Biomechanical Evaluation of the Accuracy in Radiographic Assessment of Femoral Component Migration Measurement after Total Hip Arthroplasty

Introduction: Implant subsidence is one criteria utilized to monitor for prosthesis loosening after total hip arthroplasty (THA) with initial implant subsidence assessment often done utilizing plain radiographs. The specific aim of this study was to identify the most reliable references when using plain radiographs to establish an image magnification with the goals being easy to use, inexpensive, reliable, and accurate. Methods: Two femoral stem implants (stem lengths: 127mm, 207mm) were utilized to simulate hemiarthroplasty of the hip with composite femurs. Different combinations of femoral stem distances from the radiographic film (ODD), source-detector differences (SDD), hip rotation, and hip flexion were elected. Standardized anterior-posterior pelvis for each parameter combination setup were taken. Radiographic measurements (head diameter, stem length, stem seating length) were undertaken five times by three examiners. Radiographic image magnification factors were generated from two references (head diameter and stem length). Radiograph measurement reproducibility and stem seating length errors using these magnification factors were evaluated. Results: High level of repeated measurements reliability was found for head diameter (99 ± 0%) and stem length (90 ± 7%) measurements, whereas seating length measurements were less reliable (76 ± 6%). Stem length error using the femoral head magnification factor yielded 11% accuracy. Stem seating length error using both magnification factors were not reliable (< 7% accuracy). All parameters, except SDD, showed significant effect on calibrated measurement error. Conclusions: Current methods of assessing implant subsidence after THA using plain radiographs are inaccurate or reliable. Clinicians should recognize these limitations and be cautious when diagnosing implant stability using plain radiographs alone

Exceptional points in topological edge spectrum of PT symmetric domain walls

We demonstrate that the non-Hermitian parity-time (PT) symmetric interfaces formed between amplifying and lossy crystals support dissipationless edge states. These PT edge states exhibit gapless spectra in the complex band structure interconnecting complex-valued bulk bands as long as exceptional points (EPs) of edge states exist. As a result, regimes exist where the edge states can spectrally overlap with the bulk continuum without hybridization, and leakage into the bulk states is suppressed due to the PT symmetry. Two exemplary PT symmetric systems, based on valley and quantum hall topological phases, are investigated, and the connection with the corresponding Hermitian systems is established. We find that the edge states smoothly transit to the valley edge states found in Hermitian systems if the magnitude of gain/loss vanishes. The topological nature of the PT edge states can be established within the non-Hermitian Haldane model, where the topological invariance is found to be unaffected by gain or loss. Nonreciprocal PT edge states are discovered at the interfaces between PT-Haldane phases, indicating the interplay between the gain/loss and the magnetic flux. The proposed systems are experimentally feasible to realize in photonics. This has been verified by our rigorous full-wave simulations of edge states in PT-symmetric silicon-based photonic graphene.Comment: 24 pages, 9 figures, 2 table

Quantitative test of general theories of the intrinsic laser linewidth

We perform a first-principles calculation of the quantum-limited laser linewidth, testing the predictions of recently developed theories of the laser linewidth based on fluctuations about the known steady-state laser solutions against traditional forms of the Schawlow-Townes linewidth. The numerical study is based on finite-difference time-domain simulations of the semiclassical Maxwell-Bloch lasing equations, augmented with Langevin force terms, and thus includes the effects of dispersion, losses due to the open boundary of the laser cavity, and non-linear coupling between the amplitude and phase fluctuations ($\alpha$ factor). We find quantitative agreement between the numerical results and the predictions of the noisy steady-state ab initio laser theory (N-SALT), both in the variation of the linewidth with output power, as well as the emergence of side-peaks due to relaxation oscillations.Comment: 24 pages, 10 figure

Evaluation on the efficacy of microbial approaches in the control of Ganoderma boninense and their effects to soil microbial diversity

Basal Stem Rot (BSR) is the most destructive disease of oil palm (Elaeis guineensis Jacq.) which caused by bracket fungus; Ganoderma boninense. With no remedy to date, this disease has jeopardized the industry of oil palm critically. Several approaches including cultural, chemical, mechanical and biological measures have been reported in attempt to control this disease, but unfortunately, none have given satisfactory result. Therefore, a more reliable approach that could manage this disease, besides a continuous and sustainable oil palm production is worth to be further investigated. Introduction of microbes in disease management have been used for decades. An astute observation of low incidence of disease due to Ganoderma pathogen in natural ecosystem suggests that a healthy natural ecosystem can hinder the incidence of Ganoderma pathogen outbreak. In this respect, study on the potential of microbes in suppressing the growth of Ganoderma boninense and its effect to the soil microbial diversity were investigated in this project. Three microbes-based products which are Living Soil Microbes (LSM), Agrinos (AGN) and Agriorganica (AO) were tested in this study. LSM contains multi-strain of Bacillus spp. and Trichoderma spp., whereas AGN consist of Bacillus spp., Pseudomonas spp. and Aspergillus sp. Meanwhile, AO comprises of three living food microbes which are Lactobacillus, Nattobacillus and Saccharomyces cerevisiae developed from Japanese fermentation and brewing technology. To examine the ability of the treatments in reducing BSR disease incidence, assessments in nursery and field trial were conducted. The results from both trials showed that LSM, AGN and AO were able to reduce the colonization of G. boninense based on the reduction of ergosterol content compared to untreated control

Impact of Cigarette Smoking on Re-operation and Revision Surgery after Femoral Neck Fracture Treatment

Introduction. Smokers and nicotine users have a higher risk of femoral neck fracture non-union and prolonged time to fracture union. The impact of smoking resulting in revision surgery after fixation of femoral neck fractures, however, rarely has been studied. The aim of this retrospective study was to review if cigarette smoking had an influence on re-operation and revision after femoral neck fracture treatment. Methods. Three groups of patients (Group 1: active smokers; Group 2: former smokers; and Group 3: non-smokers) who sustained a femoral neck fracture from January 2012 through August 2018 were included. Outcomes investigated included femoral neck fracture type, operative fixation type, fixation failure, and time interval between initial fixation and revision. Results. A total of 1,452 subjects were identified (Group 1: 165 subjects; Group 2: 507 subjects; and Group 3: 780 subjects). In the male population, Groups 1 and 2 had higher rates of femoral neck fracture than Group 3. Twelve cases required revisions (Group 1: three cases (6%); Group 2: two cases (2%); Group 3: seven cases (4%)), with all but one revision within the first year following initial fixation. Group 1 patients tended to be younger than the other two groups. Conclusion. Smoking has a positive association with the risk of femoral neck fracture amongst active and former male smokers. This study concluded that active smokers have a higher risk of non-union compared with non-smokers or former smokers. Smoking history, especially heavy or long-term, should play a role in deciding which fixation construct type to use for femoral neck fractures

Clinical Outcome of Different Post-operative Prophylactic Strategies on Symptomatic Venous Thromboembolism after Total Knee Arthroplasty

INTRODUCTION. The objective of this study was to evaluate the use of different postoperative prophylactic strategies on the rates of symptomatic venous thromboembolic events (VTE) incidence after primary total knee arthroplasty (TKA). METHODS. A retrospective study of patients who had undergone primary TKA procedure was performed from January 2015 through July 2020. Outcomes examined prophylaxis medication used during inpatient care and outpatient care, amount of medication, length of medication, complications occurring within 90 days postoperatively, including symptomatic VTE (deep venous thrombosis (DVT) and pulmonary embolism (PE)), gastrointestinal bleeding requiring medical attention, change in management protocols after post-operative complications and mortality. RESULTS. 5,663 cases were included (mean age 66±10years, mean BMI 34.1±7.1kg/m2). The overall post-operative complication rate was 0.9% (DVT: 0.5%, PE: 0.3%, VTE: 0.04%, and GI bleeding: 0.09%). Enoxaparin (Lovenox) use as inpatient anticoagulation medication was significantly reduced (67% vs 13%, p<0.001), and apixaban (Eliquis) was significantly increased (6% vs 49%, p<0.001). Average hospital stays were significantly reduced among the years (3±2days vs 2±1days, p<0.001), and complication rates were not significantly different between the five years (~1%, p<0.001). Most post-operative complications occurred on either aspirin 325mg (36%) or apixaban (26%). However, the relative risk ratio results indicating that utilization of warfarin (Coumadin), rivaroxaban (Xarelto), and aspirin 81 mg as outpatient anticoagulation medication were more likely to increase the risk of symptomatic VTE incidence compared to other anticoagulants. The average time of complication detected was 21±21days (range: 1-87days). >54% of complication events occurred after the patient had completed their medication (enoxaparin, rivaroxaban and apixaban).  CONCLUSIONS. The observed incidence of symptomatic VTE in this study is similar to previous studies regardless of the type of postoperative inpatient or outpatient prophylaxis prescribed. The ultimate choice of prophylaxis should remain with the treating physician and their knowledge of a particular patient’s medical history