Bone anchors, after insertion into bone, are designed to remain in place and provide a platform for holding tissue. A method of ultrasonically embedding bone anchors into bone without pre-drilling an anchor receiving hole into the bone has been developed. Also described is an improved bone anchor embedding...http://www.google.es/patents/US5993458?utm_source=gb-gplus-sharePatente US5993458 - Method of ultrasonically embedding bone anchors
