for G2). Mean bone losses were 15.4cm (range: 2 to 25; SD: 5.6) for G1 and 10.6cm (range: 3 to 19; SD: 5.2) for G2. In the first group, all patients healed primarily, with a mean time of 5.9 months (range: 4 to 8; SD: 1.6). In the second group, 2 of 16 patients did not healed; for the others 14, healing mean time was 6.9 months (range: 3 to 12; SD: 2.7). The short-term and long-term complications rates were 38% to 19% for G1 and 50% to 31% for G2, respectively. Regarding the donor site, the fibulas reconstructed spontaneously with a mean time of 4.8 months (range: 3 to 6; SD: 1.2). The integration of a nonvascularized fibula during the second stage of the induced membrane technique appears to improve the consolidation rate in the pediatric population. Level III-Retrospective comparative study.

Unit cell consolidation of a PVD incorporated soft soil: Comparative of 2D axisymmetric and plane strain analysis considering ideal and actual drain

The paper presents two-dimensional (2D) finite element-based study of a surcharge-induced consolidating unit cell model comprising fully saturated soft soil. Radial drainage in the unit cell is ensured through a single prefabricated vertical drain (PVD) along with vertical drainage through the top surface. Finite element based 2D axisymmetric and plane strain modelling has been conducted by considering the smearing of cohesive medium. The PVD is represented by both 1D drain element (ideal drain) and through geometric modelling considering well resistance. The parameters for the ‘Soft Soil’ model for the cohesive medium are adopted from the subsurface data at Krishnapatnam Ultra Mega Power Project (KUMPP), India. Comparative assessment of unit-cell consolidation is carried out between the 2D axisymmetric and equivalent plane strain condition based on Hird’s permeability compatibility approach. The two approaches yielded noticeable disparity in the time rates of consolidation for time factor ≤ 0.4, beyond which the disparity decreases, and the two methods lead to identical results beyond time factor = 4. Further, the influence of permeability of a geometrically modelled PVD and the height of unit cell on the time-rate of consolidation is elucidated, thereby manifesting the importance of well resistance and drainage length in such analyses.

Performance improvement of nanocolloidal silica-aluminate cement composite grouting materials with organic acids

The combination of nanocolloidal silica and aluminate cement is a potential technical approach to solve the problem of mudstone grouting, but there is a lack of high-performance admixtures to improve early strength and gel time. The effects of three common organic acids, citric acid, tartaric acid and malic acid, on the properties of the composite slurry were explored. Meanwhile, the influence of citric acid on the fluidity and microstructure characteristics of the composite slurry was deeply analysed. Finally, the key engineering properties such as injectability and reinforcement of composite slurry were explored. The main conclusions were as follows: the citric acids had a significant beneficial effect on the compressive strength and gel time. After the addition of 4% citric acid, the consolidation rate of the composite slurry was 92.68%, the compressive strength was 39.22 MPa, the consolidation rate and compressive strength were at high levels, and the gel time was 90–110 min. The main reasons for the excellent strength performance were the dense microstructure, CAH10 and C2AH8 hydrates and 98.68% of pores having pore sizes less than 20 nm. The composite slurry can be injected in the rock with average pore throat diameter of 15.14 μm. The hydration products could be better combined with mudstone, the rock softening zone was smaller than that of ordinary Portland cement, and the composite slurry could reduce the softening phenomenon of mudstone. The findings of this work could provide guidelines for the development of high-performance grouting materials and solving the reinforcement problem of mudstone.