**2. Method**

### **2.1 Modern method**

Mohammed et al. [13] reported that 3D scanning method of positives obtainment and CAD design of splints is quicker, non-invasive and provides greater accuracy in reproduction. On the other hand, they also report that AM splint requires longer fabrication time, which is still acceptable but less than desirable with respect to it potentially meaning an additional visitation by a potential patient. The disadvantage of longer production time is also reported by Buonamici et al. [14], however, they suggest the adoption of modern method due to the incredible benefits in terms of weight, expected comfort, breathability and the possibility of washing the immobilized segment. Barios-Muriel et al. [15], Fitzpatrick et al. [16] and Chen et al. [17] also support this theory. Li et al. [18] proposed a splint design method, which reduces the duration of the modeling phase and reduces the manufacturing phase by using multiple 3D printers to produce individual parts of the orthosis. 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. However, the total man-hours are reduced because of the minimal supervision necessary during the 3D printing. The cost of the AM back brace is therefore competitive compared to the production cost of a thermoformed back brace, that typically ranges from 250 to 500 euros due to the long labor time. Also, Hale et al. [21] found out that scanning to delivery of an individual AM neck brace, which takes approximately 6 weeks to produce by the traditional way, was approximately 72 hours, and the production costs of both methods is comparable.

These facts confirm the practical application of modern methods in orthoses production. The goal of this study is to apply these modern methods in the production of individual arm and forearm orthoses and propose a methodology.

#### **2.2 Positives obtaining**

3D scanning technology, specifically the Artec Eva (Artec 3D, Luxembourg, Luxembourg) handheld scanner, was used to create the positive of the patient's upper limb segment. A handheld scanner is a device that constantly creates images of an object by creating real-time images of the scanned object in the software of the given scanner. Using this modern method of data acquisition, we can generate a 3D model of the patient's body segment, for which an orthosis will be designed. One of the advantages of a handheld 3D scanner is that the device is compact, lightweight, portable and requires only 1 person and a laptop to operate.

The subjects´ arm and forearm were scanned with the entire upper limb being abducted with 30° rotation in the shoulder joint and 100° flexion in the elbow joint, with the thumb in opposition to the fingers and wrists at a 10° to 20° extension, and the elbow placed on a table for better support (**Figure 1**). All subjects had sufficient strength to hold the segment in position for the time which the area of interest was scanned. The scanning frequency was set to 8fps (frames per second) and no errors occurred during the positives obtaining. For this experiment, as seen in **Figure 2**, the arm and forearm of 10 adult subjects were scanned and processed.

**Figure 1.** *Arm and forearm scanning process.*

**Figure 2.** *Obtained models of 3D scans.*

### **2.3 Orthoses 3D modeling**

The Autodesk Meshmixer (Autodesk, Inc., San Rafael, CA, USA) software was used to create a digital model of the orthosis. It is a freely available modeling software in which it is possible to create and edit 3D objects. The shape of the device was sketched directly on a 3D model of a patient's upper limb segment, which we obtained by 3D scanning. When creating the contour of the device, we had to consider the coverage of the area of the segment sufficient for the orthosis to secure the wrist, thumb and the overall attachment of the device to the forearm.

The sketch of the orthosis' surface was then copied and placed on the 3D positive to create a 0.5 mm gap between the device and the area of interest. The creation of such a gap, or "offset", is important so that after the application of a real device to a given segment, there is no surface pressure, which would result in negative effects on the patient's upper limb. We can correct the size of the gap regarding whether a bio-compatible lining, which eliminates skin irritation, will be applied to the orthosis (**Figure 3**).

After creating a copy of the orthosis surface and applying the offset, the material thickness was set. Thickness of 2 mm was chosen when designing the orthosis. The thickness and choice of material is important in terms of strength and flexibility to avoid damage during use and repeated application to the given segment.

*Orthoses Development Using Modern Technologies DOI: http://dx.doi.org/10.5772/intechopen.95463*

In the last step, the surface and edges of the model were smoothened, and the design of the final model was revised. Ten individual orthoses were designed and produced using FDM additive manufacturing technology.

#### **2.4 Orthoses additive manufacturing**

All models were manufactured on the Fortus 450mc (Stratasys Ltd., Rehotov, Israel) professional 3D printer using ABS-M30i bio-compatible polymer with a T16 tip and SR-30 support material with a T12SR30 tip. Since this printer has pre-set printing parameters for individual materials, the settings were not edited. Printing settings are listed in **Table 1**.

All models were printed one-by-one and positioned on the removable printing plate, which is stuck on the printer bed with the dorsal side oriented on the bottom (**Figure 4**).

After the manufacturing process, the printing plate was removed from the printer, all orthoses have been manually extracted and the support structures have


**Table 1.** *Printing settings.* been thoroughly removed. Final orthoses, as seen in **Figure 5**, have not been post processed chemically, or sand blasted.
