Three dimensional printing of a low-cost middle-ear training model for surgical management of otosclerosis.

BACKGROUND

Surgical management of otosclerosis is technically challenging with studies demonstrating that outcomes are commensurate with surgical experience. Moreover, experts apply less force on the ossicular chain during prosthesis placement than their novice counterparts. Given the predicted decreasing patient pool and the rising cost of human temporal bone specimens it has become more challenging for trainees to receive adequate intraoperative or laboratory-based experience in this procedure. As such, there is a need for a low-cost training model for the procedure. Here we describe such a model.

METHODS

A surgical model of the middle ear was designed using computer aided design (CAD) software. The model consists of four components, the superior three dimensional (3D)-printed component representing the external auditory canal, a 90° torsion spring representing the incus, a 3D-printed base with a stapedotomy underlying the torsion spring, and a 3D-printed phone holder to facilitate video-recording of trials and subsequent calculation of the force applied on the modeled incus. Force applied on the incus is calculated based on Hooke's Law from post-trial computer-vision analysis of recorded video following experimental determination of the spring constant of the modeled incus.

RESULTS

The described model was manufactured with a total cost of $56.50. The spring constant was experimentally determined to be 97.0 mN mm/deg, resulting in an ability to detect force applied to the modeled incus across a range of 1.2 to 5200 mN.

CONCLUSIONS

We have created a low-cost middle-ear training model with measurable objective performance outcomes. The range of detectable force exceeds expected values for the task.Level of Evidence: IV.