The persistent uncertainty that looms over the search for solutions to health problems offers important conceptual insights for the study of technological change. This paper explores the notion of hybridization, namely the embodiment of multiple competing operational principles within a single medical device, as strategy to deal with the practical shortcomings due to said uncertainty. The history of the development of the hybrid artificial disc affords the elaboration of an alternative view of hybridization and, at the same time, the articulation of a dualism between medical science as area of basic research (e.g. what disease is) and as practical knowledge (e.g. how disease can be tackled). © 2011 Elsevier Inc.