Methods for medical applications

Robot-assisted radical prostatectomy (RARP) has become a standardized practice in contemporary prostate cancer surgical procedures. Nowadays, the use of tailored surgical procedures in urologic surgery aims to maximize treatment efficacy while minimizing its impact on patient functions and health-related quality-of-life parameters. Augmented reality (AR) technology appears as a significant development in Image Guided Surgery (IGS) integrating surgical navigation with 3D virtual organ models registered on to the real patient's anatomy. In particular, AR provides surgeons the ability to see through solid objects; as such, it has been exploited in different surgical specialties. In this paper, we present the development of a software system augmenting the spatial navigation of the surgical environment allowed by surgical robots. The application is able to visualize the 3D virtual model of the organ (prostate and kidneys) targeted by the surgical procedure, overlay it over its real counterpart, as captured by the endoscope camera, using of registration and tracking techniques in real time, and stream the augmentation to the surgeon.

Keywords: Augmented reality (AR) , Image Guided Surgery (IGS) , Minimally invasive surgery (MIS) , Robotic surgery

The ovary is a dynamic mechanoresponsive organ. In vitro, tissue biomechanics was reported to affect follicle activation mainly through the Hippo pathway. Only recently, ovary responsiveness to mechanical signals was exploited for reproductive purposes. Unfortunately, poor characterization of ovarian cortex biomechanics and of the mechanical challenge hampers reproducible and effective treatments, and prevention of tissue damages. In this study the biomechanical response of ovarian cortical tissue from abattoir bovines was characterized for the first time. Ovarian cortical tissue fragments were subjected to uniaxial dynamic testing at frequencies up to 30 Hz, and at increasing average stresses. Tissue structure prior to and after testing was characterized by histology, with established fixation and staining protocols, to assess follicle quality and stage. Tissue properties largely varied with the donor. Bovine ovarian cortical tissue consistently exhibited a nonlinear viscoelastic behavior, with dominant elastic characteristics, in the low range of other reproductive tissues, and significant creep. Strain rate was independent of the applied stress. Histological analysis prior to and after mechanical tests showed that the short-term dynamic mechanical test used for the study did not cause significant tissue tear, nor follicle expulsion or cell damage.

Keywords: Biomechanics , Creep , Elastic modulus , Ovarian tissue , Tensile test , Viscous behavior

A number of surgical practices are aimed to compensate for tissue relaxation or weakened/atrophied muscles by means of suture prostheses/thread lifts. The success rate of these procedures is often very good in the short term, while it is quite variable among subjects and techniques in the middle-long term. Middle-long term failures are mostly related to suture distraction, loosening or wear, coming from repeated loading cycles. In this work, an experimental device to perform ex vivo tests on prosthetic sutures has been set up. An equine laryngoplasty has been used as a benchmark, being representative of sutures aimed to compensate for atrophied muscles. The peculiarity of this experimental set up is that the suture is on-site and it has been tightened with known, repeated loads, which do not depend on thread deformation at different load levels. Preliminary tests have been performed applying over 3000 load cycles and finally a tensile test up to rupture. Force/displacement curves obtained with this experimental set up have been reported and parameters useful to classify the biomechanical performance of sutures versus time (mainly its creep behaviour), have been outlined. Results have outlined that the organ-suture system undergoes significant creep over 3000 cycles, and this should be taken into account in order to foresee its long-term behaviour; in addition, the suture anchorage to cartilage should be improved. The experimental set up can be used to perform on-site testing of sutures, taking into account the compliance and creep response at both suture anchorage ends, in order to compare different surgeries and different kinds of thread.

Keywords: Creep , Distraction , Failure , Neuropathy , Suture testing , Tissue relaxation

Intramedullary nails constitute a viable alternative to extramedullary fixation devices; their use is growing in recent years, especially with reference to self-locking nails. Different designs are available, and it is not trivial to foresee the respective in vivo performances and to provide clinical indications in relation to the type of bone and fracture. In this work a numerical methodology was set up and validated in order to compare the mechanical behavior of two new nailing device concepts with one already used in clinic. In detail, three different nails were studied: (1) the Marchetti-Vicenzi's nail (MV1), (2) a revised concept of this device (MV2), and (3) a new Terzini-Putame's nail (TP) concept. Firstly, the mechanical behavior of the MV1 device was assessed through experimental loading tests employing a 3D-printed component aimed at reproducing the bone geometry inside which the device is implanted. In the next step, the respective numerical model was created, based on a multibody approach including flexible parts, and this model was validated against the previously obtained experimental results. Finally, numerical models of the MV2 and TP concepts were implemented and compared with the MV1 nail, focusing the attention on the response of all devices to compression, tension, bending, and torsion. A stability index (SI) was defined to quantify the mechanical stability provided to the nail-bone assembly by the elastic self-locking mechanism for the various loading conditions. In addition, results in terms of nail-bone assembly stiffness, computed from force/moment vs. displacement/rotation curves, were presented and discussed. Findings revealed that numerical models were able to provide good estimates of load vs. displacement curves. The TP nail concept proved to be able to generate a significantly higher SI (27 N for MV1 vs. 380 N for TP) and a greater stiffening action (up to a stiffness difference for bending load that ranges from 370 Nmm/° for MV1 to 1,532 Nmm/° for TP) than the other two devices which showed similar performances. On the whole, a demonstration was given of information which can be obtained from numerical simulations of expandable fixation devices.

Keywords: biomechanical stability , experimental tests , flexible bodies , intramedullary nails , Marchetti-Vicenzi nail , multibody analysis , stiffness

A number of applications in the surgical practice are based on tensile sutures aimed to keep soft tissues in place and compensate the exit of neuropathies, prolapses or general tissue relaxation. Long-term behaviour of these constructs need to be carefully examined in order to define tensile forces to be applied and to compare different suture anchors. Data here reported refer to equine laryngoplasties, where a suitable loading system has been designed in order to be able to test sutures in-sito, applying known forces (“On-site testing of sutured organs: an experimental set up to cyclically tighten sutures” (Pascoletti et al., 2020 [1])). The loading protocol was made of two steps: in the first step, 3000 loading cycles have been performed; in the following step, a tensile test up to rupture was performed. Cyclic load/displacement curves allow evaluating suture distraction, as a consequence of suture migration and/or soft tissues creep. Tensile curves allow evaluating the residual thread strength and its ultimate displacement. These data can provide a detailed insight of long-term suture behaviour and can be a reference to compare different threads and/or suture anchors.

Keywords: Creep , Distraction , Failure , Neuropathy , Suture testing , Tissue relaxation

The design of loading systems to test biologic samples is often challenging, due to shape variability and non-conventional loading set-ups. In addition to this, large economic investments would not be justified since the loading set up is usually designed for one single or for a limited range of applications. The object of this work is the development of a loading set-up finalised to on-site testing of sutures whose main function is applying a localised tensile load. The main challenges of this design process can be so summarized: • Applying cyclic tensile loads on the suture wire, mimicking the physiologic condition where both suture anchorage points have a certain compliance; • Designing a loading system as versatile as possible, in order to be able to accommodate organs with different geometries and sizes; • Keeping low both the complexity and costs of realization.All these considerations and the design calculi are here reported in detail, discussing the novelty of the system, and its main advantages.

Keywords: Anchorage points migration , Cyclic loads , On-site testing of prosthetic sutures , Suture distraction , Suture test

This paper presents an approach for monitoring exercises of hand rehabilitation for post stroke patients. The developed solution uses a leap motion controller as hand-tracking device and embeds a supervised machine learning. The K-nearest neighbor methodology is adopted for automatically characterizing the physiotherapist or helper hand movement resulting a unique movement pattern that constitutes the basis of the rehabilitation process. In the second stage, an evaluation of the patients rehabilitation exercises results is compared to the movement pattern of the patient and results are presented, saved and statistically analyzed. Physicians and physiotherapists monitor and assess patients' rehabilitation improvements through a web application, furthermore, offer medical assisted rehabilitation processes through low cost technology, which can be easily exploited at home. Recorded tracked motion data and results can be used for further medical study and evaluating rehabilitation trends according to patient's rehabilitation practice and improvement.

Keywords: Hand rehabilitation , K-nearest neighbor , Leap motion controller

Introduction: Miniscrew-assisted rapid palatal expansion (MARPE) appliances utilize the skeletal anchorage to expand the maxilla. One type of MARPE device is the Maxillary Skeletal Expander (MSE), which presents four micro-implants with bicortical engagement of the palatal vault and nasal floor. MSE positioning is traditionally planned using dental stone models and 2D headfilms. This approach presents some critical issues, such as the inability to identify the MSE position relative to skeletal structures, and the potential risk of damaging anatomical structures. Methods: A novel methodology has been developed to plan MSE position using the digital model of dental arches and cone-beam computed tomography (CBCT). A virtual model of MSE appliance with the four micro-implants was created. After virtual planning, a positioning guide is virtually designed, 3D printed, and utilized to model and weld the MSE supporting arms to the molar bands. The expansion device is then cemented in the patient oral cavity and micro-implants inserted. A clinical case of a 12.9-year-old female patient presenting a Class III malocclusion with transverse and sagittal maxillary deficiency is reported. Results: The midpalatal suture was opened with a split of 3.06 mm and 2.8 mm at the anterior and posterior nasal spine, respectively. After facemask therapy, the sagittal skeletal relationship was improved, as shown by the increase in ANB, A-Na perpendicular and Wits cephalometric parameters, and the mandibular plane rotated 1.6° clockwise. Conclusion: The proposed digital methodology represents an advancement in the planning of MSE positioning, compared to the traditional approach. By evaluating the bone morphol-ogy of the palate and midface on patient CBCT, the placement of MSE is improved regarding the biomechanics of maxillary expansion and the bone thickness at micro-implants insertion sites. In the present case report, the digital planning was associated with a positive outcome of maxillary expansion and protraction in safety conditions.

Keywords: CBCT , CBDP , Cephalometrics-based digital planning , MARPE , Miniscrew-assisted rapid palatal expansion , MSE , TAD , Virtual planning , Workflow

Introduction: As we enter the era of "big data," an increasing amount of complex health-care data will become available. These data are often redundant, "noisy," and characterized by wide variability. In order to offer a precise and transversal view of a clinical scenario the artificial intelligence (AI) with machine learning (ML) algorithms and Artificial neuron networks (ANNs) process were adopted, with a promising wide diffusion in the near future. The present work aims to provide a comprehensive and critical overview of the current and potential applications of AI and ANNs in urology. Evidence Acquisition: A non-systematic review of the literature was performed by screening Medline, PubMed, the Cochrane Database, and Embase to detect pertinent studies regarding the application of AI and ANN in Urology. Evidence Synthesis: The main application of AI in urology is the field of genitourinary cancers. Focusing on prostate cancer, AI was applied for the prediction of prostate biopsy results. For bladder cancer, the prediction of recurrence-free probability and diagnostic evaluation were analysed with ML algorithms. For kidney and testis cancer, anecdotal experiences were reported for staging and prediction of diseases recurrence. More recently, AI has been applied in non-oncological diseases like stones and functional urology. Conclusions: AI technologies are growing their role in health care; but, up to now, their "real-life" implementation remains limited. However, in the near future, the potential of AI-driven era could change the clinical practice in Urology, improving overall patient outcomes.

Keywords: Artificial intelligence , Big data , Urologic neoplasms , Urology

The application of CAx tools in surgery is representing a breakthrough for clinical practice, both in terms of effectiveness and costs. Working directly on the patient's own diagnostic images, this approach provides powerful tools for pre-operative simulation, complex-surgery planning, quantitative evaluation of asymmetry or dysmorphism and for the design of the patient-specific instrumentation. To exploit its full potential, methodologies are being developed to automatize and simplify the existing tools and strategies, in order to make them available also to less experienced CAx users, or directly to the surgeons. With this aim, it is proposed a methodological procedure to automatically create a Statistical Shape Model of the cranial vault starting from a Training Set of pathologically unaffected adult crania. The Statistical Shape Model is useful as a template for a data-driven restoration of the physiological shape of the considered anatomy. The proposed procedure provides a reliable strategy for robust automatic detection of shape correspondence. Not requiring any user intervention, the number of samples in the Training Set can be increased at will to consequently increase the variability, and therefore the accuracy, of the resulting parametric model.

Keywords: CAx , Reverse engineering , Statistical Shape Model

Implant fixed dental prostheses are widely used for the treatment of edentulism, often preferred over the screw-retained ones. However, one of the main features of an implant-supported prosthesis is retrievability, which could be necessary in the case of implant complications. In this study, the retrievability of implant-fixed dental prostheses was investigated considering two of the main factors dental practitioners have to deal with: the abutments geometry and the luting agent. Impulsive forces were applied to dental bridge models to simulate crowns' retrievability in clinical conditions. The number of impulses and the impulsive force delivered during each test were recorded and used as retrievability indexes. One-hundred-and-five tests were conducted on 21 combinations of bridges and luting agents, and a Kruskal-Wallis test was performed on the results. The abutment geometry significantly influenced the number of impulses needed for retrieval (p < 0.05), and a cement-dependent trend was observed as well. On the other hand, the forces measured during tests showed no clear correlation with bridge retrievability. The best retrievability was obtained with long, slightly tapered abutments and a temporary luting agent.

Keywords: Abutments geometry , Coronaflex , Dental bridge , Luting agents , Retrieval

Cement-retained implant-supported prosthetics are gaining popularity compared to the alternative screw-retained type, a rise that serves to highlight the importance of retrievability. The aim of the present investigation is to determine the influence of luting agent, abutment height and taper angle on the retrievability of abutment-coping cementations. Abutments with different heights and tapers were screwed onto an implant and their cobalt-chrome copings were cemented on the abutments using three different luting agents. The removals were performed by means of Coronaflex®. The number of impulses and the forces were recorded and analyzed with a Kruskal-Wallis test. Harvard cement needed the highest number of impulses for retrieval, followed by Telio CS and Temp Bond. However, abutment height and taper showed a greater influence on the cap's retrievability (p < 0.05). Long and tapered abutments provided the highest percentage of good retrievability. The influence of the luting agent and the abutment geometry on the cap's retrieval performed by Coronaflex® reflects data from literature about the influence of the same factor on the maximum force reached during uniaxial tensile tests. The impulse force was slightly affected by the same factors.

Keywords: Abutments geometry , Coronaflex , Dental cements , Dental implants , Retrievability

A number of studies have recently demonstrated that the geometry of scaffolds for bone tissue engineering significantly affects the tissue differentiation process and the rate of bone tissue regeneration. These findings and the possibility of fabricating any kind of sophisticated geometries by additive manufacturing techniques led many researchers throughout the world to investigate strategies for the design of scaffolds and for the optimization of their geometry. In this chapter, after revising the numerical optimization algorithms recently implemented to determine the best scaffold geometry we will investigate, in particular, those that are mechanobiology-driven. These algorithms perturb the scaffold microarchitecture until the optimal scaffold geometry, i.e., the geometry that allows maximizing the amounts of bone forming within the scaffold pores, is computed. Different applications of these algorithms to different regular and irregular scaffold geometries will be shown.

Keywords: Beam-based scaffold , Irregular scaffold , Mechanobiology , Mechanoregulation algorithm , Regular scaffold

Introduction of collision models aided surgeons to plan their resection of the femoral and acetabular impinging deformities. Their application on the hip joint is particularly interesting in association with hip arthroscopy because with technique the vision is limited and identifying friction's zones is not easy. Although their large diffusion in the market, they still presents several limits. First, the 3D reconstruction has been used only in the preoperatory phase. Its use inside the operatory room is still not available. Furthermore the actual software lack of a pure automatized program to create the 3D model of the hip. Second, nowadays collision model's software separate and study only the bony part of the hip, erasing from the 3D reconstruction soft tissues. Third, the programs currently developed use statistical data as reference to 3d virtual models and the motion between the hip's bones. They base the motion analysis on the comparison between data extrapolated from the healthy population and data from the patient exam, consequently image processing may be inaccurate. Although according to our opinion collision model are useful even with their actual limits, in this chapter we describe the limits of the actual software and their potential development. © 2020 by Nova Science Publishers, Inc. All rights reserved.

Light activated composites are the most popular choice in the field of dental restoration. They generally show internal stress even after a prolonged time period. The knowledge of mechanical properties and residual stress should provide interesting information on the clinical performance of such materials. Accordingly, in the current research experimental analyses were carried out to assess the effect of the curing process on the properties of one of the most commonly employed light activated dental composites (Gradia Direct—GC Corporation, Japan). At 10 min, 1 h and 24 h after light curing, the bending modulus (4.7–6.2 GPa) as well as the punching performance (peak load of 12.1–17.5 N) were evaluated for the micro-hybrid composite. Scanning electron microscopy also allowed to analyze the fracture surface. Residual stresses ranging from 0.67 ± 0.15 MPa to 1.12 ± 0.17 MPa were measured by means of the thin-ring-slitting approach reported in the literature, according to measurement time and cutting time.

Keywords: CAD/CAM system , Dental materials , Mechanical and morphological properties , Residual stress

The control of the process–structure–property relationship of a material plays an important role in the design of biomedical metal devices featuring desired properties. In the field of endodontics, several post-core systems have been considered, which include a wide range of industrially developed posts. Endodontists generally use posts characterized by different materials, sizes, and shapes. Computer-aided design (CAD) and finite element (FE) analysis were taken into account to provide further insight into the effect of the material–shape combination of metal posts on the mechanical behavior of endodontically treated anterior teeth. In particular, theoretical designs of metal posts with two different shapes (conical-tapered and conical-cylindrical) and consisting of materials with Young's moduli of 110 GPa and 200 GPa were proposed. A load of 100 N was applied on the palatal surface of the crown at 45◦ to the longitudinal axis of the tooth. Linear static analyses were performed with a non-failure condition. The results suggested the possibility to tailor the stress distribution along the metal posts and at the interface between the post and the surrounding structures, benefiting from an appropriate combination of a CAD-based approach and material selection. The obtained results could help to design metal posts that minimize stress concentrations.

Keywords: Computer-aided design (CAD) , Dental materials , Finite element analysis , Image analysis , Mechanical properties , Metal posts

In a complex case of speech disorder, the communication is entrusted to systems equipped with a speech synthesizer. When the user has a motor disability, in addition, hardware and software interfaces are personalized to make technology more accessible. Interaction design methods can be applied to develop improved assistive systems and, particularly, for Augmentative and Alternative Communication (AAC). Interaction design methods and usability evaluation could have a positive impact in reducing product barriers and improving performances as the effort state associated to its use can be reduced. Minimizing cognitive and physical efforts through the development of new solutions and interface optimization can be challenging. A usability test and an interface optimization of a personalized AAC system developed for a student of the University of Naples Federico II with complex communication needs due to a traumatic injury and motor impairment are discussed to fix usability issues, highlight critical areas and design new prototypes.

Keywords: Augmentative and alternative communication , Biomedical devices , Disability , Interaction design , Learnability , Usability

Mechanical and architectural features play an important role in designing biomedical devices. The use of materials (i.e., Ti6Al4V) with Young's modulus higher than those of natural tissues generally cause stress shielding effects, bone atrophy, and implant loosening. However, porous devices may be designed to reduce the implant stiffness and, consequently, to improve its stability by promoting tissue ingrowth. If porosity increases, mass transport properties, which are crucial for cell behavior and tissue ingrowth, increase, whereas mechanical properties decrease. As reported in the literature, it is always possible to tailor mass transport and mechanical properties of additively manufactured structures by varying the architectural features, as well as pore shape and size. Even though many studies have already been made on different porous structures with controlled morphology, the aim of current study was to provide only a further analysis on Ti6Al4V lattice structures manufactured by selective laser melting. Experimental and theoretical analyses also demonstrated the possibility to vary the architectural features, pore size, and geometry, without dramatically altering the mechanical performance of the structure.

The accurate location of the mid-sagittal plane is fundamental for the assessment of craniofacial dysmorphisms and for a proper corrective surgery planning. To date, these elaborations are carried out by skilled operators within specific software environments. Since the whole procedure is based on the manual selection of specific landmarks, it is time-consuming, and the results depend on the operators' professional experience. This work aims to propose a new automatic and landmark-independent technique which is able to extract a reliable mid-sagittal plane from 3D CT images. The algorithm has been designed to perform a robust evaluation, also in the case of large defect areas. The presented method is an upgraded version of a mirroring-and registration technique for the automatic symmetry plane detection of 3D asymmetrically scanned human faces, previously published by the authors. With respect to the published algorithm, the improvements here introduced concern both the objective function formulation and the method used to minimize it. The automatic method here proposed has been verified in the analysis of real craniofacial skeletons also with large defects, and the results have been compared with other recent technologies.

Keywords: Cranio-maxillofacial , Feature recognition , Medical imaging , Mid-sagittal plane , Symmetry analysis