This study investigated the use of fused deposition modeling (FDM), three-dimensional (3D) printed models, of the ovine stomach to learn surface and topographical anatomy. The objectives were: i) to faithfully reproduce the external morphology, the normal volume and the correct positioning of the four compartments of the stomach ii) to facilitate students the spatial visualization of the organ with emphasis on the complex relationship stomach-greater omentum. The model was built based on surface scanning. To obtain the images the ovine stomach was scanned using a 3D surface scanner. Assessment of the model was performed through surveys to first-year veterinary students after the practical sessions in which, they studied and compared both real and 3D-printed specimens. Regarding morphology no significant differences were reported, students were equally able to identify the different structures and compartments on the 3D-printed model. Understanding of both spatial position and relationship of the stomach with neighboring anatomical structures was easier achieved with the 3D-printed model. Other advantages of the 3D-printed model were handle-resistance and ease of handling, availability and reduction of animal specimens. We propose that 3D-printed ovine stomach by surface scanning is a valuable simple model to support learning of surface and topographical anatomy.

Total limb amputation is quite common in small animals, although most of the indicated pathologies do not need such a restrictive procedure. Exo-endoprosthesis is a suggested alternative for the enhancement of the biomechanical situation of these patients. 3D printing of the internal part of exo-endoprostheses in polyether ether ketone (PEEK) is evaluated. Two different shapes of this internal part—one for radius’ and the other for cylindrical medullary cavities—were assessed. Proper PEEK temperature settings for 3D printing, the internal part of exo-endoprostheses, by fused filament fabrication (FFF) were obtained. Printing trials were carried out for different dimensions and printing orientation of these parts to achieve the best bone anchorage and thread strength outcomes. Pull-off strength tests for different surfaces of the internal part were performed with a best outcome for positive surfaces. All printed internal parts were inserted in canine tibiae and radii for an ex vivo assessment of bone anchorage and thread strength parameters. The best printing results were obtained at 410 and 130°C of the nozzle and bed temperatures, respectively. Also, a positive correlation was observed between the printing code, quality, and take-off time, while inverse correlation was shown between the take-off and the printing code, or quality, just like the print-bed temperature and the printing code. The positive surfaces had the best pull-off strength outcomes. Excellent bone anchorage and thread strength outcomes were obtained for one variant of each internal part shape. Designed devices had shown good threaded rod’s fitting inside the PEEK plug and perfect bone anchorage of the PEEK plug for tibiae and radii. In addition, iteration of manufacturing PEEK small devices by FFF technology has been shown due to small standard deviation of most variants.

Exo-endoprosthesis is a limb salvage procedure for animals, although only expensive metal devices have been described. Now-a-days, new materials for this type of implant could be considered due to novel and affordable manufacturing techniques. However, a factor of safety (FoS) should be considered. There are kinetic and kinematic studies of canine natural gaits, which can be used to establish an FoS for mechanical tests for new non-metallic devices. Polyetheretherketone (PEEK) is used in different specialties in human medicine. Its mechanical properties (and its close mechanical stiffness to that of bone) make this polymer an alternative to metals in veterinary traumatology. PEEK could also be used in 3D printing. The suitability of a novel inner part of an exo-endoprosthesis manufactured by fuse deposition modeling (FDM) was presented in this study for long canine bones. Mechanical characterization of 3D-printed PEEK material and ex vivo mechanical tests of a customized endoprosthesis were performed to address it. Young's modulus of 3D-printed PEEK suffered a reduction of 30% in relation to bulk PEEK. Customized 3D-printed PEEK endoprostheses had promising outcomes for the tibiae of 20 kg dogs. Pure compression tests of the non-inserted endoprostheses showed a maximum force of 936 ± 199 N. In the bending tests of non-inserted endoprostheses, the PEEK part remained intact. Quasistatic mechanical tests of bone-inserted endoprostheses (compression-bending and pure compression tests) reached a maximum force of 785 ± 101 N and 1,642 ± 447 N, respectively. In fatigue tests, the samples reached 500,000 cycles without failure or detriment to their quasistatic results. These outcomes surpass the natural weight-bearing of dogs, even during a galloping pace. In conclusion, the 3D-printed PEEK part of the endoprosthesis for an exo-endoprosthesis can withstand loading, even during a galloping pace.

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