Alireza Nouri

Background: Finger orthoses are essential for treating injuries, deformities, and disorders of the upper limbs by supporting, immobilizing, or correcting deformities. Recent advances in three-dimensional (3D) printing have significantly enhanced precision and customization compared to traditional fabrication methods such as thermoplastic molding, plaster or fiberglass casting, and the use of prefabricated splints. Methods: The present review was conducted using PubMed, Scopus, and other databases with keywords such as “hand therapy”, “additive manufacturing”, “finger and thumb”, and “orthosis”. Only English-language publications were considered, with a primary focus on articles published between 2010 and 2025. Key themes were identified and categorized into conditions necessitating finger orthoses, types and classifications, ergonomic design considerations, and advancements in additive manufacturing. Results: Finger orthoses address musculoskeletal injuries, inflammatory diseases, and neuromuscular disorders. Three-dimensional printing provides enhanced customization, reduced material waste, rapid prototyping, and the ability to create complex geometries, improving patient comfort and functionality. Conclusions: Finger orthoses effectively treat various conditions by supporting and stabilizing fingers. A thorough understanding of anatomy, biomechanics, and fabrication methods is crucial for achieving functional and comfortable designs. Three-dimensional printing offers a transformative approach to producing lightweight, customizable, and cost-effective orthoses, enabling innovative and personalized solutions. By bridging clinical needs and design strategies, this review may guide future innovations in patient-specific orthotic development.

Bone scaffolds serve a crucial role in tissue engineering, particularly in facilitating bone regeneration where natural repair is insufficient. Despite advancements in the fabrication of polymeric bone scaffolds, the challenge remains to optimize their mechanical resilience. Specifically, research on the fatigue behaviour of polymeric bone scaffolds is scarce. This study investigates the influence of pore architecture on the mechanical performance of poly-lactic-acid (PLA) scaffolds under quasi-static and cyclic compression. PLA scaffolds with a 60% porosity were fabricated using extrusion-based 3D printing in various designs: Gyroid, Lidinoid, Fischer–Koch, IWP, and Voronoi. Results demonstrated that Gyroid scaffolds had the highest compressive strength (6.6 MPa), followed by Lidinoid, Fischer–Koch, IWP, and Voronoi designs. Increased strut thickness was linked to higher compressive strength. However, normalized fatigue resistance showed a different pattern. While scaffolds resisted fatigue cycles at low strain amplitudes, fatigue damage was observed at higher strains. Voronoi structures exhibited the highest normalized fatigue performance, enduring around 58,000 cycles at 85% strain amplitude, followed by Gyroid, Fischer–Koch, Lidinoid, and IWP structures. Enhanced fatigue performance in different topologies correlated with the minimum cross-sectional area of scaffolds. Given the importance of both static and fatigue strength, the Gyroid topology emerges as the superior choice overall.

Ankle–foot orthoses (AFOs) assist patients with gait impairment by correcting ankle and foot deformities, restoring mobility, reducing pain, and providing protection and immobilization. AFOs can effectively manage various types of gait pathologies, including foot drop, crouch gait, equinus gait, and stiff knee gait. AFOs are available in prefabricated or custom‐made forms in various designs. The selection criteria for the fabrication of an AFO are the duration of usage, the amount of applied force, the degree of axial loading, the patient's skin condition, and the cost. The accessibility of diverse materials in the last century has significantly improved orthoses. Ideal orthotic materials must be light, stiff, and strong, and can be made of plastics, metals, polymer‐based composites, leather, or a hybrid of different materials. A deeper understanding of the materials employed in the fabrication of AFOs holds the potential for more advanced and efficient orthoses, which can improve patients’ ability to ambulate in the real world. The present review provides insight into the various materials utilized for the fabrication of AFOs and describes the benefits and challenges associated with the materials. An attempt has also been made to highlight typical gait pathologies and design concepts in response to them.

Metal additive manufacturing (AM) is an innovative manufacturing technique that can build complex and high value metal parts layer by layer using a computerized three‐dimensional solid model. Powder bed fusion (PBF) is one of the most common AM techniques. It sequentially processes a powdered feedstock in thin layers and solidifies it by either a laser beam or an electron beam. However, PBF induces microstructural defects that can adversely affect the performance of the manufactured components. These undesirable defects including voids and porosities must be avoided or minimized to limit their negative effects on mechanical properties and to ensure the consistency and repeatability of AM parts. The present article provides an overview of the formation mechanisms of pores in AM metals and some emerging techniques for the detection and quantification of pores. The review also highlights other common defects in PBF parts such as microstructural features associated with keyhole mode of melting.

Thermal spraying (TS) is a suitable method to protect a substrate or to improve its surface properties and achieve the specific surface requirements for a prescribed service environment. In this method the feedstock material is heated up to a melted or semi‐melted state, accelerated to high speed by an energetic flow and sprayed onto a prepared substrate. Powders are the most commonly used feedstock materials in the TS process. Their composition, size distribution, morphology, physical and mechanical properties determine the coating microstructure and related thermo‐mechanical performance. Among other variables, powder morphology plays a fundamental role to ensure the consistency and reproducibility of the feeding mechanism, to control the interaction between feedstock particles and TS heat source, and to influence the microstructure of the coating. This review highlights the crucial function of powder morphology in TS and proposes introductory information on the importance of powder morphology in cold spraying.