http://www.techdirt.com/articles/20100421/1451179133.shtml

http://readwrite.com/2009/07/02/study_says_patents_hinder_in...

http://archive.mises.org/10217/yet-another-study-finds-paten...

http://www.healio.com/orthotics-prosthetics/development-fina...

https://docs.google.com/viewer?a=v&q=cache:_DA2suNYWFoJ:...

Skip to the conclusion in the last paper.