Search Results (118)

This study presents the design, fabrication, and clinical validation of a lightweight, body-powered prosthetic index finger actuated via metacarpophalangeal (MCP) joint motion. The proposed system incorporates an underactuated, cable-driven mechanism combining rigid and compliant elements to achieve passive adaptability and embodied intelligence, supporting intuitive user interaction. Results indicate that the prosthesis successfully mimics natural finger flexion and adapts effectively to a variety of grasping tasks with minimal effort. This study was conducted in accordance with ethical standards and approved by the Institutional Review Board (IRB), Project No. 670161, titled “Biologically-Inspired Synthetic Finger: Design, Fabrication, and Application.” The findings suggest that the device offers a viable and practical solution for individuals with partial hand loss, particularly in settings where electrically powered systems are unsuitable or inaccessible. Full article

The research presented in this paper focuses on the utilization of 3D printing technology in the design and manufacture of a prosthetic hand, equipped with a digit replicator. The subject of this study was a young man who had undergone the amputation of two fingers on his right hand. The electronic control of the movement of the finger copy was developed using Arduino language. A concept and outline drawings were developed in ProCreate. Three-dimensional scan of the hand and forearm was made using an EinScan PRO HD SHINING 3D scanner. Using CAD software—Autodesk Inventor and Autodesk Meshmixer, the prosthesis was designed. Printing was carried out on a 3D printer of the i3 MK3 and MK3+ series using a PLA (polylactic acid) filament. It was determined that PLA is an optimal material for printing, as it is considered to be safe for future patients’ skin. Work on the electronic circuitry started in Autodesk TinkerCad simulation software, allowing the code to be verified and ensuring the safety of the control system. The prosthesis’s design demonstrates the potential to reach as many people in need as possible by using readily available, low-cost, and easy-to-use components. Full article

Sonomyography (SMG) is a method of controlling upper-limb prostheses through an innovative human–machine interface by monitoring forearm muscle activity through ultrasonic imaging. Over the past two decades, SMG has shown promise, achieving over 90% accuracy in classifying hand gestures when combined with artificial intelligence, making it a viable alternative to electromyography (EMG). However, up to now, there are few reports of a system integrating SMG together with a prosthesis for testing on amputee subjects to demonstrate its capability in relation to daily activities. In this study, we developed a highly efficient human–machine interface algorithm for controlling a prosthetic hand with 6-DOF using a wireless and wearable ultrasound imaging probe. We first evaluated the accuracy of our model in classifying nine different hand gestures to determine its reliability and precision. The results from the offline study, which included ten healthy participants, indicated that nine different hand gestures could be classified with a success rate of 100%. Additionally, the developed controlling system was tested in real-time experiments on two amputees, using a variety of hand function test kits. The results from the hand function tests confirmed that the prosthesis, controlled by the SMG system, could assist amputees in performing a variety of hand movements needed in daily activities. Full article

Hands are central to nearly every aspect of daily life, so losing an upper limb due to amputation can severely affect a person’s independence. Robotic prostheses offer a promising solution by mimicking many of the functions of a natural arm, leading to an increasing need for advanced prosthetic designs. However, developing an effective robotic hand prosthesis is far from straightforward. It involves several critical steps, including creating accurate models, choosing materials that balance biocompatibility with durability, integrating electronic and sensory components, and perfecting control systems before final production. A key factor in ensuring smooth, natural movements lies in the method of control. One popular approach is to use electromyography (EMG), which relies on electrical signals from the user’s remaining muscle activity to direct the prosthesis. By decoding these signals, we can predict the intended hand and arm motions and translate them into real-time actions. Recent strides in machine learning have made EMG-based control more adaptable, offering users a more intuitive experience. Alongside this, researchers are exploring tactile sensors for enhanced feedback, materials resilient in harsh conditions, and mechanical designs that better replicate the intricacies of a biological limb. This review brings together these advancements, focusing on emerging trends and future directions in robotic upper-limb prosthesis development. Full article

Integrating bioinspired design and additive manufacturing into engineering education fosters innovation to meet the growing demand for accessible, personalized assistive technologies. This paper presents the outcomes of an international course, “3D Prosthetics and Orthotics”, offered to undergraduate students in the Biomimetic program at Westfälische Hochschule (Germany), in collaboration with the 3D Orthotics and Prosthetics Laboratory at the Federal University of São Paulo—UNIFESP (Brazil). The course combined theoretical and hands-on modules covering digital modeling (CAD), simulation (CAE), and fabrication (CAM), enabling students to develop bioinspired assistive devices through a Project-based learning approach. Working in interdisciplinary teams, students addressed real-world rehabilitation challenges by translating biological mechanisms into engineered solutions using additive manufacturing. Resulting prototypes included a hand prosthesis based on the Fin Ray effect, a modular finger prosthesis inspired by tendon–muscle antagonism, and a cervical orthosis designed based on stingray morphology. Each device was digitally modeled, mechanically analyzed, and physically fabricated using open-source and low-cost methods. This initiative illustrates how biomimetic mechanisms and design can be integrated into education to generate functional outcomes and socially impactful health technologies. Grounded in the Mao3D open-source methodology, this experience demonstrates the value of combining nature-inspired principles, digital fabrication, Design Thinking, and international collaboration to advance inclusive, low-cost innovations in assistive technology. Full article

Background: Trapeziometacarpal (TM) joint arthritis is a common condition causing pain and functional limitations, particularly in activities requiring pinch and grip strength. Surgical options such as interposition trapeziectomy and prosthetic joint replacement have demonstrated varying degrees of success. However, the role of post-operative rehabilitation in optimizing outcomes for these procedures remains underexplored. Effective rehabilitation may be critical for restoring strength, range of motion (ROM), and overall hand function; yet, no consensus exists on the best approach for either surgical modality. This study aims to evaluate the impact of post-operative rehabilitation on functional and clinical outcomes in patients undergoing interposition trapeziectomy versus prosthetic replacement for TM joint arthritis. Methods: A retrospective cohort study was conducted on patients treated for TM joint arthritis between November 2023 and October 2024. Patients were divided into two groups based on the surgical procedure: interposition trapeziectomy and prosthetic replacement. Patients randomly followed post-operative rehabilitation protocols, auto-assisted exercises, or no type of rehabilitation. The outcomes assessed included pain (VAS), return to work or heavy activities, post-operative complications, hand function (DASH score), and patient satisfaction at 1 and 6 months after surgery. Results: The prosthesis group consisted of 30 patients, while 31 patients underwent interposition trapeziectomy. Patients in both groups showed good improvements in pain, ROM, and hand function post rehabilitation. The prosthetic group demonstrated a faster recovery of strength and higher early satisfaction scores, but in the long term, the results were overlapping. No significant differences were observed in long-term functional outcomes or patient satisfaction at 6 months. In the trapeziectomy group, for patients who followed a rehabilitation program, no significant differences were found. Conclusions: Post-operative rehabilitation finds its place in recovery after both interposition trapeziectomy and prosthetic replacement for TM joint arthritis. While prosthetic replacement allows for quicker functional recovery, interposition trapeziectomy offers comparable long-term results with a lower complication profile. Tailored rehabilitation protocols may enhance outcomes and should be considered an integral part of TM joint arthritis management in selected patients. Full article

A multitude of factors, including accidents, chronic illnesses, and conflicts, contribute to rising global amputation rates. The World Health Organization (WHO) estimates that 57.7 million people lived with traumatic limb amputations in 2017, with many lacking access to affordable prostheses. This study presents a preliminary framework for a low-cost, electromyography (EMG)-controlled upper limb prosthesis, integrating 3D printing and EMG sensors to enhance accessibility and functionality. Surface electrodes capture bioelectric signals from muscle contractions, processed via an Arduino Uno to actuate a one-degree-of-freedom (1-DoF) prosthetic hand. Preliminary results demonstrate reliable detection of muscle contractions (threshold = 7 ADC units, ~34 mV) and motor actuation with a response time of ~150 ms, offering a cost-effective alternative to commercial systems. While limited to basic movements, this design lays the groundwork for scalable, user-centered prosthetics. Future work will incorporate multi-DoF control, AI-driven signal processing, and wireless connectivity to improve precision and usability, advancing rehabilitation technology for amputees in resource-limited settings. Full article

Upper limb prostheses face acceptance challenges due to factors such as discomfort, limited functionality, high weight, and elevated costs. Despite the availability of advanced models with sophisticated technologies, their accessibility remains limited to individuals with greater financial means. This study presents the development of a parametric hand prosthesis designed for total or partial amputations, utilizing additive manufacturing and affordable hypoallergenic materials. The parametrization was based on customized anthropometric geometries, modeled using CAD software, with structural validation conducted through finite element analysis under static forces. The printing material was characterized according to ASTM D638 standards. The results indicate that the prosthesis provides a personalized, functional, and accessible solution that meets the specific needs of users. It is concluded that the use of additive manufacturing and parametric design not only reduces costs and improves accessibility but also enables the creation of devices tailored to individual user characteristics, promoting greater functionality and quality of life. Full article

To improve the adaptability of the hand prosthesis, we propose a new smart control for a physiological finger prosthesis using the advantages of the deep deterministic policy gradient (DDPG) algorithm. A rigid body model was developed to represent the finger as a training environment. The geometric characteristics and physiological physical properties of the finger available in the literature were assumed, but the joint’s stiffness and damping were neglected. The standard DDPG algorithm was modified to train an artificial neural network (ANN) to perform two predetermined trajectories: linear and sinusoidal. The ANN was evaluated through the use of a computational model that simulated the functionality of the finger prosthesis. The model demonstrated the capacity to successfully execute both sinusoidal and linear trajectories, exhibiting a mean error of $3.984\pm 2.899$ mm for the sinusoidal trajectory and $3.220\pm 1.419$ mm for the linear trajectory. Observing the torques, it was found that the ANN used different strategies to control the movement in order to adapt to the different trajectories. Allowing the ANN to use a combination of both trajectories, our model was able to perform trajectories that differed from purely linear and sinusoidal, showing its ability to adapt to the movement of the physiological finger. The results showed that it was possible to develop a controller for multiple trajectories, which is essential to provide more integrated and personalized prostheses. Full article

Trapeziometacarpal joint osteoarthritis (TMJ OA) is a progressive condition, particularly affecting postmenopausal women. Various surgical techniques have been proposed, but the optimal approach remains debated. This clinical study compares the clinical, functional, and radiological outcomes of two surgical treatments: suspension tenoplasty using the flexor carpi radialis tendon (Altissimi technique, AST) and a dual-mobility prosthesis. The main complications associated with these procedures include postoperative pain, De Quervain’s syndrome, radial nerve injuries, and prosthetic component mobilization. In prosthetic arthroplasty, the most common complication is component mobilization (8%), while in tenoplasty, postoperative pain is the most frequent (15%). A total of 36 patients were randomized into two groups: 18 patients underwent AST (Group A), and 18 received trapeziometacarpal joint arthroplasty (Group B). Functional outcomes were assessed using the Disabilities of the Arm, Shoulder and Hand (DASH), Visual Analogue Score (VAS), and Michigan Hand Outcomes Questionnaire (MHQ) at 3, 6, 12, and 24 months. Range of motion (ROM), Kapandji score, pulp pinch strength, hand grip strength (Jamar dynamometer), and radiological maintenance of the trapezial space (step-off measurement) were also evaluated. Both procedures resulted in significant pain reduction (VAS, p < 0.05) and functional improvement (DASH, MHQ, p < 0.05). ROM increased significantly in both groups. The Kapandji scores improved from 4.0 ± 1.1 to 9.2 ± 1.2 (Group A) and 4.3 ± 0.8 to 7.8 ± 1.4 (Group B) (p < 0.05). Group B grip strength results showed a greater increase in hand grip strength than Group A (p = 0.23). The radiographic step-off showed slight proximal migration of the first metacarpal in Group A, whereas Group B maintained joint height. No implant loosening or major complications were reported in either group. Both suspension tenoplasty and dual-mobility arthroplasty are effective in TMJ OA. AST ensures joint stability with minimal radiographic changes, whereas TJA provides superior grip strength and ROM recovery. The absence of major complications suggests that TJA is a safe alternative to AST, but its higher cost and potential for implant-related complications must be considered. Full article

Background/Objectives: Individuals with transradial limb loss or absence often retain the ability to pro-supinate their forearm, but the traditional design of the prosthesis precludes this motion from being used for direct prosthesis control. Methods: A prosthetic arm was created for a single user that employed a novel split inner socket to allow pro-supination of the residuum to control a powered prosthetic wrist rotator. A total of 14 subjects (13 able-bodied subjects and one prosthesis user) performed the Refined Clothespin Relocation Test. The user performed the test with their own and a novel research prosthesis, which allowed independent hand and wrist function. Movements of limb segments were recorded using a motion capture system and an analysis of limb segment angles and compensatory motion was made. Results: The research prosthesis reduced compensation in the trunk and head and reduced pain in some joints, while the time to complete the test increased. Conclusions: This method has the potential to create additional intuitive control channels for transradial prostheses. Full article

Background/Objectives: Various surgical methods have been proposed for the treatment of comminuted Mason III/IV radial head fractures. In particular, the advantages and disadvantages between prosthesis implantation (RHA) or radial head resection (RHR) are not sufficiently quantified in the current literature. Methods: A systematic literature search was conducted using PubMed Web of Science, Cochrane Library, and Embase in February 2024. Studies conducted on patients with Mason type III or IV radial head fractures and studies relating to surgical methods, including radial head resection or Radial head prosthesis implantation, were included. The two methods were evaluated in terms of clinical and functional results through the DASH score (Disability of the arm, shoulder, and hand), Mayo Elbow Performance Index (MEPI), and flexion-extension range of motion. The onset of osteoarthritis and complications were also assessed. Risk of bias and quality of evidence were assessed using Cochrane guidelines. Results: A total of 345 articles were evaluated and, of these, 21 were included in the study for a total of 552 patients. The results of the meta-analysis showed no significant differences in favor of RHA or RHR in terms of Mayo Elbow Performance (p = 0.58), degrees of flexion (p = 0.689), degrees of extension deficit (p = 0.697), and overall incidence of complications (p = 0.389), while it highlighted a statistically significant difference in terms of DASH score (19.2 vs. 16.2, respectively; p = 0.008) and subjects who developed osteoarthritis (13.4% vs. 47.3%, respectively; p = 0.046). Conclusions: The results of this meta-analysis confirm that both surgical methods provide good functional outcomes, with no significant differences in MEPI, DASH, and range of motion. However, a higher incidence of post-traumatic osteoarthritis was observed in patients undergoing RHR. Additionally, RHR patients exhibited slightly worse functional outcomes in the DASH score; however, this difference is not substantial enough to be considered clinically significant. These findings suggest that while both techniques are viable, RHA may be preferable in patients at higher risk of joint degeneration and instability, and the choice of treatment should be tailored to individual patient characteristics. Full article

Background/Objectives: The subject of this work is the reconstruction of the inner mechanics of Götz von Berlichingen’s second iron hand. The complex inner mechanics were unknown until Christian von Mechel published a detailed description in 1815. In this artificial hand, each finger can be engaged individually in its three joints and the thumb in one joint. Methods: Based on this description, the individual components were reconstructed at an enlarged scale of 2:1 using computer-aided design (CAD) software and a three-dimensional (3D) printer for the mechanisms. In addition, a finite element method (FEM) analysis was carried out for the components exposed to the greatest stress in order to identify critical areas. Results: By making some adjustments to the mechanics, it was possible to reproduce the mechanisms on a scale of 2:1 on the basis of the index finger. However, when the model was rescaled to 1:1, the internal plastic components were too fragile. This problem was caused by the properties of the 3D printing materials and could be solved by manufacturing the springs from steel. Conclusions: This work aims to make a valuable contribution to the preservation and understanding of the historical artificial second iron hand of Götz von Berlichingen. It once again demonstrates the very precise and detailed craftsmanship of goldsmiths of that time. Full article

A significant number of people with disabilities rely on assistive devices, yet these technologies often face limitations, including restricted functionality, inadequate user-centered design, and a lack of standardized evaluation metrics. While upper-limb prosthetics remain a key research focus, existing commercial solutions still fall short of meeting daily reliability and usability needs, leading to high abandonment rates. CYBATHLON integrates assistive technologies into daily living tasks, driving innovation and prioritizing user needs. In CYBATHLON 2024, the HANDSON hand secured first place in the arm prosthesis race, showcasing breakthroughs in human–robot integration. This paper presents the HANDSON hand’s design, core technologies, training strategies, and competition performance, offering insights for advancing multifunctional prosthetic hands to tackle real-world challenges. Full article