Graph-based knowledge representation is a hot topic for some years and still has a lot of research potential, particularly in the advancement in the application of graph-theory for creating benefits in the biomedical domain. Graphs are most powerful tools to map structures within a given data set and to recognize relationships between specific data objects. Many advantages of graph-based data structures can be found in the applicability of methods from network analysis, topology and data mining (e.g. small-world phenomenon, cluster analysis). In this paper we present the state-of-the-art in graph-based approaches for multi-touch interaction on mobile devices and we highlight some open problems to stimulate further research and future developments. This is particularly important in the medical domain, as a conceptual graph analysis may provide novel insights on hidden patterns in data, hence support interactive knowledge discovery.