Methods for medical applications

This paper proposes a systematic approach for involving the clinicians in the design of medical devices, here used for the development of a soft robotic glove for rehabilitation. The approach considers the integration of different methodologies that take into account the emotional information of the clinicians considered as end–users (i.e. Kano–Kansei) and a deep analysis of the needs of both the patients and the clinicians (i.e. house of quality). Based on this user–centered approach, the paper develops different rehabilitation concepts realized through the technique referred to as design of experiments. Finally the optimal one is chosen re–involving the clinicians and using the ANOVA analysis.

Keywords: Hand rehabilitation , Product development , Soft robotics , User-centred design

This paper presents the use of surface electromyographic (sEMG) signals for the actuation of soft pneumatic artificial muscles. The idea behind this paper is finding a relationship between a natural muscle and an artificial muscle, do it through an analysis of the sEMG data. We start from the characterization of a specific soft pneumatic artificial muscle and we relate the root mean square value of the sEMG signal to the contraction of the actuator itself. This work might pave the way for the development of intuitive wearable interfaces for the actuation of soft robots.

Keywords: Human biosignal , Soft actuators , Surface electromyographic sensors , Wearable technologies

The evaluation of hip implantation success remains one of the most relevant problems in orthopaedics. There are several factors that can cause its failure, e.g.: aseptic loosening and dislocations of the prosthetic joint due to implant impingement. Following a total hip arthroplasty, it is fundamental that the orthopaedist can evaluate which may be the possible risk factors that would lead to dislocation, or in the worst cases, to implant failure. A procedure has been carried out with the aim of evaluating the Range of Movement (ROM) of the implanted prosthesis, to predict whether the inserted implant is correctly positioned or will be prone to dislocation or material wear due to the malposition of its components. Leveraging on a previous patented methodology that consists in the 3D reconstruction and movement simulation of the hip joint, this work aims to provide a more effective visualization of the simulation results through Mixed Reality (MR). The use of MR for the representation of hip kinematics and implant position can provide the orthopaedic surgeon with a deeper understanding of the orientation and position of implanted components, as well as the consequences of such placements while looking directly at the patient. To this end, an anchoring system based on a body-tracking recognition library was developed, so that both completely automatic and human-assisted options are available without additional markers or sensors. An Augmented Reality (AR) prototype has been developed in Unity 3D and used on HoloLens 2, integrating the implemented human-assisted anchoring system option.

Keywords: Computer-aided surgery , HoloLens 2 , Mixed reality , THA assessment , Total hip arthroplasty

The study of predictive models describing the biological processes relating extra-cellular mechanical stimuli to structural responses of living cells, or even a differentiation, as in the case of mesenchymal stem cells (MSCs), is a relevant aspect in mechanobiology. A preliminary phase for these studies is the assessment of the mechanical behavior of whole living cells or their subcellular components, often performed by means of Atomic Force Microscopy (AFM). In this study we developed a numerical optimization framework aiming at matching the computed results obtained from a sequence of FEM simulations to an experimental AFM report curve associated to a MSC under investigation, in order to extract the elastic parameters of subcellular components and to assess how the mechanical response changes if the stress fibers network present in the interior of the cell is activated or not. By means of the proposed study, we extracted a set of Young's moduli for the main subcellular components, which resulted comparable to the values computed by means of the Hertzian contact theory, and was also in good agreement with the related literature. By neglecting the effect of the tensioning pre-stress field induced by the stress fibers network, an underestimation of the Young's moduli of subcellular components, up to a 15% in magnitude, was obtained.

Keywords: Finite element method , Mechanical simulation , Mechanobiology , Stem cells , Stress fibers

During past years, the pandemic has revealed the importance of having a solid care system prepared to face emergencies. In this context, digital solutions demonstrated a high potential in dealing with critical conditions and ensuring the delivery of care. However, telemedicine has not yet succeeded in becoming a stable part of ordinary care. The integration of innovative telemedicine technologies with a set of well-organized activities plays a crucial role in the release of high-quality services. Processes modeling before the introduction of telemedicine services is a leverage to prepare the base for an effective and efficient shift to digital care. Hence, the present research customizes a modeling technique in four steps for a preliminary analysis of processes where to introduce televisits. A special attention is given to the collection of consistent knowledge about care processes, often lack and incomplete in public hospitals scenarios. The approach has been applied to the AS-IS process of the heart failure clinic of a large Italian hospital before the introduction of televisits. Integrated Definition for Function Modeling (IDEF) diagrams have allowed the hierarchical decomposition of complex phases in simpler tasks, the acquisition of consciousness and the updating of information. Diagrams have been created and used as a source of a common language to discuss about weaknesses of the current process and its possible improvements. Obstacles to the upcoming televisits services have been objectively highlighted, such as the need to reduce employed applications, the removal of printed material and the streamlining of unnecessary operations.

Keywords: Healthcare processes , IDEF0 , Process modeling , Televisits

Tracheomalacia (TM) is a tracheal weakening that causes the cartilage structure to collapse during breathing. The term tracheobronchomalacia (TBM) is used when the bronchi are also implicated in the disease. This illness can be treated in a variety of methods, including the insertion of stents in the cartilage-restricted region. Stents are commercially available in numerous sizes (diameter and length), different shapes and materials. The shape of the stent is chosen based on where the disease is located, while the size is derived from measurements on CT images or by endoscopic investigations. This task is extremely critical for the patient's health since improper stent can have serious and even deadly repercussions for the patient. Therefore, it is necessary to choose a stent that fits the patient's anatomy as closely as possible. To this end, it is possible to employ a three-dimensional model of the investigated anatomy and choose the most suitable type of stent following measurements made on the model itself. In this work, a method to assist physicians in the choice of the stent to be used in TM or TBM patients, is proposed. By analyzing the tracheobronchial tree and measuring successive cross-sections along the centerline of the lumen, the automated procedure allows to localize the diseased area and to identify the optimal shape and size of the stent to be implanted. Four case studies of paediatric patients were performed and the results were validated by a team of physicians specialized in the treatment of upper and lower airways.

Keywords: 3D modelling , Airway obstruction , Reverse engineering , Stent

When dealing with craniofacial impairments, restoring the morphological condition is as crucial as restoring the functional ones to avoid psychosocial disabilities for the patient. For this aim, the accurate location of the midsagittal plane is essential for performing reliable symmetry analyses and guiding effective surgery planning. To provide a fully automatic and landmark-independent approach, capable of providing a midsagittal plane for craniofacial skeleton even from anatomical models with high asymmetries, an innovative method, called MaWR-method, was developed by the authors in a previous work. This paper further investigates the MaWR-method by evaluating its capacity to produce a successful outcome even in the worst-case scenario that may be considered in maxillofacial surgery, namely panfacial fractures. In all the test cases considered in this work, the method proved robust and reliable in its original design. It provided a consistent result requiring no user involvement, even when dealing with extreme asymmetries because of extensive and complex fractures.

Keywords: Feature recognition , Mid-sagittal plane , Symmetry analysis , Symmetry plane detection

In this paper, a semi-automatic procedure to perform point clouds registration is presented. The method was developed for upper limb 3D scanning. During the acquisition, several frames are acquired from different points of view, to obtain a full 360° acquisition of the arm. Each frame stores both the point clouds coordinates and the corresponding RGB image. During post-processing, the RGB image is elaborated through a neural network, to detect relevant key points of the hand, which are then projected to the point clouds. The corresponding key points detected from different acquisitions are then used to automatically obtain a rough 3D rotation that aligns the point clouds corresponding to different perspectives in a common reference frame. Finally, the registration is refined through an iterative closest point algorithm. The method was tested on actual arm acquisitions, and the registration results are compared with the conventional fully manual 3-2-1 registration procedure, showing promising results of the proposed method.

Keywords: Neural network , Semi-automatic registration , Upper limb 3D scan

The orbital walls and floor are common sites of facial bone fracture and may cause severe functional impairment. The complex geometry of the bony orbit makes anatomical reconstruction extremely challenging, with main issues related to the implant's correct shaping, positioning, and orientation inside the orbital cavity. This study proposes an innovative medical device to place patient-specific implants in fractured eye sockets properly. The device must be used with the developed improved version of a tailored implant shaping mould. The design of the orbital implant positioner followed specific clinical and technical requirements and specifications investigated through the Quality Function Deployment method. The device has been conceived to be simple, economical, capable of managing deantigenated bones or titanium meshes for orbital floor and wall, and reusable multiple times. The positioner consists of two handles hinged together and adequately coupled by a spring to allow the grasping and placing of the implant. Positioner and mould have been manufactured in polyamide using the Selective Laser Sintering technique. The system accuracy assessment resulted in promising outcomes. The mould can precisely shape the implant with a lower than 0.1 mm deviation. The implant positioner can place the implant with a rotation angle around the orbital rim of barely 7.1° and 1.2 mm deviation in the mediolateral direction (no deviations in the anteroposterior and superior-inferior directions occur)

Keywords: Computer-aided design , Craniomaxillofacial surgery , Implant design , Medical devices , Rapid prototyping

These authors presented an automatic computer-based method for morphological feature segmentation and recognition for thoracic and lumbar human vertebrae in a previous paper. The method analyses high-density discretized models by segmentation and recognition rules codifying the vertebra morphology information, which does not change between different subjects. The methodology has been demonstrated to be valid and repeatable in segmenting and recognizing morphological features of vertebrae. The proposed one gives repeatable and reproducible results concerning the traditional manual methods. Nonetheless, the method has been tested only on human lumbar and thoracic vertebrae without distinctive pathologies. This paper aims to extend this methodology for much wider use by analyzing single vertebrae affected by common defectiveness in archaeological and medical fields. The results of the experimentations, analyzed by a skilled anthropologist and radiologist, show that the method correctly segments the analyzed morphological features, also for thoracic and lumbar vertebrae with defectiveness: in particular, defects that alter the shape of features or the symmetry of the vertebra, determine the absence of a feature, or heavily change the spatial distribution of the anterior part respect to the posterior one, have been analyzed.

Keywords: 3D medical image analysis , Feature recognition , Thoracic and lumbar vertebrae analysis , Vertebrae analysis computer-based methods

In the field of medical image processing, the resolution capacity exhibited by the initial diagnostic investigations is becoming increasingly important. With respect to them, in fact, the row image set is subjected to three-dimensional reconstruction analysis, by partitioning the regions of interest, as well as to local investigations, aimed, for example, at the extrapolation of topological information, relating to the morphology of the object that needs to be investigated. The accuracy of these functions is, however, difficult to quantify, due to the lack of three-dimensional models that act as a reference Gold Standard. The reproduction of CT-type diagnostic acquisitions, starting from a virtual scanning procedure of a starting known three-dimensional geometry is used. To do this, triangular tessellated three-dimensional models of various geometries were examined. These were broken down into cubic elements, equal in size to those of a common voxel, thus resulting in a volume scan simulation of the original region considered. The structure thus obtained was then subjected to skeletonization and medial axis algorithms to evaluate the effectiveness of some of the most commonly used functions in medical processing. A virtual scanning model of this type can be an extremely effective evaluation analysis tool in discriminating the resolutive quality of the medical image processing functions. From a qualitative comparison of this type, it is possible to optimize automated anatomical investigation algorithms, making a significant contribution in the refinement of the techniques, now more and more demanding, of image processing in the biomedical field.

Keywords: Medical image acquisition , Thinning and Medial Axis , Voxelization

Anterior Cruciate Ligament (ACL) is one of the most injured ligaments. Various researches have studied the relationship between ACL rupture and the bony morphology attempting to understand why ACL rupture occurs. The most investigated predisposing factors in the scientific literature are mainly related to the femoral intercondylar notch and the tibial plateau. The aim of the present research is to create a semi-automatic tool for assessing the risk of developing an ACL injury. A package, named ACL Morsky, has been created in 3D Slicer to follow the entire workflow. The process starts with the load of DICOM data. Three-dimensional models are reconstructed by means of segmentation. Then, five parameters, considered risk factors for the ligament rupture, are measured both in 2D images and on 3D models. A specific algorithm compares the measured values with the range in literature to evaluate the probability of developing an ACL injury. The physician is provided with a report for the patient and his/her risk factors. Knowing in advance the risk of rupture can help in reducing it with preventive plans.

Keywords: 3D Slicer , Knee Injury , Knee Risk Assessment , Ligament Risk Factors , Morphological Parameters

The demand for orthodontic and aesthetic treatments, aimed at having healthier teeth and more beautiful smiles, is increasingly growing. The devices on which these treatments are based must be rigorously bespoke for each patient. This is amplifying the need to develop digitized workflows, ranging from scanning to Additive Manufacturing (AM). The present work proposes an alternative workflow for designing and manufacturing orthodontic aligners, also known as clear aligners, starting from the intraoral scanning of the patient's dentition. Orthodontic aligners are an alternative to metal brackets to correct dental malocclusions and they are often preferred by the patients because of their lower impact on facial aesthetics and for their higher comfort. The orthodontic treatments based on the aligners utilize a series of aligners, each one with a geometry slightly different from the previous one. The use of the single aligners is aimed to apply a force to the teeth and gradually aligning them until the end of the treatment. The workflow we propose in the present study is based on the following three main stages: intraoral scanning of the patient's dentition, design of the aligners through a semi-automatic algorithm, and the direct additive manufacturing of the aligners through VAT photopolymerization technique. The possibility to directly additive manufacturing the aligners allows us to rethink the current orthodontic treatments. The aligners geometry can be re-designed, with the possibility of locally manipulating the thickness. This approach would allow the regulation of the amount of force applied locally to the tooth, thus optimizing the treatment and its duration. A feasibility study of the proposed workflow is reported in the present paper, with a focus on the semi-automatic design algorithm and on the additive manufacturing process of the aligners.

Keywords: Additive Manufacturing , Bespoke Medical Devices , Dental Appliances , Design Algorithms for Medical Applications , DfAM

The human hand is a versatile and complex body part. It permits difficult movements with various degrees of precision and force. Several causes can lead to upper limb damage, including musculoskeletal disorders and diseases like stroke. The impairment can affect daily living activities. Patients usually undergo rehabilitation therapy with medical personnel for a long time after the traumatic event. In most cases, they use off-the-shelf medical devices. However, the shape of the upper limbs can differ a lot among people. A bespoke rehabilitative device could provide better comfort and usability, but the design process can be challenging. This work aims to present a digital workflow to generate a 3D virtual reconstruction of the patient's upper limb structure, to be used in the device design. Starting from a 3D scan acquisition of the patient's upper limb, the algorithm allows the creation of a polygonal mesh of the arm and the hand by a semi-automatic procedure. The algorithm uses neural networks' capability to automatically detect the upper limb's landmarks to localize the joints' coordinates. The joints' positions can be used to build a virtual skeleton for a 3D model of a human arm. The mesh of the model is subsequently wrapped around the scan of the real arm. The output consists in the 3D rigged model of the patient's upper limb with a manifold mesh that can be deformed using its virtual skeleton. The results have been assessed with patients who had sports injuries or strokes. The 3D deviations between the scan acquisition of the arm and the resulting model have been evaluated.

Keywords: 3D scan , 3D virtual reconstruction , automatic landmarks detection , neural network , upper limb rigged model

In the field of optical 3D scanning for healthcare applications, low-cost depth cameras can be efficiently used to capture geometry at video frame rates. However, the complete reconstruction of anatomical geometries remains challenging since different scans, collected from multiple viewpoints, must be aligned into a common reference frame. This paper proposes a fully automatic procedure to align scans of the upper limb patient's anatomy. A 3D optical scanner, obtained by assembling three depth cameras, is used to collect upper limb acquisitions. A relevant dataset of key points on the hand and the forearm geometry is then determined and used to automatically obtain a rough 3D alignment of the different scans. Hand key points are identified through a neural network, which works on RGB images captured by the depth cameras; forearm key points are recognized by directly processing the point clouds through a specifically designed algorithm that evaluates the skeleton line of the forearm. The approach was tested on forearm acquisitions, and the results were compared to alternative alignment methodologies.

Keywords: 3D optical scanning , automatic point clouds alignment , depth cameras , upper limb anatomy

The treatment of burn scars is a much discussed and sensitive topic because an improper therapy can have a significant impact on the quality of people's lives. To accurately assess both the health of scars and the outcomes of treatment, the medical evaluation should be based on objective measurements of progression over time. To overcome the limitations of subjective assessment is to leverage, 3D scanning technologies can be used to acquire topological information about the lesions and extract a set of relevant statistical parameters describing them. Accordingly, the present work aims at addressing both efficiency and reliability of a preliminary method based on the objective investigation of the surface topography of burn scars by applying it on several patients of the Meyer Children's Hospital burns department. A commercial 3D scanner is used to acquire 3D data relative to the scars of five patients. By applying a method based on the computational analysis of scan data, a significant number of roughness-related parameters are retrieved. This information is used to create a coherent dataset that allows the severity of burn scars to be inferred objectively. The developed method facilitates the evaluation of treatment efficacy by assessing wound healing during follow-up visits.

Keywords: 3D scan , Burn scar , Surface roughness

During the last decades, metal-based biomaterials have been extensively explored to be used as biocompatible metals for biomedical applications, owing to their superior mechanical properties and corrosion resistance. Consequently, for long-term implanted medical devices, to assure the biomaterials' reliability, functionality, and biocompatibility, studying the various bio-tribological damage mechanisms to obtain the optimum properties is one of the most important goals. In this review, we consider the most important metal-based biomaterials such as stainless steel, alloys of titanium (Ti), cobalt-chromium (Co-Cr), and Nichel-Titatium (Ni-Ti), as well Magnesium (Mg) alloys and with Tantalum (Ta), emphasizing their characteristics, clinical applications, and deterioration over time. The influence of metal elements on biological safety, including significant effects of metal-based biomaterials in dentistry were discussed, considering the perspectives of surface, mechanical properties, corrosion behaviors, including interactions, bio-mechanisms with tissues, and oral environments. In addition, the role of the oral microbiota was explored due to its role in this erosion condition, in order to further understand the mechanism of metal-based biomaterials implanted on the microflora balance of aerobic and anaerobic bacteria in an oral environment.

Keywords: biochemistry , biomedical applications , biotribology , immunity , metal-based biomaterials , microbiology , oral implants , oral microbiota , toxicology

Analyzing pathological movements can substantially help neurologists in the diagnosis and treatment improvement for patients with Parkinson's disease (PD). A linkage between the intensity and characteristics of moving and walking disorders and the stage and types of PD can be actually established. The main aim of this study is to develop an effective methodology that allows to evaluate, in real time and / or in deferred time, movements and posture of PD patients in their usual living environments. For this purpose, a wearable suit with Inertial Measurement Unit (IMU) sensors was designed; it has made it possible to acquire linear and angular signals of displacement, velocity and acceleration of the most relevant body points of the patients. The filtered and integrated signals were then used to animate a human parametric multibody model that virtually reproduces in real time and / or in deferred patient's movements and posture. Serving as the patient's “avatar”, the multibody model enables the neurologist to carry out an accurate assessment of the patient's movements and posture (freezing, festination, postural balance) as well as to measure disease progression and response to interventions. If compared to traditional 3D video-based motion analysis systems, the proposed method has the advantage of providing a more accurately measurable patients movements analysis and comparison performed in their usual living environments in real-world conditions.

Keywords: 3D posture analysis , Human parametric multibody model , Inertial Measurement Unit sensors , Motion recognition algorithms , Parkinson's disease movements

Finite element modelling of the lumbar spine is a challenging problem. Lower back pain is among the most common pathologies in the global populations, owing to which the patient may need to undergo surgery. The latter may differ in nature and complexity because of spinal disease and patient contraindications (i.e., aging). Today, the understanding of spinal column biomechanics may lead to better comprehension of the disease progression as well as to the development of innovative therapeutic strategies. Better insight into the spine's biomechanics would certainly guarantee an evolution of current device-based treatments. In this setting, the computational approach appears to be a remarkable tool for simulating physiological and pathological spinal conditions, as well as for various aspects of surgery. Patient-specific computational simulations are constantly evolving, and require a number of validation and verification challenges to be overcome before they can achieve true and accurate results. The aim of the present schematic review is to provide an overview of the evolution and recent advances involved in computational finite element modelling (FEM) of spinal biomechanics and of the fundamental knowledge necessary to develop the best modeling approach in terms of trustworthiness and reliability.

Keywords: biomechanics , computational simulations , finite element analysis , lumbar spine , modelling , spinal column

Nowadays the rehabilitation process involves the patient and the therapist, that must interact to recover the motion of limbs and the strength of related muscles to restore the initial functionalities. The therapy relies on the experience and sensitivity of the therapist that identifies the rehabilitation exercises which are necessary to recover the expected ability. To prevent inappropriate practices an interesting aid may come by mixing collaborative robots, namely Cobots, and additive manufacturing technologies. The proper integration of a Cobot assistant and custom-printed training objects enables a significant improvement in the effectiveness of the therapy action and the related user experience since the programmed trajectories can mimic the movements related to activities of daily living. To this aim, this work describes an integrated approach to support the design of Cobot assisted rehabilitative solutions. The object selected by the patient and therapist, the motion pattern, the clamping area, and loads on the limb represents the design requirements. The motion trajectories defining the specific training tasks are the starting point to the optimal placement within the Cobot workspace. Specifically, manipulability maps can provide an objective evaluation of the locations where the exercises are performed at the best of workspace and configuration of the Cobot. A simple upper limb rehabilitation exercise based on a demonstrative handle has been selected to prove the effectiveness of the proposed approach. The results confirm that the manipulability index can be adopted to drive the preliminary design of the Cobotic solution toward a feasible configuration.

Keywords: Assisted Rehabilitation , Cobot , Integrated Design , Manipulability Index , Occupational Therapy