A retractor and a surgical tool are positioned within a cannula, and a dissection cradle of the retractor is positioned at the distal end of the cannula. The retractor includes a dissection cradle that is resiliently supported along an axis skewed relative to the axis of the cannula. The dissection cradle,...http://www.google.de/patents/US7476198?utm_source=gb-gplus-sharePatent US7476198 - Cannula-based surgical instrument
