Biomechanical evaluation of different plunger size and plunger position on removing soft contact lenses and rigid gas permeable contact lenses.

BACKGROUND: To avoid risks of mucosal infection from contact lenses removal, a contact lens plunger is often used. OBJECTIVE: Given various types of contact lens plungers available on the market, no study has yet been done on mechanical effects of the contact lens plunger on contact lens removal. Here, this study used finite element analysis to investigate the effects of plunger size and plunger position on the removal of soft and rigid gas permeable (RGP) contact lenses. METHODS: First, we established finite element analysis models for the plunger, contact lens, cornea, and aqueous humor. The plunger is made of mostly silicone rubber, and the contact lenses are mainly made of soft and hard material. The part of the plunger used for removal was located either at the central or the edged position, with pulling 1 mm distance. The main parameters observation indicators of in this study were the reaction force at the fixed end of the cornea, aqueous humor, the von Mises stress of the plunger, the contact lenses, and the cornea. RESULTS: Results of this study showed that when a plunger of a larger diameter was used, the reaction force of the plunger was also larger, especially when applied to RGP lenses, which required a slightly larger force (∼0.27 N). Also, when removing a RGP lens from the edge, there was a greater stress at the edge of the contact lens (2.5799 MPa), and this caused a higher stress on both the cornea (0.0165 MPa) and the aqueous humor (0.00114 MPa). CONCLUSIONS: When using a plunger with a larger diameter to remove a RGP lens, although a larger force required, the relatively larger contact area likely reduced the stress on the cornea and aqueous humor, thereby reducing the risk of eye injury. In addition, when removing a RGP lens, the results of this study recommended it to be removed from the plunger edge, as that facilitated the removal of contact lens.

Bleeding Risk of Cold Versus Hot Snare Polypectomy for Pedunculated Colorectal Polyps Measuring 10 mm or Less: Subgroup Analysis of a Large Randomized Controlled Trial.

INTRODUCTION: Concerns regarding bleeding remain in cold snare polypectomy (CSP) for small pedunculated (0-Ip) polyps. The aim of this study was to compare the risk of CSP and hot snare polypectomy (HSP) for such lesions. METHODS: Data on 0-Ip colorectal polyps ≤10 mm were extracted from a large, pragmatic, randomized trial. Immediate postpolypectomy bleeding (IPPB), defined as the perioperative use of a clip for bleeding, was evaluated through polyp-level analysis. Delayed postpolypectomy bleeding (DPPB), defined as bleeding occurring within 2 weeks postoperatively, was assessed at the patient-level among patients whose polyps were all ≤10 mm, including at least one 0-Ip polyp. RESULTS: A total of 647 0-Ip polyps (CSP: 306; HSP: 341) were included for IPPB analysis and 386 patients (CSP: 192; HSP: 194) for DPPB analysis. CSP was associated with a higher incidence of IPPB (10.8% vs 3.2%, P < 0.001) but no adverse clinical events. The procedure time of all polypectomies was shorter for CSP than for HSP (123.0 ± 117.8 vs 166.0 ± 237.7 seconds, P = 0.003), while the procedure time of polypectomies with IPPB were similar (249.8 ± 140.2 vs 227.4 ± 125.9 seconds, P = 0.64). DPPB was observed in 3 patients (1.5%) in the HSP group, including one patient (0.5%) with severe bleeding, but not in the CSP group. DISCUSSION: Despite CSP being associated with more IPPB events, it could be timely treated without adverse outcomes. Notably, no delayed bleeding occurred in the CSP group. Our findings support the use of CSP for 0-Ip polyps ≤ 10 mm.

Mechanical behaviors of titanium, nickel-titanium, and stainless elastic intramedullary nail in fixation of tibial diaphyseal fractures.

INTRODUCTION: Elastic nails have been widely used in the diaphyseal fracture fixation of long bones in adolescents. However, high complication rates have been reported in cases involving weights exceeding 55 kg. The existing nails are fabricated with different metals in clinical settings; however, the effect of the materials on the mechanical responses of the fractured bone remains unclear. Hence, the present study is conducted to compare the mechanical responses of typically used metals, namely titanium, stainless, and nickel-titanium, for elastic nails in the fixation of tibial diaphyseal fractures. MATERIAL AND METHODS: A sawbone tube is used to determine the contact force, which is developed after constraining the nail inside the narrow canal using different nail materials. Furthermore, a finite element (FE) model of the tibial diaphyseal fracture is developed to predict the fracture gap deformation based on different nail materials under axial compression and bending loads. The push-out force in the FE simulation is compared with that of a case without an end cap. RESULTS: In the sawbone tube, the results indicate that the contact force developed by the titanium nail is significantly higher than those developed by stainless and nickel-titanium nails. The contact forces developed by the titanium, stainless steel, and nickel- titanium nails are 385 (SD 34), 358 (SD 49), and 258 (SD 42) N, respectively. In the FE simulation, the titanium nail yields the highest push-out force when an end cap is not used, and the push-out forces in axial compression are 201, 183, and 87 N in the titanium, stainless, and nickel-titanium nails under axial compression, respectively. By contrast, the stainless nail yields the smallest gap deformation when an end cap is used. CONCLUSION: Results of the present study show that the end cap is an important factor affecting the mechanical responses of nails fabricated using different materials. Titanium nails are preferred when an end cap is not used, whereas stainless nails are preferred when an end cap is used.

Cold Versus Hot Snare Polypectomy for Small Colorectal Polyps : A Pragmatic Randomized Controlled Trial.

BACKGROUND: Although cold snare polypectomy (CSP) is considered effective in reducing delayed postpolypectomy bleeding risk, direct evidence supporting its safety in the general population remains lacking. OBJECTIVE: To clarify whether CSP would reduce delayed bleeding risk after polypectomy compared with hot snare polypectomy (HSP) in the general population. DESIGN: Multicenter randomized controlled study. (ClinicalTrials.gov: NCT03373136). SETTING: 6 sites in Taiwan, July 2018 through July 2020. PARTICIPANTS: Participants aged 40 years or older with polyps of 4 to 10 mm. INTERVENTION: CSP or HSP to remove polyps of 4 to 10 mm. MEASUREMENTS: The primary outcome was the delayed bleeding rate within 14 days after polypectomy. Severe bleeding was defined as a decrease in hemoglobin concentration of 20 g/L or more, requiring transfusion or hemostasis. Secondary outcomes included mean polypectomy time, successful tissue retrieval, en bloc resection, complete histologic resection, and emergency service visits. RESULTS: A total of 4270 participants were randomly assigned (2137 to CSP and 2133 to HSP). Eight patients (0.4%) in the CSP group and 31 (1.5%) in the HSP group had delayed bleeding (risk difference, -1.1% [95% CI, -1.7% to -0.5%]). Severe delayed bleeding was also lower in the CSP group (1 [0.05%] vs. 8 [0.4%] events; risk difference, -0.3% [CI, -0.6% to -0.05%]). Mean polypectomy time (119.0 vs. 162.9 seconds; difference in mean, -44.0 seconds [CI, -53.1 to -34.9 seconds]) was shorter in the CSP group, although successful tissue retrieval, en bloc resection, and complete histologic resection did not differ. The CSP group had fewer emergency service visits than the HSP group (4 [0.2%] vs. 13 [0.6%] visits; risk difference, -0.4% [CI, -0.8% to -0.04%]). LIMITATION: An open-label, single-blind trial. CONCLUSION: Compared with HSP, CSP for small colorectal polyps significantly reduces the risk for delayed postpolypectomy bleeding, including severe events. PRIMARY FUNDING SOURCE: Boston Scientific Corporation.

Biomechanical comparison of different screw-included angles in crossing screw fixation for transverse patellar fracture in level walking: a quasi-dynamic finite element study.

BACKGROUND: A minimally invasive technique with various screw configurations without open surgery is currently used for the fixation of transverse patellar fractures. Percutaneous crossing screw configuration has been reported to have a good bone union rate in patellar fractures. However, the difference in mechanical stability of the fractured patella between different screw-included angles has not been fully investigated. Hence, this study aims to compare the mechanical stability of parallel and crossing screw fixations with different screw-included angles for the fixation of transverse patellar fractures during level walking. METHODS: A finite element knee model containing a patella with a transverse fracture is created. Two headless compression screws with different angles (0°, 30°, 60°, and 90°) are used to fix the fracture. The loading conditions of the knee joint during level walking are used to compare the stability of the fractured patella with different fixation screw configurations. RESULTS: The results indicate that the maximum fracture gap opening distance increased with an increase in the included angle. Two parallel screws yield the smallest gap distance among all screw configurations. The maximum gap opening distances at the anterior leading edge of the fractured patella with two parallel screws and two screws having an included angle of 90° are 0.73 mm and 1.31 mm, respectively, at 15% walking cycle. CONCLUSIONS: Based on these results, the superior performance of two parallel screws over crossing screw fixations in the fixation of transverse patellar fractures is established. Furthermore, the smaller the angle between the crossing screws, the better is the stability of the fractured patella.

Anterior tibial artery pseudoaneurysm as a rare technical complication after corrective fibular osteotomy: a case report.

INTRODUCTION: Partial fibular osteotomy has been recognized as a surgical alternative to treat medial compartment osteoarthritis of the knee. Related peroneal neuropathies are of concern among the relatively few complications after this procedure. In our clinical practice, the osteotomy level has therefore been modified to avoid the above defects. However, a rare case of vascular injury was encountered. Herein we describe an accidental anterior tibial artery pseudoaneurysm as a rare technical complication after this corrective osteotomy. CASE PRESENTATION: A 55-year-old male visited our emergency room, presenting a painful swelling over his right anterolateral shin along with surrounding ecchymosis. Thirteen days ago, he just underwent a corrective fibular osteotomy over his right painful varus knee at our institute, and was discharged after an uneventful postoperative stay. Urgent angiography revealed an out-pouching vascular lesion, pseudoaneurysm, involving his right anterior tibial artery. Prompt endovascular repair with stent insertion and balloon compression successfully stopped the persistent extravasation from the injured artery. Follow-up angiography as well as outpatient review confirmed the regression of this lesion and associated symptoms without sequelae. CONCLUSION: Although corrective fibular osteotomy is a simple surgical procedure, it is not free of complications. The suggested osteotomized level in the pertinent literature predisposes patients to certain neuromuscular deficits, which could be avoided by the modified level of osteotomy. However, our case highlights surgeons' familiarity with certain risky neurovascular structures around the osteotomy site and corresponding technical considerations. A recent surgical history along with alarming symptoms/signs should arouse clinical suspicion, aid in timely identification and make appropriate interventions for potential vascular complications.

Randomized controlled trial of early endoscopy for upper gastrointestinal bleeding in acute coronary syndrome patients.

Acute upper gastrointestinal bleeding (UGIB) in acute coronary syndrome (ACS) patients are not uncommon, particularly under dual antiplatelet therapy (DAPT). The efficiency and safety of early endoscopy (EE) for UGIB in these patients needs to be elucidated. This multicenter randomized controlled trial randomized recent ACS patients presenting acute UGIB to non-EE and EE groups. All eligible patients received intravenous proton pump inhibitor therapy. Those in EE group underwent therapeutic endoscopy within 24 h after bleeding. The data regarding efficacy and safety of EE were analyzed. It was early terminated because the UGIB rate was lower than expected and interim analysis was done. In total, 43 patients were randomized to non-EE (21 patients) and EE (22 patients) groups. The failure rate of control hemorrhage (intention-to-treat [ITT] 4.55% vs. 23.81%, p < 0.001; per-protocol [PP] 0% vs. 4.55%, p = 0.058) and 3-day rebleeding rate (ITT 4.55% vs. 28.57%, p = 0.033; PP 0% vs. 21.05%, p = 0.027) were lower in EE than non-EE group. The mortality, minor and major complication rates were not different between two groups. Male patients were at higher risk of minor and major complications after EE with OR (95% CI) of 3.50 (1.15-10.63) and 4.25 (1.43-12.63), respectively. In multivariate analysis, EE was associated with lower needs for blood transfusion (HR 0.13, 95% CI 0.02-0.98). Among patients who discontinued DAPT during acute UGIB, a higher risk (OR 5.25, 95% CI 1.21-22.74) of coronary artery stent re-thrombosis within 6 months was noticed. EE for acute UGIB in recent ACS patients has higher rate of bleeding control, lower 3-day rebleeding rate and lower needs for blood transfusion, but more complications in male patients. Further enrollment is mandatory to avoid bias from small sample size (ClinicalTrial.gov Number NCT02618980, registration date 02/12/2015).

Numerical Comparison of Restored Vertebral Body Height after Incomplete Burst Fracture of the Lumbar Spine.

BACKGROUND AND OBJECTIVES: Vertebral compression fracture is a major health care problem worldwide due to its direct and indirect negative influence on health-related quality of life and increased health care costs. Although a percutaneous surgical intervention with balloon kyphoplasty or metal expansion, the SpineJack, along with bone cement augmentation has been shown to efficiently restore and fix the lost vertebral height, 21-30% vertebral body height loss has been reported in the literature. Furthermore, the effect of the augmentation approaches and the loss of body height on the biomechanical responses in physiological activities remains unclear. Hence, this study aimed to compare the mechanical behavior of the fractured lumbar spine with different restored body heights, augmentation approaches, and posterior fixation after kyphoplasty using the finite element method. Furthermore, different augmentation approaches with bone cement and bone cement along with the SpineJack were also considered in the simulation. MATERIALS AND METHODS: A numerical lumbar model with an incomplete burst fracture at L3 was used in this study. Two different degrees of restored body height, namely complete and incomplete restorations, after kyphoplasty were investigated. Furthermore, two different augmentation approaches of the fractured vertebral body with bone cement and SpineJack along with bone cement were considered. A posterior instrument (PI) was also used in this study. Physiological loadings with 400 N + 10 Nm in four directions, namely flexion, extension, lateral bending, and axial rotation, were applied to the lumbar spine with different augmentation approaches for comparison. RESULTS: The results indicated that both the bone cement and bone cement along with the SpineJack could support the fractured vertebral body to react similarly with an intact lumbar spine under identical loadings. When the fractured body height was incompletely restored, the peak stress in the L2-L3 disk above the fractured vertebral body increased by 154% (from 0.93 to 2.37 MPa) and 116% (from 0.18 to 0.39 MPa), respectively, in the annular ground substance and nucleus when compared with the intact one. The use of the PI could reduce the range of motion and facet joint force at the implanted levels but increase the facet joint force at the upper level of the PI. CONCLUSIONS: In the present study, complete restoration of the body height, as possible in kyphoplasty, is suggested for the management of lumbar vertebral fractures.

Brand interchangeability of pepsinogen tests in the real-world setting after eradication of Helicobacter pylori: a community-based study.

BACKGROUND: Serum pepsinogen (PG) is recommended as a screening test for premalignant gastric lesions. However, real-world evidence demonstrating its applicability and equivalence between different test brands is limited. METHODS: Mass screening began in 2018 in a high-risk Taiwanese population after eradication of Helicobacter pylori, with the first stage of two PG tests (GastroPanel®, Helsinki, Finland and LZ-Test®, Tokyo, Japan) and the second stage of endoscopy. A positive test was defined as PG-I < 30 ng/mL or PG-I/II ratio < 3 for GastroPanel® and PG-I ≤ 70 ng/mL and PG-I/II ratio ≤ 3 for LZ-Test®. Index lesions included atrophic gastritis and intestinal metaplasia. Test performance was evaluated based on the participation rate, positivity rate, referral rate, positive predictive value (PPV), and the detection rate. RESULTS: Among 7616 eligible participants, 5117 (67.2%) received PG tests and 284 (5.6%) tested positive. Of those who tested positive, 105 (37.0%) underwent endoscopy. Overall PPVs for atrophic gastritis and intestinal metaplasia were 12.4% and 18.9%, respectively, with detection rates of 2.5 and 3.9 per 1000, respectively. Correlations of numerical measures between tests were high and the agreements of test results were substantial. The PPVs (16.3% vs. 16.3% and 23.8% vs. 21.3%, P = 1.00 and 0.71, respectively), detection rates (2.5 vs. 2.5 and 3.7 vs. 3.3 per 1000, P = 1.00 and 0.27, respectively), and the stage distributions of gastritis were all comparable, which were confirmed by multiple regression analyses. CONCLUSIONS: PG testing is effective for mass screening after eradication of H. pylori. Tests from different manufacturers, even using different analytical methods and cutoff criteria, can perform equivalently.

Triangular configuration with headless compression screws in the fixation of transverse patellar fracture.

A triangular configuration with three parallel cannulated screws is an established treatment for fixing transverse patellar fractures; however, the stability achieved with this approach is slightly lower than that attained with cannulated screws combined with anterior wiring. In the present study, triangular configurations were modified by partially or totally replacing the cannulated screws with headless compression screws (HCSs). Through finite element simulation involving a model of distal femoral, patellar, and proximal tibial fractures, the mechanical stability levels of the modified triangular configurations were compared with that of two cannulated screws combined with anterior wiring. Four triangular screw configurations were developed: three HCSs in a forward and backward triangular configuration, two deep cannulated screws along with one superficial HCS, and two superficial cannulated screws with one deep HCS. Also considered were two parallel cannulated screws (inserted superficially or deeply) combined with anterior wiring. The six approaches were all examined in full knee extension and 45° flexion under physiological loading. The highest stability was obtained with the three HCSs in a backward triangular configuration, as indicated by the least fragment displacement and the smallest fracture gap size. In extension and flexion, this size was smaller than that observed under the use of two deeply placed parallel cannulated screws with anterior wiring by 50.3% (1.53 vs. 0.76 mm) and 43.2% (1.48 vs. 0.84 mm), respectively. Thus, the use of three HCSs in a backward triangular configuration is recommended for the fixation of transverse patellar fractures, especially without the use of anterior wiring.

Computational comparison of three different cage porosities in posterior lumbar interbody fusion with porous cage.

Porous interbody cages, manufactured using additive laser melting technology, have recently been used in lumbar fusion surgery. The major advantage of a porous cage is the presence of space inside the cage for bone ingrowth. However, the biomechanical effects of different porosities on the lumbar segment with and without bone fusion (ingrowth) are still unclear. Hence, the present study aimed to compare the biomechanical responses, including the stress and range of motion (ROM) of the lumbar L3-L4 segments with three different types of porous cages along with a posterior instrument (PI) with and without bone fusion using computer simulation. A lumbar L3-L4 segment model with a PI and porous cages was used in this study. Three different porosities, namely 12.5, 41.2, and 80.84% were used. The diameter of the pores of the porous cage was uniformly set to 0.5 mm. In addition, a traditional PEEK cage was used in this study. Two different bone statuses, with and without bone fusion (ingrowth into the pores of the porous cage and the inner space of the PEEK cage), were considered. The results indicated that although the contact pressure on the bone surface reduced, the cage stress increased with increasing cage porosity. Furthermore, cage stress and contact pressure also increased in cases with bone fusion compared with those without bone fusion. The contact pressure on the bone surface with a cage porosity of 80.8% decreased by 40% (from 943.1 to 575.5 MPa), 37.7% (from 133 to 82.9 MPa), 40.4% (from 690.8 to 412 MPa), and 34.2% (from 533 to 351.1 MPa), respectively, for flexion, extension, lateral bending, and rotation, respectively, compared with that with a cage porosity of 12.5%. The rotational ROM of the PEEK cage with bone fusion was clearly larger than those of the porous cages. Porous cages have recently become popular owing to improved manufacturing technology. This study provides scientific data on the strength and weakness of porous cages with different porosities for clinical use.

Risk stratification for gastric cancer after Helicobacter pylori eradication: A population-based study on Matsu Islands.

BACKGROUND AND AIM: The reliable method to stratify the gastric cancer risk after Helicobacter pylori eradication remains an elusive goal. METHODS: Mass eradication of H. pylori began in 2004 in a high-risk population. After eradication, a screening program involving first-stage serological tests (pepsinogen-I, pepsinogen-II, H. pylori immunoglobin G, and gastrin-17) and second-stage endoscopic examination was launched in 2015-2018. Index lesions included gastric cancer or extensive premalignant lesions. We evaluated the performance of the serological tests to "rule in" and "rule out" the risk based on positive and negative likelihood ratios, respectively. The methylation levels of microRNA-124a-3 in the stomach were measured to indicate genetic damage. RESULTS: Among 6512 invited subjects, 3895 (59.6%) participated. Both gastrin-17 and pepsinogen tests were normal in 3560 (91.4%) subjects; 206 (5.3%) gastrin-17 and 129 (3.3%) pepsinogen tests were abnormal. Years after eradication, the severity of gastritis had fallen greatly, and extensive premalignant lesions or gastric cancer frequently occurred in newly non-atrophic-appearing mucosa. Pepsinogen testing could moderately predict atrophic gastritis (positive likelihood ratio: 4.11 [95% confidence interval: 2.92-5.77]; negative likelihood ratio: 0.14 [0.10-0.19]). Gastrin-17 was not useful (0.66 and 1.20, respectively). However, pepsinogen testing poorly predicted the index lesions (2.04 [1.21-3.42] and 0.57 [0.34-0.95]). DNA methylation levels in the post-eradication mucosa were more discriminative for predicting index lesions (3.89 [2.32-6.54] and 0.25 [0.15-0.42]). CONCLUSIONS: After eradication, pepsinogen false-negative results become more frequent because histology is improved but genetic damage may persist. Direct testing for genetic damage offers better discrimination.

Role of an additional third screw in the fixation of transverse patellar fracture with two parallel cannulated screw and anterior wire.

BACKGROUND: Two parallel cannulated screws along with an anterior wire to construct a tension band is a popular approach in transverse patellar fractures. However, the optimal screw proximity, either deep or superficial screw placements, remains controversial. Hence, a new concept of the addition of a third screw to form a triangular configuration along with the original two parallel screws was proposed in this study. Therefore, the biomechanical effect of the additional third screw on the stability of the fractured patella was investigated with finite element (FE) simulation. METHODS: An FE knee model including the distal femur, proximal tibia, and fractured patella (type AT/OTA 34-C) was developed in this study. Four different screw configurations, including two parallel cannulated screws with superficial (5-mm proximity) and deep (10-mm proximity) placements and two parallel superficial screws plus a third deep screw, and two parallel deep screws plus a third superficial screw, with or without the anterior wire, were considered for the simulation. RESULTS: Results indicated that the addition of a third screw increased stability by reducing the dorsal gap opening when two parallel screws were deeply placed, particularly on the fractured patella without an anterior wire. However, the third screw was of little value when two parallel screws were superficially placed. In the existence of two deep parallel screws and the anterior wire, the third screw reduced the gap opening by 23.5% (from 1.15 mm to 0.88 mm) and 53.6% (from 1.21 mm to 0.61 mm) in knee flexion 45° and full extension, respectively. Furthermore, in the absence of the anterior wire, the third screw reduced the gap opening by 73.5% (from 2 mm to 0.53 mm) and 72.2% (from 1.33 mm to 0.37 mm) in knee flexion 45° and full extension, respectively. CONCLUSION: Based on the results, a third cannulated screw superficially placed (5-mm proximity) is recommended to increase stability and maintain contact of the fractured patella, fixed with two parallel cannulated screws deeply placed (10-mm proximity), particularly when an anterior wire was not used. Furthermore, the third screw deeply placed is not recommended in a fractured patella with two parallel superficial screws.

Computational comparison of different plating strategies in medial open-wedge high tibial osteotomy with lateral hinge fractures.

BACKGROUND: Lateral hinge fracture (LHF) is associated with nonunion and plate breakage in high tibial osteotomy (HTO). Mechanical studies investigating fixation strategies for LHFs to restore stability and avoid plate breakage are absent. This study used computer simulation to compare mechanical stabilities in HTO for different LHFs fixed with medial and bilateral locking plates. METHODS: A finite element knee model was created with HTO and three types of LHF, namely T1, T2, and T3 fractures, based on the Takeuchi classification. Either medial plating or bilateral plating was used to fix the HTO with LHFs. Furthermore, the significance of the locking screw at the combi hole (D-hole) of the medial TomoFix plate was evaluated. RESULTS: The osteotomy gap shortening distance increased from 0.53 to 0.76, 0.79, and 0.72 mm after T1, T2, and T3 LHFs, respectively, with medial plating only. Bilateral plating could efficiently restore stability and maintain the osteotomy gap. Furthermore, using the D-hole screw reduced the peak stress on the medial plate by 28.7% (from 495 to 353 MPa), 26.6% (from 470 to 345 MPa), and 32.6% (from 454 to 306 MPa) in T1, T2, and T3 LHFs, respectively. CONCLUSION: Bilateral plating is a recommended strategy to restore HTO stability in LHFs. Furthermore, using a D-hole locking screw is strongly recommended to reduce the stress on the medial plate for lowering plate breakage risk.

Application of Helicobacter pylori stool antigen test to survey the updated prevalence of Helicobacter pylori infection in Taiwan.

BACKGROUND AND AIM: The reported prevalence of Helicobacter pylori infection in Taiwan was 54.4% in 1992. An updated prevalence of H. pylori infection in asymptomatic adults is lacking in Taiwan. We aimed to assess the updated age-standardized prevalence of H. pylori infection in asymptomatic subjects and in patients with dyspepsia and to assess the accuracy of H. pylori stool antigen (HpSA) test for screening of H. pylori in Chinese population. METHODS: Asymptomatic adult subjects (N = 189) were screened for H. pylori infection using HpSA, serology, and 13 C-urea breath test (13 C-UBT) in 2016-2017. Adult patients with dyspepsia (N = 145) were screened for H. pylori using 13 C-UBT, HpSA, serology, rapid urease test, and histology during 2016-2018. Two types of HpSA, including the Diagnostec HpSA ELISA Kit (HpSA ELISA) and Rapid Test Kit (HpSA Rapid), were used in this study. Sensitivity, specificity, and accuracy of the HpSA tests were calculated using the 13 C-UBT as golden standard test. RESULTS: The unadjusted prevalence of H. pylori was 21.2% in asymptomatic adults and 37.9% in patients with dyspepsia (P < 0.001). The age-standardized prevalence of H. pylori was 28.9% in asymptomatic adults in Taiwan. Of the 334 patients included for analysis, the area under the curve of HpSA ELISA test was 0.978, and the optimal cutoff value of optical density was 0.03. The sensitivity, specificity, and accuracy of the HpSA ELISA were 0.929, 0.983, and 0.967, respectively. The sensitivity, specificity, and accuracy of the HpSA Rapid were 0.929, 0.958, and 0.949, respectively. CONCLUSIONS: The prevalence of H. pylori infection has decreased in Taiwan. HpSA test is an accurate tool for screening of H. pylori in Chinese population.

Computational comparison of bone cement and poly aryl-ether-ether-ketone spacer in single-segment posterior lumbar interbody fusion: a pilot study.

Posterior lumbar interbody fusion (PLIF) with a spacer and posterior instrument (PI) via minimally invasive surgery (MIS) restores intervertebral height in degenerated disks. To align with MIS, the spacer has to be shaped with a slim geometry. However, the thin spacer increases the subsidence and migration after PLIF. This study aimed to propose a new lumbar fusion approach using bone cement to achieve a larger supporting area than that achieved by the currently used poly aryl-ether-ether-ketone (PEEK) spacer and assess the feasibility of this approach using a sawbone model. Furthermore, the mechanical responses, including the range of motion (ROM) and bone stress with the bone cement spacer were compared to those noted with the PEEK spacer by finite element (FE) simulation. An FE lumbar L3-L4 model with PEEK and bone cement spacers and PI was developed. Four fixing conditions were considered: intact lumbar L3-L4 segment, lumbar L3-L4 segment with PI, PEEK spacer plus PI, and bone cement spacer plus PI. Four kinds of 10-NM moments (flexion, extension, lateral bending, and rotation) and two different bone qualities (normal and osteoporotic) were considered. The bone cement spacer yielded smaller ROMs in extension and rotation than the PEEK spacer, while the ROMs of the bone cement spacer in flexion and lateral bending were slightly greater than with the PEEK spacer. Compared with the PEEK spacer, peak contact pressure on the superior surface of L4 with the bone cement spacer in rotation decreased by 74% (from 8.68 to 2.25 MPa) and 69.1% (from 9.1 to 2.82 MPa), respectively, in the normal and osteoporotic bone. Use of bone cement as a spacer with PI is a potential approach to decrease the bone stress in lumbar fusion and warrants further research.

Long-term changes of gut microbiota, antibiotic resistance, and metabolic parameters after Helicobacter pylori eradication: a multicentre, open-label, randomised trial.

BACKGROUND: In first-line treatment of Helicobacter pylori, we have previously shown that the eradication frequency was 83·7% (95% CI 80·4-86·6) for triple therapy for 14 days (T14; lansoprazole 30 mg, amoxicillin 1 g, and clarithromycin 500 mg, all given twice daily), 85·9% (82·7-88·6) for concomitant therapy for 10 days (C10; lansoprazole 30 mg, amoxicillin 1 g, clarithromycin 500 mg, and metronidazole 500 mg, all given twice daily), and 90·4% (87·6-92·6) for bismuth quadruple therapy for 10 days (BQ10; bismuth tripotassium dicitrate 300 mg four times a day, lansoprazole 30 mg twice daily, tetracycline 500 mg four times a day, and metronidazole 500 mg three times a day). In this follow-up study, we assess short-term and long-term effects of these therapies on the gut microbiota, antibiotic resistance, and metabolic parameters. METHODS: This was a multicentre, open-label, randomised trial done at nine medical centres in Taiwan. Adult patients (>20 years) with documented H pylori infection were randomly assigned (1:1:1, with block sizes of six) to receive T14, C10, or BQ10. We assessed long-term outcomes (reinfection frequency, changes in the gut microbiota, antibiotic resistance, and metabolic parameters) in patients with available data, excluding all protocol violators and those with unknown post-treatment H pylori status. Faecal samples were collected before treatment and 2 weeks, 2 months, and at least 1 year after eradication therapy. Amplification of the V3 and V4 hypervariable regions of the 16S rRNA was done followed by high-throughput sequencing. Susceptibility testing for faecal Escherichia coli and Klebsiella pneumoniae was done. This trial is complete and registered with ClinicalTrials.gov, NCT01906879. FINDINGS: Between July 17, 2013, and April 20, 2016, 1620 participants were randomly assigned to the three treatment groups (540 [33%] per group). 1214 (75%) attended 1-year follow-up and are included in this analysis. Compared with baseline, alpha diversity was significantly reduced 2 weeks after T14 (p=0·0002), C10 (p<0·0001), and BQ10 (p<0·0001) treatment. Beta diversity was also significantly altered 2 weeks after T14 (p=0·0010), C10 (p=0·0001), and BQ10 (p=0·0001). Alpha diversity and beta diversity were restored at week 8 (p=0·14 and p=0·918, respectively) and 1 year (p=0·14 and p=0·918) after T14, but were not fully recovered at week 8 and after 1 year in patients treated with C10 (p=0·0001 and p=0·013 at week 8; p=0·019 and p=0·064 at 1 year) and BQ10 (p<0·0001 and p=0·0002; p=0·001 and p=0·029). A transient increase at week 2 after T14 and C10 of the resistance rates of E coli to ampicillin-sulbactam (12% [15/127] to 66% [38/58] for T14, 7% [10/135] to 64% [28/44] for C10), cefazolin (13% [16/127] to 43% [25/58] for T14, 10% [13/135] to 41% [18/44] for C10), cefmetazole (8% [10/127] to 26% [15/58] for T14, 4% [5/135] to 18% [8/44] for C10), levofloxacin (8% [10/127] to 35% [20/58] for T14, 7% [10/135] to 32% [14/44] for C10), gentamicin (13% [19/146] to 47% [27/58] for T14, 15% [22/149] to 45% [20/44] for C10), and trimethoprim-sulfamethoxazole (33% [48/146] to 86% [50/58] for T14, 28% [42/148] to 86% [38/44] for C10; p<0·05 in paired samples in the above analyses) returned to basal state at week 8 and after 1 year. Although bodyweight and body-mass index slightly increased, there were significant improvements in metabolic parameters, with a decrease in insulin resistance, triglycerides, and LDL and an increase in HDL. Overall, there was no significant change in the prevalence of metabolic syndrome at week 8 and 1 year after T14, C10, and BQ10. INTERPRETATION: Eradication of H pylori infection has minimal disruption of the microbiota, no effect on antibiotic resistance of E coli, and some positive effects on metabolic parameters. Collectively, these results lend support to the long-term safety of H pylori eradication therapy. FUNDING: National Taiwan University Hospital and Ministry of Science and Technology of Taiwan.

Finite element study of the effects of fragment shape and screw configuration on the mechanical behavior of tibial tubercle osteotomy.

PURPOSE: Tibial tubercle osteotomy (TTO) is a surgical technique used in the management of severe fractures of the knee joint and revision total knee arthroplasty. Limited research discusses the performance of the osteotomy and fixation of the TTO with screws. Therefore, this study investigated the effects of fragment shape and screw configuration on the mechanical behavior in the fixation of the TTO using the finite element (FE) method. METHODS: FE TTO models with three fragment shapes and three screw configurations were developed. The three fragment shapes were a step cut, bevel cut, and straight cut. The screw configurations were two parallel horizontal and downward screws and two trapezoidal screws. A 1654-N upward tension force was applied on the tibia tubercle, and the distal end of the tibia was completely fixed. RESULTS: The results indicated that the step cut resulted in higher stability than the bevel and straight cut, but the stress was higher as well. Among the screw configurations, two parallel downward screws resulted in the highest stability, given the same fragment shape. In the horizontal configuration, the step cut tibia developed the largest contact force to achieve stability of the bone fragment under loading. CONCLUSION: The fragment shape with a step cut and fixation with two parallel horizontal or downward screws are suggested for TTO, while the trapezoidal screw configuration is not suggested. Furthermore, the downward screw configuration is a suitable strategy to reduce bone stress.

Mechanical analysis of a dental implant system under 3 contact conditions and with 2 mechanical factors.

STATEMENT OF PROBLEM: A unidiameter abutment attached to a large-diameter implant has been reported to result in an unexpectedly high failure rate, inconsistent with the general understanding of dental implant mechanics. PURPOSE: The purpose of this finite element analysis study was to investigate the mechanical mechanism underlying these unexpected failures with the hypothesis that the cold welding or interference fit interface between abutment and implant increases the failure probability of a large-diameter implant system with a unidiameter abutment. MATERIAL AND METHODS: A conical implant system with different abutment gingival heights and implant diameters was analyzed for 3 contact conditions of the abutment-implant interface (bond and frictional coefficients of 0.3 and 0.7). A computer model was created using computed tomography images, and an oblique load of 100 N was applied to the abutment to determine the mechanical effect of the implant diameter and gingival height under the 3 contact conditions. RESULTS: When the abutment-implant interface was bonded, the peak stress of the abutment increased and that of the bone decreased with increasing implant diameter. When friction was applied to the abutment-implant interface, the peak stress of the implant, screw, and bone decreased with increasing implant diameter. Furthermore, the peak stress of the implant system and bone increased when the abutment gingival height increased under all contact conditions. CONCLUSIONS: Cold wielding or interference fit at the abutment-implant interface can prevent a screw fracture; however, it puts high stress on the unidiameter abutment neck when the implant diameter is increased. Screw loosening may lead to a slide between the abutment and implant, considerably increasing the stress of the screw. A system with a narrow diameter implant may cause an implant fracture rather than an abutment fracture when friction is applied to the abutment-implant interface.

Gap between the fragment and the tibia affects the stability of tibial tubercle osteotomy: A finite element study.

Tibial tubercle osteotomy (TTO) is commonly performed in cases of complicated juxta-articular trauma or revision total knee arthroplasty. However, strategies for firmly fixing the resulting osteotomy bone fragment are not sufficiently understood. This study aims to investigate the effect of the location of the gap between the fragment and the tibia and with various fixed screw configurations on TTO stability, contact force on the fragment, and bone stress by using the finite element method. A TTO model with a 1-mm gap, either above or below the fragment, was developed. Furthermore, five screw configurations, including two parallel horizontal screws placed at 20- and 30-mm intervals, two parallel downward screws, two trapezoid screws, and two divergent screws, were used. A vertically upward 1600-N force was applied on the tibial tubercle to mimic a worst-case condition. Placing the fragment close to the superior cutting plane (above the gap) yielded greater stability and less stress on the bone than did placing it close to the inferior cutting plane. The superior cutting plane of the tibia generated the largest contact force on the superior plane of the fragment for static balance under loading. Additionally, among all screw configurations, the configuration involving two parallel downward screws resulted in the highest stability but also the greatest stress on the cortical bone. The fragment obtains a solid barrier and support from the tibia immediately after surgery to against the patellar tension force when the fragment is close to the superior cutting plane of the tibia.