Innovation in medicine is a complex process that unfolds unevenly in time and space. It is characterised by radical uncertainty
and emerges from innovation systems that can hardly be comprehended within geographical, technological or institutional boundaries.
These systems are instead highly distributed across countries, competences and organisations. This paper explores the nature,
rate and direction of the growth and transformation of medical knowledge in two specific areas of research, interventional
cardiology and glaucoma. We analyse two large datasets of bibliometric information extracted from ISI and adopt an empirical
network approach to try to uncover the fine structure of the relevant micro-innovation systems and the mechanisms through
which these evolve along trajectories of change shaped by the search for solutions to interdependent problems.