The Role of 3D Printing in Colorectal Surgery: Current Evidence and Future Perspectives

Results

Preoperative planning. One article described a randomized controlled trial where 3D anatomic replicas of patients with anorectal fistulas were produced and assessed by sixth year resident surgeons, resulting in higher overall scores in fistula assessment tests and better scores in preoperative planning. Participants of the group that utilized the 3D models stressed that they improved their preoperative awareness and noted the value of 3D models in surgical training (14).

Another study produced superior mesenteric vascular models of 22 patients and compared the accuracy of visual and physical models in regard to patient anatomy, assessing their value in surgical planning and navigation in right hemi-colectomy with extended D3 mesenterectomy (15). Results showed acceptable dimensional correlations among 3D printed models, visual STL models and operational tissue anatomy of the mesenteric vessels. The weakest correlations were found for intra-venous distances between 3D models and peri-operational measurements, due to the unique physiological and volumetric traits of veins regarding dilatability and volume changing. However, the study concluded that 3D printed models are promising as adjuncts to preoperative planning and as a tool for peri-operative navigation.

Garcia-Granero et al. produced a 3D model to examine the vascular anatomy of a patient with right colon cancer and planned a laparoscopic right hemicolectomy with complete mesocolic excision and high tie ligation of ileocolic, right colic and right branch of the middle colic vessels with dissection of gastrocolic trunk of Henle and surgical trunk of Gillot and high tie of the superior right colic vein (16). In order to facilitate navigation among vessels with high variance in the area of the gastrocolic trunk of Henle and the surgical trunk of Gillot, they produced a personalized 3D model of their patient's anatomy. Observations on the efficacy of their endeavour were not mentioned.

More studies appear to have successfully created anatomic replicas that correlated well to the anatomy of the patients. Hamabe and Ito created two 3D pelvic models, one of a healthy male and one of a female patient with rectal cancer (17). These models facilitated the observation of deeper anatomic structures of the pelvis.

Sahnan et al. examined the efficacy of producing 3D models of complex perianal fistulas, stressing that although 3D reproduction of patient images offers no new information to the 2D images, they can improve conceptualization, providing a more realistic representation of anatomy, aiding clinical communication and surgical planning (18).

Finally, in one study, a stent with tailor-made proportions was created specifically for a patient with an entero-cutaneous fistula, providing superior results to traditional plugging techniques (19).

Training the surgeon and the patient. Although the benefits of the applications of 3D printing technology in surgical training are established [reviewed in (20)], there are not enough data in the literature to provide a solid conclusion as to the benefits of 3D printing applications specifically in the field of colorectal surgery.

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Figure 2.

PRISMA flow diagram.

Bageas et al. noted that touching, manipulating and exploring the patient's pathology on the 3D model improved the quality of training offered to resident surgeons, enhancing surgical skills (14).

Sahnan et al. mentioned that benefits of 3D printing to more experienced surgeons could be more difficult to ascertain, but could be more beneficial to those with less experience (18). Indeed, articles providing sufficient and thorough data to reach a well-documented conclusion are scarce. Thus, more similarly planned studies aiming to investigate the role of 3D printing in colorectal surgeon training need to be produced in order for more sufficient data to be available.

Apart from surgical training, 3D printing technology can also be employed to enhance patient training. Tominaga et al. used 3D printing technology to create patient-specific stoma models prior to surgery (21). The group created a new tool for patient training, improving patients' understanding of daily stoma care and reducing the time needed for the acquisition of this new skill, potentially reducing future stoma-related complications such as peri-stoma skin lesions.

Material use and costs. Multiple 3D printing techniques are available, providing variable results and costs. Criteria to determine the choice of each technique include cost, type of tissue (vessels, muscles, hollow viscus, et cetera), and production time for available models (10). It should be noted that cost naturally appears as a barrier. In our research, costs greatly varied mainly based on the selection of materials used for 3D printing. Another matter to be considered is the software needed for the transition from 2D images to a 3D digital model. While there is a vast array of available software, both free and paid, choice of software is a factor that could potentially increase costs. Further editing is also possible, requiring extra pieces of software. Even after its production, the physical 3D model can be further adjusted in order to enhance the final product (15).

Finally, the implementation of the product comes into play. On one hand, the production of anatomic replicas requires choosing materials based on the focused anatomic region. On the other hand, production of protheses such as stents requires that the materials used for the production of the final product should be sterilizable (19). Table II presents the types of hardware, software and materials used in each retrieved study, as well as the approximate cost per unit produced.