The use of additive manufacturing in medicine can be applied in various fields, ranging from surgical planning in traumatology or urology[8–10] to the creation of orthoses or splints[11] or even to tissue engineering and regenerative medicine[12]. Personalized treatment can be easily achieved due to additive manufacturing that allows the creation of devices designed by assisted design[1]. Currently, our group has achieved this personalization in the fistula treatment by using for the first time a bioscanner to define the wound area on a patient’s body.
As a result of the cases studied in this work, we can see the different clinical situations that can arise in the case of an enteroatmospheric fistula and understand the need for the personalization of devices for the treatment of this pathology. The first clinical results of the application of this therapy have been widely described by Durán et al.[13] from our working group which corroborates the efficacy and safety of the application of the device generated by the methodology presented in this work.
A benefit of this methodology is that the image-obtaining process is harmless to the patients. Therefore, it can be repeated as much as needed. Additionally, once bought the bioscanner, there are no additional costs of maintenance. These characteristics make this technique potentially useful not only for the treatment of enteroatmospheric fistulas but also for the design of other medical devices for other pathologies.
Similar techniques and devices aim to perform the same function as the device we have presented in this work. In 2002, Subramainam et al.[14] proposed the idea of isolating the abdominal wound and the intestinal discharge from the fistulose surface. To carry out this isolation, different conventional devices have been used, such as a bottle nipple[15], a plastic roll of tape, wrapping it with gauze and placing Duoderm® in the base[16], and other commercial devices such as the PPM Fistula Adapter™[17, 18]. The methods described so far isolate the intestinal content of the wound by creating a floating stroma over an NPWT device that assists in wound granulation. However, none of these devices consider the huge clinical variability in enteroatmospheric fistulas. Current 3D printing techniques facilitate device customization for clinical applications. Xu et al.[19] described a 3D-printed intraluminal stent that aims to restore intestinal continuity to reduce intestinal leakage.
Although it seemed promising, their rates of intestinal leakage into the wound were unmanageable, particularly when enteral nutrition was added to the patient. The device we present does not intend to restore intestinal continuity, but to achieve fistula ostomization since no work has been found with successful results. Our device aims to isolate de wound from the intestinal content similarly to previous studies[14–17], with the additional advantages of personalized therapy in these patients. Although similar works[17] have implemented devices for enteroatmospheric fistula treatment, the one presented in this article results considerably more advantageous, thanks to its potential personalization and its conical morphology, essential for the NPWT system.
For the manufacture of the device, PCL[20–22] and polyamide[23, 24] were used, one of the most widely used materials for 3D printing. PCL is approved by the Food and Drug Administration (FDA) of the United States of America[21]. Previous studies have shown that this material stimulates the migration of muscle cells and the growth and proliferation of fibroblasts, chondrocytes, and mesenchymal stem cells, which leads us to think about its good behavior in healing[20, 22, 25]. Polyamide is a medical-grade biomaterial that has been utilized in surgical guides and instruments[23, 24]. Some studies [26–28] reported good properties of this biomaterial, such as attachment, proliferation, and migration of chondrocytes. However, these biomaterials are not flexible and they may cause discomfort to the patients and limit their movement.
Layton[15] presented the use of a bottle nipple for isolating fistulas. This technique allows greater patient mobility due to the flexibility of the instruments. However, this device could not be applied in 75% of the cases presented due to the extensive surface occupied by the fistula and the large debit that was expelled. Our personalized device allows great mobility to the patients, avoiding muscle mass loss and enabling them to start early the motor rehabilitation usually needed in these cases.
Another of the problems encountered with these devices is that the PCL material does not adhere correctly to the NPWT system adhesives. To solve this, we lined the device with transparent polyurethane adhesive dressings (Opsite®, Smith, and Nephew), thus achieving an adherent surface on which to stick the NPWT system adhesives successfully. However, the use of polyamide devices did not show this drawback and allowed an optimal adhesion to the NPWT system.
The sterilization of the devices with hydrogen peroxide using Sterrad 100nx (Johnson & Johnson, USA) posed a challenge due to the device deformation caused by the temperatures and high pressures. However, using Sterrad 100S (Johnson & Johnson, USA), the devices maintained their shape. Our future research line could be focused on the improvement of the sterilization process of the devices. Another limitation of this methodology is the fact that a bioscanner with white light technology is not available in many hospitals, and therefore the externalization of this methodology is challenging.