3-D-Printed Models for Temporal Bone Training: A Validity Study
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Published on: September 7, 2019
Andreas Frithioff, Martin Frendø, Kenneth Weiss1
1Department of Civil and Mechanical Engineering, Technical University of Denmark, Kgs. Lyngby.
Objective:
3-D printing offers convenient and low-cost mastoidectomy training; nonetheless, training benefits using 3-D-printed temporal bones remain largely unexplored. In this study, we have collected validity evidence for a low-cost, 3-D-printed temporal bone for mastoidectomy training and established a credible pass/fail score for performance on the model.
Study Design:
A prospective educational study gathering validity evidence using Messick's validity framework.
Setting:
Seven Danish otorhinolaryngology training institutions.
Participants:
Eighteen otorhinolaryngology residents (novices) and 11 experienced otosurgeons (experts).
Intervention:
Residents and experienced otosurgeons each performed two to three anatomical mastoidectomies on a low-cost, 3-D-printed temporal bone model produced in-house. After drilling, mastoidectomy performances were rated by three blinded experts using a 25-item modified Welling scale (WS).
Main Outcome Measure:
Validity evidence using Messick's framework including reliability assessment applying both classical test theory and Generalizability theory.
Results:
Novices achieved a mean score of 13.9 points; experienced otosurgeons achieved 23.2 points. Using the contrasting groups method, we established a 21/25-point pass/fail level. The Generalizability coefficient was 0.91, and 75% of the score variance was attributable to participant performance, indicating a high level of assessment reliability. Subsequent D studies revealed that two raters rating one performance or one rater rating two performances were sufficiently reliable for high-stakes assessment.
Conclusion:
Validity evidence supports using a low-cost, 3-D-printed model for mastoidectomy training. The model can be printed in-house using consumer-grade 3-D printers and serves as an additional training tool in the temporal bone curriculum. For competency-based training, we established a cut-off score of 21 of 25 WS points using the contrasting groups method.
