A Coupled Bio-Chemo-Hydro-Mechanical Model for Bio-cementation in Porous Media

A key challenge involving microbial induced carbonate precipitation (MICP) is lack of rigorous yet practical theoretical models to predict the intricate biological-chemical-hydraulic-mechanical (BCHM) processes and the resulting bio-cement production. This paper presents a novel BCHM model based on multiphase, multispecies reactive transport approach in the framework of poroelasticity, aimed at achieving reasonable prediction of the produced bio-cement, and the enhanced geomechanical characteristics. The proposed model incorporates four key components: (i) coupling of hydro-mechanical stress/strain alterations with bio-chemical processes; (ii) stress/strain changes induced due to precipitation and growth of bio-cement within the porous matrix; (iii) spatiotemporal variability in hydraulic and stiffness characteristics of the treated medium; (iv) and velocity dependency of the attachment rate of bacteria. The fully-coupled BCHM model predicts key unknown parameters during treatment including: concentration of bacteria and chemical solutions, precipitated calcium carbonate, hydraulic properties of the solid skeleton, and in-situ pore pressures and strains. The model was able to reasonably predict bio-cementation from two different laboratory column experiments. The Kozeny–Carman permeability equation is found to underestimate permeability reductions due to bio-cementation, while the Verma–Pruess relation could be more accurate. A sensitivity analysis revealed bio-cement distribution to be particularly sensitive to the attachment rate of bacteria.

A Nomogram for Predicting the Residual Back Pain after Percutaneous Vertebroplasty for Osteoporotic Vertebral Compression Fractures

Objective. Current findings suggest that percutaneous vertebroplasty (PVP) is a suitable therapeutic approach for osteoporotic vertebral compression fractures (OVCFs). However, a significant minority of patients still experience residual back pain after PVP. The present retrospective study was designed to determine the risk factors for residual back pain after PVP and provides a nomogram for predicting the residual back pain after PVP. Methods. We retrospectively reviewed the medical records of patients with single-segment OVCFs who underwent bilateral percutaneous vertebroplasty. Patients were divided into group N and group R according to the postoperative VAS score. Group R is described as the VAS score of residual back pain ≥ 4. Pre- and postoperative factors that may affect back pain relief were evaluated between two groups. Univariate and multivariate logistic regression analysis were performed to identify risk factors affecting residual back pain after PVP. We provided a nomogram for predicting the residual back pain and used the receiver operating characteristic curve (ROC), concordance index (C-index), calibration curve, and decision curve analyses (DCA) to evaluate the prognostic performance. Results. Among 268 patients treated with PVP, 37 (13.81%) patients were classified postoperative residual back pain. The results of the multivariate logistical regression analysis showed that the presence of an intravertebral vacuum cleft (IVC) (OR 3.790, P = 0.026 ), posterior fascia oedema (OR 3.965, P = 0.022 ), severe paraspinal muscle degeneration (OR 5.804, P = 0.01 ; OR 13.767, P < 0.001 ), and blocky cement distribution (OR 2.225, P = 0.041 ) were independent risk factors for residual back pain after PVP. The AUC value was 0.780, suggesting that the predictive ability was excellent. The prediction nomogram presented good discrimination, with a C-index of 0.774 (0.696∼0.852) and was validated to be 0.752 through bootstrapping validation. The calibration curve of the nomogram demonstrated a good consistency between the probabilities predicted by the nomogram and the actual probabilities. The nomogram showed net benefits in the range from 0.06 to 0.66 in DCA. Conclusions. The presence of IVC, posterior fascia oedema, blocky cement distribution, and severe paraspinal muscle degeneration were significant risk factors for residual back pain after PVP for OVCFs. Patients with OVCFs after PVP who have these risk factors should be carefully monitored for the possible development of residual back pain. We provide a nomogram for predicting the residual back pain after PVP.

ANALISIS MODEL TRANSSHIPMENT DALAM PROSES DISTRIBUSI PRODUK SEMEN DI CV BANGUN KREASI ABADI

Bangun Kreasi Abadi is one of the distributors working with PT. Jui Shin Indonesia in marketing and distributing Garuda cement products to several regions in West Java, especially the city of Bandung. In the distribution process, CV Bangun Kreasi Abadi does not send its cement products directly to consumers, but CV. Bangun Kreasi Abadi uses two warehouses as transit points for the delivery of cement products for several regions. The transshipment method has several problems because in the distribution process, products are not sent directly to consumers but must pass through several transit points first. This will result in large costs because the delivery process will be twice as long and will also result in a longer lead time. This study aims to determine the optimal allocation of Garuda cement distribution to produce minimum transportation costs from distributors to warehouses and from warehouses to service points (retailers) using the Transshipment method with the help of Lingo Solver Software. The result of transportation costs from distributors to warehouses is Rp. 25,655,900 and transportation costs from warehouses to retailers of Rp. 26,140,220, the total cost of Garuda cement distribution is Rp. 51,796,120.

Effects of Bone Cement Distribution On Adjacent Endplates After Percutaneous Vertebroplasty For Thoracolumbar Fractures: A Finite Element Analysis

BACKGROUND: Percutaneous vertebroplasty (PVP) is a common surgical method for the treatment of thoracolumbar compression fractures. Currently, no biomechanical analysis has been performed examining the effects of cement distribution and positioning on the overall thoracolumbar range of motion (ROM) and the stress applied to adjacent endplates.METHODS: A model of PVP following vertebral compression fracture was established based on computed tomography data. Cement was injected into the T12 vertebral body. Depending on the location of the injection site, the model was divided into a median cement model, a left cement model, an upper-left cement model, and a lower-left cement model. The postoperative thoracolumbar ROM and biomechanical changes to the adjacent endplates were analyzed.RESULTS: After cement injection, the overall ROM for the thoracolumbar region increased compared with that before cement injection. The maximum ROM of flexion was 9.28° for the left model; the maximum ROM of extension was 10.90° for the upper-left model; the maximum left and right rotations were 8.47° and 8.52°, respectively, for the left model; the maximum left bending was 13.10° for the left model; and the maximum right bending was 13.43° for the left model. The stress applied to the adjacent vertebral endplate in the median cement model increased compared with the intact model, and the von Mises stress (VMS) value changed with different cement positions.CONCLUSION: After cement injection, the overall stress value of the endplate adjacent to the vertebral body increased, and when the position of the cement shifts, the maximum VMS increased further for some positions, and the stress value for the endplate adjacent to the vertebral body increased, which may cause fractures in the relative position.

Influence of bone cement distribution on outcomes following percutaneous vertebroplasty: a retrospective matched-cohort study

Objective To evaluate the influence of insufficient bone cement distribution on outcomes following percutaneous vertebroplasty (PVP). Methods This retrospective matched-cohort study included patients 50–90 years of age who had undergone PVP for single level vertebral compression fractures (VCFs) from February 2015 to December 2018. Insufficient (Group A)/sufficient (Group B) distribution of bone cement in the fracture area was assessed from pre- and post-operative computed tomography (CT) images. Assessments were before, 3-days post-procedure, and at the last follow-up visit (≥12 months). Result Of the 270 eligible patients, there were 54 matched pairs. On post-operative day 3 and at the last follow-up visit, significantly greater visual analogue scale (VAS) pain scores and Oswestry Disability Index (ODI) scores were obtained in Group B over Group A, while kyphotic angles (KAs) and vertebral height (VH) loss were significantly larger in Group A compared with Group B. Incidence of asymptomatic cement leakage and re-collapse of cemented vertebrae were also greater in Group A compared with Group B. Conclusions Insufficient cement distribution may relate to less pain relief and result in progressive vertebral collapse and kyphotic deformity post-PVP.

Clinical observation of two bone cement distribution modes after percutaneous vertebroplasty for osteoporotic vertebral compression fractures

Background Current findings suggest that percutaneous vertebroplasty(PVP) is a suitable therapeutic approach for osteoporotic vertebral compression fractures (OVCFs). The present retrospective study aimed to investigate the differences in clinical efficacy and related complications between the two bone cement distribution modes. Methods We retrospectively reviewed the medical records of the patients with single-segment OVCFs who underwent bilateral percutaneous vertebroplasty. Patients were divided into blocky and spongy group according to the type of postoperative bone cement distribution. Clinical efficacy and related complications was compared between the two bone cement distribution modes on 24 h after the operation and last follow-up. Results A total of 329 patients with an average follow up time of 17.54 months were included. The blocky group included 131 patients, 109 females(83.2 %) and 22 males(16.8 %) with a median age of 72.69 ± 7.76 years, while the Spongy group was made up of 198 patients, 38 females(19.2 %) and 160 males(80.8 %) with a median age of 71.11 ± 7.36 years. The VAS and ODI after operation improved significantly in both two groups. The VAS and ODI in the spongy group was significantly lower than that in the blocky group, 24 h postoperatively, and at the last follow-up. There were 42 cases (12.8 %) of adjacent vertebral fractures, 26 cases (19.8 %) in the blocky group and 16 cases (8.1 %) in the spongy group. There were 57 cases (17.3 %) of bone cement leakage, 18 cases (13.7 %) in blocky group and 39 cases (19.7 %) in the spongy group. At 24 h postoperatively and at the last follow-up, local kyphosis and anterior vertebral height were significantly corrected in both groups, but gradually decreased over time, and the degree of correction was significantly higher in the spongy group than in the block group. The change of local kyphosis and loss of vertebral body height were also less severe in the spongy group at the last follow-up. Conclusions Compared with blocky group, spongy group can better maintain the height of the vertebral body, correct local kyphosis, reduce the risk of the vertebral body recompression, long-term pain and restore functions.

TRANSPORTATION OPTIMIZATION MODEL USING THE DISTANCE MATRIX: A CASE OF CEMENT DISTRIBUTION FROM SELECTED COMPANIES TO DISTRIBUTION CENTERS IN EBONYI STATE

Ascertaining an optimal cement distribution plan for cement companies in Nigeria has remained a challenge. The absence or fluctuation of data for estimating the cost of transporting cement from each source to each distribution center is a big stumbling block whenever modeling attempts are being made via transportation algorithms. This work has succeeded in removing these challenges by providing a Transportation Optimization Model for cement distribution using transportation Distance Matrix instead of transportation Cost Matrix. This research seeks to improve supply in the Nigerian cement industry. Three selected factories (Gboko, Port-Harcourt and Calabar) and four major distribution centers (Abakaliki, Onueke, Ohaozara and Afikpo) in Ebonyi state were considered for this work. The result of the findings using the Vogel Approximation Method, minimized the total transportation distance and by implication the total transportation costs.

Percutaneous Osteoplasty under Fluoroscopy and Cone-Beam CT guidance for Painful Sternal Metastases

Background: Although percutaneous osteoplasty (POP) has been widely accepted and is now being performed for the treatment of painful bone metastases outside the spine, there are only scarced reports regarding osteoplasty in painful sternal metastases.Case presentation: The paper reported four patients with painful sternal metastasis who underwent POP under fluoroscopic and cone-beam CT guidance. The patients were three men and one woman (mean age, 66.25 years). Primary tumor location in lung is 3 cases, in thyroid is 1 case. In these cases, Pain was measured using a numerical rating scale (NRS), with scores ranging from 0 (no pain) to 10 (worst pain imaginable). The scores on the NRS in the four patients before POP were 9, 8, 8, and 9. After POP, the NRS scores decreased to 2, 3, 2, and 2, respectively, in follow-up at 6 months. Conclusions: POP is a safe and effective treatment for pain caused by metastatic bone tumors in the sternum. However, care and at tention should be paid to the insertion of a needle and cement distribution for better treatment effect

Is unilateral transverse process-pedicle percutaneous kyphoplasty a better choice for osteoporotic thoracolumbar fractures in the old patients?

Background A few reports have shown that unilateral transverse process-pedicle percutaneous kyphoplasty is a good choice for patients with osteoporotic vertebral compression fracture (OVCF). However, this issue remains controversial and the related comprehensive research was lacked. Methods A retrospective study was conducted on patients receiving PKP surgery for OVCF. Patients were divided into three groups according to surgical approach. Symptom and radiographical evaluation were performed preoperatively, 1-month postoperatively, 1-year postoperatively and follow-ups. And follow-ups were repeated every year. Visual Analogue Scale Score (VAS), Oswestry Disability Index (ODI) scores, anterior vertebral height, coronal Cobb angle and sagittal Cobb angle was determined and compared among three groups. Results Totally 447 patients were included with an average age of 76.6 ± 7.2 years old. UTP showed significantly shorter surgical duration (p < 0.001), lower cement volume (p < 0.001) but higher cement leakage proportion (p = 0.044). No significant statistical difference was found in terms of improvement rates among three groups. Besides, it was notable that the a significantly higher coronal Cobb angle was observed in UTP group, and a about 4°coronal correction was found after UTP PKP. Conclusion UTTP PKP could achieve similar symptoms relief and kyphosis correction as UTP and BTP PKP. However, it had shorter surgical time and less radio exposure than BTP PKP, lower risk of cement leakage and higher proportion of bilaterally cement distribution than UTP PKP. It seemed to be a better choice for patients with OVCF. In addition, we found that UTP PKP was especially fit for OVCF patients with asymmetrical vertebral compression.