Prosthesis, Volume 6, Issue 3 (June 2024) – 20 articles

Surgical aortic valve replacement (SAVR) was the only symptom relieving and life-prolonging treatment until transcatheter aortic valve implantation (TAVI) became available. This option was introduced to treat old and high-risk patients. In a series of 2500 consecutive patients referred for SAVR with a biologic heart valve (BHV) prosthesis, their age, comorbid conditions, the complexity of the procedure, postoperative outcome, need for resources, and long-term survival were compared in patients before versus after the introduction of TAVI. Although the Carpentier-Edwards valve was used in most patients, the outcomes with respect to several other BHV types were studied. Patients undergoing isolated SAVR (i-SAVR) were studied separately from those who underwent SAVR with a concomitant procedure (c-SAVR). The number of referrals increased over time until 2016, whereafter the reimbursement for TAVI broadened. Age, prior percutaneous coronary interventions, diabetes, and chronic renal disease increased over time in both groups, while atrial fibrillation, the need for emergent SAVR, and other comorbid conditions increased significantly only in the c-SAVR group. Postoperative acute renal injury, conduction defects, and bleeding increased over time in both groups. The need for renal replacement therapy increased in both surgical groups, but this was more pronounced in c-SAVR; the need for a pacemaker implant (p < 0.001), blood products, and reintervention increased only in the c-SAVR group. There was a moderate but non-significant increase in the 30-day mortality for both groups over time. Furthermore, the long-term survival of both groups did not change after the introduction of TAVI. The Carpentier-Edwards Perimount valve showed good long-term results for durability. The Perceval device was used in older patients and showed good hemodynamic results, but the need for a postoperative permanent pacemaker implant was high. The results seem to indicate that a broader reimbursement for TAVI was warranted after its introduction in 2008. Nevertheless, with the development of newer devices for SAVR, surgery will remain one of the major treatment options for aortic valve disease. Full article

Frontal plane ankle motion is important for balance in walking but is seldom controlled in robotic prostheses. This article describes the design, control and performance of a semi-active two-degree-of-freedom robotic prosthetic ankle. The mechanism uses a non-backdrivable wedge cam system based on rotating inclined planes, allowing actuation only during swing phases for low power, light weight and compactness. We present details of the mechanism and its kinematic and mechatronic control, and a benchtop investigation of the system’s speed and accuracy in ankle angle control. The two-axis ankle achieves angular reorientation movements spanning ±10 deg in any direction in less than 0.9 s. It achieves a plantarflexion/dorsiflexion error of 0.35 ± 0.27 deg and an inversion/eversion error of 0.29 ± 0.25 deg. Backdriven motion during walking tests is negligible. Strengths of the design include self-locking behavior for low power and simple kinematic control. Two-axis ankle angle control could enable applications such as balance augmentation, turning assistance, and wearable perturbation training. Full article

Prosthetic socket manufacturing is experiencing a revolutionary shift towards using digital methods, such as 3D scanning and 3D printing. However, using digital methods requires the clinician to transfer their skills from making sockets by hand to making sockets with a computer. This shift in practice may change the socket geometry and fit; however, to what extent is unknown. Thus, the aim of this study was to explore the feasibility of analyzing geometric and clinical differences between digitally- and manually-designed sockets. Nine adult inpatients with below-knee amputation were recruited. Two sockets were 3D printed for each participant from 3D socket models that were developed from: (1) 3D scanning a manually-modified hand-casted positive mold of the residuum; and (2) a digitally-modified 3D scan of the residuum. Manual and digital procedures were compared for three measures: final socket geometry, the Socket Comfort Score, and a patient experience survey. Feasibility data were collected to measure protocol implementation fidelity to inform a future larger study. These data revealed that 89% of participants followed the intended protocol, no participants dropped out, and only one adverse event was report. As no significant geometric differences were found and participants experienced similar comfort scores between manually- and digitally-designed sockets, study feasibility was determined to be successful. Thus, a randomized control trial study will be conducted to draw statistically relevant conclusions from these outcome measures that may provide meaningful information for improving digital design procedures. Full article

Mechanical and thermal trauma during implant surgery may be reasons for initial peri-implant bone loss. Temperature development during drilling and implant insertion were quantified in this series of in vitro and animal experiments. Polyurethane foam material mimicking different classes of alveolar bone was used as a model material for simulating implant surgery. Using thermocouples, temperature development was determined in the model material at depths of 3 mm and 10 mm during site preparation and implant insertion. Additionally, an infrared camera allowed for measuring drill temperatures both in vitro and as part of an animal trial using an intraoral minipig model. Drill diameter and repeated usage of drills did not have a major effect on temperature generation. The addition of a diamond-like carbon coating, bone density, predrilling, and irrigation heavily affected intraosseous temperatures. In vivo, applying regular drill protocols, an intraosseous temperature rise of approximately 3 °K was determined. Implant geometry as well as the amount of undersizing of an osteotomy governed heat generation during implant insertion. Drill protocols and the amount of undersizing of an implant osteotomy constitute parameters by which clinicians can limit trauma during implant surgery. Full article

Purpose: In incomplete spinal cord injury (SCI), there is a partial decrease in motor or sensory or autonomic function. Mainly due to the motor impairment in SCI, a muscle–machine interface is a tool that can bring functional benefits to this population. Objective: To investigate the feasibility of the non-invasive myoelectric signal–functional electrical stimulation (MES-FES) interface on the response of the quadriceps muscle in an individual with incomplete SCI. Methods: This is a quasi-experimental, uncontrolled, longitudinal case report study carried out with an individual with incomplete SCI in the chronic phase. The assessments performed before (pre) and after eight (post₈) interventions were neuromuscular assessment (surface electromyography (EMG) in rectus femoris (RF) and vastus lateralis (VL) muscles); muscle strength (load cell); knee extension range of motion (goniometry); spasticity (Modified Ashworth Scale); and quality of life (Spinal Cord Injury Quality-of-Life Questionnaire (SCI-QoL.Br)). The MES-FES interface was associated with physical therapy exercises on the extension knee joint muscle group. Results: Improvement in neuromuscular activation (normalized increase in EMG_RMS of 2% (RF) and 3.3% (VL)) and synchronism of the motor units (normalized reduction in EMG_MDF of 22.8% (RF) and 5.9% (VL)); 1.4 kgf increase in quadriceps strength; 10.6° increase in knee joint extension amplitude; 1 point spasticity reduction; improved quality of life, confirmed by a 12-point reduction in the SCI-QoL.Br score. Moreover, along with interventions, the participant increased the correct FES activation rate, indicating a user learning curve ($\rho$ = 0.78, p-value = 0.04). Conclusions: The MES-FES interface associated with physical therapy promotes neuromuscular and quality of life improvements in the SCI participant. Full article

Background: The use of magnification appears to offer advantages in dental preparation for fixed prosthetics and is widely employed in clinical practice, although it has not yet been thoroughly documented. Therefore, the primary objective is to determine the impact of magnification on the quality of finish lines during the performance of preparations for fixed prostheses. Methods: Sixty-four natural teeth were randomized into two groups: Group O (preparation without additional magnification) and Group L (preparation with Kitus^® 2.5× magnifying glasses). The teeth were prepared for full crowns, and the finish lines were evaluated under the OPMI^® PicoZeiss dental microscope at 10× magnification, based on the criteria of Continuity, Roughness, and Thickness. Results: There were no significant differences between the groups in any of the parameters evaluated. In Thickness, Group O had a median (IQR) of 600 µm (500; 800 µm) and Group L, 600 µm (400; 800 µm). Group L was Continuous in 64.8% of the cases, Slightly Continuous in 26.1% of the evaluations, and Not Continuous in 9.1% of the cases, thus having a slight advantage over Group O, whose values were 58.0%, 35.2%, and 6.8%, respectively. Group L was Polished in 71.0% of the cases and Rough in 29.0% of the evaluations, against 69.3% and 30.7% of Group O, respectively. These results were obtained using IBM SPSS ^® software, version 29.0. Conclusions: The 2.5× magnification magnifiers demonstrated a slight positive impact on improving the quality of dental preparations for fixed prostheses. Nevertheless, since the results are not statistically significant, it is difficult to extrapolate them to the broader population. Full article

To evaluate the flexural strength and flexural modulus of three recently introduced 3D-Printed resins and compare them with the flexural properties of other well known, already commercialized, and extensively used resin based dental materials. Three 3D-printed dental resins, a fiber-reinforced epoxy resin, a heat-cured bis-acrylate-based composite resin, two conventional CAD/CAM PMMA, and a graphene-reinforced CAD/CAM PMMA, were selected for this study. Ten prismatic-shaped specimens (2 × 2 × 25 mm) were fabricated for each material (n = 10). All specimens underwent a three-point bending test using a universal testing machine and were loaded until fracture. Flexural strength (MPa) and flexural modulus (MPa) mean values were calculated and compared using the on ranks One-Way ANOVA test. Scanning electron microscope analysis of the 3D-printed resins was performed. Significantly different flexural properties were recorded among the tested materials. The fiber-reinforced epoxy resin exhibited the highest flexural strength (418.0 MPa) while, among the 3D-printed resins, the best flexural strength was achieved by Irix-Max (135.0 MPa). Irix-Plus and Temporis led to the lowest mean flexural strength values (103.9 MPa and 101.3 MPa, respectively) of all the CAD/CAM milled materials, except for the conventional PMMA by Sintodent (88.9 MPa). The fiber-reinforced epoxy resin also showed the highest flexural modulus (14,672.2 MPa), followed by the heat-cured bis-acrylate composite (10,010.1 MPa). All 3D-printed resins had a higher flexural modulus than the conventional PMMA materials. CAD/CAM fiber-reinforced epoxy resin excels in flexural strength, with Irix-Max showing promising flexural properties, which could encourage its use for permanent restorations. Caution is needed with Irix-Plus and Temporis due to their lower flexural strength compared to other traditional materials. Full article

Background: This pilot study aimed to evaluate the effectiveness of digitally crafted customized healing abutments in stabilizing peri-implant soft tissues following tooth extraction and assess the preservation of peri-implant soft tissue architecture over 5 years. Material and Methods: Forty patients (age ≥ 25 years) were divided into test (n = 20) and control (n = 20) groups. The test group received dental implants with immediate loading after tooth extraction, along with customized healing abutments fabricated using CAD/CAM technology. The control group received dental implants with immediate loading without customized healing abutments. The primary outcome was the change in distance between the peri-implant soft tissue margin and implant fixture surface from baseline to 5 years post implantation. Results: In the test group, there was a significant decrease in the distance between the peri-implant soft tissue margin and fixture surface from baseline to 5 years (p < 0.001), with pairwise comparisons showing significant differences between multiple time points (p < 0.05). The control group showed less pronounced changes over time. Conclusions: Within the limitations of this pilot study, digitally fabricated customized healing abutments appear effective in stabilizing peri-implant soft tissues and preserving soft tissue architecture around dental implants over 5 years following immediate implant placement. Randomized controlled trials are needed to confirm these findings. Full article

The surgical management of adult spinal deformities (ASDs) involves a wide variety of complex and technically challenging operative techniques. Despite numerous publications examining the relationship between surgeon experience and outcomes in ASD, no systematic review or meta-analysis exists. This first-time systematic review and meta-analysis examines the impact of surgeon experience on the surgical parameters and complication rates for the surgical management of ASD. Four databases were used for the initial search of this study from database inception until 22 September 2023. The inclusion criteria required articles that examined the outcomes for surgery for ASD, stratified outcomes by surgeon experience and/or the learning curve as a proxy for surgeon experience, and utilized adult patients (>18 years of age). Seven articles met the criteria for final inclusion. Patients in the Experienced Surgeon group had statistically significantly lower levels of EBL with no significant difference in operative time after surgery for ASD compared to patients in the Inexperienced Surgeon group via a meta-analysis of three articles. Patients in the Experienced Surgeon group had a statistically significantly lower total complication rate compared to patients in the Inexperienced Surgeon group via a meta-analysis. Increased surgeon experience resulted in lower levels of EBL, without a significant difference in the operative time after surgery for ASD. Full article

This study presents a novel approach to sternum prosthesis design, aiming to address the limitations of the current solutions by employing compliant mechanisms. The research focuses on developing a prosthetic design capable of generating lifting movements on ribs during breathing. First, a videogrammetry experimental test and virtual simulations were conducted to ascertain the vertical forces applied to each sternum joint. Subsequently, a compliant mechanism design was initiated, involving optimization and finite element analysis (FEM). A comprehensive kinematic performance analysis was performed to evaluate the prosthetic design. The results indicate that the obtained displacements of each rib closely align with those reported in the existing literature, demonstrating the effectiveness of the proposed solution. In conclusion, the developed sternum prosthesis exhibits the capability to recover approximately 56% of the ribs’ natural movements, highlighting its potential as an innovative and promising solution in the field of chest prosthetics. Full article

In implantology, among the key choices, to obtain predictable results, it is essential to establish, using cone beam computed tomography (CBCT), the bone site and where to insert the implants; during the surgical phase, these sites must be identified on the oral mucosa. Surgical templates are a valid aid, especially in complex cases which require the insertion of more than three or four implants. In cases of a single implant, on the other hand, surgical guides are rarely used, and the implant is often inserted freehand; therefore, the identification of the implant site on the oral mucosa (after choosing the location on the CBCT) is more difficult. For this reason, the clinician uses the teeth in the arch as a reference. This study evaluates the ability of the human eye to identify, on the oral mucosa, where the implant collars will be positioned, the position of which has previously been chosen on the CBCT, in cases where the hands-free surgical technique (without surgical guides) is used. The verification of this precision is carried out using particular thermo-printed templates which contain radiopaque metal spheres. The results show that, in the freehand technique, it is difficult to precisely identify the implant sites (chosen via X-ray) on the mucosa, especially when they are far from natural teeth adjacent to the edentulous area. In case of monoedentulism, the freehand implant technique seems to be applicable by expert implantologists with a reduced risk of error; in fact, clinical experience helps to find the correct correspondence between the implant site chosen on the CBCT and its identification on the mucosa. The level of experience is fundamental in the clinician’s decision about whether or not to use surgical guides; in fact, doctors with little experience should use surgical guides even in the simplest cases to reduce the risk of error. Full article

This retrospective cohort study assesses the effectiveness of straight-stem cementless versus cemented prostheses in hip replacement surgeries for elderly patients with femoral neck fractures. We analyzed 80 patients aged 70 and over who underwent surgery between 2018 and 2021. Clinical outcomes were evaluated using the Harris Hip Score, WOMAC Score, and Visual Analogue Scale, alongside radiological assessments through Brooker’s classification. Preoperative Dorr classification and five postoperative criteria (subsidence, cortical hypertrophy, pedestal sign, radiolucent lines, and stress shielding) were used to assess implant efficacy. The results demonstrated satisfactory mid-term outcomes for both groups, with slightly higher clinical scores observed in the cementless stem group. The Harris Hip Score (HHS) averaged 74.4 ± 6.7 in the cemented group and 79.2 ± 10.4 in the cementless group, with a statistically significant difference (p = 0.0146). The WOMAC Score showed an average of 30.1 ± 4.6 in the cemented group compared to 27.1 ± 6.9 in the cementless group, also indicating a statistically significant improvement (p = 0.0231). However, radiographic findings call for a re-evaluation of long-term stability. Our statistical analysis, which included power calculation and multivariate analysis to adjust for confounding variables, offers a comprehensive assessment of implant effectiveness. The findings contribute to the ongoing debate on the choice between cemented and cementless prostheses, indicating that both are viable options catering to different patient needs. Further research overcoming this study’s limitations is crucial for a deeper understanding of optimal treatment strategies in hip replacement surgery for the elderly. Full article

This manuscript introduces a novel two-step technique for fabricating mobile dentures post-extraction to streamline prosthodontic rehabilitation. The study utilizes various materials, including dental polymers, metals, ceramics, and composite materials, each chosen for their unique properties that contribute to the final prosthesis’s functionality, durability, and esthetics. The detailed procedure involves an initial occlusal registration immediately following tooth extraction, capturing precise occlusal relationships and a comprehensive dental impression. This approach reduces clinical visits and leverages optimal alveolar ridge morphology. The expected results highlight the efficiency of the technique, reducing treatment time without compromising quality and potentially improving patient satisfaction and prosthodontic outcomes. This innovative method conclusively promises rapid, efficient, and patient-centered dental rehabilitation, emphasizing the need for future research to validate its effectiveness and explore long-term outcomes. Full article

This study delves into an in-depth examination of the biomechanical characteristics of various materials commonly utilized in the fabrication of artificial ankle joints. Specifically, this research focuses on the design of an ankle joint resembling the salto-talaris type, aiming to comprehensively understand its performance under different loading conditions. Employing advanced finite element analysis techniques, this investigation rigorously evaluates the stresses and displacements experienced by the designed ankle joint when subjected to varying loads. Furthermore, this study endeavors to identify the vibrating frequencies associated with these displacements, offering valuable insights into the dynamic behavior of the ankle joint. Notably, the analysis extends to studying random frequencies across three axes of motion, enabling a comprehensive assessment of directional deformities that may arise during joint function. To validate the effectiveness of the proposed design, a comparative analysis is conducted against the star ankle design, a widely recognized benchmark in ankle joint prosthetics. This comparative approach serves dual purposes: confirming the accuracy of the findings derived from the salto-talaris design and elucidating the relative efficacy of the proposed design in practical application scenarios. Full article

Considering the rapid evolution of lithium silicate-based glass ceramics (LSCs) in dentistry, this review paper aims to present an updated overview of the recently introduced commercial novel LSCs. The clinical and in vitro English-language literature relating to the microstructure, manufacturing, strengthening, properties, surface treatments and clinical performance of LSC materials was obtained through an electronic search. Findings from relevant articles were extracted and summarised for this manuscript. There is considerable evidence supporting the mechanical and aesthetic competency of LSC variants, namely zirconia-reinforced lithium silicates and lithium–aluminium disilicates. Nonetheless, the literature assessing the biocompatibility and cytotoxicity of novel LSCs is scarce. An exploration of the chemical, mechanical and chemo-mechanical intaglio surface treatments—alternative to hydrofluoric acid etching—revealed promising adhesion performance for acid neutralisation and plasma treatment. The subtractive manufacturing methods of partially crystallised and fully crystallised LSC blocks and the additive manufacturing modalities pertaining to the fabrication of LSC dental restorations are addressed, wherein that challenges that could be encountered upon implementing novel additive manufacturing approaches using LSC print materials are highlighted. Furthermore, the short-term clinical performance of zirconia-reinforced lithium silicates and lithium–aluminium disilicates is demonstrated to be comparable to that of lithium disilicate ceramics and reveals promising potential for their long-term clinical performance. Full article

The demand for affordable prostheses, particularly in low- and middle-income countries (LMICs), is significant. Currently, the majority of prosthetic sockets are manufactured using monolithic thermoplastic polymers such as PP (polypropylene), which lack durability, strength, and exhibit creep. Alternatively, they are reinforced with consumptive thermoset resin and expensive composite fillers such as carbon, glass, or Kevlar fibres. However, there are unmet needs that amputees face in obtaining affordable prosthetic sockets, demanding a solution. This study utilises self-reinforced PET (polyethylene terephthalate), an affordable and sustainable composite material, to produce custom-made sockets. Advancing the development of a unique socket manufacturing technique employing a reusable vacuum bag and a purpose-built curing oven, we tested fabricated sockets for maximum strength. Subsequently, a prosthetic device was created and assessed for its performance during ambulation. The mechanical and structural strength of PET materials for sockets reached a maximum strength of 132 MPa and 5686 N. Findings indicate that the material has the potential to serve as a viable substitute for manufacturing functional sockets. Additionally, TOPSIS analysis was conducted to compare the performance index of sockets, considering decision criteria such as material cost, socket weight, and strength. The results showed that PET sockets outperformed other materials in affordability, durability, and strength. The methodology successfully fabricated complex-shaped patient sockets in under two hours. Additionally, walking tests demonstrated that amputees could perform daily activities without interruptions. This research makes significant progress towards realising affordable prostheses for LMICs, aiming to provide patient-specific affordable prostheses tailored for LMICs. Full article

The study of the phenomena occurring in the plantar region is remarkably intriguing, especially when performing a normal gait cycle where the foot is under loading conditions. The effects presented in the foot while walking provide relevant indicators regarding clinical means for enhancing regular performance or rehabilitation therapies. Nevertheless, more than traditional methods are needed to biomechanically evaluate foot structural conditions, leading to an incomplete database for determining the patient’s needs so that advanced methodologies provide detailed medical assessment. Therefore, it is necessary to employ technological engineering tools to optimize biomechanical plantar pressure evaluations to reach suitable personalized treatments. This research initially evaluated numerically the pressure points in the foot sole region in each one of the five stance phases in a normal gait cycle. Medical imaging techniques were utilized to construct an anatomically accurate biomodel of the soft tissues of the right foot. The Finite Element Method was employed to predict peak plantar pressure in barefoot conditions for all stance phases; results from this case study presented a close alignment with gait experimental testing implemented to analyze the feasibility and validation of all mechanical considerations for the numerical analyses. Hence, having a solid foundation in the biomechanical behavior from the first case study close estimates, a 3D-printable patient-specific insole was designed and numerically analyzed to observe the mechanical response in the plantar critical zones utilizing a personalized orthotic device. Results from the second case study notably demonstrated a crucial decrement in excessive pressure values. Employing morphological customization orthopedics modeling combined with 3D-printable materials is revolutionizing assistive device design and fabrication techniques. The fundamental contribution of this research relies on deepening the knowledge of foot biomechanics from an interdisciplinary approach by numerically analyzing pressure distribution in critical regions for all five stances phases; thus, based on the methods employed, the results obtained contribute to the advances of patient-specific foot orthopedics. Full article

Implant-supported-screw-retained prostheses are highly popular. Some of the most frequent complications are connected with the mechanical properties of the fixing elements. These include abutment screw loosening or even screw fracture. Using an intermediate abutment can offer several advantages. However, few studies detail how this affects the mechanical behavior of dental restorations. This study focuses on understanding the mechanical behavior of implant-supported restorations with a transepithelial component compared to direct implant-supported restoration. It was carried out using the finite element method (FEM) and was experimentally validated. The results showed that in the case of transepithelial-supported restoration, the prosthetic screw mounted over the transepithelial component suffered higher stress than the one screwed directly into the implant. After applying a cyclic fatigue load, it was experimentally proven that, in the transepithelial-supported restorations, the fuse changed from being the screw that went into the implant to being the upper one. In conclusion, we can state that the use of an intermediate abutment in dental restoration not only provides better protection for the rest of the dental restoration but also allows for easier repair in the event of a fracture. This can potentially lead to more efficient procedures and improved patient outcomes. Full article