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The BES TEST™ (Bone Elastic Structure Test), is a recently developed software medical device that detects pathological changes of bone trabecular architecture by measuring its elastic characteristics, known to be directly related to its resistance. The results are expressed by the Bone Structure Index (BSI) or by its T-score, that is the number of standard deviations from the healthy population average. Purpose: Evaluate the precision of BES TEST™ under reproducibility conditions, defined as repeated measurements on the same or similar objects which include different locations, operators, and measuring systems. Methods: A total of 51 replicate measurements were performed by four different operators on five different phantoms. Each phantom was 3D printed using Stereolithography (SLA) and Fused Deposition Modeling (FDM) and has a unique internal structure that mimics trabecular bone. ISO 5725 guidelines were followed for the interpretation of results. Results: The 3D-printed phantoms performed like real bones when analyzed with BES TEST™. The reproducibility 95% Confidence Interval expressed in BSI is [Formula: see text], which corresponds in T-score to [Formula: see text]. The Least Significant Change in BSI is [Formula: see text], which corresponds to [Formula: see text]. Conclusion: The reproducibility of BES TEST™ within the admissible range is not inferior to that of gold standard tests for osteoporosis. 3D printing proved a valuable tool to perform reliable replicate measurements without having patients undergo unnecessary tests.

Additive manufacturing played a keyrole in investigating the precision of a recently-developed device that measures the elastic characteristics of the trabecular bone by simulating the application of loads on a virtual biopsy obtained from radiographic images of the proximal epiphyses in the patient’s hand fingers. The simulation results are combined in a Bone Structure Index (BSI), which has shown to be able to detect trabecular bone alterations due to osteoporosis or other pathological situations. In order to obtain a large number of measurements without having voluntary patients undergo unnecessary radiations, the precision assessment tests were carried out on a 3D-printed phantom hand, in which different mimicked trabecular structures (chips) were inserted. Each mimicked bone had a unique internal structure and density and was 3D-printed using radiopaque composite materials. Fifteen different chips were additively manufactured; 20 measurements were performed on each chip. BSI and BSI_T-score precision values were computed according to ISO 5725 and ISCD standards. For all the chips, no relationship was found between the mean [Formula: see text] and standard deviation [Formula: see text] of the measurements in each chip. The range of the 95% confidence interval ([Formula: see text]) was computed assuming the repeatability standard deviation [Formula: see text] as the known standard deviation of the measurement method (average of [Formula: see text] values): [Formula: see text], corresponding to [Formula: see text]. Least Significant Change was evaluated as well: [Formula: see text], corresponding to [Formula: see text]. The 95% confidence intervals are small when compared to the commonly-accepted diagnostic values, where a patient is classified as osteoporotic if T-score -1 and osteopoenic if -2.5

Stereolithography (SLA) is becoming a more and more popular 3D-printing method. Improvement in material properties encourages makers and engineers to embrace this technology even for load-bearing applications. Mechanical properties of 3D-printed materials are difficult to obtain from technical datasheets and, even when available, these data are often unreliable, since they depend strongly on the specific printing parameters applied. Therefore, it is often necessary to perform an in-house mechanical characterization. In this work, tensile tests are performed with a basic in-house-designed tester on SLA 3D-printed specimens; these are printed at different orientations on a Formlabs™ Form 2™ using Clear V4™ resin. The ultimate tensile strength, Young’s modulus, strain at maximum stress and strain at break are calculated. No relationship is found between printing angle and mechanical characteristics; therefore, this 3D-printed material can be considered isotropic. Results are compared with the manufacturer’s datasheet: the measured maximum stress is slightly lower than that stated by Formlabs™, while the modulus is nearly the same. Strain at maximum stress and strain at break were also measured but were not reported in the available datasheet.

Due to its building process, the mechanical properties of a 3D-printed object are substantially different from those of the same object, made of the same material, but obtained by a different manufacturing process. Tensile tests were carried out on standard specimens, which were 3D-printed with a Builder Premium™ FDM printer. Three different plastic and composite materials were tested and their stress-strain curves were obtained; significant parameters such as ultimate tensile strength and Young’s modulus were calculated and compared.

Additive manufacturing is gaining greater and greater popularity in recent years: thanks to a dramatic reduction of costs and increasing print quality, more and more people are attracted to 3D printing, even for the production of end-use load-bearing parts. Today, there are no universally accepted norms that guide the engineer through the uncertain task of predicting the mechanical behavior of 3D-printed parts. Even though there are numerous reports and articles in literature regarding this topic, the designer will have to rely mostly on his own mechanical tests. This paper describes the design of an in-house-built machine for 3D-printed material tensile testing. The accuracy of this test-rig has been verified through comparison of results on different 3D-printed specimens: these were realized through fused deposition modelling (FDM) and were divided into four distinct sets, based on the material and their orientation on the buildplate. Some samples were printed in PLA, others in XTCF-20™: a composite material made of a matrix of Amphora™ polymer reinforced with 20% in weight carbon short fibers. PLA samples were printed flat on the buildplate, on one side and standing: this affects directly the orientation of the plastic fibers. Tensile tests were performed both on ours and on a high-end commercial testing machine, following the ISO 527 norm. Maximum stress, strain at maximum stress and Young’s modulus were calculated for each tested specimen: these measures allowed to compare the results of the two testers. Results proved coherent, thus validating the in-house machine, which was realized for a fraction of the cost of an equivalent commercial model.

Additive manufacturing offers several advantages when compared to conventional manufacturing technologies, especially where large scale customization is requested. In this article, a procedure for the design of a fully-customized 3D-printed ankle-foot orthosis (AFO) is described, with reference to a case study regarding a 21-year-old woman with an injured ankle. The first step is the acquisition of the geometrical data from the patient’s foot: this is done using photogrammetry. The second step is the data conversion and import in a CAD modeler; SolidWorks™ is chosen for this purpose. The AFO is modelled parametrically around the foot mesh and optimized in order to resist the predicted mechanical stresses. Finally, the device is 3D-printed on an FDM printer and tested on the patient. An excellent geometrical correspondence between the AFO and the patient’s foot is highlighted: this leads to great comfort and enhances medical functionality. The described procedure can be easily automated, further reducing the lead time and costs of the whole process

Background: Increasing incidence of head and neck cancer (HNC) in young adults has been reported. We aimed to compare the role of major risk factors and family history of cancer in HNC in young adults and older patients. Methods: We pooled data from 25 case-control studies and conducted separate analyses for adults 45 years old (’older adults’, 17 700 cases and 22 704 controls). Using logistic regression with studies treated as random effects, we estimated adjusted odds ratios (ORs) and 95% confidence intervals (CIs). Results: The young group of cases had a higher proportion of oral tongue cancer (16.0% in women; 11.0% in men) and unspecified oral cavity / oropharynx cancer (16.2%; 11.1%) and a lower proportion of larynx cancer (12.1%; 16.6%) than older adult cases. The proportions of never smokers or never drinkers among female cases were higher than among male cases in both age groups. Positive associations with HNC and duration or pack-years of smoking and drinking were similar across age groups. However, the attributable fractions (AFs) for smoking and drinking were lower in young when compared with older adults (AFs for smoking in young women, older women, young men and older men, respectively, =19.9% (95% CI = 9.8%, 27.9%), 48.9% (46.6%, 50.8%), 46.2% (38.5%, 52.5%), 64.3% (62.2%, 66.4%); AFs for drinking = 5.3% (-11.2%, 18.0%), 20.0% (14.5%, 25.0%), 21.5% (5.0%, 34.9%) and 50.4% (46.1%, 54.3%). A family history of early-onset cancer was associated with HNC risk in the young [OR = 2.27 (95% CI = 1.26, 4.10)], but not in the older adults [OR = 1.10 (0.91, 1.31)]. The attributable fraction for family history of early-onset cancer was 23.2% (8.60% to 31.4%) in young compared with 2.20% (-2 .41%, 5.80%) in older adults. Conclusions: Differences in HNC aetiology according to age group may exist. The lower AF of cigarette smoking and alcohol drinking in young adults may be due to the reduced length of exposure due to the lower age. Other characteristics, such as those that are inherited, may play a more important role in HNC in young adults compared with older adults.