A fastening system for bone screws used in spinal fixation systems for reshaping the spine of a patient. The bone screw has threads on one end for anchoring in the spine. The other end has a spherical head with a multi sided recess formed therein for engagement with an appropriate driving tool. The system...http://www.google.com.au/patents/US20080287998?utm_source=gb-gplus-sharePatent US20080287998 - POLYAXIAL BONE SCREW
