This scoping review provides the first summary of the applications of 3D printing in the field of device creation in ostomy and ECT and EAF fistula management within the field of colorectal surgery. The current level of knowledge remains limited with only a small number of studies identified, despite there being a larger base of literature for other applications of 3D printing within colorectal surgery with two existing systematic reviews. Although the review’s results demonstrate successes within different approaches in the field, these must be considered in the context of their limitations such as small sample sizes and recent applications. Most of these applications remain at the ‘proof of concept’ stage, and literature remains limited to case reports. More focussed research and larger scale trials involving larger patient groups must be conducted to progress to adoption of these applications in clinical practice. Healthcare professionals must be prepared to adopt 3D-printing into health practice, as usability and cost-effectiveness of these technologies increase with new developments in the field, and to shape the new landscape in which 3D-printing is used in medicine.
The studies could be subdivided into ostomy, ECF/EAF fistula and patient education devices. Most devices were designed to be personalised to each patient and used TPU as materials. The specific technologies used were diverse, with a wide range of techniques and approaches employed to design each device. However, the principles of 3D printing remained consistent throughout, with many different modalities used to derive information via scanning, design of the device and subsequent printing and application.
Ostomy:
Zahia et al shows that ostomy patches can be created via 3D printing technology from information derived from different 3D scanning modalities. (15) Yeh et al demonstrates the design of a low-cost ostomy bag using 3D printing, although it was not tested on any patients. (16) These studies demonstrate the proof-of-concept ideas that can be applied to future studies with patient cohorts.
Fistula:
The management of complex enterocutaneous fistulas had the highest number of case reports, with a majority originating from Asia. The reports describe the use of fused deposition modelling alongside thermoplastic urethane and polylactic acid to custom design patches that were personalised to each patient’s fistula. These proof of concept studies seek to block the enteroatmospheric fistula to manage the condition in the short and long term, although challenges included wide clinical variability and the device potentially changing the shape of the wound. (17) (18) (19) (20)
Patient Models:
Cosman et al describes a 3D printed flange stabiliser for patients with spinal cord injury (21). Tominaga et al describes a case in which 3D printed stoma models are used to discuss care and problems with patients. (22) This study highlighted the effectiveness of 3D printed models in teaching patients with dementia management of ostomy devices. 3D printed models can facilitate self-management of ostomies in patients who might otherwise struggle to due to their physical or mental disabilities, which can lead to better compliance, patient autonomy and outcomes.
Advantages and Disadvantages
3D printing has many advantages to traditional methods of device creation in the context of colorectal surgery. Advantages described in the included papers were reduced hospital length of stay, quicker recovery, and restoration of function. Patients were able to be discharged at an earlier date and this has additional advantages for the hospital. The studies also identified the quick process of creation and manufacturing the devices using 3D printing, alongside the availability of the materials used. Most studies described using thermoplastic materials, which has mechanical strength, flexibility and biocompatibility. (23) One study described modifications in printing technique to optimise the material properties of the devices used to fabricate the products. The general desirable characteristics were materials that were lightweight and strong to allow patients to continue with normal life with comfort and reduces the strain placed on the delicate tissues. Much consideration is given to the setup of the 3D printers and the thickness and infill settings, alongside optimisation of the software files used. The files were stored digitally and modified as required, with changing patient measurements. This customisation allows a more accurate fidelity and representation of the device required for the patients. In addition, cost considerations and waste reduction using the process of 3D printing in comparison to traditional manufacturing methods makes it an advantageous avenue to continue research.
Nevertheless, the limitations of 3D printing technology are that it is yet to be employed on a wider scale in clinical practice. A common drawback observed in the articles included issues with fit within changing anatomy and compromised viability of the skin and soft tissues. The relative inaccessibility of the software used to novices or untrained clinicians, as noted in many of the studies involved collaboration with engineering departments and expert consultants, may be a potential barrier to its adoption. The process of designing a customised product with complex dimensions without the necessary engineering expertise may be a long and arduous process. Although open-source designs exist for free online, concerns regarding lack of regulation and expertise limit its use. Studies on the viability and long-term safety of these devices are yet to be conducted.
Publication Bias (Is this point better made in the discussion rather than methods?)
A renowned source of bias in reviews is publication bias, which describes the trend that studies with statistically and clinically significant findings tend to be more likely to be published than their counterpart with no or little significant findings. Thus, it must be noted that this scoping review may be subject to publication bias. In addition, the potential detrimental statistical false positive influence of publication bias, particularly in small to medium samples, together with high heterogeneity in study methods and 3D-printing methods, has meant that conducting a meta-analysis would have not been feasible.
Future Directions
The lack of literature and robust evidence available on 3D printing in colorectal surgery is a significant limitation. A common issue is the lack of patient data and the low level of evidence, as many of the studies were case descriptions with single individuals. It is not possible to extrapolate such data, and more trials and studies must be conducted with 3D printing and colorectal surgery. A recommendation for future research are to automate the 3D printing process for the novice user, and to make these technologies available in developing countries as an accessible low-cost tool (24). (25)