- Design
- Randomised controlled trial, 1:1 allocation, linear mixed-effects analysis; level of evidence II
- Population
- 40 consecutive adult primary cochlear implantations by seven attending and five trainee surgeons at one high-volume centre
- Primary outcome
- Intraoperative cognitive load on the Surgery Task Load Index
- Effect
- Attendings 3.8 with model versus 5.5 without (p<0.01); residents 7.2 versus 4.8 (p=0.02); fellows 8.2 versus 8.0 (p=0.88)
Patient-specific 3D-printed models are usually justified on the assumption that seeing the anatomy in the hand helps everyone. This randomised controlled trial tested that during cochlear implantation, and the answer depends entirely on who is holding it.
Forty consecutive adult primary cochlear implantations by seven attending and five trainee surgeons at a large centre were randomised 1:1 to standard planning from imaging alone, or standard planning plus intraoperative inspection of a patient-specific 3D-printed temporal bone. The primary outcome was intraoperative cognitive load on the Surgery Task Load Index, analysed with linear mixed-effects models.
Attending surgeons had lower overall cognitive load with the model (3.8 versus 5.5, p<0.01), driven by reduced physical fatigue. Residents had higher overall load (7.2 versus 4.8, p=0.02), with both mental (p=0.01) and physical fatigue (p<0.001) increased. Fellows showed no overall difference (8.2 versus 8.0, p=0.88) but rated case complexity lower while reporting more physical fatigue. All groups rated the models accurate and useful, particularly for teaching and for anticipating anatomical boundaries.
The explanation the authors give is the interesting one: for an experienced surgeon the model is a reference that offloads working memory; for a trainee it is another object to interpret alongside the imaging and the operative field, and interpreting it costs effort. That argues for selective use rather than blanket adoption.
- Give the model to the surgeon who already knows the anatomy, not to the one learning it
- For trainees, the model may still be valuable outside theatre — the trial measured intraoperative load only
- Cognitive load is a proxy; this trial measured no surgical outcome
- Forty cases across twelve surgeons is small, and the subgroups are smaller still
- Ask what the model is for before ordering one: reference, rehearsal, or teaching are different uses
Why it matters
It undermines the assumption that a physical model helps every surgeon in the room equally.
Don't overread it
Cognitive load is a surrogate; no surgical or audiological outcome was measured.
The statistics, in plain English
These are subgroup results from a 40-case trial, so each experience level rests on a handful of operations — the attending and resident differences are statistically significant but come from very few cases. Cognitive load on Surg-TLX is a validated measure of how effortful the surgeon found the case, not of how well the case went. Nothing here says the models change complication rates or electrode placement either way.
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