Methods for medical applications

The musculoskeletal disorders represent one of the most common problems in industrial environment; they impact the health of workers and employees. In this work we present a preliminary study towards the use of biomechanical models for improving classic methods for ergonomic assessment in industry. To this end, we use OpenSim, a software for biomechanical simulation and analysis. With OpenSim, we reconstruct the human motion corresponding to the execution of industrial tasks, performed in laboratory settings. In particular, we compute the evolution over time of the joint angles that, according to a classic observation method for ergonomic assessment, are needed to evaluate the risks associated to the musculoskeletal disorders for the upper limb.

Keywords: biomechanics , digital human model , ergonomics , industry

In this work we present a study for the experimental reconstruction of the human shoulder torque in the sagittal plane, since this is usually overloaded in industrial overhead tasks. To this end, we measure the three-dimensional motion of the human upper limb while performing selected movements using an optical motion capture system. Then, using a skeleton model implemented in one of the most common software for industrial ergonomic assessment, we reconstruct the shoulder angle and torque in the sagittal plane. A possible exploitation of this reconstruction strategy is presented for active compensation of this torque. The implementation of this simple strategy in a custom developed assistive device could augment human workers in performing repetitive jobs.

Keywords: biomechanics , digital human models , human motion analysis , industrial assistive devices

In this work we will show some preliminary results on the use of a wearable inertial system for assessment of performances and infringements in race-walking. The proposed system is composed by two parts, one for measurement and one for management purposes. The management unit is based on biomechanical-based parameters for evaluating performances and infringements. The preliminary experimental results are promising towards the use of this system in real field training and competition scenarios, to respectively assist coaches and judges.

Keywords: race-walking , sports biomechanics , wearable inertial sensors

Purpose: To examine the influence of different bulk and block composite and flowable and glass-ionomer material combinations in a multi-layer technique and in a unique technique, in deep Class I dental restorations. Methods: 3D CAD of the sound tooth were built-up from a CT scan dataset using reverse engineering techniques. Four restored tooth models with Class I cavity were virtually created from a CAD model of a sound tooth. 3D-finite element (FE) models were created and analyzed starting from CAD models. Model A with flowable resin composite restoring the lower layer and bulk-fill resin composite restoring the upper layer, model B with glass-ionomer cement (GIC) restoring the lower layer and bulk-fill resin composite restoring the upper layer, model C with block composite as the only restoring material and model D with bulk-fill resin composite as the only restoring material. Polymerization shrinkage was simulated with the thermal expansion approach. Physiologic masticatory loads were applied in combination with shrinkage effect. Nodal displacements on the lower surfaces of FE models were constrained in all directions. Static linear analyses were carried out. The maximum normal stress criterion was used to assess the influence of each factor. Results: Considering direct restoring techniques, models A, B and D exhibited a high stress gradient at the tooth/restorative material interface. Models A and D showed a similar stress trend along the cavity wall where a similar stress trend was recorded in the dentin and enamel. Model B showed a similar stress trend along enamel/restoration interface but a very low stress gradient along the dentin/restoration interface. Model C with a restoring block composite material showed a better response, with the lowest stress gradient at the dentin, filling block composite and enamel sides.

We propose to use an industrial redundant manipulator (KUKA LBR iiwa robot) as a haptic device to provide high force feedback for an orthopedic surgeon while performing the reaming of the acetabula in a virtual environment. Real experiments have been performed to validate the virtual reality training framework. The results show that the system resulted to be intuitive and reliable from the users experience.

Keywords: medical robotics force feedback virtual reality training

Purpose: Shoulder instability and reduced range of motion are two common complications of a total reverse shoulder arthroplasty. In this work, a new approach is proposed to estimate how the glenoid component positioning can influence the stability and the range of motion of a reverse shoulder prosthesis. Materials and methods: A standard reverse shoulder prosthesis has been analysed. To perform virtual simulation of the shoulder-prosthesis assembly, all the components of the prosthesis have been acquired via a 3D laser scanner and the solid models of the shoulder bones have been reconstructed through CT images. Loads on the shoulder joint have been estimated using anatomical models database. A new virtual/numerical procedure has been implemented using a 3D parametric modelling software to find the optimal position of the glenosphere. Results: Several analyses have been performed using different configurations obtained by changing the glenoid component tilt and the lateral position of the glenosphere, modified through the insertion of a cylindrical spacer. For the analysed case study, it was found that the interposition of a spacer (between the baseplate and the glenoid) and 15° inferior tilt of the glenosphere allow improving the range of motion and the stability of the shoulder. Conclusions: Some common complications of the reverse shoulder arthroplasty could be effectively reduced by a suitable positioning of the prosthesis components. In this work, using a new method based on virtual simulations, the influence of the glenosphere positioning has been investigated. An optimal configuration for the analysed case study has been found. The proposed approach could be used to find, with no in vivo experiments, the optimal position of a reverse shoulder prosthesis depending on the different dimensions and shape of the bones of each patient.

Keywords: CAD modelling & simulation , Digital shape acquisition , Instability ratio , Reverse shoulders prosthesis , ROM

This scientific work aims at developing an innovative virtual platform to design lower limb prosthesis centered on the virtual model of the patient and based on a computer-aided and knowledge-guided approach. The main idea is to develop a digital human model of the amputee to be used by the prosthetist in a full virtual environment in which a platform provides a set of interactive tools to design, configure, and test the prosthesis. This virtual platform permits to design and configure the whole prosthesis, in particular, the 3D model of the assembled prosthesis, crucial to define the prosthesis setup and patient's walking performance. An ad-hoc computer-aided design system has been developed in house to design the 3D model of the socket according to traditional operations made by technicians during traditional manufacturing process. Moreover, a finite element model has been defined to study the contact between residual limb and socket. The resulting 3D model of the socket can be realized by exploiting multimaterial additive manufacturing technology. Finally, the developed platform also permits to handle contact pressures and patient's gait data in a unique application through the use of a low-cost motion capture (MOCAP) system. The whole platform has been tested with the help of an Italian orthopedic laboratory. The developed platform is a promising solution to develop the check socket, and the application may be used also for training purpose for junior orthopedic technicians.

Keywords: Low-cost MOCAP system , Lower limb prosthesis , Pressure analysis , Socket design and 3D modeling

Nowadays, healthcare centers are not familiar with quantitative approaches for patients' gait evaluation. There is a clear need for methods to obtain objective figures characterizing patients' performance. Actually, there are no diffused methods for comparing the pre- and post-operative conditions of the same patient, integrating clinical information and representing a measure of the efficiency of functional recovery, especially in the short-term distance of the surgical intervention. To this aim, human motion tracking for medical analysis is creating new frontiers for potential clinical and home applications. Motion Capture (Mocap) systems are used to allow detecting and tracking human body movements, such as gait or any other gesture or posture in a specific context. In particular, low-cost portable systems can be adopted for the tracking of patients' movements. The pipeline going from tracking the scene to the creation of performance scores and indicators has its main challenge in the data elaboration, which depends on the specific context and to the detailed performance to be evaluated. The main objective of this research is to investigate whether the evaluation of the patient's gait through markerless optical motion capture technology can be added to clinical evaluations scores and if it is able to provide a quantitative measure of recovery in the short postoperative period. A system has been conceived, including commercial sensors and a way to elaborate data captured according to caregivers' requirements. This allows transforming the real gait of a patient right before and/or after the surgical procedure into a set of scores of medical relevance for his/her evaluation. The technical solution developed in this research will be the base for a large acquisition and data elaboration campaign performed in collaboration with an orthopedic team of surgeons specialized in hip arthroplasty. This will also allow assessing and comparing the short run results obtained by adopting different state-of-the-art surgical approach for the hip replacement.

In the last years, the advent of innovative technologies for tracking human motions is increasing the interest of physicians and physiotherapist, who would like to introduce new instruments for a more objective assessment of the rehabilitation processes. At present, many motion tracking systems have been developed and their ease of use and low-cost may represent the key aspects for which these systems could be really adopted both in rehabilitation centers and in rehabilitation programs at home. Several research studies confirmed the importance of continuing rehabilitation programs at home with the aim to maintain patients' health condition at a suitable level for daily life activities. Physicians and physiotherapists need methods and tools, which can be simply adaptable for each type of patients' category and type of rehabilitation according to the assessed pathology. For achieving this need, the technology has to be suitable for both the patient side and medical personnel side. The most suitable technology for the patients are motion tracking devices which can be used through traditional IT, such as laptops, smartphones and tablets. Also for medical personnel the ease of use is very important, physicians would like to check the patient's rehab exercises according to their medical knowledge by exploiting daily life technology. This research work investigates on which are the best user-friendly programming tools and low-cost technology for 3D hand and finger tracking for the development of a serious game for rehabilitation exercises. The tasks are designed according to physiotherapists' recommendations, in order to be customizable for any single user. The following sections will describe the method, the tools adopted, and the application developed.

Keywords: Hand tracking , Leap motion device , Low-cost technology , Post-stroke rehabilitation , Unity

Low cost marker-less motion capture (Mocap) systems can be considered an interesting technology for the objective assessment of rehabilitation processes. In particular, this paper presents a feasibility study to introduce a Mocap system as a tool to assess shoulder rehabilitation. The movements of a shoulder are complex and challenging to be captured with a marker-less system because the skeleton avatar usually oversimplifies shoulder articulation with a single virtual joint. The designed solution integrates a low-cost Mocap system with image processing techniques and convolutional neural networks to automatically detect and measure potential compensatory movements executed during an abduction, which is one of the first post-surgery exercises for shoulder rehabilitation. First, we introduce the main steps of a reference roadmap that guided the development of the Mocap solution for rehab assessment of injured shoulder. Then, the acquisition of medical knowledge is presented as well as the new Mocap solution based on the integration of convolutional neural networks and 2D motion tracking techniques. Finally, the application which automatically evaluates abductions and makes available the measurements of the scapular elevations is described. Preliminary study and future works are also presented and discussed.

Keywords: Blender , Marker-less Motion capture system , Open source SDK , OpenPose , Shoulder rehabilitation

The rehabilitation process of patients after spinal cord injury (SCI) is usually based on subjective visual assessment by medical staff of rehabilitation centers. During the process, the medical personnel train patients to manage wheelchair and they learn how to use their sensible body parts in order to have a satisfactory life-style. Furthermore, physiotherapists and physicians have to control patients to prevent wrong postures that could cause further disorders. This paper describes how a low-cost marker-less motion capture system can be exploited to create an objective assessment procedure. Three Microsoft Kinect v2 sensors have been used to track patients using their wheelchairs along a straight path. The three sensors are arranged to optimize the acquisition. Thanks to the collaboration with the medical staff, we identified the set of parameters necessary to monitor patients' performance. An ad hoc application has been developed to provide the physicians with the right set of data easy readable to assess the patients along the rehabilitation process. The application has been tested involving twenty volunteers. Finally, results reached so far and further developments are summarized and discussed.

Keywords: Assessment of rehabilitation processes , Low-cost marker-less motion capture system , Microsoft Kinect v2 , Spinal cord injury

The use of fast and accurate scanning systems for human body digitization might pave the way towards the development of less invasive processes for medical manufacturing. In this work, an advanced measurement system for human body 3D reconstruction is used to design tailored assistive devices. The system is a photogrammetric 3D body scanner developed by the authors.

Keywords: 3D body measurements , assistive devices , medical manufacturing

Background: Clear aligners (CA) are among the most chosen orthodontic therapies for patients who require an invisible treatment. Previous studies showed that the thermoforming process and the complexity of the intraoral environment might alter the properties of these devices. The aim of the current prospective clinical study was to assess the thickness changes of the CA after 10 days of intraoral use. The secondary aim was to assess the reproducibility of the thermoforming process, in terms of aligner thickness. Materials and methods: CA from 18 consecutive patients (13 women, 5 men, mean age 28.8 ± 9.6 years) were investigated. Before intraoral exposure (T0), the thickness of the unused CA was measured at different occlusal points on a 3D model with a dedicated software (Geomagic Qualify 2013; 3D Systems, Rock Hill, SC, USA). Two CA configurations were studied: passive maxillary aligner (P—no tooth movement; no shape for attachments) and active maxillary aligner (A—tooth movement; shape for attachments and divot). The used aligners were returned after 10 days (T1) and the thickness measurements were repeated. A Student's t test for paired data (T1 vs. T0) was applied to compare the thicknesses of used and unused devices (significance level after Bonferroni correction for multiple comparison was set at p < 0.0014). Furthermore, to study the reproducibility of the thermoforming process, P and A aligners were thermoformed twice, and the thicknesses of the two unused thermoformed devices were compared by means of Student's t test for paired data (significance level after Bonferroni correction for multiple comparison was set at p < 0.0014) and Dahlberg's error. Results: The thermoforming process showed good reproducibility for both aligner configurations, with a maximum Dahlberg's error of 0.13 mm. After intraoral use, the thickness of P showed some statistically significant, but not clinically relevant, thickness changes as compared to the unused aligners, while A did not show any significant changes. Conclusion: Considering the thickness changes, the thermoforming process is reliable both with active and passive aligner configurations. Also, the CA examined show good thickness stability after physiological intraoral ageing in a population of healthy adults.

Keywords: Adult , Aesthetic , Clear aligners , Dimensional stability , Intraoral ageing , Mechanical proprieties , Orthodontic appliance , Thermoforming , Thermoplastic

Aim. To evaluate the biomechanical effects of four different auxiliary-aligner combinations for the extrusion of a maxillary central incisor and to define the most effective design through finite element analysis (FEA). Materials and Methods. A full maxillary arch (14 teeth) was modelled by combining two different imaging techniques: cone beam computed tomography and surface-structured light scan. The appliance and auxiliary element geometries were created by exploiting computer-aided design (CAD) procedures. The reconstructed digital models were imported within the finite element solver (Ansys® 17). For the extrusion movement, the authors compared the aligner without an attachment with three auxiliary-aligner designs: a rectangular palatal attachment, a rectangular buccal attachment, and an ellipsoid buccal attachment. The resulting force-moment (MF) system delivered by the aligner to the target tooth and the tooth displacement were calculated for each scenario. Results. The maximum tooth displacement along the z-axis (0.07 mm) was obtained with the rectangular palatal attachment, while the minimum (0.02 mm) was obtained without any attachments. With the ellipsoid attachment, the highest undesired moments Mx and My were found. The rectangular palatal attachment showed the highest Fz (2.0 N) with the lowest undesired forces (Fx = 0.4 N; Fy = -0.2 N). Conclusions. FEA demonstrated that the rectangular palatal attachment can improve the effectiveness of the appliance for the extrusion of an upper central incisor.

Purpose: Pectus arcuatum is an anterior chest wall deformity that requires transverse wedge sternotomy. Determining and delivering the correct cutting angle are crucial for successful correction. This report describes the early clinical experience with a novel cutting template technology able to deliver the optimal cutting angle. Description: From patients' computed tomographic scans, the optimal cutting angle is obtained using computer-aided design. A template comprising slots tilted at the right cutting angle and a safety block to avoid damaging the posterior periosteum is printed through additive manufacturing. Evaluation: The template allows surgeons to perform a precise wedge sternotomy, safely sparing the posterior periosteum in all patients, without complications. Postoperative chest roentgenograms and clinical photographs demonstrate optimal sternal realignment and cosmetic outcome. In this report, the mean operative time was 110 minutes. All patients were successfully discharged, with a mean length of stay of 4 days. Conclusions: Transverse wedge sternotomy aided by a computer-aided design–devised cutting template may reduce the technical challenge of this procedure, thereby increasing its safety and reducing operative times and hospital stay. Further research on long-term patient outcomes is necessary.

Pectus Arcuatum, a rare congenital chest wall deformity, is characterized by the protrusion and early ossification of sternal angle thus configuring as a mixed form of excavatum and carinatum features. Surgical correction of pectus arcuatum always includes one or more horizontal sternal osteotomies, consisting in performing a V-shaped horizontal cutting of the sternum (resection prism) by means of an oscillating power saw. The angle between the saw and the sternal body in the V-shaped cut is determined according to the peculiarity of the specific sternal arch. The choice of the right angle, decided by the surgeon on the basis of her/his experience, is crucial for a successful intervention. The availability of a patient-specific surgical guide conveying the correct cutting angles can considerably improve the chances of success and, at the same time, reduce the intervention time. The present paper aims to propose a new CAD-based approach to design and produce custom-made surgical guides, manufactured by using additive manufacturing techniques, to assist the sternal osteotomy. Starting from CT images, the procedure allows to determine correct resection prism and to shape the surgical guide accordingly taking into account additive manufacturing capabilities. Virtually tested against three case studies the procedure demonstrated its effectiveness.

Keywords: Biomedical devices , CAD , Design for additive manufacturing , Medical imaging

Te design of bone scafolds for tissue regeneration is a topic of great interest, which involves diferent issues related to geometry of architectures, mechanical behavior, and biological requirements, whose optimal combination determines the success of an implant. Additive manufacturing (AM) has widened the capability to produce structures with complex geometries, which should potentially satisfy the diferent requirements. These architectures can be obtained by means of refned methods and have to be assessed in terms of geometrical and mechanical properties. In this paper a triply periodic minimal surface (TPMS), the Schwarz's Primitive surface (P-surface), has been considered as scafold unit cell and conveniently parameterized in order to investigate the efect of modulation of analytical parameters on the P-cell geometry and on its properties. Several are the cell properties, which can afect the scafold performance. Due to the important biofunctional role that the surface curvature plays in mechanisms of cellular proliferation and diferentiation, in this paper, in addition to properties considering the cell geometry in its whole (such as volume fraction or pore size), new properties were proposed. Tese properties involve, particularly, the evaluation of local geometrical-diferential properties of the P-surface. Te results of this P-cell comprehensive characterization are very useful for the design of customized bone scafolds able to satisfy both biological and mechanical requirements. A numerical structural evaluation, by means of fnite element method (FEM), was performed in order to assess the stifness of solid P-cells as a function of the changes of the analytical parameters of outer surface and the thickness of cell. Finally, the relationship between stifness and porosity has been analyzed, given the relevance that this property has for bone scafolds design.

Purpose: The study aims to investigate the correlations between positron emission tomography (PET) texture features, X-ray computed tomography (CT) texture features, and histological subtypes in non-small-cell lung cancer evaluated with 2-deoxy-2-[18F]fluoro-D-glucose PET/CT. Procedures: We retrospectively evaluated the baseline PET/CT scans of 81 patients with histologically proven non-small-cell lung cancer. Feature extraction and statistical analysis were carried out on the Matlab platform (MathWorks, Natick, USA). Results: Intra-CT correlation analysis revealed a strong positive correlation between volume of the lesion (CTvol) and maximum density (CTmax), and between kurtosis (CTkrt) and maximum density (CTmax). A moderate positive correlation was found between volume (CTvol) and average density (CTmean), and between kurtosis (CTkrt) and average density (CTmean). Intra-PET analysis identified a strong positive correlation between the radiotracer uptake (SUVmax, SUVmean) and its degree of variability/disorder throughout the lesion (SUVstd, SUVent). Conversely, there was a strong negative correlation between the uptake (SUVmax, SUVmean) and its degree of uniformity (SUVuni). There was a positive moderate correlation between the metabolic tumor volume (MTV) and radiotracer uptake (SUVmax, SUVmean). Inter (PET-CT) correlation analysis identified a very strong positive correlation between the volume of the lesion at CT (CTvol) and the metabolic volume (MTV), a moderate positive correlation between average tissue density (CTmean) and radiotracer uptake (SUVmax, SUVmean), and between kurtosis at CT (CTkrt) and metabolic tumor volume (MTV). Squamous cell carcinomas had larger volume higher uptake, stronger PET variability and lower uniformity than the other subtypes. By contrast, adenocarcinomas exhibited significantly lower uptake, lower variability and higher uniformity than the other subtypes. Conclusions: Significant associations emerged between PET features, CT features, and histological type in NSCLC. Texture analysis on PET/CT shows potential to differentiate between histological types in patients with non-small-cell lung cancer.

Keywords: Non-small-cell lung cancer , Radiomics , Texture analysis , [ F] FDG PET/CT 18

This paper compares the effects of colour pre-processing on the classification performance of H&E-stained images. Variations in the tissue preparation procedures, acquisition systems, stain conditions and reagents are all source of artifacts that can affect negatively computer-based classification. Pre-processing methods such as colour constancy, transfer and deconvolution have been proposed to compensate the artifacts. In this paper we compare quantitatively the combined effect of six colour pre-processing procedures and 12 colour texture descriptors on patch-based classification of H&E-stained images. We found that colour pre-processing had negative effects on accuracy in most cases – particularly when used with colour descriptors. However, some pre-processing procedures proved beneficial when employed in conjunction with classic texture descriptors such as co-occurrence matrices, Gabor filters and Local Binary Patterns.

Keywords: Colour , Eosin , Hematoxylin , Histology , Texture