Tilt Deformation Research Articles

Monitoring of Surface Deformation in the Xi'an Coal Mine, Liaoyuan, Based on Time-Series InSAR

In this study, we employed SBAS-InSAR and Stacking-InSAR methods to monitor and analyze the surface deformation of coal mines in the Xi'an District of Liaoyuan. The Pearson correlation coefficient of the deformation results obtained from the two methods is 0.9. Moreover, the deformation regions monitored by the two techniques exhibit a high degree of consistency in their spatial distribution, validating the accuracy of our monitoring results. Using the monitoring data derived from InSAR and field investigations, we revealed the spatial distribution characteristics of surface subsidence and its temporal evolution between 2018 and 2021. Our findings indicate that subsidence predominantly occurred in five regions, with subsidence velocity slowing after October 2020, suggesting a gradual weakening of surface deformation activities. Additionally, we analyzed surface deformation indicators, such as tilt and curvature, revealing the complexity of the deformation areas characterized by multiple tilt and curvature deformation centers. These results provide a crucial scientific basis for geological disaster prevention and ecological restoration in the mining area, aiding the development of more effective management and restoration strategies.

Changing magma recharge/discharge dynamics during the 2020–22 lava fountaining activity at Mt. Etna revealed by tilt deformation and volcanic tremor

Mt. Etna exhibited 62 lava fountaining events between December 13, 2020 and February 21, 2022. We analyzed tilt deformations and volcanic tremor amplitude time series, to characterize both eruptions and the preceding preparatory phases in terms of magnitude and speed of development of the volcanic phenomena, as well as to reconstruct the processes that took place inside the plumbing system and drove this intense period of activity. Based on deflation amplitudes associated with lava fountains and according with other retrieved parameters (i.e., magnitude of inflations, inflation and deflation velocities and volcanic tremor amplitudes), three periods have been distinguished. Period I displays higher values of all the aforementioned parameters, interpreted as conspicuous volumes of volatile-rich magma transferred towards the surface. Period II shows lower values evidencing lack of important new injections of magma from depth, whereas period III reveals a general increasing trend possibly related to gas flushing from magma residing in deeper portions of the plumbing system. Detailed elaborations of tilt signals allowed the identification of short-lived inflations accompanying the early stages of lava fountains during period II. Our results reveal significant correlations between amplitude and velocity of tilt and volcanic tremor signals associated with lava fountains and evidence the crucial role of gas in the inflation-deflation cycles.

Impacts of Surface Deformation Induced by Underground Mining of Metal Mines on Above-Ground Structures: A Case Study

The surface deformation caused by underground mining seriously affects the normal life and personal safety of local residents and also causes unfavorable factors for the safe and efficient exploitation of underground resources. While the study of surface deformation caused by underground mining of metal mines requires a large amount of measured data as support, the measured data is particularly scarce, which severely hinders the study of surface deformation caused by underground mining. In this paper, in order to study the impact of underground mining on surface structures in metal mines, we take the Fu Lao Zhuang Iron Mine in Anhui Province, China, as the research object and put forward a comprehensive measurement method based on the flat plate beam theory. Using empirical formulas combined with the methods of thickness-to-span ratio and the relaxation coefficient, etc., we carry out numerical simulation calculations for the displacement of the surface triggered by the mining of the ore body by using FLAC3D software. We calculate the maximum inclination deformation, curvature, and horizontal deformation values of the ground surface by referring to the displacement and deformation with reference to the displacement and deformation formula; the maximum tilt deformation, curvature, and horizontal deformation values of the ground surface are calculated, and finally, the permissible values of the design specifications are combined to make a judgment. The research results of this paper put forward the prerequisite for improving the surface deformation induced by underground mining.

Osteotomies around the knee alter alignment of the ankle and hindfoot: a systematic review of biomechanical and clinical studies

Purpose Emerging reports suggest an important involvement of the ankle/hindfoot alignment in the outcome of knee osteotomy; however, a comprehensive overview is currently not available. Therefore, we systematically reviewed all studies investigating biomechanical and clinical outcomes related to the ankle/hindfoot following knee osteotomies. Methods A systematic literature search was conducted on PubMed, Web of Science, EMBASE and Cochrane Library according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and registered on international prospective register of systematic reviews (PROSPERO) (CRD42021277189). Combining knee osteotomy and ankle/hindfoot alignment, all biomechanical and clinical studies were included. Studies investigating knee osteotomy in conjunction with total knee arthroplasty and case reports were excluded. The QUality Appraisal for Cadaveric Studies (QUACS) scale and Methodological Index for Non-Randomized Studies (MINORS) scores were used for quality assessment. Results Out of 3554 hits, 18 studies were confirmed eligible, including 770 subjects. The minority of studies (n = 3) assessed both high tibial- and distal femoral osteotomy. Following knee osteotomy, the mean tibiotalar contact pressure decreased (n = 4) except in the presence of a rigid subtalar joint (n = 1) or a talar tilt deformity (n = 1). Patient symptoms and/or radiographic alignment at the level of the ankle/hindfoot improved after knee osteotomy (n = 13). However, factors interfering with an optimal outcome were a small preoperative lateral distal tibia angle, a small hip–knee–ankle axis (HKA) angle, a large HKA correction (>14.5°) and a preexistent hindfoot deformity (>15.9°). Conclusions Osteotomies to correct knee deformity alter biomechanical and clinical outcomes at the level of the ankle/hindfoot. In general, these changes were beneficial, but several parameters were identified in association with deterioration of ankle/hindfoot symptoms following knee osteotomy.

Plain Ankle Radiographs Underestimate Valgus Tibiotalar Tilt in Progressive Collapsing Foot Deformity: A Comparative Analysis with WBCT

Category: Ankle Arthritis Introduction/Purpose: Detection and accurate assessment of valgus tibiotalar tilt are important for staging and surgical planning of progressive collapsing foot deformity (PCFD). Plain ankle radiographs (XRs) have been used to evaluate this condition, but recent literature suggests that XRs may underestimate ankle deformities when compared to weightbearing computed tomography (WBCT), which is becoming increasingly utilized in PCFD evaluation. However, the discrepancies between these methods have not been explored. This study aims to: 1) determine the difference in tibiotalar tilt measurements between XRs and WBCTs; 2) compare the prevalence of significant valgus tibiotalar tilt (>4 degrees) between XRs and WBCTs in PCFD patients; and 3) determine the radiographic characteristics of patients who exhibit a discrepancy between XR and WBCT in the presence of significant valgus tibiotalar tilt. Methods: One hundred thirty-eight PCFD patients (Mean age: 55.1 years) having both WBCT and ankle XRs were reviewed. On ankle XRs, tibiotalar tilt (TTXR) and medial distal tibial angle (MDTAXR) were measured. On WBCT, the TTWBCT and MDTAWBCT were assessed at three locations (25% [anterior], 50% [middle], and 75% [posterior] of the sagittal dimension of the distal tibial plafond) in coronal views (Figure 1). The degree of tibiotalar tilt and prevalence of significant valgus tibiotalar tilt were compared between TTXR and the TTWBCT. Bland-Altman plots compared the mean TT and MDTA from XRs to those of the three coronal WBCT images to determine which region in WBCT is most similar to the XRs in each measurement. The radiographic characteristics of patients with and without a discrepancy between XRs and WBCTs for the presence of significant valgus tibiotalar tilt were examined via subgroup analysis. Results: Mean TTXR and TTWBCT were 1.5 (standard deviation [SD] 3) and 4.1(SD 3) degrees, respectively, indicating that XRs underestimate tibiotalar tilt by 63.4%. The prevalence of significant valgus tibiotalar tilt was 10.1% on XRs and 37.7% on WBCTs. Half the patients (4/8) who had bone-on-bone contact with tibiotalar tilt on WBCT didn’t exhibit such findings on XR (Figure 1). Bland-Altman plots showed that TTXR and MDTAXR best correlate with middle TTWBCT and MDTAWBCT (Figure 2). Subgroup analysis revealed that patients who exhibited significant valgus tibiotalar tilt on WBCTs, but not XRs, had smaller anterior TTWBCT and MDTAWBCT than those without such discrepancy (p <.05, Table 1), indicating that patients with a greater varus deformity on the anterior distal tibia are more likely to exhibit the discrepancy. Conclusion: This study demonstrates that ankle XRs underestimate valgus tibiotalar tilt compared to WBCTs in PCFD patients. The ankle XR parameters had the strongest correlation with those of the midpoint of the tibiotalar joint in WBCT and understated anterior side tilt and distal tibial deformity, likely due to beam projection angle and superimposition. Based on the findings of this study, WBCTs may be useful for detecting actual deformities in the ankle joint in PCFD patients; nevertheless, surgeons must be cognizant that they may underestimate the deformity in the anterior ankle when using conventional radiographs to assess ankle deformities in PCFD.

Factors Influencing Ground Settlement during Tunnel Proximity Construction

Adjacent tunnel excavation has an adverse impact on existing structures. Based on the engineering project of the Donghuashan Tunnel under-crossing an existing tunnel, this paper designed 25 sets of orthogonal numerical simulation tests to investigate the influential mechanisms of five parameters on ground displacement and deformation. The influential factors are skew angle (α), proximity distance (l), buried depth (h), clearance (D), and ratio of tunnel clearances (ν). The orthogonal test results revealed that (1) the new tunnel clearance is the main impact factor of both ground settlement and curvature deformation, (2) ground horizontal movement is most significantly influenced by the skew angle between the existing tunnel and the new tunnel, and (3) the new tunnel buried depth is the key influential parameter for ground tilt deformation as well as horizontal deformation. The conclusions of this research suggest that during the period of railway planning, it is very important to plan the buried depths and spans of new tunnels rationally to minimize disturbance to existing tunnels.

Accuracy of radiographic measurements of fracture-induced deformity in the distal radius.

Management of the distal radius fracture (DRF) is to some extent based on radiographic characterization of fracture displacement. It remains unclear, however, if the measurements used to quantify displacement are accurate. To quantify accuracy of two radiographic measurements: dorsal/volar tilt and fracture compression, measured indirectly as ulnar variance (UV), using radiostereometric analyses (RSA) as reference standard. Twenty-one fresh frozen non-fractured human cadaveric forearms (right = 11, left = 10) were thawed and eligible for inclusion. The forearms were mounted on a custom made platform that allowed for controlled forearm rotation, and they underwent two rounds of imaging (both rounds consisted of RSA and radiographs). In round one, the non-fractured forearms were radiographed. In round two, artificial DRF´s with compression and dorsal angulation were created and imaging procedures repeated. Change in tilt and UV between the non-fractured and later fractured forearms was defined as fracture-induced deformity. Deformity was measured radiographically and additionally calculated using RSA. Bland Altman analyses were used to estimate agreement between radiographically measured, and RSA calculated, fracture-induced deformity. Our results indicated that radiographs underestimate the amount of fracture-induced deformity. Mean measured differences (bias) in dorsal tilt deformity between radiographs and RSA were -2.5° for both observers. The corresponding values for UV were -1.4mm and -1.5mm. Quantifying fracture-induced deformity on radiographs underestimated the actual deformity when compared to RSA calculated deformity. These findings suggest that clinicians, at least in part, base fracture management and potentially corrective surgery on inaccurate measurements.

Relationship between sacral‐abdominal wall distance and grip strength in postmenopausal osteoporotic patients

AbstractBackgroundAn increase in waist circumference (WC) is a factor in lifestyle‐related diseases. The rectus abdominis muscle is a skeletal muscle that attaches to the pelvis from the xiphoid process and is thought to be affected by kyphosis deformity and posterior pelvic tilt. The purpose of this study is to examine differences between sacral‐abdominal wall distance (SAD) and WC and to determine whether they are associated with fall risk, frailty, markers of sarcopenia (grip strength and lean body mass), and spinal alignment. A secondary objective is to examine these differences by stratification by grip strength.MethodsThis retrospective study included 239 women aged 65 years or older (mean age 76.5 ± 6.7 years) attending an outpatient osteoporosis clinic. Bone mineral density and skeletal body composition (muscle mass index and trunk lean mass) were measured using dual‐energy X‐ray absorptiometry. SAD, pelvic tilt, and sagittal longitudinal axis were measured from simple X‐ray images of the spine sides. WC, grip strength, frailty, and fall risk score were investigated. Statistics were performed using Stat Flex, with two‐sided P < 0.05 being significantly different.ResultsWC was correlated with SAD (R = 0.68, P < 0.001). The SAD cut‐off value for a WC of 90 cm was 167 mm. The relationship between grip strength, SAD, and WC, weaker grip strength was associated with greater SAD; however, no significant difference was noted in WC. WC was not correlated with pelvic alignment but was correlated with body mass index (P < 0.01). Meanwhile, SAD was correlated with body mass index, pelvic tilt, sagittal longitudinal axis (P < 0.01), spinal alignment, and WC. Logistic regression analysis was performed with a grip strength of less than 18 kg as the objective variable. We found that the conditions for a grip strength of less than 18 kg were older age (P < 0.001), increased SAD (P = 0.02), and decreased trunk lean body mass. There was a decrease in grip strength (P < 0.05) and an increase in frailty (P < 0.05) and falls (P < 0.01) score in patients with SAD of 167 mm or greater.ConclusionsSAD and WC were found to be correlated; SAD was associated with body weight, posterior pelvic tilt, and anterior spinal tilt deformity, while WC was related to body weight. Increased SAD was found to be linked with decreased grip strength and increased risk of falls. This study was the first to examine a new measurement, SAD, for its utility in assessing grip strength, spinal alignment, frailty, and fall risk.

Dynamic prediction of displacement and deformation of any point on mining surface based on B-normal model.

The surface displacement and deformation of goaf caused by coal mining destroy the underground rock structure and surface ecological environment in the mining area and endanger the safety of human life and property. An accurate and efficient dynamic prediction system of mining subsidence is indispensable. Given the limited scope of the application of the probability integral model on the edge of the mobile basin, its poor prediction effect, and its low accuracy, a new mining subsidence prediction model based on the Boltzmann function is proposed. Combined with the transformed normal distribution time function, a B-normal prediction model that can predict the dynamic displacement and deformation of any point on the surface was constructed. The global optimal solution of the parameters of the dynamic prediction model was inversed by introducing particle swarm optimization shuffled frog leaping intelligent algorithm (PSO-SFLA), and then, the model was applied to the 8102 working face of the Guobei coal mine to dynamically predict the subsidence, inclination, curvature, horizontal displacement, and horizontal deformation of the goaf surface. The prediction results showed that on the strike and dip observation lines, the prediction accuracy of the dynamic subsidence and horizontal displacement of the surface could reach the centimeter level, the predicted root mean square error (RMSE) of dynamic tilt and horizontal deformation was less than 0.51 mm/m, and the predicted RMSE of dynamic curvature was within 0.020 mm/m2. The prediction results reflected the dynamic evolution law of surface displacement and deformation and verified the reliability of the B-normal dynamic prediction model, which can fully meet the needs of practical engineering applications.

OSTEOTOMIES AROUND THE KNEE INTERFERE WITH ALIGNMENT OF THE HINDFOOT: KNEE SURGEONS SHOULD NOT FORGET THE ANKLE JOINT. A SYSTEMATIC REVIEW OF BIOMECHANICAL AND CLINICAL STUDIES

Several emerging reports suggest an important involvement of the hindfoot alignment in the outcome of knee osteotomy. At present, studies lack a comprehensive overview. Therefore, we aimed to systematically review all biomechanical and clinical studies investigating the role of the hindfoot alignment in the setting of osteotomies around the knee.A systematic literature search was conducted on multiple databases combining “knee osteotomy” and “hindfoot/ankle alignment” search terms. Articles were screened and included according to the PRISMA guidelines. A quality assessment was conducted using the Quality Appraisal for Cadaveric Studies (QUACS) - and modified methodologic index for non-randomized studies (MINORS) scales.Three cadaveric, fourteen retrospective cohort and two case-control studies were eligible for review. Biomechanical hindfoot characteristics were positively affected (n=4), except in rigid subtalar joint (n=1) or talar tilt (n=1) deformity. Patient symptoms and/or radiographic alignment at the level of the hindfoot did also improve after knee osteotomy (n=13), except in case of a small pre-operative lateral distal tibia- and hip knee ankle (HKA) angulation or in case of a large HKA correction (>14.5°). Additionally, a pre-existent hindfoot deformity (>15.9°) was associated with undercorrection of lower limb alignment following knee osteotomy. The mean QUACS score was 61.3% (range: 46–69%) and mean MINORS score was 9.2 out of 16 (range 6–12) for non-comparative and 16.5 out of 24 (range 15–18) for comparative studies.Osteotomies performed to correct knee deformity have also an impact on biomechanical and clinical outcomes of the hindfoot. In general, these are reported to be beneficial, but several parameters were identified that are associated with newly onset – or deterioration of hindfoot symptoms following knee osteotomy. Further prospective studies are warranted to assess how diagnostic and therapeutic algorithms based on the identified criteria could be implemented to optimize the overall outcome of knee osteotomy.Remark: Aline Van Oevelen and Arne Burssens contributed equally to this work

Double‐loop settlement monitoring system based on laser collimation

AbstractWith the rapid development of urbanization, high‐rise buildings have risen from the ground, but in the long‐term use of the building, there will be settlement, tilt, displacement, and other deformations, which will seriously bring disasters. At present, there is a lack of an application‐level settlement monitoring system for the monitoring of these buildings, and there are problems of low intelligent monitoring level and low monitoring accuracy, so this paper proposes a double‐loop monitoring system based on laser collimation. The system combines distributed computing, spot image processing, embedded computing, laser collimation technology etc., to design settlement monitoring equipment and corresponding software. Finally, the data processing is carried out by the double‐loop calculation algorithm to obtain the sedimentation amount of the analyte. The test results show that the whole system can be intelligently and accurately monitored, and the monitoring accuracy can reach the millimetre level.

Osteotomies Around the Knee Interfere with Alignment of the Hindfoot: A Systematic Review of Biomechanical and Clinical Studies

Category: Hindfoot; Ankle Introduction/Purpose: Several emerging reports suggest an important involvement of the hindfoot alignment in the outcome of knee osteotomy. At present these studies are scattered across the literature and lack a comprehensive overview. Therefore, we aimed to systematically review all biomechanical and clinical studies investigating the role of the hindfoot alignment in the setting of osteotomies around the knee. Methods: A systematic literature search was conducted on following databases: Pubmed, EMBASE, Cochrane Library and Web of Science. Search terms consisted of 'knee osteotomy' combined with 'hindfoot/ankle alignment'. Inclusion criteria were all English language studies analyzing the association between knee osteotomy and hindfoot alignment comprising biomechanical or clinical outcomes. Exclusion criteria consisted of knee osteotomy performed in conjunction with total knee arthroplasty and level V studies. A quality assessment was conducted using the Quality Appraisal for Cadaveric Studies (QUACS) - and modified methodologic index for non-randomized studies (MINORS) scales. This protocol was performed according to the PRISMA guidelines and registered on PROSPERO (CRD42021277189). Results: Eighteen studies were confirmed eligible and consisted of a cadaveric (n=3) -, retrospective cohort (n=14) - and case- control (n=2) study design. Following knee osteotomy, biomechanical hindfoot characteristics were also positively affected (n=4), except in rigid subtalar joint (n=1) or talar tilt (n=1) deformity. Patient symptoms and/or radiographic alignment (Fig. 1a) at the level of the hindfoot did also improve after knee osteotomy (n=13). However this did not apply in case of a small pre-operative lateral distal tibia- and hip knee ankle (HKA) angulation (Fig. 1b) or in case of a large HKA correction (>14.5°). Additionally, a pre- existent hindfoot deformity (>15.9°) was associated with undercorrection of lower limb alignment following knee osteotomy. The mean QUACS score was 61.3% (range: 46-69%) and mean MINORS score was 9.2 out of 16 (range 6-12) for non-comparative and 16.5 out of 24 (range 15-18) for comparative studies. Conclusion: Osteotomies performed to correct knee deformity have also an impact on biomechanical and clinical outcomes of the hindfoot. In general, these are reported to be beneficial, but several parameters were identified that are associated with newly onset - or deterioration of hindfoot symptoms following knee osteotomy. These results should be interpreted in light of the moderate methodological quality of the included studies. Therefore, further prospective studies are warranted to assess how diagnostic and therapeutic algorithms based on the identified criteria could be implemented to optimize the overall outcome of knee osteotomy in relation to the foot and ankle.

Effectiveness of Ilizarov Ankle Arthrodesis in the Treatment of End-Stage Varus Ankle Osteoarthritis: A Retrospective Study.

ObjectiveTo evaluate the outcomes of Ilizarov ankle arthrodesis in the treatment of end‐stage varus ankle osteoarthritis (OA).MethodsThis was a retrospective study of 63 patients with varus ankle OA who underwent Ilizarov ankle arthrodesis between June 2013 and December 2018. There were 24 males and 39 females with an average age of 56.57 ± 4.45 years (range, 47–64 years). Thirty‐six cases were affected on the left side, and 27 were affected on the right side. The patients' mean body mass index (BMI) was 25.18 ± 2.93 kg/m2. According to the modified Takakura staging criteria, there were 18 cases of stage 3b (28.57%) and 45 cases of stage 4 (71.43%). Nine patients were primary (14.29%), 48 were traumatic (76.19%), and six were caused by rheumatoid OA (9.52%). Functional assessments were performed according to the American Orthopedic Foot and Ankle Society (AOFAS) ankle‐hindfoot score, Ankle Osteoarthritis Scale (AOS), and visual analogue scale (VAS). The tibial anterior surface angle (TAS), coronal plane tibial‐talar angle (CPT), talar tilt angle (TT), deformity angle (DA), and tibial lateral surface angle (TLS) were assessed on X‐ray films.ResultsThe average operation time was 147.84 ± 13.67 min (range, 135–168 min). The average follow‐up time was 34.24 ± 8.72 months (range, 24–61 months). Bony fusion was achieved in all ankles, and the fusion time was 12.43 ± 1.99 weeks on average. The average AOFAS score at the final follow‐up increased from 42.14 ± 8.66 to 80.90 ± 6.80. The average VAS score and AOS pain and disability scores at the final follow‐up decreased from 7.29 ± 1.27 to 2.24 ± 0.94, from 67.94 ± 7.68 to 27.92 ± 5.82, and from 71.64 ± 9.37 to 41.32 ± 8.99, respectively. The average TAS, CPT, and TLS at the final follow‐up increased from 77.76° ± 4.44° to 89.81° ± 1.25°, from 69.04° ± 3.73° to 90.43° ± 1.80°, and from 82.14° ± 3.77° to 88.67° ± 2.50°, respectively. The average TT and DA at the final follow‐up decreased from 8.76° ± 4.30° to 2.05° ± 1.28° and from 20.95° ± 3.73° to 1.57° ± 0.93°, respectively. Three patients developed superficial pin tract infections, all settled with local dressing and antibiotic treatment. Two patients were found to have subtalar arthritis and underwent conservative treatment.ConclusionAnkle arthrodesis using the Ilizarov technique is efficient in treating end‐stage varus ankle OA.

Spinopelvic Balance Restoration Using Posterior Vertebral Column Resection in Fixed Lumbosacral Deformity Following Pyogenic Spondylodiscitis

Background Data: Several articles reported on PVCR for correction of thoracolumbar deformities that followed tuberculous spondylodiscitis. But fewer focused on fixed lumbosacral deformity secondary to L5 pathology. Study Design: A retrospective cohort study. Purpose: This article aims to determine the degree of spinopelvic parameters correction after posterior vertebral column resection (PVCR) of the fifth lumbar vertebra (L5) in lumbosacral deformities secondary to pyogenic spondylodiscitis and define its relation to patients` clinical and functional outcomes. Patients and Methods: This retrospective study included 12 patients with kyphotic lumbopelvic spinal deformity secondary to healed pyogenic spondylodiscitis at the lumbosacral junction. The study included seven males (58.3%) and five females (41.7%) with a mean age of 37.5 ± 7.61 years. Patients were treated with posterior vertebral column resection (PVCR). Plain radiography, computed tomography (CT), and Magnetic Resonance Imaging (MRI) were performed on all patients, and the following parameters were measured using the Surgimap (version: 2.2.13) computer program: lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), and focal deformity angle. Bony fusion is assessed using postoperative X-rays and/or CT. Visual Analogue Scale (VAS) for both leg and back pain and the Oswestry Disability Index (ODI) were assessed preoperatively and at the last follow-up. Results: The follow-up period lasted for 16 months (12–18). The solid union was achieved in all patients in 8.17 ± 1.52 months with no major postoperative complications. The mean kyphotic deformity was significantly corrected to -5.69° ± 6.77 (p

Tilt deformation and instability of the slope for predicting rainfall-induced landslide

Tilt deformation and instability of the slope for predicting rainfall-induced landslide

169. Lumbar spine sagittal mismatch deformity negatively affects total knee arthroplasty outcomes

<h3>BACKGROUND CONTEXT</h3> The relationship between total hip arthroplasty (THA) and the spine has been extensively explored. Studies have shown that alterations to sagittal spinal alignment before and after THA affect outcomes in conjunction with acetabular component positioning. However, there is currently a paucity of data regarding the potential relationships between pre-existing spinal deformity and clinical outcomes following total knee arthroplasty (TKA). <h3>PURPOSE</h3> This study analyzes the novel relationship between spinal alignment and TKA outcomes. We sought to address this deficit in the literature, provide clinical evidence to adjust surgeon and patient expectations postoperatively, and urge surgeons to consider spinal alignment evaluation prior to TKA whenever mismatch deformity is suspected. <h3>STUDY DESIGN/SETTING</h3> This is a single center retrospective cohort comparison of 933 TKAs performed by 7 surgeons at our institution from 2017-2020 for primary osteoarthritis. <h3>PATIENT SAMPLE</h3> Of the 94 TKAs that met inclusion criteria, 53 patients were found to have sagittal mismatch deformity of the spine, whereas 41 patients did not have spinal malalignment. There we no differences noted with respect to sex, age, laterality of TKA, body mass index (BMI), bone density, or coronal spinal alignment. <h3>OUTCOME MEASURES</h3> Postoperative outcomes of interest include: incidence of manipulations under anesthesia (MUA), inability to achieve range of motion (ROM)>0-120, total arc of motion (AOM) at the knee, the preoperative to postoperative change in AOM, and presence of a knee flexion contracture. <h3>Methods</h3> A total of 933 TKAs were performed at our institution from 2017-2020. Subjects were excluded if primary TKAs were not performed for osteoarthritis or if lumbar spinal imaging was insufficient to measure sagittal parameters of interest: pelvic incidence (PI), sacral slope, pelvic tilt, lumbar lordosis (LL) and mismatch deformity (MD). After exclusion, 94 TKAs were included for review. MD was defined by |PI-LL|>10°. This resulted in 53 subjects with MD and 41 without MD. Clinical outcomes above were assessed and compared between groups. <h3>Results</h3> There were no significant differences in demographics, BMI, preoperative AOM/ROM, or opiate use. TKAs with MD were more likely to have MUA (p=0.026), ROM<0-120 (p<0.001), decreases in AOM on average of 16 degree (p<0.001), and a flexion contracture (p=0.01). There were no differences in radiolucencies of TKA components postoperatively nor materials used. <h3>Conclusions</h3> Preexisting MD may adversely affect clinical outcomes after TKA. Statistically and clinically significant decreases in postoperative AOM/ROM, increased likelihood of flexion contracture, and increased needs for MUA were all noted in those with preoperative MD. These novel findings should prompt suspicion and possible workup in patients suspected of having sagittal malalignment prior to undergoing TKA. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

Fast detection method of transmission line defects and faults based on airborne laser LiDAR

In view of the fact that it is difficult for transmission line operators to find transmission line defects and accurate location information in time, and in the face of the discovered transmission line defects, they are unable to quickly and accurately return detailed defect information to provide urgent repair to provide rectification solutions, etc., this paper proposes a fast transmission line defect fault detection method based on airborne laser LiDAR, and compares and analyzes it by using laser point cloud data in different periods. It is found that there are some defects such as the interruption of the transmission line channel and the sinking of the tower foundation. Using laser point cloud data, the tilt detection and deformation of poles and towers are found, and large-scale topographic maps are quickly generated to quickly restore the three-dimensional channel environment of transmission lines, so as to provide auxiliary decision-making for transmission line defects and fault rectification schemes. The digital and scientific management of transmission line defects and equipment fault detection are realized through laser point cloud.

Addressing posterior tilt displacement during surgery to lower failure risk of sub-capital Garden types 1 and 2 femoral fractures.

Sub-capital femoral fractures (SCFF) are impacted or non-displaced in Garden types 1 and 2, respectively. Non-surgical treatment is protected weight-bearing combined with physiotherapy and radiographic follow-up in selected patients. Traditionally, in situ pinning is the surgical treatment of choice. The aim of this study was to estimate whether the valgus deformity in Garden types 1 and 2 (AO classification 31B1.1 and 31B1.2) SCFF is a virtual perception of a posterior tilt deformity and if addressing this deformity improves patients' outcomes. The records of 96 patients with Garden Types 1 and 2 SCFF treated in tertiary medical center between 1/2014 and 9/2017 were retrospectively reviewed. They all had preoperative hip joint anteroposterior and lateral radiographic views. 75 patients had additional computed tomography (CT) scans. Femoral head displacement was measured on an anteroposterior and axial radiograph projections and were performed before and after surgery. Preoperative 3D reconstructions were performed for a better fracture characterization, and assessment of the imaging was performed by the first author. The average age of the study cohort was 73years (range 28-96, 68% females). There were 58 right-sided and 38 left-sided fractures. Ninety patients had Type 1 and six patients had Type 2 fractures. The average preoperative posterior tilt was 15 degrees and the average valgus displacement was 10 degrees on plain radiographs compared to 28 degrees and 11 degrees, respectively, on CT scans. Posterior tilt was found with a virtual perception as valgus-impacted fractures. The postoperative posterior tilt was corrected to an average of 3 degrees and the valgus displacement to 5 degrees. CT provides an accurate modality for measuring femoral head displacement and fracture extent. The posterior tilt displacement should be addressed during surgery to lower failure risk and the need for additional procedures. TLV-0292-15. IV.

A Model Study of Building Seismic Damage Information Extraction and Analysis on Ground-Based LiDAR Data

Earthquake disasters can have a serious impact on people’s lives and property, with damage to buildings being one of the main causes of death and injury. A rapid assessment of the extent of building damage is essential for emergency response management, rescue operations, and reconstruction. Terrestrial laser scanning technology can obtain high precision light detection and ranging (LiDAR) point cloud data of the target. The technology is widely used in various fields; however, the quantitative analysis of building seismic information is the focus and difficulty of ground-based LiDAR data analysis processing. This paper takes full advantage of the high-precision characteristics of ground-based LiDAR data. A triangular network vector model (TIN-shaped model) was created in conjunction with the alpha shapes algorithm, solving the problem of small, nonvisually identifiable postearthquake building damage feature extraction bias. The model measures the length, width, and depth of building cracks, extracts the amount of wall tilt deformation, and labels the deformation zone. The creation of this model can provide scientific basis and technical support for postearthquake emergency relief, assessment of damage to buildings, extraction of deformation characteristics of other structures (bridges, tunnels, dams, etc.), and seismic reinforcement of buildings. The research data in this paper were collected by the author’s research team in the first time after the 2013 Lushan earthquake and is one of the few sets of foundation of LiDAR data covering the full range of postearthquake building types in the region, with the data information mainly including different damage levels of different structural types of buildings. The modeling analysis of this data provides a scientific basis for establishing the earthquake damage matrix of buildings in the region.

Surface tilt deformation of soil landslides based on laboratory and field tests

Surface tilt deformation of soil landslides based on laboratory and field tests