3D printing orthopedic scoliosis braces: a test comparing FDM with thermoforming

Abstract

In recent years, 3D printing gained considerable attention in the orthopedic sector. This work evaluates the feasibility of producing orthopedic scoliosis braces by 3D printing, comparing performance and costs with classical thermoforming procedures. Critical parameters, such as manufacture time, mechanical properties, weight, and comfort are carefully considered. Polyethylene terephthalate glycol-modified (PETG) was selected among the several filaments materials present on the market. Printed samples were analyzed with electronic microscope, tensile, and impact tests and compared with thermoformed polyethylene (PE) and polypropylene (PP) samples. Moreover, a cost analysis was carried out for the specific application. The thermoformed brace of a volunteer patient affected by scoliosis was reproduced using reverse-engineering techniques. The model was then printed as a single piece and postprocessed by an expert orthotist. Subsequently, the patient wore the brace in a pilot case to compare comfort and mechanical effectiveness. Results show that the 3D printing fabrication method is able to provide a valid alternative to the current fabrication methods, being also very competitive in terms of costs. The morphological analysis does not show critical defects in 3D printed samples, while the mechanical tests highlighted their anisotropy, with an overall brittleness of PETG samples in the direction orthogonal to the fibers. However, in terms of mechanical stresses, a back brace should never reach the polymer yield stress, otherwise the shape would be modified and the therapeutic effect could be compromised. Finally, the patient reported the perception of improved support and no significant comfort differences compared with the thermoformed brace.

Rapid Development of an Injection Mold with High Cooling Performance Using Molding Simulation and Rapid Tooling Technology

“…The alternative coolants such as cool air [ 63 ] or oil [ 64 ] can also be used in the experiment for investigating the difference in the cooling performance of an injection mold with optimum CCCs. Lastly, the molds or dies with CCCs fabricated by the proposed method can also be employed in metal injection molding [ 65 ], rotational molding [ 66 ], centrifugal molding, thermoforming [ 67 ], transfer molding [ 68 ], hot stamping [ 69 ], plastic injection molding [ 70 , 71 ], microinjection molding [ 72 , 73 ], or blow molding [ 74 ]. These issues are currently being investigated and the results will be presented in a later study.…”

Enhancing the Structural Strength for Injection Molding Tooling With Conformal Cooling Channels Using ANSYS Software

“…According to the results described above, the ndings of this study are very practical and can provide a reference for the design of molds or dies with conformal cooling channel, especially for the fabrication of the injection molding tooling with conformal cooling channels using the technologies such as atom diffusion additive manufacturing (ADAM), electron beam melting (EBM) [33], SLM [34], selective laser sintering (SLS) [35], diffusion bonding (DB) [36], direct metal deposition (DMD) [37], or direct metal laser sintering (DMLS) [38] because the fabrication costs is costly. The fabricated molds or dies can be employed in metal injection molding [39], rotational molding [40], centrifugal molding, thermoforming [41], transfer molding [42], and hot stamping [43], plastic injection molding [44], or blow molding [45]. In addition, injection molding tooling with conformal cooling channels fabricated by DMLS, ADAM, EBM, SLM, SLS, DB, or DMD employs a hybrid machining process that results in the coolant leaking from the connection locations.…”

Orthoses Development Using Modern Technologies

“…For these reasons the ABS-M30i has been chosen as the most suitable material. Other materials like PETG or PLA can be used for orthosis production [20], but since this 3D printer does not support these materials, they were not chosen for this study.…”

“…When comparing production costs of orthoses produced by AM or conventionally, in an analysis done by Fernandez-Vincente et al [19] the cost of AM thumb orthoses is reduced by a half compared to the traditional method of production. When producing larger orthotic devices, Redaelli et al [20] reported that the AM fabrication of back braces can provide a valid alternative to the current fabrication methods. The overall production time from initial scanning to delivery to the patient took approximately a full working day, similarly to what is required by the thermoforming process.…”