# A Novel 3D-Printed Training Platform for Ossiculoplasty with Objective Performance Evaluation
## 1 Introduction  
Ossiculoplasty (OPL) is the surgical procedure aimed at restoring the continuity of the ossicular chain to improve hearing function in patients with conductive or mixed hearing loss. This surgery is commonly performed as part of tympanoplasty in cases of chronic otitis media (COM), trauma, or neoplasm [1, 2, 3], where the ossicular chain is eroded or fixed. Either autologous or heterologous materials can be used as prosthesis for OPL. While synthetic prostheses are pre-formed and do not usually require specific modeling before positioning into the middle ear, autologous materials (bone or cartilage) require proper graft remodeling to adapt to the residual ossicular chain and the tympanic membrane [4, 5, 6, 7, 8].  
The delicate anatomy of the middle ear, combined with the small dimensions of grafts and prostheses, involves precise handling and expertise to safely and effectively manipulate these minute structures. Given the technical complexity of OPL, proper training is essential both for prosthesis positioning and, in autologous techniques, prosthesis sculpting [9, 10]. Traditional training using cadaveric temporal bones provides the most realistic surgical experience of ear surgery. However, within cadaveric courses, time for OPL training is often constrained, as priority is typically given to comprehensive temporal bone dissection, rather than specific ossicular reconstruction skills. Additionally, the use of the cadaveric model poses challenges, such as limited availability, high costs and biological risks.  
In recent years, new technologies such as 3D printing are becoming more popular as an alternative for training purposes. Particularly, 3D-printed models present the advantage of being able to standardize the training experience for all participants, providing a consistent platform for skill development. In addition to combining anatomical realism with reproducibility and scalability at relatively low costs, they provide the possibility to replicate complex anatomies and, most importantly, pathologies. These models have been already experienced for anatomical education [11], patient communication [12, 13], preoperative planning [14, 15] and surgical training [16, 17, 18]. Also, animal models [19, 20, 21, 22], synthetic temporal bone models [23, 24, 25], and virtual reality simulators [26, 27] were developed for training purposes across various fields of otorhinolaryngology, enabling residents to build confidence and skills before performing surgical procedures in a clinical setting. Most studies in the literature focus on temporal bone surgical simulators suited for microscopic dissection under both healthy and pathological conditions. Some authors have designed passive prostheses for ossicular chain reconstruction, prototyping them using 3D printing [28, 29, 30, 31, 32]. Other groups have focused on 3D-printed models for educational purposes [33], though few have specifically targeted ossiculoplasty. Existing temporal bone models are primarily aimed at mastoid dissection or endoscopic surgery, with limited emphasis to ossiculoplasty techniques [34, 35, 36].  
The primary aim of this study was to develop a reliable training platform for ossiculoplasty with autologous remodeled incus, based on 3D printing. The feasibility of simulating incus remodeling and positioning of the reshaped ossicle into a pathological middle ear model was evaluated during dedicated training sessions involving medical students. Moreover, we tested the hypothesis that practicing the remodeling technique on a three-times magnified (3:1) incus model prior to using a real-sized incus could improve training performance.