In Fused Deposition Modeling (FDM), which is a common thermoplastic Additive Manufacturing (AM) method, the polymer model material that is in the form of a flexible filament is heated above its glass transition temperature (T_g) to a semi-molten state in the head’s liquefier. The heated material is extruded in a rastering configuration onto the building platform where it rapidly cools and solidifies with the adjoining material. The heating and rapid cooling cycles of the work materials exhibited during the FDM process provoke non-uniform thermal gradients and cause stress build-up that consequently result in part distortions, dimensional inaccuracy and even possible part fabrication failure. Within the purpose of optimizing the FDM technique by eliminating the presence of such undesirable effects, real-time monitoring is essential for the evaluation and control of the final parts’ quality. The present work investigates the temperature distributions developed during the FDM building process of multilayered thin plates and on this basis a numerical study is also presented. The recordings of temperature changes were achieved by embedding temperature measuring sensors at various locations into the middle-plane of the printed structures. The experimental results, mapping the temperature variations within the samples, were compared to the corresponding ones obtained by finite element modeling, exhibiting good correlation.

This work aims at the determination of the coefficient of thermal expansion (CTE) of parts manufactured through the Fused Deposition Modeling process, employing fiber Bragg grating (FBG) sensors. Pure thermoplastic and composite specimens were built using different commercially available filament materials, including acrylonitrile butadiene styrene, polylactic acid, polyamide, polyether-block-amide (PEBA) and chopped carbon fiber-reinforced polyamide (CF-PA) composite. During the building process, the FBGs were embedded into the middle-plane of the test specimens, featuring 0° and 90° raster printing orientations. The samples were then subjected to thermal loading for measuring the thermally induced strains as a function of applied temperature and, consequently, the test samples’ CTE and glass transition temperature (T_g) based on the recorded FBG wavelengths. Additionally, the integrated FBGs were used for the characterization of the residual strain magnitudes both at the end of the 3D printing process and at the end of each of the two consecutively applied thermal cycles. The results indicate that, among all tested materials, the CF-PA/0° specimens exhibited the lowest CTE value of 14 × 10⁻⁶/°C. The PEBA material was proven to have the most isotropic thermal response for both examined raster orientations, 0° and 90°, with CTE values of 117 × 10⁻⁶/°C and 108 × 10⁻⁶/°C, respectively, while similar residual strains were also calculated in both printing orientations. It is presented that the followed FBG-based methodology is proven to be an excellent alternative experimental technique for the CTE characterization of materials used in 3D printing.

Customized wrist splints, particularly for upper extremity orthoses like wrist support braces, are commonly used across numerous clinical scenarios. However, the traditional process for producing personalized wrist splints is largely manual and highly dependent on the expertise of orthopedic specialists. This experience-based approach often leads to suboptimal outcomes, necessitating further refinement of the designs. Recent advancements in Additive Manufacturing (AM) have brought significant innovation to various industries, including orthopedics. This study aims to present a comprehensive methodology that integrates advanced design tools, like 3D Scanning, with digital manufacturing techniques to produce tailored wrist splints. The produced hand brace aims to offer enhanced mechanical performance and comfort by precisely fitting an individual’s anatomy while minimizing material usage and weight. To achieve optimal design efficiency, the study explores the application of a topology optimization (TO) approach for design, while the manufacturing process utilizes Fused Deposition Modeling (FDM), an evolving technology within the additive manufacturing (AM) sector.

Purpose: Total hip arthroplasty is among the most successful orthopedic procedures; however, approximately 10%–20% of patients require revision surgery within 15–20 years. Potential failure mechanisms at the bone–implant interface include stress shielding and excessive micromotion. This experimental work aims at examining the optimal ratio of femur length and stem length with respect to primary stability and stress shielding effect, employing a validated finite element analysis. Methods: One hundred human femora were reconstructed from computed tomography (CT) scans, and for each femur, 13 personalized cementless stems were designed with varying lengths (70–130 mm, in 5 mm increments), resulting in 1300 finite element models. Each model was analyzed under standardized joint and muscle loading conditions. The model was validated experimentally after cadaveric implantation with digital image correlation (DIC) under static loading. Primary outcomes included micromotion at the bone–implant interface and proximal stress shielding. Optimal stem length was determined as the ratio of stem‐to‐femur length that minimized the combined normalized scores of micromotion and stress shielding. The effect of stem‐to‐femur length ratio was analysed with linear regression. Results: The analysis revealed a correlation between femoral length and stem length. Longer stems provided better initial stability and reduced micromotion. On the other hand, shorter stems demonstrated less proximal stress shielding and a better stress distribution resembling that of the intact femur. The optimal stem length was found to be 18.5% ± 2.7% (mean ± SD) of the femur length in terms of the mean of calculated micromotions and stress shielding, indicating that personalized stem length selection can enhance the bone–implant osseointegration. Conclusion: The selection of a stem length that corresponds proportionally to femoral length can improve primary stability and stress shielding upon implantation, highlighting the importance of enhancing initial fixation in order to extend the lifespan of hip replacements. Level of Evidence: N/A.

Customized wrist splints, particularly for upper extremity orthoses like wrist support braces, are commonly used across numerous clinical scenarios. However, the traditional process for producing personalized wrist splints is largely manual and highly dependent on the expertise of orthopedic specialists. This experience-based approach often leads to suboptimal outcomes, necessitating further refinement of the designs. Recent advancements in Additive Manufacturing (AM) have brought significant innovation to various industries, including orthopedics. This study aims to present a comprehensive methodology that integrates advanced design tools ,like 3D Scanning, with digital manufacturing techniques to produce tailored wrist splints. The produced hand brace aims to offer enhanced mechanical performance and comfort by precisely fitting an individual’s anatomy while minimizing material usage and weight. To achieve optimal design efficiency, the study explores the application of a Topology Optimization (TO) approach for design, while the manufacturing process utilizes Fused Deposition Modeling (FDM), an evolving technology within the Additive Manufacturing (AM) sector.

This article presents the design, construction, and validation of an open-source apparatus for biomechanical testing of hip implants. The device enables controlled axial loading of implant constructs, addressing common limitations in terms of cost, complexity, and adaptability. The design emphasizes reproducibility, using widely available components and specimen-specific 3D-printed alignment tools, while ensuring high accuracy in load application and displacement measurement. The apparatus replicates physiological stance-phase loading (1.00× body weight (BW) axial, ~1.55× BW abductor, ~2.47× BW joint compression forces). The displacement values obtained by the validated finite element model and the Digital Image Correlation (DIC) technique on cadaveric specimens were compared and a mean displacement difference of 0.17 mm ± 0.09 mm was observed. Detailed build instructions and step-by-step operating protocols are provided, along with access to open-source CAD files. This work aims to facilitate broader access to customized biomechanical testing solutions for orthopedic research and education.