This paper investigates the impact of several factors related to manufacturing, design, and post-processing on the dimensional accuracy of holes built in the additively manufactured parts obtained by material extrusion process (MEX). Directly fabricated holes in the 3D prints are commonly used for joining with other parts by means of mechanical fasteners, thus producing assemblies or larger parts, or have other functional purposes such as guiding the drill in the case of patient-personalized surgical guides. However, despite their spread use and importance, the relationship between the 3D-printed holes’ accuracy and printing settings is not well documented in the literature. Therefore, in this research, test parts were manufactured by varying the number of shells, printing speed, layer thickness, and axis orientation angles for evaluating their effect on the dimensional accuracy of holes of different diameters. In the same context of limited existing information, the influence of material, 3D printer, and slicing software is also investigated for determining the dimensional accuracy of hole-type features across different manufacturing sites, a highly relevant aspect when using MEX to produce spare or end-use parts in a delocalized production paradigm. The results of this study indicated that the layer thickness is the most relevant influence factor for the diameter accuracy, followed by the number of shells around the holes. Considering the tested values, the optimal set of values found as optimizing the accuracy and printing time was 0.2 mm layer thickness, two shells, and 50 mm/s printing speed for the straight holes. Data on the prints manufactured on different MEX equipment and slicers indicated no statistically significant difference between the diameters of the holes. The evaluation of 3D-printed polylactic acid test parts mimicking a surgical template device with inclined holes showed that the medical decontamination process had more impact on the holes’ dimensional variability than on their dimensional accuracy.

Additively manufactured wrist–hand orthoses (3DP-WHOs) offer several advantages over traditional splints and casts, but their development based on a patient’s 3D scans currently requires advanced engineering skills, while also recording long manufacturing times as they are commonly built in a vertical position. A proposed alternative involves 3D printing the orthoses as a flat model base and then thermoforming them to fit the patient’s forearm. This manufacturing approach is faster, cost-effective and allows easier integration of flexible sensors as an example. However, it is unknown whether these flat-shaped 3DP-WHOs offer similar mechanical resistance as the 3D-printed hand-shaped orthoses, with a lack of research in this area being revealed by the literature review. To evaluate the mechanical properties of 3DP-WHOs produced using the two approaches, three-point bending tests and flexural fatigue tests were conducted. The results showed that both types of orthoses had similar stiffness up to 50 N, but the vertically built orthoses failed at a maximum load of 120 N, while the thermoformed orthoses could withstand up to 300 N with no damages observed. The integrity of the thermoformed orthoses was maintained after 2000 cycles at 0.5 Hz and ±2.5 mm displacement. It was observed that the minimum force occurring during fatigue tests was approximately −95 N. After 1100–1200 cycles, it reached −110 N and remained constant. The outcomes of this study are expected to enhance the trust that hand therapists, orthopedists, and patients have in using thermoformable 3DP-WHOs.

This research examines the flexural fatigue response of 3D-printed foot orthoses produced from various thermoplastic polyurethane (TPU) filaments, including Filaflex 60A, Filaflex 70A, Filaflex 82A, PolyFlex 90A, and varioShore. To subject the insoles to repeated flexion in the metatarsophalangeal area, specialized equipment was developed. A real-world testing scenario was applied to the Filaflex 82A insole, demonstrating that it can sustain over 1,400,000 steps over several months of normal walking (a cadence of approximately 120 steps per minute). Consequently, the experimental conditions were adjusted to double this pace to obtain pertinent results within a shorter testing timeframe. The insoles were subjected to 250 cycles per minute at constant clamping pressures of 176 kPa in the forefoot region. The objective of the evaluation was to determine if 700,000 testing cycles, equivalent to more than two and a half months of daily walking, would induce any damages in the internal structure (infill failure) or external condition (delamination, cracks) of the insoles. Except for compression marks, particularly notable on the foamed material (varioShore TPU) within the clamping zones of the testing device, none of the tested insoles exhibited any signs of external damage after 700,000 cycles. Moreover, the deformations observed in the insoles were non-permanent and nearly entirely disappeared within a few days of rest. The only insole that displayed deterioration of the infill structure was a TPU 82A insole that had been previously worn and then left on a shelf for approximately one year in uncontrolled conditions before being tested at repeated flexion on the apparatus. Additionally, a fifteen-minute walking test was carried out to assess the comfort of each insole, and it was found that the varioShore model, which had a 20% infill density and was 3D-printed at a temperature of 220 °C, stood out as the most comfortable among the tested insoles.

In recent years, the application of 3D-printed implant cages or trusses for foot arthrodesis has emerged as a personalized approach to address complex bone defects and deformities. Twenty studies involving different regions of the foot, such as the ankle and subtalar joints, were reviewed to document the 3D-printed custom solutions. The design of these implants is also discussed, including custom titanium trusses and lattice structures, which can promote osseointegration and fit the bone geometries. From a mechanical perspective, these implants proved to be stable and compatible with natural bone, aiming to reduce stress shielding while offering the mechanical strength needed for optimal outcomes. This systematic survey also addresses the additive manufacturing processes involved, namely EBM, SLM, or DMLS. Clinical cases were focused on patients with large bone loss, failed prior fusions, and deformity corrections, with the follow-up results showing high rates of fusion and functional improvement. Of the analyzed studies, three provide level III evidence, while the rest provide level IV or V, consisting of case series or reports. Since 2015, 148 patients have been reported to receive such implants. This review addresses the question, “how effective are 3D-printed titanium cage implants in foot arthrodesis in addressing large bone defects and deformities?” It is the first review to gather data on the use of such customized implants in foot arthrodesis, providing critical insights to enhance their application, including amputation avoidance. This study highlights the advantages of personalized 3D-printed implants in achieving a better anatomical fit, improving clinical outcomes, and ensuring faster recovery times, while also addressing considerations such as the cost and the need for long-term clinical data.

Background/Objectives: Severe acetabular bone loss, particularly Paprosky type IIIA and IIIB defects and pelvic discontinuity, represents a major challenge in revision total hip arthroplasty (rTHA). Custom-made acetabular implants offer a patient-specific reconstructive option when conventional techniques may not provide adequate fixation. This systematic review evaluated the clinical outcomes, implant survivorship, complication profile, and methodological quality of custom-made acetabular implants used in complex rTHA. Methods: A systematic literature search of PubMed, ScienceDirect, and Web of Science was performed to identify eligible studies published between January 2000 and December 2025 reporting outcomes of custom-made acetabular implants in rTHA. Thirty-six eligible clinical publications were included in the qualitative synthesis. Potentially overlapping or longitudinally related patient cohorts were identified and not treated as independent populations when interpreting outcomes. Data extraction included study design, patient and defect characteristics, implant type, follow-up duration, implant survivorship, functional outcomes, complications, and re-revision. Methodological quality was assessed using the Methodological Index for Non-Randomized Studies (MINORS). Results: Reported implant survivorship ranged from 72.4% to 100% across the included studies, with several series reporting survivorship above 90% at mid- to long-term follow-up. Functional outcomes generally improved following reconstruction, while aseptic loosening was relatively uncommon. Infection and instability were important causes of reoperation and implant failure. Methodological quality was variable: among the 34 non-comparative publications, MINORS scores ranged from 6 to 13 out of 16, while the two comparative publications scored 15/24 and 14/24. Considerable heterogeneity in patient populations, defect severity, implant design, follow-up duration, and outcome reporting precluded quantitative pooling. Conclusions: Custom-made acetabular implants represent a potential reconstructive option for carefully selected patients undergoing complex rTHA for severe acetabular bone loss and pelvic discontinuity. Published studies report favorable implant survivorship and improvements in functional outcomes; however, the evidence is derived predominantly from retrospective, non-comparative series and does not establish superiority over alternative reconstructive strategies. Prospective, multicenter, comparative investigations using standardized outcome definitions and longer follow-up are needed to better define long-term effectiveness.