Table 3.

Defining characteristics of phases of surgical and interventional innovations (adapted from http://www.ideal-collaboration.net/about-ideal/ideal-summary-tables/)

	1. Idea	2a. Development	2b. Exploration	3. Assessment	4. Long-term monitoring
Purpose	Proof of concept	Development	Learning	Assessment	Surveillance
Number and types of patients	Single digit; highly selected	Few; selected	Many; may expand indications	Many; expanded indications	All eligible
Number and types of surgeons	Very few	Few; innovators and some early adopters	Many; innovators, early adopters, early majority	Many; early majority	All eligible
Study types	Structured case reports	Prospective development studies	Research databases; feasibility RCT	Surgical randomised controlled studies	Prospective registries