REVIEW | doi:10.20944/preprints202301.0091.v1
Subject: Medicine And Pharmacology, Cardiac And Cardiovascular Systems Keywords: Transcatheter aortic valve replacement,; endocarditis; prosthetic valve endocarditis
Online: 5 January 2023 (02:35:38 CET)
Although initially conceived for high-risk patients who are ineligible for surgical aortic valve replacement (SAVR), transcatheter aortic valve replacement (TAVR) is now recommended in a wider spectrum of indications including young patients. However, as for SAVR, TAVR is also associated with a risk of infectious complications, namely prosthetic valve endocarditis (PVE). As the number of performed TAVR procedure increases, and despite the low incidence of PVE post TAVR, clinicians should be familiar with the associated risk factors and the clinical presentation. Whereas the diagnosis of native valve endocarditis can be straightforward applying the modified Duke criteria, the diagnosis of PVE is more challenging given its atypical symptoms, lower sensitivity of the criteria, and low diagnostic yield of conventional echocardiography. Delay in proper management can be associated with increased morbidity and mortality. Therefore, clinicians should have a high index of suspicion and initiate proper work-up according to the severity of illness, the underlying host, and the local epidemiology of the causative organisms. The most common causative pathogens are Gram-positive bacteria such as S. aureus, coagulase negative staphylococci, Enterococcus spp. and Streptococcus spp. (particularly the viridans group) and, less likely Gram-negative and fungal pathogens. The high prevalence of antimicrobial resistance complicates the choice of therapy. There remain controversies regarding the optimal management strategies including indications for surgical interventions. Surgical assessment is recommended early in the course of illness and surgical intervention should be considered in selected patients. As in other PVE, duration of therapy depends on the isolated pathogen, the host, and the clinical response. Since TAVR is a relatively new procedure, the outcome of TAVR-PVE is yet to be fully understood.
ARTICLE | doi:10.20944/preprints202306.0184.v1
Subject: Medicine And Pharmacology, Cardiac And Cardiovascular Systems Keywords: mitral valve,; infective endocarditis; minimally invasice cardiac surgery; mini-thoracotomy; cardiac reoperation; prosthetic valve endocarditis; systemic embolization
Online: 2 June 2023 (10:32:03 CEST)
Background. Minimally invasive surgery via right mini-thoracotomy has become the standard of care for the treatment of mitral valve disease worldwide, particularly at high volume centers. In recent years, the spectrum of indications has progressively shifted and extended to fragile and higher risk patients, also addressing more complex mitral valve disease and ultimately including patients with native or prosthetic infective endocarditis. The rationale for the adoption of the minimally invasive approach is to minimize the surgical trauma, promote an earlier postoperative recovery and reduce the incidence of surgical wound infection and other nosocomial infections. The aim of this retrospective observational study is to evaluate the effectiveness and the early and late outcome in patients undergoing minimally invasive surgery for mitral valve infective endocarditis. Methods. Prospectically collected data regarding minimally invasive surgery in patients with mitral valve infective endocarditis were entered into a dedicated database for the period between January 2007 and December 2022 and retrospectively analyzed. All comers during the study period underwent a preoperative evaluation based upon clinical history and anatomy for the allocation to the most appropriate surgical strategy. Selection for the mini-thoracotomy approach was primarily driven by a thorough transthoracic and especially transesophageal echocardiographic evaluation, coupled with total body and vascular imaging. Results. During the study period, 92 patients underwent right mini-thoracotomy to treat native (80/92, 87%) or prosthetic (12/92, 13%) mitral valve endocarditis at our institution, representing 5% of the patients undergoing minimally invasive mitral surgery. Twenty-six (28%) patients had undergone previous cardiac operations, whereas 18 (20%) presented preoperatively with complications related to endocarditis, most commonly systemic embolization. Sixty-nine and 23 patients, respectively, underwent early surgery (75%) or were operated on after the completion of targeted antibiotic treatment (25%). A conservative procedure was feasible in 16/80 (20%) patients with native valve endocarditis. Conversion to standard sternotomy was necessary in a single case (1.1%). No cases of intraoperative iatrogenic aortic dissection were reported. Four patients died perioperatively, accounting for a thirty-day mortality of 4.4%. Causes of death were refractory heart or multiorgan failure and/or septic shock. New onset stroke was observed postoperatively in one case (1.1%). Overall actuarial survival rate at 1 and 5 years after operation was 90.8% and 80.4%, whereas freedom from mitral valve reoperation at 1 and 5 years was 96.3% and 93.2%, respectively. Conclusions. The present study shows good early and long-term results in higher-risk patients undergoing minimally invasive surgery for mitral valve infective endocarditis. Total body, vascular and echocardiographic screening represent the key points to select the optimal approach and allow the extension of indications for minimally invasive surgery to sicker patients, including active endocarditis and sepsis.
Subject: Public Health And Healthcare, Physical Therapy, Sports Therapy And Rehabilitation Keywords: prosthetics; prosthetic socket; prosthetic socket fitting; biofeedback; rehabilitation; amputation
Online: 6 October 2021 (12:58:45 CEST)
Obtaining a good socket fit is an iterative process dependent on the skill and experience of the prosthetist creating it, and requiring individualisation based on the size and shape. There is no standard measurement system used to aid prosthetic socket creation, despite the severe impacts on physical health and quality of life if one is ill-fitting. Pressure sensors embedded in a prosthetic socket were used to collect data at the socket-residuum interface. To choose an interpolation method, a 2D grid was used, with previously collected walking test pressure data, to simplify the sensor array with a border for extrapolation. Four multivariable interpolation methods were evaluated to create a colour map of the pressure data. Radial Basis Function interpolation was chosen as it produced a clear image with a graduated interpolation between data points and was used to create a colour map across the surface of a 3D prosthetic socket model. For the model to be accessible to clinical audiences, a desktop application was created using PyQt to view the model. The created application allowed for connection to the sensors via Bluetooth, with the pressure data updating the colour map on the 3D model in real-time. The created application shows the potential for a clinical product, however further development informed by feedback from rehabilitation clinicians and prosthesis users is required
ARTICLE | doi:10.20944/preprints202011.0640.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: Arthroplasty; prosthetic joint replacement; prosthetic joint infection; systemic antibiotic prophylaxis; Antibiotics; chlorhexidine gluconate; coagulase-negative staphylococci; tuf gene sequencing; staphylome; microbiome
Online: 25 November 2020 (12:56:25 CET)
The aim was to study alterations of bacterial communities in patients undergoing hip or knee arthroplasty to assess the impact of chlorhexidine gluconate soap decolonisation and systemic antibiotic prophylaxis. A Swedish multicentre, prospective collection of samples obtained from elective arthroplasty patients (n=83) by swabbing anterior nares, skin sites in the groin and the site of planned surgery, before and after arthroplasty surgery, was analysed by 16S rRNA (V3-V4) gene sequencing and a complementary targeted tuf gene sequencing approach to comprehensively characterise alterations in staphylococcal communities. Significant reductions in alpha diversity was detected for both bacterial (p=0.04) and staphylococcal (p=0.03) groin communities after arthroplasty surgery with significant reductions in relative Corynebacterium (p=0.001) abundance and S. hominis (p=0.01) relative staphylococcal abundance. In nares, significant reductions occurred for S. hominis (p=0.02), S. haemolyticus (p=0.02), and S. pasteuri (p=0.003) relative to other staphylococci. S. aureus colonised 35% of anterior nares before and 26% after arthroplasty surgery. S. epidermidis was the most abundant staphylococcal species at all sampling sites. No bacterial genus or staphylococcal species increased significantly after arthroplasty surgery. Application of a targeted tuf gene sequencing approach provided auxiliary staphylococcal community profiles and allowed species-level characterisation directly from low biomass clinical samples.
REVIEW | doi:10.20944/preprints202305.0146.v1
Subject: Engineering, Mechanical Engineering Keywords: prosthetic devices; metamaterials; auxetic structure; negative Poisson’s ratio; metastructure
Online: 3 May 2023 (12:31:06 CEST)
Prosthetics have come a long way since their inception, and recent advancements in materials science have enabled the development of prosthetic devices with improved functionality and comfort. One promising area of research is the use of auxetic metamaterials in prosthetics. Auxetic materials have a negative Poisson's ratio, which means that they expand laterally when stretched, unlike conventional materials, which contract laterally. This unique property allows for the creation of prosthetic devices that can better conform to the contours of the human body and provide a more natural feel. In this review article, we provide an overview of the current state of the art in the development of prosthetics using auxetic metamaterials. We discuss the mechanical properties of these materials, including their negative Poisson's ratio and other properties that make them suitable for use in prosthetic devices. We also explore the limitations that currently exist in implementing these materials in prosthetic devices, including challenges in manufacturing and cost. Despite these challenges, the future prospects for the development of prosthetic devices using auxetic metamaterials are promising. Continued research and development in this field could lead to the creation of more comfortable, functional, and natural-feeling prosthetic devices. Overall, the use of auxetic metamaterials in prosthetics represents a promising area of research with the potential to improve the lives of millions of people around the world who rely on prosthetic devices.
ARTICLE | doi:10.20944/preprints202308.0554.v2
Subject: Public Health And Healthcare, Public Health And Health Services Keywords: endovascular procedure; peripheral arterial disease; femoral popliteal bypass; prosthetic graft
Online: 10 August 2023 (08:37:05 CEST)
Aim. Atherosclerotic complex femoropopliteal lesions have traditionally been treated with bypass surgery. A prosthetic graft is used to save the vein graft for more distal revascularization or when unavailable. However, the endovascular approach has gained popularity and is offered as first-line strategy for complex lesions. This study aimed to evaluate whether endovascular procedures for complex femoropopliteal native lesions can be a first-line treatment strategy over open surgery with prosthetic bypass in patients with peripheral arterial disease (PAD). Methods. A retrospective study was conducted between 2013 and 2021 to identify patients with symptomatic PAD who required limb revascularization at the femoropopliteal segment and complex lesions (TASC II C and D). Primary endpoints were technical success, primary patency, freedom from clinically driven target lesion revascularization (cdTLR), freedom from major adverse limb and cardiovascular events (MALE and MACE), freedom from limb loss, and survival. Secondary endpoints were length of in-hospital stay, duration of the procedure, and costs. Results. We identified 185 limbs among 174 suitable candidates for comparison, wherein 105 were treated with endovascular procedure and 80 with femoral popliteal prosthetic bypass. Most patients in both groups presented with chronic limb-threatening limb ischemia, and all were ASA >3. There were more octogenarians (p = 0.02) and patients with coronary disease (p = 0.004) in the endovascular group. Median follow-up was 30 months. Technical failure rate for endovascular procedures was 4.8% vs 0% in the open group (p 0.003). Freedom from MACE was similar in both groups. The endovascular group showed superior primary patency (p<0.0001), cdTLR (p<0.0001), MALE (p<0.0001), and freedom from limb loss (p = 0.0018) at 24 months. Further analysis performed for the open above-the-knee subgroup showed that the aforementioned endpoints were similar at 12 months, and favoured the endovascular group at 24 months. Procedural time and in-hospital stay were longer in the open group (p<0.0001 and p<0.001). Finally, procedural cost was 10-fold lower in the endovascular bypass group than in the prosthetic bypass group. Conclusion. Endovascular procedures for complex femoropopliteal lesions are safe in patients at high risk for surgery and show better outcomes at 24 months than prosthetic bypasses. The latter may be considered as an alternative in cases of endovascular failure.
REVIEW | doi:10.20944/preprints202305.1471.v1
Subject: Medicine And Pharmacology, Dentistry And Oral Surgery Keywords: full arch; mandibular atrophy; short dental implants; short implants; prosthetic
Online: 22 May 2023 (07:26:03 CEST)
Background: This study aimed to evaluate survival rate, marginal bone levels, and full arch prosthetic success on short implants when placed in areas of severely resorbed and edentulous mandibles. Methods: This is a systematic review of all randomized controlled trials of at least 10 patients with a control group in which bone augmentations were performed that were published between January 2010 and February 2023. Only 3 relevant studies met the inclusion criteria. Results: It obtained demonstrate that short-term dental implant survival rates ranged from 94.2% to 97.4% with a 5-year follow-up and the prosthetic success rate varied by 62% during the same follow-up. The mean marginal bone level values of the affected short implants ranged from 0.2 mm to 0.6 mm. Conclusions: The data obtained demonstrated that short dental implants positioned with criterion and precision as a full-arch fixed support are a valid therapeutic choice for the medium-long term rehabilitation of severe edentulous mandibular atrophy.
REVIEW | doi:10.20944/preprints202110.0243.v1
Subject: Chemistry And Materials Science, Medicinal Chemistry Keywords: fluorine-18; prosthetic group; 18F-fluoroglycosylation; positron emission tomography; PET
Online: 18 October 2021 (11:10:02 CEST)
In the field of 18F-chemistry for the development of radiopharmaceuticals for positron emission tomography (PET), various labeling strategies by the use of prosthetic groups have been im-plemented, including chemoselective 18F-labeling of biomolecules. Among those, chemoselec-tive 18F-fluoroglycosylation methods focus on the sweetening of pharmaceutical radiochemistry by offering a highly valuable tool for the synthesis of 18F-glycoconjugates with suitable in vivo properties for PET imaging studies. A previous review covered the various 18F-fluoroglycosylation methods that have been developed and applied as of 2014 [Maschauer and Prante, BioMed. Res. Int. 2014, 214748]. This paper is an updated review, providing the recent progress in 18F-fluoroglycosylation reactions and the preclinical application of 18F-glycoconjugates, including small molecules, peptides, and high-molecular-weight proteins.
Subject: Medicine And Pharmacology, Ophthalmology Keywords: visual cortical prosthesis; brain-machine interface; electrical stimulation; prosthetic vision
Online: 23 March 2021 (10:42:30 CET)
The electrical stimulation of the visual cortices has the potential to restore vision to blind individuals. Until now, the results of visual cortical prosthetics has been limited as no prosthesis has restored a full working vision but the field has shown a renewed interest these last years thanks to wireless and technological advances. However, several scientific and technical challenges are still open in order to achieve the therapeutic benefit expected by these new devices. One of the main challenges is the electrical stimulation of the brain itself. In this review, we analyze the results in electrode-based visual cortical prosthetics from the electrical point of view. We first briefly describe what is known about the electrode-tissue interface and safety of electrical stimulation. Then we focus on the psychophysics of prosthetic vision and the state-of-the-art on the interplay between the electrical stimulation of the visual cortex and phosphene perception. Lastly, we discuss the challenges and perspectives of visual cortex electrical stimulation and electrode array design to develop the new generation implantable cortical visual prostheses.
ARTICLE | doi:10.20944/preprints202010.0568.v1
Subject: Engineering, Automotive Engineering Keywords: prosthetic hand; MyWare sensor; force sensing resistors, human hand anatomy
Online: 28 October 2020 (08:22:25 CET)
The present paper describes the development of a prosthetic hand based on the human hand anatomy. The hand phalanges are printed by using 3D printed with Polylactic Acid material. One of the main contributions is the investigation on the prosthetic hand joins; the proposed design enables to create personalized joins that allow the prosthetic hand a high level of movement by increasing the degrees of freedom of the fingers. Moreover, the driven wire tendons show a progressive grasping movement, being the friction of the tendons with the phalanges very low. Another important point is the use of force sensitive resistors for simulating the hand touch pressure. These are used for the grasping stop simulating touch pressure of the fingers. Surface Electromyogram (EMG) sensors allow the user to control the prosthetic hand grasping start. Their use may provide the prosthetic hand the possibility of classification of the hand movements. The practical results included in the paper prove the importance of the soft joins for the object manipulation and to get adapted to the object surface. Finally, the force sensitive sensors allow the prosthesis to actuate with more naturalness by adding conditions and classifications to the Electromyogram sensor.
ARTICLE | doi:10.20944/preprints202306.0973.v1
Subject: Medicine And Pharmacology, Dentistry And Oral Surgery Keywords: PEEK; Computer occlusal analysis; Bruxism; Parafunctional activities; Prosthetic rehabilitation; OHIP-49
Online: 14 June 2023 (03:56:08 CEST)
The aim of this article was to evaluate properties of new polymer material, based on PEEK, for FPDs in patients with parafunctions. Methods: Prospective clinical study involved patients with diagnosed signs and symptoms of parafunctions, restored with 100 units, PEEK based FPDs, veneered with composite material. During one year observation period the following parameters were evaluated: color changes, periodontal indices, treatment success using FDI criteria, occlusal parameters, patient-reported outcome measures (OHIP-49) and occurrence of complications. Results: Spectrophotometry revealed that 63% of bridges experienced changes for L*, a*, b* color parameters, but it was not clinically significant for patients. Periodontal indices (PI, GI, BOP) revealed statistically significant higher values around restorations. According to FDI criteria, therapy was considered successful and 86.7% of FPDs were acceptable. Computerized occlusal analysis demonstrated no significant difference in the number of occlusal contacts and the intensity of relative forces between restoration and control side. Results of OHIP-49 questionnaire showed improved patient’s quality of life. Complications appeared in a limited number of cases. Conclusion: PEEK based FPDs could be indicated for successful prosthodontic rehabilitation in patients with parafunctional activities, but further material improvements and long-term clinical trials should be conducted to analyze performance of this material in challenging cases, for patients with CMD and in implant therapy.
ARTICLE | doi:10.20944/preprints202207.0021.v1
Subject: Biology And Life Sciences, Biology And Biotechnology Keywords: artificial neural networks; biological neural networks; cortical prosthetic vision; machine vision; neuromorphic hardware; neuroprosthesis
Online: 1 July 2022 (17:01:32 CEST)
Sense element engagement theory explains how neural networks produce cortical prosthetic vision. A major prediction of the theory can be tested by developing a device which is expected to enable perception of continuous forms in altered visual geometries. The research reported here completes several essential steps in developing this device: (1) replication of simulations that are consistent with the theory using the NEST simulator, which can also be used for full-scale network emulation by a neuromorphic computer; (2) testing whether results consistent with the theory survive increasing the scale and duration of simulations; (3) establishing a method that uses numbers of spikes produced by network neurons to report the number of phosphenes produced by cortical stimulation; and (4) simulating essential functions of the prosthetic device. NEST simulations replicated early results and increasing their scale and duration produced results consistent with the theory. A decision function created using multinomial logistic regression correctly classified the expected number of phosphenes for 2080 spike number distributions for each of three sets of data, half of which arise from simulations expected to yield continuous visual forms on an altered visual geometry. A process for modulating electrical stimulation amplitude based on intermittent population recordings that is predicted to produce continuous visual forms was successfully simulated. The classification function developed using logistic regression will be used to tune this process as the scale of simulations is further increased.
ARTICLE | doi:10.20944/preprints202012.0245.v1
Subject: Medicine And Pharmacology, Immunology And Allergy Keywords: preload loss; conical abutment screw; Multi-Unit-Abutment; OT-Bridge; prosthetic connection; implant-supported prosthesis; loosening torque; tightening torque
Online: 10 December 2020 (10:21:40 CET)
Background: To compare the loss of preload in absence of loading and after a fixed number of ideal masticatory cycles in two different connection systems using all-on-four prosthetic model. Methods: Two equal models of an edentulous mandible rehabilitated with all-on-four technique with two types of abutment system (MUA and OT-Bridge) supporting a hybrid prosthesis, were used. Initial torque values of the prosthetic fixing screw, after ten minutes from initial screw tightening and after 400000 masticatory cycles were registered using a mechanical torque gauge. Differences between initial and final torque values were reported for each anchoring system and the two systems were finally compared. Results: No statistically significant differences regarding the loss of preload between MUA and OT-Bridge system were found after 400000 masticatory cycles; however, in MUA system it was found between anterior and posterior implant screws. A significant difference in preload loss was found only for MUA system comparing the initial screw torque to that measured after 10 minutes from the tightening in absence of cyclic loadings. Conclusions: MUA and OT-Bridge are reliable prosthetic anchoring systems able to tolerate repeated masticatory cycles also on distal cantilever in all-on-four rehabilitation model without any significant loss of preload in screw tightening