A pedicle-screw assembly has a screw extending along an axis and having a threaded shaft and a round head, an inner cap part carried on the head and swivelable on the head, and an outer cap part forming with the inner cap part a seat adapted to hold an end of a distraction/stabilizing rod. The outer...http://www.google.ca/patents/US6402752?utm_source=gb-gplus-sharePatent US6402752 - Polyaxial pedicle-screw
