Three-dimensional printing and cochlear implantation: a systematic review.

PURPOSE: This systematic review aims to evaluate the applications of three-dimensional (3D) printing in cochlear implantation (CI), focusing on its roles in surgical training, pre-operative planning, intraoperative assistance, and device innovation. METHODS: A systematic search of PubMed, Scopus, Web of Science, and Google Scholar was conducted from inception to August 30, 2025. Keywords included "Cochlear Implant" OR "Cochlear Implantation" AND "3D printing". Additional articles were identified through manual cross-referencing. Eligible studies were original research articles in English that investigated the use of 3D printing in CI. Exclusion criteria included reviews, conference papers, and studies unrelated to CI. Reporting completeness was evaluated using the STROBE checklist, while methodological risk of bias was independently assessed using validated, domain-specific tools (ROBINS-I, SYRCLE, and adapted QUADAS-2 domains). Due to profound study heterogeneity, a narrative synthesis was performed. RESULTS: Of the 76 publications identified, 22 studies met the inclusion criteria, with a marked increase after 2021. The included literature was divided into three functional areas: teaching models/surgical training (n = 13), preclinical research/device innovation (n = 3) and clinical/anatomical applications in humans (n = 6). The reported empirical accuracies ranged from 16 to 400 microns. The mean STROBE score was 14.8 ± 3.1, indicating moderate to high reporting quality. However, a rigorous methodological assessment revealed a high risk of bias among human and cadaveric series due to non-comparative designs and a lack of blinding on the part of the researchers, whilst studies using synthetic simulators demonstrated a predominantly low risk of bias. CONCLUSIONS: This review underscores the transformative potential of 3D printing in CI, particularly in enhancing surgical training and improving procedural outcomes. As the first systematic review focusing exclusively on cochlear-implant-specific applications, it addresses a critical gap in the literature and highlights opportunities for future research to standardize methodologies and explore long-term clinical impacts.