Prosthesis Model Research Articles

Metatarsophalangeal prosthesis for hallux rigidus. Review of current models and CartivaTM interposition endorthesis

Hallux rigidus of the first metatarsophalangeal joint affects between 35% and 60% of the population over 65 years of age and has multiple treatment options, among which we highlight metatarsophalangeal arthrodesis and prosthesis. Regarding the arthroplasty technique, we aim to provide information on the characteristics of the material, model, and design and on which one offers better results, relating it to the characteristics of the patient, such as age, presence of inflammatory joint diseases, and viability and durability of the implant. Some studies on the clinical and functional results with different prosthesis models are briefly exposed. According to the AOFAS criteria, prosthesis and arthrodesis present similar effectiveness values and the decision of which technique to use will be determined considering several factors and characteristics previously exposed. CartivaTM is a synthetic polyvinyl alcohol hydrogel implant that has a water content with a compressive and tensile modulus similar to that of human articular cartilage. Thus, it is suitable for use in metatarsophalangeal hemiarthroplasties, and published studies in this regard report excellent short- and long-term clinical results. Level of Evidence V; Therapeutic Studies; Expert Opinion.

Cloud computing-enabled IIOT system for neurosurgical simulation using augmented reality data access

In recent years, statistics have indicated that the number of patients with malignant brain tumors has increased sharply. However, most surgeons still perform surgical training using the traditional autopsy and prosthesis model, which encounters many problems, such as insufficient corpse resources, low efficiency, and high cost. With the advent of the 5G era, a wide range of Industrial Internet of Things (IIOT) applications have been developed. Virtual Reality (VR) and Augmented Reality (AR) technologies that emerged with 5G are developing rapidly for intelligent medical training. To address the challenges encountered during neurosurgery training, and combining with cloud computing, in this paper, a highly immersive AR-based brain tumor neurosurgery remote collaborative virtual surgery training system is developed, in which a VR simulator is embedded. The system enables real-time remote surgery training interaction through 5G transmission. Six experts and 18 novices were invited to participate in the experiment to verify the system. Subsequently, the two simulators were evaluated using face and construction validation methods. The results obtained by training the novices 50 times were further analyzed using the Learning Curve-Cumulative Sum (LC-CUSUM) evaluation method to validate the effectiveness of the two simulators. The results of the face and content validation demonstrated that the AR simulator in the system was superior to the VR simulator in terms of vision and scene authenticity, and had a better effect on the improvement of surgical skills. Moreover, the surgical training scheme proposed in this paper is effective, and the remote collaborative training effect of the system is ideal.

Evaluation of Bacteria in a Novel In Vitro Biofilm Model of Penile Prosthesis

BackgroundDelayed infection, thought to be due to gradual biofilm formation, remains a feared complication after inflatable penile prosthesis (IPP) insertion. Understanding and preventing biofilm formation is necessary to prevent infections. AimTo develop an in vitro model and compare growth of biofilm by different bacteria on IPPs and evaluate the anti-infective efficacy of the Coloplast Titan and AMS 700 InhibiZone. MethodsSterile IPPs (Coloplast) were cut into rings and incubated with S. epidermidis, S. aureus, P. aeruginosa, A. baumannii, or K. pneumoniae cultures in tryptic soy broth (TSB) (4 hour) to ensure adequate bacteria attachment, and then in only TSB (120 hours) to allow for biofilm formation. Rings were fixed with ethanol and biofilm measured by spectrophotometer (OD570) after crystal violet staining. This methodology was repeated for S. epidermidis and P. aeruginosa with Coloplast rings dipped in 10 ml of a 10 mg/ml Rifampin, 1 mg/ml Gentamicin, and deionized water solution and undipped AMS InhibiZone rings. Crystal violet assay (OD570) was repeated after incubation within bacteria (2 hour), and then only TSB (120 hours). OutcomesThe primary outcome of the study was OD570 readings, indirectly measuring biofilm mass on implant rings. ResultsS. epidermidis, S. aureus, A. baumannii, P. aeruginosa, and K. pneumoniae all formed significant biofilm. P. aeruginosa showed the strongest predilection to grow biofilm on IPPs. P. aeruginosa also formed significant biofilm on antibiotic-treated Coloplast and AMS rings, while S. epidermidis was inhibited. No significant difference was found in biofilm inhibition between the implants. Clinical TranslationOur findings suggest gram-negative bacteria may form biofilm more proficiently and quickly on IPPs than gram-positive organisms. Commonly used antibiotic treatments on IPPs may be effective against S. epidermidis but not against P. aeruginosa biofilm formation. Strengths & LimitationsThis is the first study comparing biofilm formation by different bacteria organisms on IPPs and the inhibitive ability of Coloplast and AMS implants against biofilm formation. Clinical data on organisms responsible for infected IPPs is needed to determine the clinical relevance of our findings. ConclusionOur novel in vitro model of biofilm formation of IPPs evaluated the effect of a gentamicin/rifampin antibiotic dip on Coloplast Titan implants and the anti-infective capacity of the minocycline/rifampin precoated AMS 700 InhibiZone against S. epidermidis and P. aeruginosa. P. aeruginosa was able to grow on both antibiotic-treated implants, with no significant difference, and should continue to be a specific target of investigation to reduce delayed post-operative IPP infections.Narasimman M, Ory J, Bartra SS, et al. Evaluation of Bacteria in a Novel In Vitro Biofilm Model of Penile Prosthesis. J Sex Med 2022;19:1024–1031.

Computer simulation of optimal lipped polyethylene liner orientation against prosthetic impingement

BackgroundLipped or elevated acetabular liners are to improve posterior stability and are widely used in hip arthroplasty. However, concerns of increasing impingement exist when using such liners and optimal orientation of the elevated rim remains unknown. We aimed to identify the impact of lipped liner on the range of motion (ROM) before impingement and propose its optimal orientation.MethodsAn isochoric three-dimensional model of a general hip-replacement prosthesis was generated, and flex-extension, add-abduction and axial rotation were simulated on a computer. The maximum ROM of the hip was measured before the neck impinged on the liner. Different combinations of acetabular anteversion angles ranging from 5 to 30 degrees, and lipped liner orientations from posterior to anterior were tested.ResultsWhen acetabular anteversion was 10 or 15 degrees, placing the lip of the liner in the posterosuperior of the acetabulum allowed satisfactory ROM in all directions. When acetabular anteversion was 20 degrees, extension and external rotation were restricted. Adjusting the lip to the superior restored satisfactory ROM. When acetabular anteversion was 25 degrees, only placing the lip into the anterosuperior could increase extension and external rotation to maintain satisfactory ROM.ConclusionsThis study showed that optimal lipped liner orientation should depend on acetabular anteversion. When acetabular anteversion was smaller than 20 degrees, placing lip in the posterior allowed an optimally ROM. When acetabular anteversion was greater than 20 degrees, adjusting lip to the anterior allowed a comprehensive larger ROM to avoid early impingement.

Evaluation of Gram Positive and Gram Negative Bacteria in a Novel In Vitro Biofilm Model of Penile Prosthesis

ABSTRACT Introduction Infection is the most feared complication of inflatable penile prosthesis (IPP), often necessitating complete removal. Late infection after IPP insertion is thought to be due to the slow formation of a biofilm. Understanding and preventing biofilm formation would be a breakthrough in preventing IPP infections. Objective We aimed to develop an in vitro model to compare formation and growth of biofilms on penile implants by bacteria commonly associated with infection. Methods Sterile IPPs (Coloplast Titan) were cut into rings and incubated with S. epidermidis, S. aureus, P. aeruginosa, or K. pneumoniae cultures in tryptic soy broth (TSB) for a 4 h attachment period, and then in only TSB for 120 h. We utilized a published and validated method to measure biofilm mass. Rings were then dipped in deionized water to wash off additional bacteria and either fixed with ethanol (EtOH) or not treated further (no fix). Fixing was employed to preserve biofilm on the rings that otherwise may have been lost during crystal violet staining. Biofilm formation was measured with a spectrophotometer (OD570) after crystal violet staining. Results All bacteria formed substantial biofilm on implant rings as measured by OD570. As expected, the gram-negative bacteria, P. aeruginosa and K. pneumoniae produced significantly more biofilm than the gram-positive S. epidermidis and S. aureus. Interestingly, P. aeruginosa formed the most biofilm by at least a factor of 6 in both testing conditions. The ethanol fixing condition produced more consistent results for the crystal violet assay. Conclusions Our novel in vitro model of biofilm formation of penile implants can be used in future studies to evaluate the effect of different antibiotic dips and anti-infective capacity of pre-coated implants against different bacteria. Our findings suggest gram-negative bacteria form faster and a greater quantity of biofilm on penile implants as compared to gram-positives. P. aeruginosa displayed the strongest predilection to form biofilm on implants compared to all other bacteria studied, and could be investigated as a specific target to reduce delayed post-operative IPP infections. Disclosure Yes, this is sponsored by industry/sponsor: Coloplast Clarification Industry funding only - investigator initiated and executed study Any of the authors act as a consultant, employee or shareholder of an industry for: Coloplast, Boston Scientific

Risk of conduction disturbances following different transcatheter aortic valve prostheses: the role of aortic valve calcifications.

OBJECTIVESTo assess the impact of prosthesis choice and aortic valve calcifications on the occurrence of conduction disturbances after transcatheter aortic valve implantation (TAVI).METHODSWe retrospectively analyzed the preoperative clinical characteristics, electrocardiograms, contrast-enhanced multidetector computed tomography scans and procedural strategies of patients who underwent TAVI in our center between January 2012 and June 2017. Quantification of calcium volume was performed for each aortic cusp above (aortic valve) and below (left ventricular outflow tract, LVOT) the basal plane. Multivariate analysis was performed to evaluate risk factors for the onset of new bundle branch block (BBB), transient and permanent atrioventricular block (tAVB, pAVB).RESULTSA total of 569 patients were included in the study. Six different prostheses were implanted (Edwards Sapien XT, n = 162; Edwards Sapien 3, n = 240; Medtronic CoreValve, n = 27; Medtronic CoreValve Evolut R, n = 21; Symetis Acurate, n = 56; Symetis Acurate neo, n = 63). The logistic regression analysis for BBB showed association with baseline left anterior hemiblock. The logistic regression for tAVB, found the prior valvuloplasty and the balloon post-dilatation associated with the outcome. Baseline left and right BBB, degree of oversizing, and LVOT calcification beneath the non-coronary cusp were associated with pAVB. Neither the prosthesis model, nor the use of a self-expandable prosthesis showed statistical significance with the above-mentioned outcomes on univariate analysis. CONCLUSIONSLVOT calcification beneath the non-coronary cusp, baseline left anterior hemiblock, right BBB, balloon post-dilatation, prior valvuloplasty and oversizing are independently associated with postprocedural conduction disturbances after TAVI. Use of a self-expandable prosthesis may show a lower incidence of AVB, if applied in lower calcified aortic valves.

Immobile Leaflets at Time of Bioprosthetic Valve Implantation: A Novel Risk Factor for Early Bioprosthetic Failure: A Novel Risk Factor for Early Bioprosthetic Failure

The clinical implications of finding immobile leaflet(s) at the time of bioprosthetic valve implantation but with acceptable prosthetic haemodynamics are uncertain. We sought to determine the characteristics of such patients and their impact on outcome. Patients with immobile leaflet at the time of surgical bioprosthetic valve implantation were identified retrospectively by a systematic search of an institutional echocardiography database (2010-2020). Intraoperative echocardiograms were reviewed de-novo to confirm immobile leaflet(s) at the time of implantation. Cases were matched 1:2 to controls with normal bioprosthetic leaflets motion for age, sex, prosthesis position, prosthesis model, size, year of implantation, and pre-implantation left ventricular ejection fraction. Proportional hazards method was used to analyse the composite endpoint of stroke, valve thrombosis or re-intervention. Immobile leaflet at the time of bioprosthetic valve implantation were found in 26 patients (median age 71 ys 39% males) following tricuspid (n=13), mitral (n=11) and aortic (n=2) valve replacements; 96% received porcine prostheses; prosthesis size was 27 mm or larger in 92%. Immobile leaflet were recorded on intraoperative reports in 16 (62%) cases. It resulted in elevated gradient or mild-moderate prosthetic regurgitation in three (12%), but none led to immediate corrective action intraoperatively. At median follow-up of 21 (4-50) months, presence of immobile leaflet was associated with composite clinical endpoint of stroke, valve thrombosis or re-intervention (hazard ratio 6.8, 95% CI 1.8-25.2, p<0.01) compared to controls. Immobile leaflet immediately post-bioprosthetic valve implantation is frequently under-recognised intraoperatively and appears to be associated with early bioprosthetic dysfunction and worse clinical outcome.

Effect of two types of shoulder prosthesis on the muscle forces using a generic multibody model for different arm motions

BackgroundThis study aims to analyze the effects of a novel dual-bearing shoulder prosthesis and a conventional reverse shoulder prosthesis on the deltoid and rotator cuff muscle forces for four different arm motions. The dual-bearing prosthesis is a glenoid-sparing joint replacement with a moving center of rotation. It has been developed to treat rotator cuff arthropathy, providing an increased post-operative functionality.MethodsA three-dimensional musculoskeletal OpenSim® model of an upper body, incorporating a natural gleno-humeral joint and a scapula-thoracic joint developed by Blana et al. (J Biomech 41: 1714-1721, 2008), was used as a reference for the natural shoulder. It was modified by integrating first a novel dual-bearing prosthesis, and second, a reverse shoulder prosthesis into the shoulder joint complex. Four different arm motions, namely abduction, scaption, internal and external rotation, were simulated using an inverse kinematics approach. For each of the three models, shoulder muscle forces and joint reaction forces were calculated with a 2 kg weight in the hand.ResultsIn general, the maximal shoulder muscle force and joint reaction force values were in a similar range for both prosthesis models during all four motions. The maximal deltoid muscle forces in the model with the dual-bearing prosthesis were 18% lower for abduction and 3% higher for scaption compared to the natural shoulder. The maximal rotator cuff muscle forces in the model with the dual-bearing prosthesis were 36% lower for abduction and 1% higher for scaption compared to the natural shoulder. Although the maximal deltoid muscle forces in the model with the dual-bearing prosthesis in internal and external rotation were 52% and 64% higher, respectively, compared to the natural shoulder, the maximal rotator cuff muscle forces were 27% lower in both motions.ConclusionThe study shows that the dual-bearing shoulder prosthesis is a feasible option for patients with rotator cuff tear and has a strong potential to be used as secondary as well as primary joint replacement. The study also demonstrates that computer simulations can help to guide the continued optimization of this particular design concept for successful clinical outcomes.

Adaptive Control System of Intelligent Lower Limb Prosthesis Based on 5G Virtual Reality

With the rapid development of computer science and technology in our country, especially the advent of the 5G network era, the emergence of smart prostheses makes it possible for disabled, injured, or amputee people with lower limbs to walk and exercise like normal people. However, due to the different selection of prosthetic materials, the final lower limb prostheses produced will also have different performance differences. How to select prosthetic materials to optimize the performance of the intelligent lower limb prosthesis is the focus of extensive discussion in the medical community. For this reason, this article takes the research of the adaptive control system of intelligent lower limb prosthesis based on 5G virtual reality as the research object. By using the current advanced 5G communication technology and virtual reality technology, a high-performance intelligent lower limb prosthesis is produced. Provide assistance with basic walking and motor abilities in daily life of patients with lower limb disabilities. This article first gives a systematic theoretical introduction to 5G virtual reality technology, expounds the current status of patients with lower limb disabilities, and proposes to use intelligent lower limb prosthetics to replace healthy lower limbs to solve the basic walking and sports needs of disabled patients in daily life and then use 5G virtual reality technology. The selection of human knee joints and ankle joints and structural system design were carried out. Finally, it was decided to use the four-bar linkage structure as the knee joint structure of the three-dimensional modeling of the intelligent lower limb prosthesis. At the end of this article, the application and simulation of the intelligent lower limb prosthesis to the human body were also carried out. The results of the experiment found that after 45 weeks of wearing exercises, the gait of the intelligent lower limb prosthesis is consistent with the expected effect whether it is walking on level ground and up and down the stairs or uphill. Due to the strong adaptiveness of the intelligent lower limb prosthesis sexual control, it can well assist the basic life movement ability of patients with lower limb disabilities.

Biomechanical analysis of a temporomandibular joint prosthesis for lateral pterygoid muscle reattachment

To analyze the biomechanical properties of a novel temporomandibular joint (TMJ) prosthesis with an attachment area for the lateral pterygoid muscle (LPM). Three prosthesis models were created and compared using finite element analysis for the displacement, stress, and strain when simulating the maximum bite force loading. A verification experiment and a compression test were conducted. The displacement, stress, and strain of the novel TMJ prosthesis were larger than the solid condylar neck prosthesis and similar to the slotted condylar neck prosthesis, but the values were far less than the yield strength of titanium alloy. The maximum stress and strain in the novel TMJ prosthesis was concentrated in the inner and boundary areas of the LPM reattachment region beside the thinnest part of the prosthesis neck. The difference in the strain values measured using the verification test and those using finite element analysis was <20%. Compression testing of the novel TMJ prosthesis revealed that the mandible fractured when the force reached 588.97 N, whereas the prosthesis itself did not break or deform. The mechanical distribution of the novel prosthesis was feasible under maximum bite force for potential clinical application.

Investigation of the marginal fit of a 3D-printed three-unit resin prosthesis with different build orientations and layer thicknesses.

PURPOSEThe purpose of this study was to analyze the marginal fit of three-unit resin prostheses printed with the stereolithography (SLA) method in two build orientations (45°, 60°) and two layer thicknesses (50 µm, 100 µm).MATERIALS AND METHODSA master model for a three-unit resin prosthesis was designed with two implant abutments. Forty specimens were printed using an SLA 3D printer. The specimens were printed with two build orientations (45°, 60°), and each orientation was printed with two layer thicknesses (50 µm, 100 µm). The marginal fit was measured as the marginal gap (MG) and absolute marginal discrepancy (AMD), and MG and AMD measurements were performed at 8 points per abutment, for 16 points per specimen. All statistical analyses were performed using SPSS software. Two-way analysis of variance (ANOVA) was separately performed on the MG and AMD values of the build orientations and layer thicknesses. Moreover, one-way ANOVA was performed for each point within each group.RESULTSThe margins of the area adjacent to the pontic showed significantly high values, and the values were smaller when the build orientation was 45° than when it was 60°. However, the margin did not differ significantly according to the layer thicknesses.CONCLUSIONThe marginal fit of the three-unit resin prosthesis fabricated by the SLA 3D method was affected by the pontic. Moreover, the marginal fit was affected by the build orientation. The 45° build orientation is recommended.

The effect of bush material property on the metal-polymer contact stress in knee megaprosthesis – An in silico study

The long bone loss management using segmental resection for the fixation between femur and tibia is called modular megaprostheses. Despite the huge development of design and materials of biomedical implants, the design issue of megaprostheses are still highly challenging. The wear and formation of wear debris of the polymer bush in the megaprosthesis is one of the significant problems faced. The objective of the study is to compare between PEEK, UHMWPE and their composites as the bush material and to find their suitability in order to reduce the polymer-metal contact stress. A three- dimensional model of the bone assembly is extracted from the Computerized Tomography (CT) scan for both femur and tibia using image processing software, Mimics. A 3D model of custom-made knee prosthesis is also developed. Both the 3D models were assembled and analyzed by giving boundary conditions with reference to the clinical conditions. The finite element analysis employed on the assembled prosthesis clearly shows the stress distribution and deformation in different parts and components of the megaprosthesis as well as adjacent femur and tibia. It is seen that the stress generated in the polymer-metal interfaces, which is one of the chief reasons behind the bush wear, could be varied by using varied bush materials.

A Biorealistic Computational Model Unfolds Human-Like Compliant Properties for Control of Hand Prosthesis.

Objective: Human neuromuscular reflex control provides a biological model for a compliant hand prosthesis. Here we present a computational approach to understanding the emerging human-like compliance, force and position control, and stiffness adaptation in a prosthetic hand with a replica of human neuromuscular reflex. Methods: A virtual twin of prosthetic hand was constructed in the MuJoCo environment with a tendon-driven anthropomorphic hand structure. Biorealistic mathematic models of muscle, spindle, spiking-neurons and monosynaptic reflex were implemented in neuromorphic chips to drive the virtual hand for real-time control. Results: Simulation showed that the virtual hand acquired human-like ability to control fingertip position, force and stiffness for grasp, as well as the capacity to interact with soft objects by adaptively adjusting hand stiffness. Conclusion: The biorealistic neuromorphic reflex model restores human-like neuromuscular properties for hand prosthesis to interact with soft objects.

The effects of bar holder material, cantilever and vertical misfit on stresses in implant supported overdentures: Three dimensional finite element analysis

Background/Aim: The aim of this study is to examine with finite element analysis the distal bar extension, the bar substructure material type and the amount of bar substructure-abutment mismatch, and the stress caused by the implant at the surrounding bone tissue in bar-retained prostheses. Material and Methods: A bar-retained prosthesis model has been designed on three implants placed in the fully toothless lower jaw at the places of both canines and the midline. Bar holder according to distal cantilever lengths was modeled to be 0 mm, 8 mm and 14 mm. The vertical incompatibility of the bar holder substructure with the abutment was modeled to be 0 µm, 100 µm and 200 µm. A total of twenty-seven (3x3x3) different models were obtained with three different bar infrastructure materials (titanium, gold and chromium-cobalt). 150 N occlusal force was applied to the central fossa of the left 1st molar tooth with a rigid food stuff. Results: In the cortical bone, the highest maximum principle stress value (2.78 MPa) was analyzed around the anterior implant socket in the model 13 (gold, cantilever 0mm, misfit 100 µm). The highest von Mises stress value (343.43 MPa, which occurred at the selected joints in bar holders) was observed in model 27 (chrome-cobalt, cantilever 14mm, misfit 200 µm). Conclusions: When the length of the cantilever is 14 mm, it causes a significant increase in stress around the implant, especially near the cantilever. It has been observed that bar infrastructures with high elastic modulus create higher stress values.

Effect of prosthetic design and restorative material on the stress distribution of implant-supported 3-unit fixed partial dentures: 3D-FEA

Objective: Evaluate the effect of Implant prosthetic designs and restorative material on the stress concentrationof 3-unit implant-supported restoration with two restorative materials. Material and Methods: Six differentscrew-retained prostheses models were virtually designed and divided according to design: fixed bridge (FB),cantilever bridge (CB), and separate crowns (SC). Then, each model was also divided into two subgroupsaccording to the material: Ultra-translucent multi-layered zirconia (Kuraray Noritake Dental Inc., Japan); or acombination of PEEK (Polyetheretherketone) framework (BioHPP, Bredent, GmbH &amp; Co., KG, Germany) andzirconia (ZR) crowns (ultra-translucent multi-layered zirconia, Kuraray Noritake Dental Inc., Japan). A verticalload of 100 N was applied statically perpendicular to the central fossa of each crown. The von-Mises stress wascomputed using Solidworks software (SolidWorks Corp, Massachusetts, USA), based on the physical parametersof the materials. Results: FB showed the lowest von Mises stress values out of all 3 design models. Moreover,the combination of PEEK and zirconia showed strain values smaller than full zirconia. The highest von Misesstress value was recorded in CB with the zirconia subgroup at (1098 MPa) while the lowest von Mises stressvalue was recorded in FB with combined PEEK and zirconia subgroup at (190 MPa). Conclusion: For three-unitimplant supported restorations, the use of PEEK framework and zirconia crowns was found to be more favorablebiomechanically regarding the prosthetic components, implant and bone stresses. KEYWORDSBiomechanics; Dental implants; Implant prosthetic designs; Finite element analysis; CAD/CAM.

Stress Shielding in the Proximal Tibia after Total Knee Arthroplasty: A Finite Element Analysis of 2- and 4-Mm-Thick Tibia Prosthesis Models

Stress Shielding in the Proximal Tibia after Total Knee Arthroplasty: A Finite Element Analysis of 2- and 4-Mm-Thick Tibia Prosthesis Models

A Cepstral Peak Prominence (CPP) Voice Analysis in Iranian Post-lingual Deaf Adult Cochlear Implant Users

In standardized connected speech samples, cepstral peak prominence (CPP) and smoothed CPP (CPPS) have been described as accurate parameters to evaluate voice quality. Lack of normal auditory feedback in post-lingually deaf CI users might influence tuning the acoustic parameters in speech production. Based on shreds of evidence, normal hearing results in suitable vocal control through the sensory-motor linkage. The main aim of the present study was to compare the cepstral values between the Iranian cochlear implant group and normal peers. Persian CAPE-V sentences were recorded from 30 CI users and 30 healthy speakers (mean age=36.7 years, SD=13.5, range=18-60 years). Thirteen /a/vowels were extracted manually from syllables. Each subject phonated sustained /a/vowel for 5 seconds. PRAAT was used to calculate CPP and CPPS. To compare two age- and gender-matched groups, the independent sample t-test was applied. Then, ANCOVA was used to assess the impact of demographic factors on cepstral scores in CI participants. Significant differences between the CI group and normal peers were discovered based on CPP and CPPS in both tasks (reading sentences and sustained vowel) (P < 0.05). Overall, CI users showed higher cepstral values. The implanted ear and prosthesis model had no significant impact on both CPP and CPPS (P ≥ 0.8). Higher CPP and CPPS values in the CI users might be due to increased phonatory instability and spectral noise, with the possibility of decreased vocal control and its quality. The outcome suggests that CI group uses a different voice control strategy. These findings should be kept in mind for intervention methods, especially by assessing vocal characteristics and considering the voice quality in adult CI users.

Novel Design and Finite Element Analysis of Diamond-like Porous Implants with Low Stiffness.

The purpose of this study was to design porous implants with low stiffness and evaluate their biomechanical behavior. Thus, two types of porous implants were designed (Type I: a combined structure of diamond-like porous scaffold and traditional tapered thread. Type II: a cylindrical porous scaffold filled by arrayed basic diamond-like pore units). Three implant-supported prosthesis models were constructed from Type I, Type II and commercial implants (control group) and were evaluated by finite element analysis (FEA). The stress distribution pattern of the porous implants were assessed and compared with the control group. In addition, the stiffness of the cylindrical specimens simplified from three types of implants was calculated. The Type I implant exhibited better stress distribution than the Type II implant. The maximum stress between the cortical bone–Type I implant interface was 12.9 and 19.0% lower than the other two groups. The peak stress at the cancellous bone–Type I implant interface was also reduced by 16.8 and 38.7%. Compared with the solid cylinder, the stiffness of diamond-like pore cylinders simplified from the two porous implants geometry was reduced by 61.5 to 76.1%. This construction method of porous implant can effectively lower its stiffness and optimize the stress distribution at the implant–bone interface.

보행 역학 데이터를 활용한 대퇴 의지 실시간 제어를 위한 딥러닝 모델 구조 연구

Training data of the deep learning model for the control of the above-knee prosthesis should have a sufficient amount of data to fit with the model. Also, this data can be used for gait classification to control the prosthesis. However, in real-time control, the number of the gait dynamics data counted by the sensor is only measured to the level that the deep learning model is difficult to learn., In this study, the most efficient deep learning model case was developed to resolve this problem in the case of a real-time control situation where data measurement time is insufficient. The data is collected through a hall sensor, load cell and Inertial Measurement Unit (IMU) mounted on the above-knee prosthesis. Subsequently, the collected data is divided into 5 phases (Loading Response (LR), Mid Stance (MS), Push Off (PO), Early Swing (ES), and Late Swing (LS)) of the gait cycle according to the point of inflection of hall sensors and load cells. Afterward, training data of the deep learning were generated by sliding window algorithm and the treated data was exercised on four deep learning models by changing the value of width and depth configurations. The results are assessed on accuracy, loss and F1-Score. In conclusion, the loss function statistically decreased in the case of the values of width and depth of the deep learning model were low. Accuracy and F1-Score were not shown significant difference statistically. Therefore, the results provided an efficient deep learning model for above-knee prosthesis to gait analysis and expected to lead to a more reasonable gait model for the control of the above-knee prosthesis via a more detailed gait classification study in the future.

Three-Dimensional Computer-Aided Design of a Full-Color Ocular Prosthesis with Textured Iris and Sclera Manufactured in One Single Print Job.

Three-dimensional (3D) printing of ocular prosthesis has been scarcely described in medical literature. Although ocular prostheses have been 3D printed successfully, iris colors are often manually added to the final product afterward. The objective was to produce a 3D-printed ocular prosthesis with textured iris and sclera in one single print job. We designed an average 3D model of an ocular prosthesis in 3D software, and took a high-resolution digital photograph of a human eye, which was processed in graphical software. By using functions called “displacement mapping” and “UV mapping” on the 3D model, the extent of height displacement was used to digitally produce a textured and colored iris and sclera on the 3D model. By using a polyjet 3D printer, different colors and materials could be used for different prosthesis components. We were able to design and 3D print a lifelike ocular prosthesis with realistic iris and sclera texture. The process took less than 4 h, of which 2.5 h are “printing time,” reducing labor time compared with conventional methods. This proof-of-concept adds valuable knowledge to the future manufacture of 3D-printed ocular prostheses, which has several benefits over the conventional production method: 3D printing is much faster, reproducible, and prostheses can easily be digitally adjusted and reprinted. This study is an important step in the development of a full-fledged 3D workflow to produce lifelike custom eye prostheses.